Abstract Volume

Congress Mexico-City, 20 - 24 June 2006 Editors

Jochen Bundschuh

María Aurora Armienta

(Germany/Argentina/Costa Rica)

(Mexico)

Prosun Bhattacharya

Jörg Matschullat

(Sweden)

(Germany)

Peter Birkle

Ramiro Rodríguez

(Mexico)

(Mexico)

International Society of Groundwater for Sustainable Development

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Welcome to the International Congress “Natural Arsenic in Groundwaters of Latin America” Dear Participant, On behalf of the whole organisational team, we welcome you heartily to this congress which tands in the tradition of the San Diego conferences and the conference held in Santiago de Chile – all dedicated to a better understanding of arsenic-related problems and challenges. At the same time, we welcome you to MexicoCity, and we hope that you will enjoy both the enlightening atmosphere of the congress and the relentless dynamics of this fascinating capital.

The Congress In many parts of the world groundwater resources – a backbone for human development – naturally contain elevated levels of arsenic (As). These As-concentrations often exceed the World Health Organisation (WHO) guideline value of 10 µg L-1. Severe health effects have been associated with elevated As-concentrations in groundwater used for drinking purposes. Many people in low income countries, particularly in South East Asia and Latin America, are most severely affected. There is increasing evidence of various susceptibility factors, e.g., malnutrition. Arsenic in groundwater poses one of the most important environmental health risks of the present century. Several million people depending on arsenic-containing groundwater for drinking purposes are at increased risk of arsenic-related health effects. So far, most research focussed on As-related cancer effects. More information about other health effects is needed and on susceptibility. During the last decade, As-rich groundwaters in South and South-East Asia have received much attention. However, the situation seems to be equally important in Latin America, where the number of studies is still relatively low, and the extent and severity of As-exposure in the population only marginally evaluated. Arsenic occurrence in groundwater in Argentina, Bolivia, Brazil, Chile, Mexico, Nicaragua, Peru, and other Latin American countries need to be in-

vestigated. Recently, in Nicaragua – a country where the groundwater arsenic problem was not assumed to exist – elevated groundwater Asconcentrations as well as As-related health effects were detected. However, the actual number of people at risk for chronic As-toxicity is not yet known. This current status of insufficient knowledge on As-occurrence and related health risks deserves attention. The sustainable land-use and agricultural practices in the Latin American countries are regionally threatened by the use of As-contaminated irrigation water. Elevated levels of natural As in groundwater from geogenic sources is therefore an issue of primary environmental concern, which limits the use of these resources for drinking or other purposes, and hinders socioeconomic growth. Hence there is a need to improve our understanding of the genesis of As-rich groundwaters, constraints on the mobility of As in groundwater and other environmental compartments, As-uptake from soil and water by plants, As-propagation through the food chain, health impacts on human beings, life stock, and other animals, assessment of environmental health risks and impacts, and As-removal technologies, to improve the socio-economic status of the affected regions.

Interdisciplinary Platform Objective The goal of the international congress "As 2006" is to bring together geo-scientists, specialists from public health, from chemical and engineering sciences involved in arsenic-related issues. The regional focus of attention is dedicated to Latin America. The conference serves as a platform for discussion and exchange of scientific knowledge and ideas to identify future research targets needed to improve the understanding of (1) the occurrence and mobility of arsenic in groundwater, (2) the health impacts and risks when using this water for drinking or irrigation purposes, and (3) to develop, evaluate, select and apply the most suitable remediation methods, which means adapted to the hydrogeological and hydrogeochemical properties of the aquifer, the specific hydrochemical composition of the groundwater, the social conditions and the economic situation

2 of the affected population and the respective water service providers.

Content

The international congress is designed to (1) create interest within the Latin American countries, affected by the presence of arseniferous aquifers, (2) to address the international scientific community in general, (3) to update the current status of knowledge on the dynamics of natural arsenic from the bedrock and soils via aquifers and groundwater to food chain, (4) to continue the important worldwide forum on improved and efficient techniques for Asremoval in regions with elevated arsenic levels in groundwater, and (5) to increase awareness among administrators, policy makers and company executives, and to improve the international cooperation on that topic. However, we strongly encourage all other researchers working on arsenic elsewhere in the world to contribute, which would strengthen this global issue.

Welcome address

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Author list

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Abstracts

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Topic list

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On behalf of the organizing comittee Jochen Bundschuh, María Aurora Armienta, Prosun Bhattacharya , Jörg Matschullat, Peter Birkle and Ramiro Rodríguez

International Society of Groundwater for Sustainable Development

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Alphabetical list of authors with page location in this abstract volume Acarapi C J ................................................... 21 Acosta-Saavedra L ....................................... 79 Aguilera-Alvarado AF.................................. 15 Aguirre RJ ...................................................... 7 Aguirre V...................................................... 22 Agusto M...................................................... 29 Ahmed KM......................................... 7, 11, 39 Alam MGM .................................................. 80 Alfaro-De la Torre MC................................. 53 Alonso MS.................................................... 50 Altamirano Espinoza M.................................. 8 Andrade G .................................................... 83 Aranyosiová, M ............................................ 19 Arenas H MJ................................................. 21 Armienta MA ................................... 10, 36, 52 Avena M................................................. 43, 64 Ávila Carrera ME ......................................... 28 Balczewski A.................................................. 7 Bandara A..................................................... 84 Banerjee K...................................................... 7 Barberá R...................................................... 42 Barahona F ................................................... 44 Barnes RM.................................................... 88 Barrera A ...................................................... 33 Bastías JM .............................................. 36, 83 Bastida M ..................................................... 79 Beltrán-Hernández RI................................... 45 Berdón V ...................................................... 62 Bhattacharya P...................... 11, 12, 39, 59, 80 Bianco de Salas G......................................... 28 Billib M ........................................................ 37 Birkle P .................................................. 12, 13 Blesa MA...................................................... 24 Bonorino G................................................... 43 Boochs PW................................................... 37 Bovi Mitre G .......................................... 28, 69 Briones-Gallardo R................................. 46, 82 Bruha T......................................................... 27 Bundschuh J ....................11, 12, 13, 44, 54, 80 Caetano LM.................................................. 20 Caldeira C L ................................................. 20 Calderón-Aranda ES..................................... 79 Calderón-Hernandez J ............................ 46, 62

Cama J...........................................................15 Cano-Aguilera I ............................................15 Canyelles C ...................................................16 Carrizales Yañez L..................................46, 62 Caselli AT .....................................................29 Castro de Esparza ML.............................16, 18 Castro-Larragoitia J.......................................53 Caussy D .......................................................19 Cebrián ME.................................26, 45, 52, 79 Cerbon M ......................................................62 Čerňanský S ..................................................19 Chandrajith R ................................................84 Charlet L .................................................64, 65 Chavez C.......................................................22 Choi H...........................................................60 Ciminelli VST.........................................20, 77 Conde P.........................................................79 Cornejo P L .............................................21, 88 Corona M ......................................................70 Cortina JL......................................................16 Cruz L ...........................................................52 Cumbal LH.............................................. 22 (2) d´Hiriart J ......................................................24 Dahmke A ...............................................40, 41 Daus B...........................................................40 De Haro-Bailón A .........................................31 de Oliveira Couto e Silva N ..............23, 47, 53 de Oliveira Vilhena MJ .................................48 Del Razo LM. 28, 33, 34, 35, 38, 45, 55, 69, 81 Del Río-Celestino M .....................................31 del Valle Hidalgo M................................24, 32 Deschamps E...............................23, 43, 48, 51 Deshpande L .................................................23 Díaz Sch O ....................................................25 Díaz-Villaseñor A ...................................26, 52 Doušová B...............................................26, 27 Driehaus W .....................................................7 Ebert M ...................................................40, 41 Espinosa M................................................8, 28 Esteller MV...................................................49 Estévez J .......................................................81 Etchichury MC..............................................50 Falcón CM ....................................................50 Farías SS .....................................28, 29, 54, 69 Farré R ..........................................................42 Fazio AM ......................................................29

4 Fernández DS ............................................... 32 Fernández RG............................................... 30 Fernández-Cirelli A...................................... 53 Fierro V ........................................................ 88 Figueroa L .................................................... 88 Flores-Valverde E......................................... 10 Font R........................................................... 31 Freitas SHD .................................................. 77 Fuitová L ...................................................... 26 Gabrio T ....................................................... 48 Gaiero D ....................................................... 65 Galindo MC .................................................. 32 Gallaga-Solorzano JC................................... 48 García JW..................................................... 50 Garcia ME .............................................. 13, 54 García MG.............................................. 24, 32 García-Chavéz E........................................... 33 García-Montalvo EA ........................ 28, 34, 81 García-Rico L ......................................... 40, 69 Garcia-Vargas G........................................... 81 Germolec DR................................................ 81 Giarolli F ................................................ 40, 41 Giménez E .................................................... 49 Giordano M .................................................. 35 Giuliano G .................................................... 85 Gonsebatt ME......................................... 35, 62 Grygar T ....................................................... 26 Guadarrama JC ............................................. 33 Gutiérrez Ospina G....................................... 35 Gutiérrez-Ojeda C ........................................ 35 Gutiérrez-Ruiz M ................................... 44, 65 Haque N........................................................ 15 Hasan MA .............................................. 11, 39 Hasan MT..................................................... 59 Helal Uddin M.............................................. 59 Hernández JC ............................................... 51 Hernández H................................................. 36 Hernández M ................................................ 62 Hernández-Ramosa I .................................... 48 Hernández-Zavala A............................... 34, 81 Herrera C ...................................................... 36 Hiriart M................................................. 26, 52 Holländer HM .............................................. 37 Hossain MA.................................................... 9 Hossain MM................................................. 59 Hugo M ........................................................ 57

Izquierdo-Vega JA ........................................38 Jacks G.................................................... 11 (2) Jakariya M...............................................11, 39 Jara-Marini ME .............................................40 Jiménez I .......................................................33 Jonsson L ......................................................11 Kanel S..........................................................61 Kanel SR .................................................60, 61 Kannel PR .....................................................61 Kinniburgh DG .............................................76 Köber R...................................................40, 41 Koloušek D .............................................26, 27 Königskötter H..............................................66 Korban Ali M..................................................9 Krüger T........................................................37 Kumar M.......................................................59 Laparra JM ....................................................42 Lara-Castro RH.............................................53 Leonhardt Palmiere HE.................................43 Lienqueo A H................................................21 Limbozzi F ....................................................43 Limón JH ......................................................35 Litter MI........................................................24 Lòpez DL ......................................................44 Lopez-Bayghen E..........................................70 López-Carrillo L ...........................................79 López-Sánchez JF ...................................67, 68 López-Zepeda JL ..........................................44 Lucho-Constantino C ..............................45, 55 Luna AL ........................................................79 Lundell L.......................................................11 Machado-Estrada BP.....................................46 Machovič V.............................................26, 27 Maciasa AE...................................................48 Madé B..........................................................85 Mahlknecht J.................................................68 Maldonado Reyes A......................................47 Mansilla H...............................................21, 88 Marcus M ......................................................44 Marijuan L ....................................................51 Mariño E .......................................................73 Martaus A................................................26, 27 Martin RA ...............................................12, 80 Martín Romero F.....................................44, 65 Mata E...........................................................63 Matin Ahmed K ............................................38

