期刊
ENVIRONMENTAL EARTH SCIENCES
卷 75, 期 8, 页码 -出版社
SPRINGER
DOI: 10.1007/s12665-016-5478-8
关键词
Groundwater; Fluoride; Na+; Bicarbonate; Gabbro; Silicate weathering; Water types
Thirty-six groundwater samples were collected from Chimakurthy area, Prakasam District, Andhra Pradesh. On hydrogeochemical evaluation, it was found to be contaminated. Based on fluoride concentration, the samples were segregated into Group A, Group B, and Group C. Fluoride concentration varies from 0.23 to 9.84 mg/l, with the mean value of 2.01 mg/l; 44 % of the tested samples had F- > 1.50 mg/l. Apart from F-, the water was contaminated with NO3- and Cl- implying both geogenic and anthropogenic pollution of the aquifer. Ionic dominance pattern was unique in samples with low, moderate to high F- concentrations. Na+ and HCO3- were progressively increasing along with F- from Group A to C, whereas Ca2+ and Mg2+ were depleting. Groundwater facies were unique among different group samples especially in end members with low and high F- concentration suggesting that F- dissolution was strongly influenced by the chemical nature of solution. Na+/Cl -molar ratio was >1, whereas Na+ + K+:Tz(+) and Ca2+ + Mg2+:Tz(+) ratios were <1 in all samples indicating that Na+ was released from silicate weathering process. It also confirms that F- was contributed from lithogenic sources of aquifer material. Mean molecular ratios of <1 for Ca2+: Mg2+ in Group B samples and 1-1.2 in Groups A and C support that the Ca2+ and Mg2+ were added into aquatic medium by calcite and dolomite dissolution. Contradictory distribution of F- in north (low) and south (high) indicates that availability of F- minerals in aquifer matrix influenced the rate of F absorption in accompanying water. Variation in F- concentration in groundwater of the core area (south) supports the hypothesis of aquatic chemistry acting as catalyst in F dissolution into formation waters even though the aquifer was enriched with F- minerals. Very high F- in groundwater in the contact zone of country rock and plutonic intrusive indicates that F- mineralization occurred under geothermal conditions. The fracture network in disturbed and fragile contact zone has facilitated development of potential aquifers and enhancement in F- concentration.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据