ISSN:
1573-2932
Keywords:
chemical forms
;
groundwater aquifers
;
lead chemistry
;
solid phases of lead
;
solubility isotherms
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract The objectives of this study were to investigate Pb contamination of a shallow groundwater aquifer underneath an industrial complex and Pb chemical forms that may be found in the study area. Concentrations of Pb in the groundwater samples ranged between 0.04 to 1570.12 µg L-1 (10-9.4 to 10-5.1 mole L-1), with an average of 88.2 µg L-1 (10-6.4 mole L-1). The results of analysis of variance showed that sampling locations had significantly (p 〈0.05) affected Pb concentrations in the groundwater samples. Contour map of Pb concentrations and Pb/Cl ratios indicated that Pb contamination of groundwater could be associated to the seepage of irrigation water, corrosion of buried metallic structure (largely of iron), and leachate from the industrial dust pile. Thermodynamic modeling approach was used to speciate total Pb concentrations in the groundwater samples. The results of these computations revealed that, in the very dilute groundwater (salinity 〈 1 parts per thousand, i.e., ppt), Pb2+ and Pb-OH complexes were the most significant chemical forms. Groundwater salinities between 1 to 5 ppt, Pb2+, Pb-OH, Pb-Cl, Pb-HCO3, and Pb-SO4 were present in appreciable concentrations, depending on their respective anionic concentrations. Over 80% of the total Pb in water was present in Pb-Cl complexes in groundwater samples with salinities 〉40 ppt. A comparison of the calculated activities of Pb2+ and the thermodynamic solubility isotherms of Pb minerals suggested that mineral Pb(OH)2(c) was too soluble to precipitate in these water samples. The distribution trend in Pb2+ activities do not support equilibrium with Pb3(PO4)2(c). Formation of PbCO3(c) and Pb2CO3Cl2(c) in the groundwater samples appeared to be the most logical option. From the foregoing, it was concluded that Pb-CO3 minerals can limit Pb solubility in saline groundwaters.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1026418513001
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