5 Matschullat J .......................................... 23, 48 Mattusch J .................................................... 40 Mejia JA ....................................................... 63 Merchant H................................................... 33 Merino MH................................................... 50 Micete S........................................................ 10 Monroy-Fernández MG................................ 82 Monroy-Torres R.......................................... 48 Montero A .................................................... 81 Montero Ocampo C ...................................... 47 Monterrosa J................................................. 44 Montoro M R.............................. 25, 31, 42, 69 Morales L ..................................................... 16 Morales VR .................................................. 62 Morell I......................................................... 49 Moreno C...................................................... 32 Morrison GM................................................ 15 Moscuzza C .................................................. 53 Mridha MAU................................................ 59 Mugica V...................................................... 52 Muñoz O................................................. 36, 83 Nahar S......................................................... 39 Navarrete R .................................................. 35 Navarro C ME .............................................. 62 Nazim Uddin M............................................ 59 Nicolli HB .............................................. 50, 76 Novák M....................................................... 80 Núñez S N .................................................... 25 Oberdá SM ................................................... 51 Orihuela DL.................................................. 51 Ortega MA.................................................... 70 Ortiz E .......................................................... 52 Ostrosky-Wegman P......................... 26, 52, 70 Oswaldo R .................................................... 57 Pande S......................................................... 23 Pant, KK ................................................. 71, 72 Pastene O R .................................................. 25 Pauli C .......................................................... 64 Pažout V ....................................................... 27 Pelallo-Martínez NA .................................... 53 Pérez-Carrera A............................................ 53 Pérez-Mohedano S ....................................... 51 Petrusevski B................................................ 30 Pflüger JC..................................................... 54 Pilar Asta M ................................................. 15 Pimentel A.................................................... 55

Poggi-Varaldo HM..................................45, 55 Ponce RI........................................................28 Pradhan B......................................................56 Preziosi E ......................................................85 Prieto-García F..............................................45 Puigdomènech AP.........................................16 Punti A ..........................................................16 Pupo I............................................................81 Queriol H ......................................................35 Quintanilla J ..................................................57 Rahman IMM................................................59 Ramanathan AL ............................................59 Ramírez E......................................................52 Ramirez P......................................................62 Ransom L ......................................................44 Raßbach K.....................................................48 Recabarren G E .............................................25 Rema P ............................................................9 Reséndiz I......................................................52 Reyes Agüero JA ..........................................46 Rinderknecht-Seijas N ..................................55 Rocha CA......................................................51 Rocha-Amador DO .......................................62 Rodríguez R ............................................36, 63 Rodríguez V ..................................................35 Román-Ross G ........................................64, 65 Ruales J .........................................................69 Rubio R ...................................................67, 68 Rüde TR........................................................66 Ruiz-Chancho MJ ...................................67, 68 Ruiz-Gonzalez Y...........................................68 Sacchi G ........................................................64 Sancha AM........................................16, 68, 69 Sánchez-Peña LC ..............................33, 38, 69 Sánchez-Soto M ............................................26 Sandoval M ...................................................70 Santiago-Garcia EJ........................................48 Sarvinder Singh T ...................................71, 72 Sastre-Conde I...............................................45 Schulz CJ ......................................................73 Segura B........................................................33 Selim HM......................................................74 Senapati K.....................................................75 Sen Gupta AK ...............................................22 Servant RE ....................................................28 Ševc J ............................................................19

6 Shi F ............................................................. 11 Silva A.......................................................... 77 Silva J ........................................................... 43 Silva JCJ....................................................... 77 Smedley PL .................................................. 76 Sordo M........................................................ 70 Soria de Paredes GN..................................... 78 Soriano T ...................................................... 44 Soto-Peña GA............................................... 79 Soto-Peredo CA............................................ 38 Sracek O ..................................... 11, 12, 32, 80 Stummeyer J ................................................. 37 Sulovsky P.................................................... 80 Tineo A......................................................... 50 Tipan R......................................................... 22 Tofalo OR..................................................... 50 Tokunaga S................................................... 80 Torres E ........................................................ 16 Tripathi P...................................................... 59 Urík M .......................................................... 19 Valcárcel L ................................................... 81 Valenzuela OL.................................. 28, 34, 81 Vasconcelos O.................................. 23, 43, 77 Vázquez-Rodríguez G .................................. 82 Vega L .......................................................... 79 Vélez P D ................................... 25, 31, 42, 69 Vieira Alves T .............................................. 51 Vilches S ...................................................... 83 Villaamil E ................................................... 69 Villalobos M........................................... 44, 65 Vithanage M................................................. 84 Vivona R ...................................................... 85 Von Brömssen M.......................................... 11 Wajrak M...................................................... 85 Wallschläger D ....................................... 86, 87 Weerasooriya R ............................................ 84 Weidner U .................................................... 48 Welter E.................................................. 40, 41 Yadav PK ..................................................... 87 Yañez J ................................................... 21, 88 Zhang H........................................................ 74 Zuñiga O....................................................... 62

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1. Me arsenic adsorption technology – A review of long-term performance in full-scale applications from Stadtoldendorf to Phoenix Roman J. Aguirre1, Kashi Banerjee1, Aaron Balczewski1, Wolfgang Driehaus2 1

U.S. Filter, 1728 Paonia Street, Colorado Springs, CO 80915, USA 2 GEH, Germany

In anticipation of the upcoming lower limit of 10 µg L-1 for Arsenic issued by the USEPA many utilities and private water companies are investigating their treatment options. A recent search of arsenic removal solutions on the internet identified 307,000 websites pages offering ‘arsenic treatment’. It can be stated that while most websites promised the ‘latest and greatest’ solution to arsenic removal, full scale experience and commercial availability of many products is non-existent or extremely lacking. As the plethora of adsorption media and revolutionary treatment approaches have gained most of the attention in the market place, successful, full-scale long-term operating experiences have not been published for many new technologies. This paper will in detail focus on longterm, full-scale arsenic adsorption installations in Germany, United Kingdom, India and the United States. Overall operating performance, influent and finished water quality, waste disposal options employed, site conditions and regional challenges will be examined and compared. Included in the analysis are comments from the operating staff providing their view point of the overall system.

2. Management of shallow groundwater arsenic: Bangladesh experiences K M Ahmed Department of Geology, University of Dhaka, Dhaka 1000, Bangladesh [email protected]

Presence of arsenic at concentrations above Bangladesh drinking water standards has emerged as serious public health hazard where at least 30 millions people are exposed. This is because of about 30% of country’s domestic hand tube wells pumping water with arsenic concentrations above 0.05 mg L-1. Despite enormous variability in spatial and vertical distribution of arsenic in groundwater, there are certain geological provinces which are less affected compared to some severely affected ones. Also there are certain aquifers which are almost fully safe compared to others which are almost entirely unsafe. There are forecasts of significant increase in cancer and other arsenic related diseases in the coming years. Access to safe water coverage has come down to 70% from 97% due to arsenic occurrences in shallow groundwater which is the main source of potable water in the country. Since first detection in 1993, lots of activities have been carried out by GOB, UN agencies, development partners and NGOs. A large number of research initiatives have also been taken by local and overseas universities and institutions. A large number of papers have been published covering various aspects of the arsenic in groundwater which have certainly the enhanced the knowledge base about occurrences, distribution and remediation of the menace. However, still there are debates about the origin and release mechanism and possible consequences of drinking high arsenic water. And the scale of mitigation does not match with the magnitude of the problem. This paper aims to review the existing knowledge base on various aspects of arsenic occurrences in Bangladesh groundwater along side critically reviewing the efforts by

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government and other agencies. As the arsenic problem occurs in many other countries, particularly in South and East Asia, Bangladesh experiences would be useful in designing mitigation strategies in other countries. For example, Bangladesh has adopted a National Arsenic Policy and Action Plan for mitigation of the issue. Such a policy can be adapted to other countries. Another commendable task carried out by the World Bank supported Bangladesh Arsenic Mitigation Water Supply Project is testing of more than 5 million wells all over the affected regions of the country. Despite questions about the validity of such tests using field kits, there good examples of using these data is designing village based mitigation strategy. Also various other research initiatives and mitigation options can be useful to countries who are trying to understand and manage the problem.

una extensión de 52 km2. El área comprende 15 comunidades con un total de 3225 habitantes (INEC,1995) y una tasa de crecimiento del 2.6% anual. Características generales. Las rocas expuestas presentan una intensa alteración hidrotermal. Fallas y fracturas NE y NW próximas a la superficie son verdaderos conductos y fuentes para que el contaminante entre al medio acuífero. Métodos de investigación. Se realizaron análisis físico-químicos del agua subterránea y arsénico total en rocas, suelos y aguas. Se hizo reconocimiento geológico, para conocer las condiciones geomorfológicos, estructurales y la zonificación de la alteración hidrotermal. Se usó geofísica (magnetometría) para identificar posibles estructuras asociadas a las concentraciones de As en las aguas subterráneas. Principales hallazgos.

