Arsenic contamination of natural waters in San Juan and La Pampa, Argentina

Abstract

Arsenic (As) speciation in surface and groundwater from two provinces in Argentina (San Juan and La Pampa) was investigated using solid phase extraction (SPE) cartridge methodology with comparison to total arsenic concentrations. A third province, Río Negro, was used as a control to the study. Strong cation exchange (SCX) and strong anion exchange (SAX) cartridges were utilised in series for the separation and preservation of arsenite (As ). Samples were collected from a range of water outlets (rivers/streams, wells, untreated domestic taps, well water treatment works) to assess the relationship between total arsenic and arsenic species, water type and water parameters (pH, conductivity and total dissolved solids, TDS). Analysis of the waters for arsenic (total and species) was performed by inductively coupled plasma mass spectrometry (ICP-MS) in collision cell mode. Total arsenic concentrations in the surface and groundwater from Encon and the San José de Jáchal region of San Juan (north-west Argentina within the Cuyo region) ranged from 9 -357 μg l -1As. Groundwater from Eduardo Castex (EC) and Ingeniero Luiggi (LU) in La Pampa (central Argentina within the Chaco-Pampean Plain) ranged from 3 -1326 μg l -1As. The pH range for the provinces of San Juan (7.2 -9.7) and La Pampa (7.0 -9.9) are in agreement with other published literature. The highest total arsenic concentrations were found in La Pampa well waters (both rural farms and pre-treated urban sources), particularly where there was high pH (typically > 8.2), conductivity (> 2600 μS cm As. Arsenic species for both provinces were predominantly As for groundwater, respectively. This translates to a relative As III abundance of 69 -100 % of the total arsenic in surface waters and 32 -100 % in groundwater. This is unexpected because it is typically thought that in oxidising conditions (surface waters), the dominant arsenic species is As V . However, data from the SPE methodology suggests that As III is the prevalent species in San Juan, indicating a greater influence from reductive processes. La Pampa groundwater had As (equating to up to 33 % of the total arsenic). Previously published literature has focused primarily on the inorganic arsenic species, however this study highlights the potentially significant concentrations of organoarsenicals present in natural waters. The potential for separating and preserving individual arsenic species in the field to avoid transformation during transport to the laboratory, enabling an accurate assessment of in-situ arsenic speciation in water supplies is discussed.

Synthesis and arsenic adsorption performances of ferric-based layered double hydroxide with α-alanine intercalation

“…Besides, anthropogenic sources like mining activities, combustion of fossil fuels, and use of arsenic pesticides produce additional negative impact. Arsenic pollution, as a worldwide problem, has been reported in a lot of countries and regions including the USA [7], Canada [8], Mexico [9], Argentina [10], Australia [11], Japan [12], China [13], India [1], Bangladesh [14] and so on [15]. Accumulation of evidences for chronic toxicological effects of arsenic in drinking water leads the World Health Organization [16], European Union [17], and the U.S. Environmental Protection Agency [18] to lower the regulatory limits and the maximum contaminant level of arsenic in drinking water from 50 to 10 μg·L 1 .…”

Arsenic speciation in polychaetes (Annelida) and sediments from the intertidal mudflat of Sundarban mangrove wetland, India

“…A quaternary pump (GP50-2 HPLC Pump and an AS-50 autosampler (Dionex, USA)) was directly coupled to an ICP-MS (Agilent 7500) for the measurement of arsenic species as described in Watts et al (2008) and O'Reilly et al (2010). An analytical column comprising of a PRP-X100 anion exchange column (250 x 4 mm, 10 μm) and a guard column of the same material (Hamilton, USA) was connected directly to the ICP nebulizer using PEEK tubing.…”

“…were achieved through the coupling of the two instruments. Chromatographic conditions utilised a gradient program using 4 and 60 mM NH 4 NO 3 as described in Watts et al (2008) and O'Reilly et al (2010).The HPLC-ICP-MS was operated in single ion monitoring mode at signal m/z 75, with a dwell time of 100 ms. The quantitative analysis of peak areas from the resultant chromatograms was performed using Agilent ICP-MS Chromatographic Data Analysis Software version B.03.06 (Agilent Technologies, UK).…”

Isolation of Mn(II), Fe(III), Cu(II) and Ni(II) ions on strongly acidic cation-exchange resins followed by determination of inorganic arsenic by anodic stripping voltammetry

“…Anodic stripping voltammetry (ASV) is successfully used for the determination of micro quantities of inorganic arsenic in various samples [7][8][9][10][11][12]. Arsenic(III) is usually analyzed in acidic medium with dilute hydrochloric acid.…”