Mobilization of arsenic and other trace elements of health concern in groundwater from the Salí River Basin, Tucumán Province, Argentina

HUGO B. NICOLLI; JORGE W. GARCÍA; CARLOS M. FALCÓN Y PAULINE L. SMEDLEY

Environmental geochemistry and Health

Springer

Lugar: Hidelberg, Duscheland; Año: 2012; p. 251 - 262

AbstractThe Sali´ River Basin in north-west Argentina (7,000 km2) is composed of a sequence of Tertiary and Quaternary loess deposits, which have been substantially reworked by .uvial and aeolian processes. As with other areas of the Chaco-Pampean Plain, groundwater in the basin suffers a range of chemical quality problems, including arsenic (con-centrations in the range of 12.2?1,660 lgL -1), .uo-ride (50?8,740 lgL -1), boron (34.0?9,550 lgL -1), vanadium (30.7?300 lgL -1) and uranium (0.03? 125 lgL -1). Shallow groundwater (depths up to 15 m) has particularly high concentrations of these elements. Exceedances above WHO (2011) guideline values are 100% for As, 35% for B, 21% for U and 17% for F. Concentrations in deep ([200 m) and artesian groundwater in the basin are also often high, though less extreme than at shallow depths. The waters are oxidizing, with often high bicarbonate concentra-tions (50.0?1,260 mg L -1) and pH (6.28?9.24). The ultimate sources of these trace elements are the volcanic components of the loess deposits, although sorption reactions involving secondary Al and Fe oxides also regulate the distribution and mobility of trace elements in the aquifers. In addition, concentra-tions of chromium lie in range of 79.4?232 lgL -1 in shallow groundwater, 129?250 lgL -1 in deep ground-water and 110?218 lgL -1 in artesian groundwater. All exceed the WHO guideline value of 50 lgL -1 . Their origin is likely to be predominantly geogenic, present as chromate in the ambient oxic and alkaline aquifer conditions. Keywords Groundwater geochemistry .Trace-element water quality .Arsenic .Loess source .Chaco-Pampean Plain Introduction The Chaco-Pampean Plain (about one million km2)is the largest and most populated geographical region in Argentina. The plain lies east of the Pampean Hills, extending from the Paraguay border in the north to the Patagonian Plateau in the south. Its central part is the H. B. Nicolli (&) Instituto de Geoqui´mica (INGEOQUI) and Consejo Nacional de Investigaciones Cienti´.cas y Te´cnicas (CONICET), Av. Ricardo Balbi´n 3100, B1663NER San Miguel, Provincia de Buenos Aires, Argentina e-mail: hbnicolli@gmail.com J. W. Garci´a .C. M. Falco´n Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucuma´n, Miguel Lillo 205, T4000JFE San Miguel de Tucuma´n, Argentina e-mail: jwgarcia@arnet.com.ar C. M. Falco´n e-mail: camafa377@yahoo.com.ar P. L. Smedley British Geological Survey, Kingsley Dunham Centre, Nicker Hill, Keyworth, Nottingham NG12 5BG, UK e-mail: pls@bgs.ac.uk 123 Environ Geochem Health (2012) 34:251?262 DOI 10.1007/s10653-011-9429-8 site of the country?s most important cities. One of the greatest obstacles for the socioeconomic regional development is the quality of the water resources available for the rural population. Saline or hard groundwater is the only water resource in wide areas, and this condition limits its use for human consumption. In addition, high trace-element concentrations (especially arsenic) often render the groundwater toxic for potable supply, cattle consumption and irrigation. A number of water-related health problems are linked to high arsenic concentrations in drinking water in the Chaco-Pampean region. From the early XIX century to 1913, the pathology was known as ??Bell-Ville disease?? because this was the city where the majority of recognized cases were found. That year, Dr. Mario Goyenechea proved by chemical analysis that arsenic caused the disease, a fact mentioned by Ci´rculo Me´dico del Rosario (1917) and described by Ayerza (1917a, b, 1918). Skin-pigmentation disorders and increase in neoplasms, particularly of the skin (squamous-cell carcinoma), bladder and digestive tract, were reported in central Argentina (Besuschio et al. 1980). The relation between As in drinking water and skin cancer was reported by Astol. et al. (1981, 1982). These health problems are regionally known as HACRE (the Spanish acronym for Hidro Arsenicismo Cro´nico Regional Ende´mico, Endemic Regional Chronic Hydro Arsenicism (Tello 1951)). Bladder cancer mortality associated with arsenic in drinking water was reported in Co´rdoba, central Argentina (Hopenhayn-Rich et al. 1996). Other studies concerned skin cancer (Cabrera and Go´mez 2003) and bladder cancer in relation to direct arsenic exposure (Bates et al. 2004). In addition, high .uoride concentrations in these waters are associated with dental .uorosis and sometimes bone .uorosis (de la Sota et al. 1997). Arsenic-and .uoride-related disease affects, potentially, four million inhabitants in the region as a whole. Moreover, the high salinity and the presence of excessive concentrations of As and F in irrigation waters are a strong limitation for agricultural production. Highly saline waters with high concentrations of potentially toxic elements (As [ 200 lgL -1;F [ 2,000 lgL -1) could lead to a risk for animals and may affect meat and milk quality. The health consequences due to other trace elements present in high concentrations and exceeding WHO guideline values assigned on health grounds is not known. The aim of the present research was to characterize the water chemistry with respect to As and associated trace elements and to determine the principal sources and controlling geochemical factors. The main water-related health problems of the region are also described. Regional setting In the sedimentary basin of Tucuma´nEastern Plain (10,000 km2), it is possible to differentiate two hydrogeological basins (Tineo 1998): the Burruyacu´ Basin in the north-eastern part and the Sali´River Basin (the study area) in the south-west and south-east of the province. The Sali´ River Basin (Fig. 1), the most important basin in Tucuma´n Province, is located between the eastern borders of the del Aconquija Ranges, the Calchaqui´es Summits and the de San Javier Ranges. The area covers almost 7,000 km2, extending as far as the structural lineament of the ??Tacanas Ridge?? and the Guasaya´n Ranges. The whole basin is covered by Quaternary sediments, which, according to geophysical studies and drilling data, may reach as much as 400 m thick. Two climatic areas are de.ned. The .rst, in the piedmont area, exhibits a moderate rainy temperate climate with rainfall reaching 2,000 mm/year. On the nearby plain, which extends from the piedmont to the eastern boundary with Santiago del Estero Province, rainfall gradually decreases until it reaches 600 mm. Winters are dry and summers, warm and humid. In the mountain area (5,000?500 m a.s.l.), steep slopes are about 10%. These facilitate runoff, particularly during the spring-summer rain period. The piedmont (500?350 m a.s.l.) has a slope decreasing to 2% and is characterized by modern deposits, alluvial fans and terrace levels with smaller grain-size towards the plain. Permeability is high, favouring water seepage for the recharge of basin aquifers. The plain (350?250 m a.s.l.) has a sharp change in slope (approximately 0.2%). This area consists of modern .uvial and aeolian deposits with intercalations of gravel and loess.