3. Distribución de la contaminación natural por arsénico en las aguas subterráneas de la subcuenca Suroeste de El Valle de Sebaco-Matagalpa, Nicaragua M. Altamirano Espinoza Centro para la Investigación de Recursos Acuáticos –Universidad Nacional Autónoma de Nicaragua (CIRA/UNAN), Managua 4598 Nicaragua; [email protected]

Un problema ambiental serio en Nicaragua es la concentración natural de arsénico en las aguas subterránea próximos a áreas mineralizadas por procesos hidrotermales producto de la dinámica de Nicaragua Occidental, donde el proceso de subducción de la placa de Cocos por debajo de la placa del Caribe es el motor principal de la formación de la Depresión de Nicaragua, la principal estructura geológica regional, en cuyo margen oriental externo ocurre el Valle de Sébaco y el área de estudio en la parte SW. Entre estas áreas podemos ubicar la parte suroeste del Valle de Sébaco, con

1- Las principales concentraciones de arsénico en roca, suelo y agua se asocian a procesos singenéticos (primarios) y epigenéticos (secundarios), evidenciados a lo largo de fallas y fracturas NE y E-W principalmente. 2- Desde el punto de vista físico químico, las muestras analizadas en los 25 pozos estudiados son consideradas aguas de buena calidad. (CAPRE,1994). Un total de 16 pozos (64%) se clasifican como aguas bicarbonatadas cálcicas. 3- Las mayores concentraciones de arsénico se encuentran asociadas a sistemas de fallas secundarias E-W las cuales favorecen la formación de micro estructuras que influencian las características propias del acuífero especialmente el espesor y la profundidad del basamento. 4- De los 57 muestras de agua captadas, el 36% presentan concentraciones de arsénico total (10 a 122 µg L-1) que sobrepasan el valor guía establecidos para agua de consumo humano. En el 93% de las muestras de

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aguas, el arsénico se encuentra como arsenatos con un estado de oxidación (V) y el 7% se encuentran como arsenito (III), el cual es la especie más toxica y móvil de arsénico. 5- En la comunidad de El Zapote se encontraron las mayores concentraciones de arsénico. En rocas y suelos, las concentraciones de arsénico total detectadas fueron de 14.98 µg g-1 y 57.19 µg g-1 respectivamente, en el agua fue de 122.15 µg L-1. Dos muestras comparativas de suelo, ubicadas fuera del área de estudio, en la entrada a Mina La India y en los alrededores de la comunidad Agua Fría, presentaron concentraciones mayores y similares a la de El Zapote con concentraciones de 95.2 y 59.5 µg g-1 respectivamente 6- La presencia de arsénico en los suelos evidencia el origen desde fuentes naturales. El contacto de la población con el xenobiótico ocurre de forma permanente no solo en la ingesta de agua si no en su actividad cotidiana incrementando el riesgo toxicológico. 4. Unacceptability of the Two Bucket Arsenic Removal Filter in Dhobawra, Bangladesh M. Anwar Hossain1, Pulok Rema2 and M. Korban Ali2 1

Department of Farm Structure, Faculty of Agricultural Engineering & Technology, Bangladesh Agricultural University, Mymensingh2202, Bangladesh 2 Faculty of Agricultural Engineering & Technology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh; [email protected]

This study aimed to determine the reasons why people unaccepting the arsenic removal technology (two bucket filter) and the causes why people return back for using tubewells water instead of arsenic removal technology’s water. Data were collected by

using an interview schedule from 85 users from Ghosh Gaon union under Dhobawra upazilla of Mymensingh district, Bangladesh between the times of Jan/2004 to Feb/2005. The most of the users are middle aged illiterate low income farmers. The large percent of respondent (50.3%) has no knowledge about arsenic diseases. There were no social/family problem faced by the users during using of two bucket filter and has no arsenic patients. Only 12.9% of the tubewells are bearing arsenic concentration over danger level. The unacceptability index (U.I) of 10-items of arsenic removal unit (two bucket filter method) ranged from 110.6 to 295.3 against a possible range 0 to 300. The score of 6 U.I exceeded 250. Among the causes ‘Very low flow of water through two bucket filter’ was found high unacceptability index (U.I) of 295.3, while, ‘Repair-Maintenance and Replacement of Sand, Coal and brick particles is not available’ was second ranked order (UI =287.2), ‘More time required to fill up a Jar of water’ the third (U.I = 286) and ‘Easily Block out of filters and Screens’ the fourth ranked order (U.I = 284.9). However, all the remaining indices of unacceptability were found above 150 except one which was 110.6. From the overall unacceptability of the users revealed that 18.8 percent of users shown medium high unacceptability, 63.5 percent users high and 17.6 percent very high unacceptability. There is 100 percent users’ currently consuming tubewells water from their own tubewells. The acceptability index (A.I) revealed that the No. 1 rank order obtained by the statements of ‘water is clean and pure’ with an acceptability index of 298.4. The No. 2 and No. 3 rank order obtained by the statements of ‘Water is safe for use and ‘Easily available in all time’ with the acceptability index of 296.5 and 268.1 respectively. From the overall acceptability it is found that 32.9 percent of users have highly accepted the tubewells water instead of two balti method, 64.7 percent users’ medium highly and only 2.4 percent users’ medium accepted.

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These research findings has recommended to the decision makers and NGO for evaluating the unacceptability and sustainability before supplying or install the arsenic removal technology in a particular area. 5. Feasability of arsenic removal from polluted water using indigenous geological materials M.A. Armienta1, S. Micete2, E. FloresValverde2 1

Instituto de Geofísica, Universidad Nacional Autónoma de México. Circuito Exterior C.U., México 04510 D.F. [email protected] 2 Posgrado en Ciencias e Ingeniería Ambientales, Universidad Autónoma Metropolitana, México D.F.

Arsenic concentrations above the Mexican drinking water standard have been measured in deep wells used for potable supply at Zimapán, México. Arsenic contamination in these wells is produced by natural processes. Lack of productive non-contaminated wells and surface water bodies in the area, gives few alternatives to As pollution. Currently, good quality water from a well located about 25 km from Zimapán, is pumped 400 m height and mixed with water from a well (Z5) containing 0.5 mg L-1 As, to supply potable water. Variations on the proportion of water from each source results on variable As concentrations, being 0.15 mg L-1 in February 2005. Iron oxides and zeolites are the geological materials most used to remove arsenic at other polluted sites. However, the geology of Zimapán with abundant limestone outcrops, prompted to study their As removal potential. Besides, previous studies have shown the capacity of limestones from this area to remove arsenic. The feasibility of the Soyatal limestone to produce clean water from the deep well Z5 was determined with batch and column tests. Batch tests were performed varying

time, rock: water ratio, and rock sizes. Results showed a 90% decrease on the arsenic concentration treating 1 liter of water with 10 g rock of a size 6.0 clearly represents a favorable media (iron hydroxides) to adsorb arsenic by Fe-LECA. The experimental data fitted the pseudo-first-order equation. For a 1 mg L-1 of arsenic concentration, the rate constant k1 of pseudo-first-order was 0.098 min-1 that represents a rapid adsorption to reach equilibrium early. Surface complexation and ion exchange proposed to be the major arsenic removal mechanisms. Column

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experiments were conducted under different bed depths, flow rates, coating duration and initial iron salts concentration for coating were tested to optimize the arsenic removal efficiency by Fe-LECA column. Volumetric design as well as higher hydraulic detention time was proposed to optimize the efficiency of the column to remove arsenic. In addition, concentrated iron salts and longer coating duration was also found very influencing parameter for arsenic removal. The maximum arsenic accumulation was found 3.31 mg of As g-1 of Fe-LECA when the column was operated at a flow rate of 10 ml min-1 and the LECA was coated with 0.1M FeCl3 suspension for 24 h coating duration. 12. Evaluación de alternativas a la mejora de la calidad del agua de pozos en las comunidades rurales de San Juan de Limay, Nicaragua Caterina Canyelles1, Ester Torres1, Laura Morales1, Clàudia Puigdomènech1, Anna Punti1, Jose Luis Cortina1, Ana Maria Sancha2

cación de algunas medidas de fácil uso y bajo costo para mejorar la calidad del agua en esta zona rural de bajos ingresos. El presente trabajo presentará los estudios realizados para determinar el nivel de contaminación de una serie de pozos de las comunidades afectadas de San Juan de Limay y una primera aproximación a la identificación del origen del As en las aguas. Finalmente el trabajo proporciona una serie de recomendaciones para la remoción de las aguas de los contaminantes identificados, especialmente del arsénico. 13. Presencia de arsénico en el agua de bebida en América Latina y su efecto en la salud pública María Luisa Castro de Esparza Asesora Regional en Aseguramiento de la Calidad y Servicios Analíticos. CEPIS / SDE / OPS; Calle Los Pinos 259, Urbanización Camacho, La Molina, Lima, Perú; [email protected]

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Department of Chemical Engineering , Universitat Politècnica de Catalunya, ETSEIB, Av. Diagonal, 647, E-08028 Barcelona (España); [email protected] 2 División de Recursos Hídricos y Medio Ambiente, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile

En los últimos años el centro de Salud de San Juan de Limay, que atiende a decenas de miles de persona anualmente, ha establecido que el agua de algunos pozos de las comunidades del municipio está contaminadas. La población tiene enfermedades con síntomas característicos de elevada presencia de microorganismos patógenos, y muy posiblemente de arsénico, además de otros contaminantes. Con objeto de tomar medidas urgentes, el centro de salud del MINSA (Ministerio de Salud) promovió el estudio de evaluación de la calidad del agua de diferentes pozos ubicados en las comunidades campesinas afectadas, estudiar la apli-

En varios países de América Latina como: Argentina, Chile, México, El Salvador; Nicaragua, Perú y Bolivia por lo menos cuatro millones de personas beben en forma permanente agua con niveles de arsénico que ponen en riesgo su salud en tal magnitud que en algunos de los países se ha convertido en un problema de salud pública. Este trabajo constituye una recopilación bibliográfica de la problemática del arsénico en el agua de bebida y sus efectos en la salud de las personas expuestas. Situación que se necesita atender a fin de minimizar sus efectos y disminuir el arsenicismo en las zonas afectadas. Se describe la presencia del arsénico en el ambiente y en las fuentes de agua para consumo humano se debe a factores naturales de origen geológico (México, Argentina, Chile, Perú, Nicaragua) a actividades antropogénicas que involucran la explotación minera y refinación de metales

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por fundición (Chile, Bolivia y Perú), procesos electrolíticos de producción de metales de alta calidad como cadmio y cinc (Brasil), y en menor proporción en la agricultura en el empleo de plaguicidas arsenicales orgánicos (México). Como se conoce en la mayoría de los casos la presencia de arsénico en aguas superficiales y subterráneas de América Latina es natural y está asociada al volcanismo terciario y cuaternario desarrollado en la Cordillera de Los Andes. Proviene de la disolución de minerales, la erosión y desintegración de rocas y por deposición atmosférica (aerosoles). En el agua puede encontrarse en su forma trivalente y pentavalente. En el agua de bebida, por lo general el arsénico se encuentra en la forma de arsenato y puede ser absorbido con facilidad en el tracto gastrointestinal en una proporción entre el 40 y 100%. El arsénico inorgánico ingerido es absorbido por los tejidos y luego se elimina progresivamente por metilación a través de los riñones, en la orina. Cuando la ingestión es mayor que la excreción, tiende a acumularse en el cabello y en las uñas. Las principales rutas de exposición de las personas al arsénico son la ingesta e inhalación. Es acumulable en el organismo por exposición crónica, y a ciertas concentraciones ocasiona alteraciones de la piel con efectos secundarios en los sistemas nervioso, respiratorio, gastrointestinal, y hematopoyético y acumulación en los huesos, músculos y piel, y en menor grado en hígado y riñones. Estudios toxicológicos y epidemiológicos confirman la información anterior e indican que la ingestión crónica de arsénico en el agua de bebida genera lesiones en la piel, la hiperpigmentación e hiperqueratosis palmo plantar; desórdenes del sistema nervioso; diabetes mellitus; anemia; alteraciones del hígado; enfermedades vasculares, cáncer de piel, pulmón y vejiga.

