Abstract
The present work focuses on the environmental problem of Thebes Plain—since considerable amounts of Cr (VI) have been reported—and tries to find out the reasons of such a phenomenon and the sources of the pollution. For this issue, a complete chemical analysis of 20 samples from the study area was conducted as well as an isotopic analysis of Cr and Sr isotopes. Hexavalent chromium pollution can be triggered by human pollutant activity or specific geological environments. Stable Cr isotopic analysis gave δ53Cr positive values in several samples which supports the second hypothesis, but the limitations of that theory do not allow safe conclusions in all cases. Nitrates and Sr ratios suggest fertilizer contamination and the presence of SiO2-leaching of silicate rocks.
Highlights
Hexavalent chromium pollution is a common phenomenon, since several case studies can be mentioned from all around the world such as Urania State of Sao Paolo, Brazil [1]; La Specia Province, Italy [2]; Leon Valley, Mexico [3]; and Mojave Desert, California, USA [4]
The study area is a complex environment where the geogenic factor plays an important role in the presence of hexavalent chromium in soil and groundwater
The theory of isotopes has to be used with great attention since hexavalent chromium tends to oxidize to trivalent chromium under suitable conditions, this results in fractionation of the considering sample and it may give positive δ53 Cr values [21] even if the Cr (VI) concentrations are from anthropogenic sources
Summary
Hexavalent chromium pollution is a common phenomenon, since several case studies can be mentioned from all around the world such as Urania State of Sao Paolo, Brazil [1]; La Specia Province, Italy [2]; Leon Valley, Mexico [3]; and Mojave Desert, California, USA [4]. Industrial activity creates wastes of Cr (VI) mainly due to treatment of inorganic and organic matters [14] Another pollutant factor is agricultural activity since several fertilizers and agrochemicals contain Cr (VI) [15]. This has been reported in fertilizers of the study area [16]. Especially from urban networks, directly lead the humid elements into the groundwater Another factor is the improper manufacture of drillings which can result in the mixture of aquifers and pipe leaching. The study area is a complex environment where the geogenic factor plays an important role in the presence of hexavalent chromium in soil and groundwater. SiO2 to check if the values match and leaching of silicate rocks takes place
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