Geochemical controls of high fluoride groundwater in Umarkot Sub-District, Thar Desert, Pakistan

被引:99
作者
Rafique, Tahir [1 ]
Naseem, Shahid [2 ]
Ozsvath, David [3 ]
Hussain, Riaz [4 ]
Bhanger, Muhammad Iqbal [5 ]
Usmani, Tanzil Haider [1 ]
机构
[1] Appl Chem Res Ctr, Karachi 75280, Pakistan
[2] Univ Karachi, Dept Geol, Karachi 75270, Pakistan
[3] Univ Wisconsin, Dept Geog Geol, Stevens Point, WI 54481 USA
[4] Geol Survey Pakistan, Div Geophys, Karachi, Pakistan
[5] Univ Karachi, ICCBS, HEJ Res Inst Chem, Karachi, Pakistan
关键词
Fluoride ions; Mineral weathering; Evaporation; Calcite precipitation; Base ion exchange; Umarkot; Thar Desert; WATER-ROCK INTERACTION; BEDROCK GROUNDWATER; SOUTH-KOREA; AREA; INDIA; CHEMISTRY; BASIN; HYDROGEOCHEMISTRY; CONTAMINATION; BICARBONATE;
D O I
10.1016/j.scitotenv.2015.05.038
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Groundwater samples (n = 152) were collected in the Thar Desert of the Umarkot Sub-District, Pakistan to evaluate the geochemical controls on the occurrence of high fluoride (F-) levels within the study area. Fluoride concentrations range from 0.06 to 44.4 mg/L, with mean and median values of 5.22 and 4.09 mg/L, respectively; and roughly 84% of the samples contain fluoride concentrations that exceed the 1.5 mg/L drinking water standard set by WHO. The overall groundwater quality reflects the influences of silicate mineral weathering and evaporation. Fluoride originates from the weathering of minerals derived from Type-A granite and possibly anion exchange (OH- for F-) on clays and weathered micas under high pH conditions. High fluoride levels are associated with Na-HCO3 type water produced by calcite precipitation and/or base ion exchange. Depleted calcium levels in groundwater allow higher fluoride concentrations to occur before the solubility limit for fluorite is reached. (C) 2015 Elsevier B.V. All rights reserved.
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页码:271 / 278
页数:8
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