El consumo de agua con arsénico a largo plazo conlleva a efectos crónicos y a la generación de arsenicismo. El tratamiento involucra proporcionar al paciente agua de bebida libre de arsénico. El siguiente paso es monitorearlo y asegurarse de que no esté expuesto a este elemento. Otros tratamientos propuestos son la quelación y la mejora de la nutrición. Su toxicidad depende del estado de oxidación, estructura química y solubilidad en el medio biológico. La escala de toxicidad del arsénico decrece en el siguiente orden: arsina > As+3 inorgánico > As+3 orgánico > As+5 inorgánico > As+5 orgánico > compuestos arsenicales y arsénico elemental. La toxicidad del As+3 es 10 veces mayor que la del As+5 y la dosis letal para adultos es de 1-4 mg As kg-1. Para las formas más comunes como AsH3, As2O3, As2O5 esta dosis varía en un rango entre 1,5 mg kg-1 y 500 mg kg-1 de masa corporal. Se ha demostrado que los niños son más sensibles que los adultos a la toxicidad por el arsénico y son los más afectados por el arsenicismo, por problemas de desnutrición y precario saneamiento en las zonas rurales dispersas (pobres). La población más afectada es la población dispersa ubicada en el área rural que consume agua sin ningún tratamiento y desconoce el riesgo al que está expuesta. Se requiere que las autoridades de salud, ambiente y saneamiento planifiquen los servicios de aprovisionamiento de agua y promuevan e intervengan en la ejecución de programas de prevención y control de riesgos del consumo del agua de bebida con niveles de arsénico superiores a los recomendados. Los programas deben involucrar la participación de las autoridades, comunidad y sistemas locales de salud.

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14. Remoción del arsénico en el agua para bebida y biorremediación de suelos

tiva (arcilla verde natural, arcillas activadas, zeolita natural y activada y carbón de hueso.

María Luisa Castro de Esparza

Chile es el país con más experiencia en el tratamiento de agua para distribución urbana, cuentan con cuatro plantas de remoción de arsénico del agua de abastecimiento (0,40 µg L-1) que tratan en conjunto 2000 L s-1 y producen agua potable con 0,040 mg As L-1. Han evaluado la mejora del sistema agregando osmosis inversa (postratamiento) y desalinización. En Perú hay una planta de remoción de arsénico que trata el agua con cloruro férrico y ácido sulfúrico.

Asesora Regional en Aseguramiento de la Calidad y Servicios Analíticos. CEPIS / SDE / OPS; Calle Los Pinos 259, Urbanización Camacho, La Molina, Lima, Perú; [email protected]

Varios países de América han reportado la existencia de población expuesta crónicamente a concentraciones de arsénico en agua de bebida, superiores a las previstas por la normatividad de los países. Es el caso de Canadá, Estados Unidos, Chile, Perú, Bolivia, México, El Salvador y Nicaragua. Algunos de estos países han resuelto total o parcialmente el problema de disposición de tecnología, dependiendo de que la población afectada fuera rural o urbana. Existen alrededor de 14 tecnologías para remover arsénico del agua con eficiencias del 70 al 99%. Los métodos de coagulación-floculación y ablandamiento con cal, son los más usados en grandes sistemas y no exclusivamente para remover el arsénico. En pequeños sistemas pueden ser aplicados el intercambio iónico, alúmina activada, osmosis inversa, nanofiltración y electro diálisis inversa. Las tecnologías emergentes son: arena recubierta con óxidos de hierro, hidróxido férrico granular, empaques de hierro, hierro modificado con azufre, filtración con zeolita, adición de hierro con filtración directa y remoción convencional de hierro y manganeso. En Latinoamérica los estudios han estado orientados al uso de la coagulación química: con sulfato de aluminio, cal hidratada y poli electrolito de sodio y han logrado tenores de arsénico a 0,12-0,15 mg L-1. Con coagulación directa sobre filtro y con coagulación-floculación han logrado alcanzar valores bajo 0,05 mg L-1. En la remoción mediante adsorción han empleado hematitas y materiales con alto contenido de hierro y superficies de carga posi-

El CEPIS/SDE/OPS, ha desarrollado y patentado el producto ALUFLOC que es una mezcla de un oxidante, arcillas activadas y un coagulante (sulfato de aluminio ó cloruro férrico). Es una metodología simple y de bajo costo que permite remover a nivel domiciliario el arsénico natural presente en las aguas subterráneas que son usadas como agua de bebida por la población rural. Se lograron niveles de remoción de hasta un 98%, usando como coagulantes Al2(SO)3. and FeCl3. Para la remediación de suelos de zonas contaminadas se ha estudiado la capacidad de algunos vegetales para absorber y concentrar las sustancias tóxicas. La Universidad de Florida ha identificado un helecho que absorbe arsénico del suelo contaminado que hiper acumula este elemento. Las tecnologías de recuperación y estabilización de arsénico en lodos, suelos y residuos de actividades industriales por lo general son precipitados con cal y soda cáustica. Luego separación por sedimentación y/o filtración. En México han obtenido un compuesto de arsénico insoluble y que también se puede emplear como materia prima en la formulación de productos solidificados para ser usados en construcción o dispuestos en un relleno sanitario. Para afrontar la problemática del agua de bebida, se debe tener en cuenta las características de las fuentes, la adecuación del

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agua, forma de distribución y/o consumo y las variantes de la tecnología a emplear considerando las características propias del lugar. En los países de Latinoamérica existe experiencia y capacidad para el desarrollo de tecnología, pero limitada por la carencia de recursos financieros, facilidades y sobre todo políticas de estado que faciliten y orienten el desarrollo de la tecnología que conlleve a la solución efectiva de problemas o satisfacción de las necesidades existentes. La población más afectada se encuentra dispersa en el área rural consume agua sin ningún tratamiento y desconoce el riesgo al que está expuesto. Es necesario desarrollar estudios piloto en forma permanente y sostenida hasta lograr una solución definitiva que pueda ser recomendada para su implementación en los programas nacionales de remoción de arsénico en el agua de bebida. 15. The World Health Organization normative roles in mitigating health impacts of arsenic in South East Asia Deoraj Caussy Department of Sustainable Development and Healthy Environment, Department of Evidence for Information and Policy, World Health Organization, Office of the South East Asia, World Health House, Ring Road, New Delhi 110 002, India; [email protected]

Ground water contamination, in excess of the World Health Organization (WHO) guideline value of 0.01 mg L-1, has been observed in many parts of the world including India, Bangladesh, Thailand, Myanmar, Nepal, China, Taiwan and Vietnam among others. In the South East Asia Region of WHO, it is currently estimated that about 40 million persons may have been exposed to contaminated ground water at various concentrations of arsenic and almost a quarter of a million exposed subjects are already showing overt symptoms of chronic

arsenic poisoning. A review of the epidemiological data shows that there is a need for internationally accepted criteria based on evidence in the following areas: Exposure assessment, case-definition and case management. This paper reviews the existing epidemiological evidence for standard case definition and management and presents WHO strategic goals to meet these objectives. Data will be presented on the formulation and validation of standard regional protocol for case definition and case management. Other mitigation strategies including applied research and community empowerment will also be presented. 16. Microbial volatilization of arsenic Čerňanský S, Urík M, Ševc J1, Aranyosiová M2 1

Institute of Geology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina G, 842 15, Bratislava, Slovakia, [email protected] 2 International Laser Center, Bratislava, Slovakia

Microorganisms have evolved diverse strategies to overcome the toxic effects of arsenic including microbial volatilization through biomethylation and bioreduction. The biological volatilization may be possibly applied as method for arsenic removal from contaminated localities. Microscopic filamentous fungi participate in this process as a part of microbial community. Because of their low nutrition demand, adaptability, high intensity and diversity of metabolism represent dominant biopotential for environment, which is realized in effecting of transformation and mobility of arsenic. Our studies have shown that the efficiency of arsenic removal is influenced by temperature, pH value, presence of oxygen, bioavailability and concentration of arsenic, and dominant species of filamentous fungi. For quantification of arsenic removal and identification of arsenic metabolites in vitro the cultivation system of different fungi (Neosartorya fischeri, Aspergillus clavatus,

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A. niger, Talaromyces wortmanii, T. flavus, T. viride, Penicillium glabrum) and cultivation media enriched by desired amount of arsenic (0,25 – 15 mg) was prepared. Fungal strains were originally isolated from sediments from locality Pezinok – Kolársky vrch (Slovakia) that is contaminated with arsenic. Total arsenic concentrations of sediments were 363-1650 mg kg-1. After a desired time of cultivation (10, 30 and 60 days) under different conditions (pH value, temperature) the total arsenic in cultivation medium and mycelium was measured using Hydride Generation Atomic Absorption Spectrometry (HG AAS). The removal of arsenic from cultivation system through microbial volatilization varied between 10 – 70% of the initial amount of arsenic depending on cultivation conditions and fungal species. For detailed chemical analysis of biological samples (mycelia) with focus on specific arsenic metabolites was used Secondary Ion Mass Spectrometry (SIMS), an analytical method based on the time of flight principle. Instrument ION-TOF, SIMS IV with unique parameters (spatial resolution 100 nm, mass resolution > 9000 m/Dm) was used in cooperation with International Laser Center in Bratislava. Volatile arsenicals have been identified during a cultivation period from myceliar head gas in cultivation system by using sorption tubes Anasorb CSC (USA). 17. Enriched arsenic precipitates obtained from diluted industrial solutions Ciminelli, Virgínia1, Caldeira, Cláudia Lima1; Lara, Michelle Caetano1 1

Dept. of Metallurgical and Materials Engineering, UFMG, Rua Espírito Santo, 35, 30160-030 Belo Horizonte, Brazil; [email protected] [email protected]

