Document Type : Original Research Paper
Authors
1 Ph.D. Student, Department of Geology, Shiraz University, Shiraz, Iran
2 Professor, Department of Geology, Shiraz University, Shiraz, Iran
Abstract
The Karstic Asmari & Jahrom Formations extensively outcrop in the Darab city region. The current Darab landfill site is located on sandy gravel alluvium, a few meters above the karstic Asmari Formation. The objective of this study was to investigate the effects of the landfill on groundwater quality. Ten karstic and alluvial exploitation wells and downstream of the landfill site were sampled to measure the concentrations of major ions, nitrates, heavy metals, trace elements, total coliform and fecal coliform. The major ions and nitrate concentrations are below the EPA Maximum Contaminant Levels (MCL). The fecal coliform exceeds the EPA MCL in most of the wells. There is no contaminant source to justify the high levels of fecal coliform in the exploitation wells. Fecal coliform is naturally present in the soil based on recent researches. The concentrations of Sb and Se are more than the EPA and WHO MCL in some of the wells. The source of these contaminants is not the Darab landfill, because no general flow direction and concentration trends are observed from the landsite towards the contaminated wells. In addition, there is no anthropogenic source of these elements in the study area. The sources of Sb and Se are most probably geogenic from limestone and shale. The volume of aquifer dynamic storage has been significantly reduced due to overexploitation and drought. Therefore, Sb and Se were dissolved in ever-decreasing volumes of water, and consequently, their concentrations increased.
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