ISSN:
1573-2932
Keywords:
Arsenic forms
;
arsenic concentrations
;
solubility isotherms
;
groundwater aquifers
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract Groundwater samples were collected from shallow aquifers underneath an industrial complex in the Eastern Province of Saudi Arabia. Arsenic (As) concentrations in the groundwater samples varied between 10−8.6 and 10−6.8 M (0.18 and 11.14 µg L−1), with an average of 10−7.5 M (2.19 μ L−1). The analysis of variance for the analytical data showed that sampling locations had significantly affected As concentrations in the groundwater samples. Analytical and thermodynamic calculations showed that H2ASO4 − was the most predominant As species in acidic groundwater samples, and HAsO4 2− was the most abundant species in alkaline groundwater samples. Concentrations of H3AsO4° and AsO4 3− were too low to be important in this study. Reduced As chemical forms were also expected to be very low. All the groundwater samples were undersaturated with respect to the thermodynamic solubility isotherms of Ca3(AsO4)2(c), Fe3(AsO4)2(c), and Mn3(AsO4)2(c) minerals. Lack of reliable thermodynamic data for these arsenates could be responsible for differences between the theoretical and measured concentrations of As in the shallow groundwater samples. The general trend in the distribution of HAsO4 2− activities in the groundwater samples was parallel to that of the Ca3(AsO4)2 solubility isotherm but different from those of Fe3(AsO4)2(c), and Mn3(AsO4)2(c). These data suggest that As concentrations in the groundwater samples were probably controlled by the precipitation and dissolution of Ca3(AsO4)2 type mineral. A three step hypothesis for As interactions in groundwater/soil system is proposed that combines both solid phase formation and adsorption of As onto the solid colloidal surfaces. This hypothesis is expected to better represent As behavior in groundwater/soil environment.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00300422
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