Arsenic is a frequent toxic element released during processing of sulfide ores. The treat-

ment of As-containing solutions involves As(III) oxidation, followed by fixation of the resulting As(V) in a solid phase. The most common residues are the crystalline ferric arsenates (e.g., scorodite, FeAsO4.2H2O) produced in the hydrothermal processing of refractory gold ores, or the arsenical ferrihydrites formed by precipitation of arsenic at moderate temperatures. The latter involves a neutralization of arsenic-rich acidic solutions and generates large volumes of ferric hydroxide/gypsum sludge (e.g., 3-6% As). Arsenic immobilization by scorodite precipitation under ambient pressure has been proposed as an alternative to the ferrihydrite process but the studies have been mostly limited to relatively concentrated solutions (10 g As L-1) and batch systems. The present work investigated the removal of arsenic from dilute solutions (1 g L-1 As) produced in the washing tower of the gas released in the roasting of a refractory gold ore. It was demonstrated that industrial solutions with low arsenic concentrations (1.1 – 0.1 g L-1) could be treated in one stage of scorodite precipitation under ambient pressure conditions, with a removal in a range of 80.5 to 94.6%. Precipitation was carried out at 95°C. In order to reach a molar Fe/As ratio of 1, required for scorodite precipitation, iron (II) sulfate was added, followed by As(III) and Fe(II) oxidation with H2O2. In order to control supersaturation and to avoid homogeneous nucleation that yields amorphous ferric arsenate pH was adjusted according to the initial arsenic concentration. The removal increased with the increase of the scorodite seed concentration and became approximately constant (85-88%) in a range of 20 to 80 g L-1 of seeds. It was shown that a surface area higher than 270 m2 g-1 As in solution was necessary to promote an arsenic removal of approximately 85%. Gypsum was an effective seed only in concentrated arsenic solutions (10 g L-1). A procedure to achieve high yields of arsenic removal in continuous system was established. Due to the low rate of crystal growth, the recycle of seeds was required. The precipitation was favored by

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the excess of iron, due to the increase of initial supersaturation obtained under these conditions. For a Fe:As molar ratio of 2:1 and 1:1, 86% and 70% of the arsenic was removed from the solution, respectively. The TCLP tests suggested that ageing plays an important role on scorodite TCLP- dissolution, which decreased from 13.66 mg As L-1 to 0.1 mg As L-1 after 8 hours of precipitation reaction in batch tests. Scorodite was the only phase identified by microRaman and X-Ray diffraction analyses of the precipitates. Advantages and difficulties of the ambient-pressure scorodite precipitation with respect to industrial applications are discussed. 18. Remoción de arsénico de aguas naturales del valle de Camarones mediante procesos inducidos por radiación solar: tecnología de descontaminación aplicable a recursos hídricos al norte del Desierto de Atacama, Chile Lorena Cornejo P.1, 2, Hugo Lienqueo A.2, Jorge Acarapi C.2, Maria J. Arenas H.2, Héctor Mansilla3, Jorge Yañez3 1

Universidad de Tarapacá, Facultad de Ciencias, Departamento de Química, AricaChile, Casilla 7-D; [email protected]. 2 Centro de Investigaciones del Hombre en el Desierto, Universidad de Tarapacá, Arica-Chile. 3 Facultad de Ciencias Químicas, Universidad de Concepción, Chile

Los poblados de Camarones, Esquiña e Illapata se encuentran insertos en el valle de Camarones al norte del Desierto de Atacama, Chile. Son beneficiados con las aguas naturales de su única fuente de recurso hídrico el río de Camarones y diversos flujos menores de agua, como vertientes y pozos que los habitantes utilizan para suplir sus necesidades de consumo personal, animal y riego. Dichas aguas presentan una contaminación natural de Arsénico, proveniente de las zonas cordilleranas, con concentraciones en el rango de

1200 a 1300 µg L-1. Este tipo de contaminación ha afectado en forma crónica a las poblaciones rurales asentadas en la zona norte del país, ocasionando diversos problemas a la salud de sus habitantes. Debido a la baja densidad poblacional que poseen estos pueblos no es factible la utilización de tecnologías de alto costo, compleja mantención u operación para lograr abastecer de agua potable a estas localidades, que es el objetivo de este trabajo. Esta problemática ha originado un interés creciente en el desarrollo de metodologías de remoción útiles para disminuir niveles de arsénico a concentraciones adecuadas para el consumo humano y se ajuste a los niveles máximos de arsénico permitidos, por normativas nacionales e internacionales (NCh 409 = 50 µg As L-1, OMS = 10 µg As L-1). Este estudio comenzó con el tratamiento de aguas sintéticas que poseían una concentración de arsénico de 500 µg L-1 y con exposición a luz artificial obteniendo resultados del 80-90% de remoción. En seguida se trabajó el diseño, adaptación y posterior aplicación de una metodología de remoción simple y económica mediante ensayos de laboratorio univariados en la ciudad de Arica. Para ello se realizaron análisis fisicoquímicos a las muestras de aguas naturales a fin de conocer su composición, y así trabajar con muestras sintéticas de igual matriz. Las variables estudiadas fueron hierro (FeSO4), citrato (C6H5Na3O7), pH, remoción en presencia y ausencia de luz solar y tiempo de exposición solar. El hierro y el citrato fueron posteriormente reemplazados por materiales de uso casero accesible al poblador rural. Finalmente, se realizaron los ensayos de remoción “in situ”con muestras de aguas reales del valle de Camarones. La información recopilada fue evaluada, utilizando un software de optimización basado en métodos de superficie de respuesta (MSR).

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La determinación de la concentración de arsénico remanente en solución, en todos los casos, fue mediante espectroscopia de absorción atómica con generación de hidruros. En conclusión, con la metodología propuesta se obtuvo una remoción de arsénico mayor al 99% en terreno, presentándose como una interesante alternativa que rinde logros favorables en la descontaminación del recurso hídrico para consumo de los habitantes del Valle de Camarones. 19. Monitoring concentrations, speciation, and mobility of arsenic in geothermal sources of Ecuador´s NorthCenter Andean Region Luis H. Cumbal, Vladimir Aguirre, Ricardo Tipan and Carlos Chavez Research Center Escuela Politecnica del Ejercito, Sangolqui, Ecuador; [email protected]

It is well known that arsenic contamination has emerged as a worldwide problem due to pollution of groundwater and surface water. In several areas of Mexico and Chile, groundwaters have been contaminated with arsenic of volcano origin. In Ecuador, the Andean Region is surrounded by volcanoes and geothermal waters and some of them are used as sources of drinking water particularly in rural areas. After petroleum contamination of a lake that is fed by geothermal waters, its water was characterized and arsenic concentrations oscillated between 390 and 670 µg L-1. At that time, it was thought that arsenic was petroleum origin; however, our research group recently measured arsenic in that lake and found concentrations in the range of 330 and 900 µg L-1. In addition, it was found that nearby thermal waters such as El Tambo swimming pool, Jamanco reservoir, and Rio Tambo watershed contained between 970 and 5080 µg L-1 of arsenic. These findings eventually indicate that

other thermal sources in Ecuador’s Andean Region can contain this toxic element. The objective of this study is to determine arsenic concentrations in thermal waters from the North-Center Andean Region of Ecuador, its chemical speciation and mobilization during the travel towards rivers, lakes, and reservoirs. With this information we will make a map to localize thermal waters with concentrations above the Ecuadorian maximum concentration level (50 µg L-1). In next stage of this study, we will investigate with local sorbents for selective arsenic removal such as zeolite or allophane rich clay. Our research will be aimed to treat thermal waters that are used as sources of drinking water in rural areas. 20. Polymer-supported Fe(III) oxide nanoparticles: A robust, reusable and arsenic-selective sorbent Luis H. Cumbal1 and Arup K. Sen Gupta2 1

Research Center of Escuela Politecnica del Ejercito, Sangolqui, Ecuador 2 Department of Civil & Environmental Engineering, Lehigh University, 13 E. Packer Ave., Bethlehem, PA 18015, USA; [email protected]

Many nanoscale inorganic particles (NIPs) such as hydrated Fe(III) oxides, Mn(IV) oxides, elemental Fe, magnetite, etc.; show excellent properties conducive to selective removal of target compounds from contaminated water bodies. Extremely high surface area to volume ratio of these tiny particles offers favorable kinetics for selective sorption and redox reactions. However, these nanoparticles cannot be used in fixed-bed columns, in-situ reactive barriers and in similar plug flow configurations due to excessive pressure drops and poor durability. Harnessing these NIPs within polymeric beads offers new opportunities that are amenable to rapid implementation in the area environmental separation and control. While the NIPs retain their intrinsic sorption/desorption, redox, acid-base or magnetic

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characteristics, the robust polymeric support offers excellent mechanical strength, durability, and favorable hydraulic properties. In this investigation commercially available cation and anion exchangers were used as host materials for dispersing nanoscale Hydrated Fe(III) Oxides (HFO) within the polymer phase using a simple thermochemical technique. The resulting polymeric/inorganic hybrid sorbent particles were subsequently used for arsenic removal in the laboratory. The major finding of this study reveals that an anion exchanger as a support of dispersed HFO particles offered considerably higher arsenate removal capacity compared to a cation exchanger, all other conditions remaining the same, the difference in selectivity and removal capacity can be attributed to functional groups of polymeric supports. In addition, hybrid polymers are amenable to efficient regeneration; thus, assuring their reuse in several sorption/desorption cycles. On the other hand, rubbing tests demonstrate that HAIX-M particles do not lose mechanical resistance and there is no fines formation. Besides, sorption tests using HAIX-M particles reveal an excellent and simultaneous removal of arsenic and perchlorate. Consequently, HAIX-M sorbents are media with enormous potential to be used in community water supplies to selectively remove arsenic and other toxic ligands. 21. Mitigation actions as a result of As

exposure investigations in Brazil Eleonora Deschamps1, Jörg Matschullat2, Olivia Vasconcelos3, Nilton de Oliveira Couto Silva4 1

Environmental Agency of the Minas Gerais State - FEAM, Av. Prudente de Morais 1671, Santa Lucia,30380-000, Belo Horizonte, Brazil; [email protected] 2 Interdisciplinary Environmental Research Center, TU Bergakademie Freiberg, Brennhausgasse 14, D-09599, Freiberg, Germany; [email protected]

3

Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais, UFMG, Brazil; olí[email protected] 4 Fundação Ezequiel Dias-FUNED, Laboratório de Contaminantes Metálicos, Belo Horizonte,MG,Brazil; [email protected]

Globally, millions of people are at risk from adverse health effects of arsenic from both acute and chronic exposure. Although most of the As exposure comes from drinking water, other important sources are through food, soil and air. In Brazil, arsenic anomalies are related to geological structures, and the additional dissipation due to centuries of gold mining and smelting activities. Most of the gold is associated with arsenopyrite and to a lesser extend with pyrite. Although not as severe and not exclusively water-related as in Bangladesh and West Bengal, Asenrichments were recently detected in environmental and biological media in the Iron Quadrangle, Minas Gerais state. This project presents the mitigation actions to improve the situation, starting with an environmental and health perception study which led to an environmental educational program. Next, appropriate tailings deposits management was started to improve control of tailings with very high As concentrations, and to slow down As-dissipation into the environment. Additionally, a water treatment plant is under construction to avoid the ingestion via As-loaded particulates in drinking water. 22. Speciation and instrumental analytical methods as effective analytical tools for quantification of arsenic in drinking water Leena Deshpande and Sunil Pande National Environmental Engineering Research Institute, Nehru Marg, Nagpur, India; [email protected]

Arsenic in ground water has been well recognized as a serious public health hazard in various parts over the globe. Despite recent developments in the quantification of arsenic in water, the method involving generation of

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arsine, colour development with Silver Diethyldithiocarbamate (SDDC) and measuring colour spectrophotometrically, still remains the method of choice in the domain of public health laboratories. This paper presents development of spectrophotometric method with modified glass assembly for arsine generation. Recovery studies of arsenic have been carried out in presence of various cations and anions. For validation of the method, its precision and accuracy was determined by analyzing synthetic water samples. Also an attempt has been made to study substitute for pyridine, which is a hazardous solvent used in the conventional SDDC Method. A rapid Hydride Generation-Inductively Coupled Plasma (HG-ICP) spectrometric method has been developed using the ICP spectrometer, which serves as an efficient analytical tool for the monitoring of low levels of arsenic in raw and potable waters. The HG-ICP method is precise and accurate as per the international norms. This method can be routinely adopted for the analysis of arsenic in water samples. 23. Arsenic removal by solar oxidation in groundwaters of Los Pereyra, Tucumán Province, Argentina Josefina d´Hiriart1, María Gabriela García2, Margarita del V. Hidalgo1, Marta I. Litter3, Miguel A. Blesa 3,4 1

Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, Argentina 2 Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Argentina 3 Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica 4 Universidad Nacional de San Martín, Argentina

Shallow groundwaters from Los Pereyra, Tucumán, are normally used for human

consumption. These waters show arsenic concentrations that exceed the Argentine standard requirements for drinking water. The SORAS method (Solar Oxidation and Removal of Arsenic) is based on the photochemical oxidation of As(III) to As(V) produced by reactive oxygen species formed in Fe/citrate containing systems, followed by As(V) adsorption onto the precipitated iron(hydroxides). SORAS method provides an economical technology to eliminate arsenic until the allowable limits. In the present work, the efficiency of As removal by solar oxidation was assessed using synthetic waters of known ionic composition and shallow groundwater samples. As the concentration of iron in the tested waters is very low and the photooxidation of As (III) at pH between 6 and 8 is favoured by citrate, studies changing the sources of iron and amounts of citrate were made. Citrate was added in the form of lemon juice. Tests carried out with synthetic waters of similar composition to the study waters showed an excellent removal, ranging between 90-60%. The efficiency of removal was much lower in well waters, between 6030%. Results showed the influence of the water matrix and the source of iron supply, both factors related to the precipitation of iron (hydr)oxides. The influence of organic matter, HCO3- content and the initial As concentration on the precipitation of (hydr)oxides and on the AsO43- adsorption was assessed. An increase in the concentration of HCO3- enhanced As removal and Fe(III) precipitation, whereas an increase of organic matter produced only a slight decrease in both factors. Removal efficiency decreased with the increase of the initial As concentration. The effect of different Fe sources on the efficiency was analyzed using synthetic goethite, Fe-oxide rich sandstones and pelites, packing wire, and nails. Removal varied between 30 to 90% depending on the experimental conditions and the nature of the

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iron source. Results obtained using nongalvanized packing wire are prominent, due to the short solar exposure time and the absence of color or turbidity in the final treated water. 24. Concentración de arsénico total e inorgánico en el sistema agua – alga – trucha Oscar Díaz Sch.1*, Nelson Núñez S.2, Estela Recabarren G.1, Rubén Pastene O.1, Dinoraz Vélez P.3, Rosa Montoro M.3 1

Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago, Chile; [email protected] 2 Programa Indígena CODELCO, Chile 3 Instituto de Agroquímica y Tecnología de Alimentos (IATA), Valencia, España

El curso del río Loa, ubicado en la II Región de Chile, presenta condiciones ecológicas especiales, particularmente debido a las altas concentraciones de As en el agua, salinidad y drenaje de los suelos. El objetivo de este trabajo, consistió en estudiar el comportamiento del arsénico y su forma inorgánica más tóxica (AsIII + AsV), en el sistema agua – alga –trucha en un área del curso del río Loa. Muestras de agua del río Loa, hábitat natural del alga (Durvillea sp) y la trucha (Orcorhynchus mykiss), fueron recolectadas en el mes de noviembre del 2000 y 2001, en una cantidad suficiente para asegurar la confiabilidad de los resultados. Las muestras de agua (500 mL en botellas de vidrio) y del alga fueron obtenidas desde 5 lugares del curso del río. Cinco ejemplares de trucha fueron recolectados desde el río mediante red de captura y luego cada organismo fue eviscerado y separada la cabeza, tronco y cola. Todo el material biológico fue lavado con agua destilada, envasado en bolsas de polietileno y congelado (-20°C) hasta ser liofilizado. La concentración de As en el agua fue medida directamente mediante espectrofotometría de absorción atómica por generación de hidruros (EAA-GH). La

determinación de arsénico total (AsT) en las muestras liofilizadas (0.25 g) se realizó mediante mineralización por vía seca y medición del analito mediante EAA – GH y flujo de inyección (EAA – GH – FI). La concentración de arsénico inorgánico (AsI), fue determinada a través de digestión ácida, su posterior extracción (CHCl3, 10 mL) y cuantificación a través de EAA – GH – FI. Altas concentraciones de As en el agua resultaron en las muestras recolectadas tanto en noviembre del 2000 (0.07 – 0.28 mg L-1) como en noviembre del 2001 (0.05 – 0.92 mg L-1) dependiendo del lugar de recolección. En el alga recolectada en noviembre de 2000 se encontró concentraciones de AsT (54.02 – 98.03 µg g-1 b.s.) y AsI (41.53 – 100.55 µg g-1 b.s.), mientras que las obtenidas en noviembre de 2001 fueron 64.74 – 86.43 µg AsT g-1 b.s. y 36.90 – 59.70 µg AsI g-1 b.s.. Altos valores del factor de bioacumulación de AsT en el alga (86 – 1281) y de AsI (42 – 1004) fueron determinados, así como el porcentaje de AsI, respecto al AsT, fluctuó entre 46 – 103%. Se observó que las concentraciones de AsT y AsI, dependen de las respectivas concentraciones existentes en el agua. Los niveles de AsT y AsI en la trucha, fueron mayores en el tronco (16.02 µg AsT g-1 y 2.40 µg AsI g-1 b.s.), observándose que el AsI representa sólo el 15% del total, a diferencia de lo que se apreció en el alga. Se concluye que existe transferencia del metaloide, del agua al alga y la trucha, no evidenciándose tal situación entre el alga y la trucha, posiblemente debido a que no existe una relación trófica entre ambos.

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25. Sodium arsenite impairs insulin secretion and transcription in pancreatic β-Cells Andrea Díaz-Villaseñor1, M. Carmen SánchezSoto2, Mariano E. Cebrián3, Patricia OstroskyWegman1 and Marcia Hiriart2 1

Department of Genomic Medicine and Environmental Toxicology, Instituto de Investigaciones Biomédicas; [email protected] 2 Department of Biophysics, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México. 3 Section of Environmental Toxicology, CINVESTAV, IPN, Mexico City, México

Chronic arsenic exposure by drinking water has been epidemiologically associated with several complex diseases and recently with type 2 diabetes. In the present study we analyzed the impairment of insulin secretion in single adult rat pancreatic β-cells treated with sodium arsenite. Insulin secretion was evaluated in vitro in a subchronic exposure model during 72 and 144 h in the presence of 1 and 5 µM sodium arsenite, in which cell viability was not significantly affected. Basal insulin secretion was not modified with 72 h treatment, but was reduced with 5 µM sodium arsenite for 144 h. Glucosestimulated insulin secretion decreased in a dose-dependent manner in such a way that cells were not longer able to distinguish between different glucose concentrations. We further demonstrated that 5 µM sodium arsenite can reduce insulin mRNA expression. Our data indicate that by impairing pancreatic β-cell functions arsenic might contribute to the development of type 2 diabetes. 26. Characterization of Fe-treated clays and zeolites as effective As sorbents B. Doušová1, T. Grygar2, A. Martaus1, D. Koloušek1, L. Fuitová1, & V. Machovič1

1

Institute of Chemical Technology in Prague, Technická 5, CZ-166 28 Prague 6; [email protected] 2 Institute of Inorganic Chemistry AS, CZ-250 68 Řež

Adsorption of arsenic from aqueous environment on clay surfaces becomes more and more important for economic reasons. Most of the considered natural alumosilicates belong to low-cost and environmentally acceptable materials. Two methods using FeII and FeIII salts were applied to the alumosilicate pre-treatment to improve their sorption efficiency to AsV and AsIII species. In the first case three samples concerning natural kaoline from the Merkur quarry, Czech Republic, calcined at 550 °C for 3 hours, raw clinoptiolite-rich tuff from the Nizne Hrabovce deposit, Slovakia, and zeolite P prepared from fly ashes were exposed to concentrated solution of FeII (0.6 M FeSO4·7H2O) for 24 hours. Within that process, Fe2+ ions are oxidized to Fe3+ ions and the mineral surface is covered with FeIII (oxidohydr)oxides whose high affinity for the AsV adsorption is well known. In all investigated systems the efficiency of AsV sorption increased significantly after the FeII treatment, i.e. from about 15% to more than 90%. In the second procedure, the sorbents were prepared from raw bentonite obtained from a mineral deposit in Cerny Vrch, Czech Republic. The bentonite was pre-treated with solutions of FeIII (0.025 M Fe(NO3)3·9H2O, 10 min; sample a) and partly hydrolyzed Fe(NO3)3·9H2O (0.025 M Fe(NO3)3·9H2O 0.05 M NaOH, overnight; sample b). The sorption efficiency of FeIII-treated bentonite to AsV increased from ~16 % in original bentonite to ~78% (sample a, treated bentonite containing Fe3+ in cation exchangeable positions) and to ~95% (treated bentonite with Fe3+ in cation exchangeable positions and in ferrihydrite). The treatment of clays and zeolites by Fe is a very simple method opening new possibilities in effective and cheap decontamination of As-polluted aqueous systems. The indi-

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vidual Fe species in the sorbents, namely Fe3+ ions in cation exchangeable positions and in hydrous ferric oxides were identified by voltammetry of microparticles, diffuse reflectance electronic spectroscopy, hightemperature X-ray diffraction, and chemical extraction by Ni-edta complex, i.e. by novel methods, which are specific and sufficiently sensitive to detect molecular and oligomeric species in the sorbents. The characterization of the solid phase with above mentioned methods will permit to identify the actual As-sorbing species and to tailor the sorbents with the optimal sorption properties. 27. Two-step in situ decontamination of mining water enriched with As and Fe B. Doušová, T. Bruha, A. Martaus, D. Koloušek, R. Pažout, V. Machovič, Institute of Chemical Technology in Prague, Technická 5, CZ-166 28 Prague 6; [email protected]

The suggested method enables the effective removal of arsenic from strongly contaminated mining water, resulting from former ore mining activity at Kutna Hora, central Bohemia. The average chemical composition of mining water is in Table 1. Table 1: Average composition of the raw mining water from Kaňk locality Compound Fe Zn Cu As Mn Cd SO42Insoluble comp. pH

Concentration [g L-1] 5.752 1.589 2.7x10-5 0.054 0.166 2.27x10-4 17.665 0.295 3.5 - 4.1

The two-step process includes partial precipitation of contaminated water with a small amount of alkaline agent. In the first step the raw water is partially precipitated

with a defined amount of alkaline agent (NaOH, Na2CO3 or Ca(OH)2) to pH value ~ 5.0. The precipitation ran under the summary equation: 2Fe2+ + O2 + 5OH- + H3O+ = 2FeO(OH) + 4H2O (I) During the first precipitation more than 90% of presented arsenic is adsorbed as AsV on the iron oxihydr(oxides) surface immediately, forming the inner-sphere complexes. About 30 – 40% of precipitated iron enables the quantitative removal of arsenic from mining water. The “arsenic“ mass from the first step is than separated by decantation and/or filtration. The final treatment of mining water runs in the second step. The liquid residue after the first step is precipitated with lime Ca(OH)2 to the pH value ~ 8.5. While arsenic was substantially removed by the first precipitation, the other components including residual iron, manganese, zinc and sulfates are precipitated quantitatively during the second step. The mass of the second precipitate depends strongly on the amount of alkaline agent used in the second step. The first step – second step precipitate ratio varies about 1:4. The higher concentration of sulfates in the final treated water relates to the application of sodium alkalies in the first step. The water solubilities of NaOH and Na2CO3 are substantially higher in comparison with Ca(OH)2 solubility. The study of AsV - Fe - SO42- changes in relation to the pH value enables to estimate the optimal conditions of the process, i.e. to produce the minimal mass of toxic precipitate while keeping ecological limits of treated water. The two step decontamination of arsenic enriched mining water improves ecological and economical aspects of the current technology.

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28. Subchronic exposure to fluoride modifies the arsenic metabolism and renal oxidative damage in mice

complex, that can reduce the bioavailability and increase the half life time in the organism for both elements.

Maribel Espinosa, Eliud A. García-Montalvo, Olga L. Valenzuela and Luz M. Del Razo

The subchronic exposure to iAs or F- caused oxidative stress, the exposure to both elements caused increase levels of renal GSH. Nevertheless, in the As-F co-exposure GSH concentrations were less than those caused by the single exposure to each xenobiotic. Besides this, the renal TBARS was higher in the iAs exposure group, whereas in the exposure to F- group the renal TBARS was increase only at the second week of exposure; this effect was similar in the coexposed group to As-F-.

Toxicology, Cinvestav-IPN, Mexico City

Inorganic arsenic (iAs) and fluoride (F-) are ubiquitous elements. Their co-exposure is frequent in several endemic areas due to the natural contamination of well water supplies destined for the human consumption. In Mexico and other areas; has been reported that the co-exposure of these two elements in high concentrations in the water can cause typical toxic effects of arsenicism and endemic fluorosis. The aim of this study was to evaluate the oxidative stress of the repeated co-exposure to arsenite (As3+) and F- in renal tissue of female C57BL/6 mice, which were divided in four groups and exposed daily via gavage during 6 weeks with: a) water (control group); b) 3 mg As3+ kg-1 day-1 of sodium arsenite, c) 10 mg F- kg-1 day-1 of sodium fluoride, and d) both As3+ and F-, (3 mg As3+ kg-1 day-1 and 10 mg F- kg-1 day-1), respectively. Urine samples were collected every two weeks (2, 4 and 6 weeks) and levels of F- and the trivalent and pentavalent arsenical species were performed. Furthermore, at the end of exposure the arsenical species (AsIII+V, MAsIII+V, DMAsIII+V) were determined in kidney homogenate. Considering the pro-oxidants antecedents associated to the exposure with iAs and F-, oxidative stress biomarkers at renal level were evaluated such as glutathione (GSH) concentrations, also the renal oxidative damage was evaluated through lipid peroxidation (TBARS). The results showed that the As3+-F- coexposure modified the pattern of arsenical species excreted and modified the urinary excretion of the F-. These results suggesting an interaction between the As3+ and the Fthrough the possible formation of As-F

In future studies to evaluate the biotransformation and the toxic effects caused by iAs exposure, the co-exposure to F- need to be considered. 29. Evaluación de riesgo toxicológico asociado a la ingesta de aguas naturalmente contaminadas con arsénico y otros oligoelementos tóxicos en La Puna, Argentina Silvia S. Farías1, Graciela Bovi Mitre2, Rebeca I. Ponce2, María E. Ávila Carrera2, Gladi Bianco de Salas1, Roberto E. Servant1 1

Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica. Av. Gral. Paz 1499. B1650KNA-San Martín. Pcia. de Buenos Aires. Argentina 2 Grupo InQA- Investigación Química Aplicada. Facultad de Ingeniería. Universidad Nacional de Jujuy. Gorriti 237-(4600) S. S. de Jujuy- Pcia de Jujuy. Argentina.

El presente trabajo fue realizado entre mayo de 2001 y julio de 2003 en el Noroeste de la República Argentina. A partir de imágenes satelitales, se estudió un área de 20 000 km2 en la zona de La Puna salto- jujeña y otra de unos 10 000 km2 en la zona de los valles y sierras sub- andinas, en las que se realizó un muestreo bajo normas de calidad, para comparar los tenores de As, B, V y F- y estimar el riesgo asociado a su ingesta.

29

Las muestras, provenientes de fuentes superficiales y subterráneas fueron analizadas mediante ICP-OES, para determinar As, B y V y cromatografía iónica para evaluar F-. En la Puna se detectaron valores de hasta 2 mg/L As, mientras que en los valles las concentraciones de As nunca fueron mayores que el límite establecido por el Código Alimentario Argentino (50 µg L-1 As). Las concentraciones de B asociadas a los máximos tenores de As treparon hasta 50 mg L-1 B, las de F- alcanzaron valores de hasta 4 mg L-1 F-, en las muestras captadas en La Puna, superando así los máximos permitidos por dicha Ley (1 y 2 mg L-1, respectivamente). Y, contrariamente a lo descrito en estudios anteriores realizados en Llanura Pampeana, no se ha observado correlación entre As y V, encontrándose concentraciones que nunca fueron mayores que 100 µg V L-1 en las dos zonas estudiadas. Una vez identificada el área impactada por estos contaminantes se evaluó la dosis de exposición para caracterización de riesgos no- cancerígenos para la población expuesta, discriminando entre adultos y niños, que por sus condiciones físicas y su menor peso corporal, constituyen el grupo de mayor riesgo. Los resultados informados se discuten en relación con una estimación preliminar de riesgo toxicológico al que están expuestos los grupos poblacionales estudiados considerando únicamente la ingesta de agua como vía de exposición para estos contaminantes críticos, especialmente el arsénico. Para ese elemento, en la zona de los valles, los valores de dosis para adultos y niños (0.8-2.0 µg kg-1 peso/día, respectivamente), nunca superaron el LOAEL- mínima concentración con la que se observan efectos tóxicos (LOAEL para riesgo no- cancerígeno * = 2.6 µg kg-1 peso corporal / día), mientras que en la zona de La Puna se determinaron valores de estas dosis com-

prendidas entre 1 y 30 µg kg-1 peso/día, para adultos, y entre 4 y 80 µg kg-1 peso/ día, para el caso de niños, valores que podrían llegar a superar en algunos casos el LOAEL para riesgo cancerígeno (15 µg kg-1 peso/día). Se propone la realización de un mapa de riesgo para estos elementos, la evaluación de los pobladores por médicos dermatólogos y psicólogos que efectúen pruebas neuroconductuales, especialmente en niños, así como también la implementación de un sistema de abatimiento sencillo y económico aplicable a poblaciones rurales dispersas. (*riesgo no-cancerígeno, relacionado con lesiones dérmicas y efectos neurológicos) 30. Arsénico y otros elementos tóxicos en aguas termales, lagos, vertientes y aguas de consumo, en las cercanías del volcán Copahue, Argentina Ana María Fazio1, Silvia S. Farías2, Alberto T. Caselli1, Mariano Agusto1 1

Departamento Ciencias Geológicas. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Pabellón 2.1428EHA Buenos Aires, Argentina 2 Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica. Av. Gral. Paz 1499. B1650KNA- San Martín. Pcia. de Buenos Aires. Argentina

El Copahue, es un volcán activo de 2297 metros de altura, localizado en la parte oriental de la zona volcánica de Los Andes, al Sur-Oeste de la República Argentina. La presencia de un lago ácido en el cráter, fuentes termales ácidas de elevada temperatura y un campo geotermal, son las expresiones superficiales de un sistema hidrotermal volcano-magmático. La principal fuente termal, de características ácidas y elevada temperatura emerge alrededor de 100 metros por debajo del lago del cráter y alimenta al llamado “Río Agrio”, que descarga 12 kilómetros más abajo en el Lago Caviahue, un espejo de agua ácida de origen glacial.

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Desde el invierno de 2003 se han venido realizando muestreos estacionales, bajo normas de calidad, para observar las variaciones en las concentraciones de aniones y de cationes presentes en las aguas bajo estudio, de forma de poder establecer tácticas de monitoreo.

ellos como “curativas”; y a prohibir su utilización en el caso que los tenores de As y otros elementos tóxicos, superen los valores establecidos por la legislación vigente al respecto.

Las muestras, provenientes de fuentes superficiales y subterráneas fueron analizadas mediante espectroscopia de emisiónplasma inductivo de argón para determinar As, Al, B, Ba, Be, Bi, Cd, Cr, Co, Cu, Fe, La, Mn, Mo, Ni, P, Pb, Sb, Se, Sr, Ti, V, Y y Zn; mediante cromatografía iónica para evaluar F-, Cl-, NO3-, SO4-, y se empleó absorción atómica en llama para cuantificar Na, K, Ca y Mg.

31. Arsenic removal using ferric chloride and direct filtration

Los tenores de As observados superaron en muchos casos valores de 5 mg As mL-1, para muestras captadas durante el invierno. Se hallaron concentraciones significativamente menores de este elemento, para muestreos realizados en otras épocas del año. Asimismo, se observaron variaciones estacionales para la mayoría de los otros elementos estudiados, muchos de ellos con niveles de toxicidad comparables al del As.

Arsenic is a carcinogenic metalloid that is currently regulated in drinking water. The levels of arsenic in finished water in an existing water treatment plant are exceeding the current regulation of 10 µg L-1. One of the available technologies for arsenic removal from groundwater is adsorption onto coagulated flocs and in this field, ferric chloride is the most commonly used coagulant for arsenic removal. This research work was conducted to explore a suitable conventional treatment technology for arsenic removal from given groundwater in order to reduce the filtrate arsenic concentration to less than 10 µg L-1.

Una vez identificado el patrón de variación de las concentraciones de los diferentes elementos a lo largo del año se procedió a establecer una frecuencia de muestreo para monitorear las aguas de consumo, y las aguas termales a las que están expuestos miles de turistas que acuden cada año, a este Centro Termal, durante períodos semanales o quincenales, en busca de alivio para el caso de patologías reumáticas y óseas, de terapias anti- estrés ó simplemente de merecido descanso y relajación. Los resultados obtenidos se han informado a las autoridades sanitarias para que alerten a los turistas sobre los peligros inherentes a la exposición prolongada a aguas naturalmente muy contaminadas, durante los baños termales que practican diariamente y por largos períodos de tiempo; a evitar la ingesta de esas aguas, consideradas por muchos de

R. G. Fernández1, B. Petrusevski2 1

Centro de Ingeniería Sanitaria - Facultad de Ingeniería, Universidad Nacional de Rosario. Riobamba 245 bis – 2000 Rosario – Argentina; [email protected] 2 UNESCO-IHE - Institute for Water Education. PO Box 3015 – NL-2601 DA Delft – The Netherlands; [email protected]

Bench scale jar test experiments and pilotscale investigations were carried out to evaluate and improve the coagulation / flocculation process for arsenic removal using ferric chloride. Model water that represented the water from the existing water treatment plant was used to investigate the effects of different conditions of pH, coagulant doses, arsenic speciation, initial arsenic concentration, temperature, and flocculation conditions on the arsenic removal efficiency by coagulation / flocculation process. Based on these bench scale experiments, a direct filtration technique to separate the formed flocs was considered as the most suitable floc

31

separation system to be applied after coagulation/flocculation process. A direct filtration pilot plant was operated to evaluate the efficiency of arsenic removal. The results of series of jar test experiments showed that As(V) could be completely removed with iron doses higher than 2 mg L1 for filtered samples and at pH value about 7.0. The lower efficiencies obtained for unfiltered samples indicate that settling mechanisms are not effective enough to ensure complete removal of As(V), even when using very high doses of coagulant. In agreement with the results of previous studies, it was found that As removal efficiency increased with the coagulant dose. Additionally it was also observed that under the given conditions As(III) removal efficiency was much lower (up to 60%) compared to As(V) removal efficiency (90 - 100%). Direct filtration with iron doses of 2 mg L-1 at pH value about 7.0, could reduce As(V) levels from 50 to 4 µg L-1 or less without any risk of iron or turbidity increasing in the filtered water within a reasonable filterrun length. Direct filtration using ferric chloride as coagulant, could be an appropriate technology to reduce arsenic levels below 10 µg L-1 for the given groundwater. 32. Rapid, clean and low-cost assessment of inorganic arsenic in the mussel Mytilus Galloprovincialis Lmk. by visible and near-infrared spectroscopy Rafael Font1, Dinoraz Vélez2, Mercedes Del Río-Celestino3, Antonio De Haro-Bailón1, Rosa Montoro2 1

Instituto de Agricultura Sostenible (CSIC). Alameda del Obispo s/n. 14080, Córdoba, Spain 2 Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Apartado 73, 46100, Burjassot (Valencia), Spain 3 CIFA, Junta de Andalucía, Apdo. 4240, 14080 Córdoba, Spain

M. galloprovincialis Lmk. represents an important resource for fishery in Spain. This production places Spain as the second producer of mussel of the world, after China. In addition, Spanish export trade for mussel is increasing quickly, mainly in Europe, where countries as Belgium imports over 12000 kg of M. galloprovincialis every day. Among the metals and metalloids present in the environment, arsenic (As) stands out because of its toxicological potential. Arsenic is found in food in various chemical forms that differ in their degree of toxicity and pathologies associated with it. The most toxic forms of As are the inorganic ones (iAs), i.e., As(III) and As(V), which are considered human carcinogens. Thus, concern for food safety in relation to iAs occurrence in foods currently calls for exhaustive controls of these molecular forms in a variety of food products. The standard methodologies for iAs determination offer a high level of precision but at the same time show some handicaps, such as high cost of analysis, slowness of operation, destruction of the sample, and use of hazardous chemicals. The availability of fast methodologies to quantify iAs levels in different kinds of foods would contribute to the drawing up of legislation to guarantee the healthiness of foods with respect to this metalloid. One approach to the consecution of such objectives is made through the use of Visible-Near-Infrared Spectroscopy (VIS-NIRS). VIS-NIRS is a valuable technique that offers speed and low cost of analysis, and also the sample is analyzed without using chemicals. The spectral information obtained from samples can be used for prediction of the iAs, once appropriate calibration equations have been prepared from sets of samples analyzed by both VIS-NIRS and conventional analytical techniques. We present in this work the potential of VISNIRS to predict iAs in different matrices of animal and plant origin. Mathematical models (calibration equations) were developed

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over the spectral data jointly with the iAs concentrations in the samples, by using Modified Partial Least Squares (PLSm) regression. On the basis of the coefficients of determination (R2) shown by the equations in the validation, and also of the standard deviation to standard error of prediction in the validation (RPD), the equations obtained displayed a high predictive ability to determine iAs in such matrices. Our results suggest that both, the VIS (chomophores) and NIR (X-H, where X= C, O, N) regions of the spectrum from the matrices used to conduct this work, contain relevant information that can be related to the iAs concentration in the samples. This pioneering use of VIS-NIRS to predict the iAs content in biological matrices represents an important saving in time and cost of analysis. 33. Intermediate to high levels of arsenic and fluoride in deep geothermal aquifers from the northwestern Chacopampean Plain, Argentina María Gabriela García1, César Moreno2, Diego Sebastián Fernández3, María Cristina Galindo2 Ondra Sracek4 and Margarita del Valle Hidalgo2 1

Centro de Investigaciones Geoquímicas y de Procesos de la Superficie. FCEFyN. Universidad Nacional de Córdoba 2 Centro de Investigaciones y Transferencia en Química Aplicada. Tucumán. FCN e IML. Universidad Nacional de Tucumán. Tucumán, Argentina. Córdoba, Argentina 3 Servicio Geológico Minero Argentino, Delegación Tucumán 4 Dep. of Geological Sciences, Faculty of Science, Masaryk University, Brno, Czech Republic

High levels of natural occurring arsenic and fluoride in groundwaters from the Chacopampean plain have been assigned to the presence of volcanic shards spread within the loess matrix. The primary source of these elements has not been determined yet but there is almost a clear understanding about the mechanisms that promote their

mobilization in the aquifers. Geochemical evidence suggests that, after being released into groundwater, the concentration of arsenic in solution is controlled by pH. Arsenic is preferentially scavenged by adsorption on Fe (hydr)oxide coatings under acidic to neutral pH conditions. The concentration of fluoride depends on the fluorite solubility and also on pH-dependent adsorption with adsorption minimum at high pH values. In the province of Tucumán, the loessic layer is restricted to the first 30 meters of the Quaternary sequence. As a consequence, most shallow groundwater is contaminated by high levels of As and F-. Groundwater in deep confined aquifers is considered to be suitable for human consumption. However, in the southern part of the province several wells show from intermediate to high concentrations of As (between 10 to 79 µg L-1) and high concentrations of F- (between 0.6 and 6.0 mg L-1). These wells that penetrate saturated layers as deep as 500 mbs, show ground water temperatures above the annual average in the region. Some authors proposed that the heat is supplied from a basaltic layer located 7000 mbs. The geochemistry of As and F- in deep aquifers shows certain characteristics that are not completely coincident with those described in the rest of the Chacopampean plain. Unlike in shallow groundwaters, the concentrations of As increase with increasing depth and temperature. The same trend is observed for F-, but the relation with depth is not such clear. Furthermore, As shows direct linear correlation with sulphate and reverse correlation with bicarbonate and calcium. F- is poorly correlated with arsenic, but highly correlated with chloride and sodium. It also shows reverse correlation with calcium. Concentrations of F- increase at increasing pH and decreasing Eh, but this trend is less evident for As. The primary source of As and F- in the deep confined aquifers can be associated with volcanic Tertiary sediments that are sup-

33

posed to be in the deepest part of the sedimentary sequence. The up-flow of geothermal fluids through structural conduits is considered negligible because ground water chemistry matches those of volcanic sediments. The mobilization of As does not seem to be controlled only by the pH, but also by other factors such as the presence of As-rich primary source sediments. The concentration of F- is not affected by the precipitation of fluorite as its supersaturation is never reached due the removal of Ca2+ by the precipitation of calcite and/or cation exchange. 34. Lipoperoxidative damage, nerve conduction and histological characteristics of sensory sural nerves of rats exposed to arsenite Erika García-Chavéz1; Bertha Segura2; Horacio Merchant3; Luz C. Sánchez-Peña1; A. Barrera1, Jose C. Guadarrama4, Ismael Jiménez4 and Luz M. Del Razo1 1

Toxicology, Cinvestav-IPN, Mexico. 2 FESIztacala, UNAM, Mexico,3IIB-UNAM, Mexico,4Physiol., Biophys. & Neurosci., CinvestavIPN, Mexico

Although the remarkable interest on toxicological properties of inorganic arsenic (iAs), it has limited amount of information on the capacity of this metalloid to interact and cause structural and functional alterations of the nervous system. Previous studies have demonstrated that humans exposed to iAs affect the central nervous system and can produce peripheral neurotoxicity. Generation of reactive oxygen species (ROS) is the major mechanism by which arsenic exerts its toxicity in a variety of tissues. ROS has been demonstrated in rat brain exposed to iAs, although their role in the peripheral nervous system is not fully established. In addition, the adverse effects of arsenical exposure have not been related to the presence of methylated arsenic species (MAs and DMAs) formed during the iAs metabolism and distributed in nervous sys-

tem, which could be in some extent responsible for the neurotoxic alterations reported. Our aim was to assess the relation of the distribution of iAs and its metabolites, its oxidative damage, nerve conduction and histological characteristics of the peripheral sural nervous of rat subchronic exposure to arsenite. Wistar male rats (200 g body weight) received sodium arsenite (10 mg kg-1 bw/day, gavage, for 30 days). Thiobarbituric acid-reactive substances (TBARS) and distribution of iAs and its metabolite in sural nerve were evaluated at the end of 30 days of exposure. Sural nerve conduction studies were performed for measurement the compound action potentials and transversal sections using standard electrophysiological and histological techniques. The results revealed oxidative damage in sural nerve as compared from control group (p