Abstract
The impact of reservoir emptying on the concentrations of dissolved heavy metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in pore and surface waters was studied in the Aar Reservoir, a small reservoir in central Germany, during and after the emptying process. This study was conducted to observe binding changes within pore waters as well as the input of dissolved heavy metals in waters of the Aar Creek, what becomes possible when the reservoirs water table is removed and lake sediments become exposed. In pore waters, no clear shifting tendencies between dissolved and sorbed heavy metal fractions could be found after the completed sediment exposure. These relatively low dynamics in pore waters can be explained by the fine texture of the lake sediments, which are characterized by a high water holding capacity, what led to high remaining water contents and therefore slowed down the redox changes. A few days after the completed emptying, a general increase of dissolved heavy metal concentrations occurred in running waters of the Aar Creek as a result of pore water drainage. Here, element specific differences in mobilization and transportation abilities were found, what can be reconstructed by the ratio of dissolved heavy metals in pore and surface waters.
Highlights
Heavy metals with a mass density of >5 g/cm3 are natural components in rocks, soils and sediments
The sampling of surface waters began on 19th August 2011, even during the emptying process of the reservoir
The lake sediments were marked by high volumetric water contents and low densities at the beginning of the field campaign
Summary
Heavy metals with a mass density of >5 g/cm are natural components in rocks, soils and sediments. In consequence of human activities (e.g. mining, industrial emissions, car emissions), heavy metals can be distributed or emitted into the environment. When they hereafter entered into sediments and soils, they can be accumulated and increased in their concentrations, because they are non-degradable. (2015) Heavy Metal Concentrations in Pores and Surface Waters during the Emptying of a Small Reservoir. The fine-grained sediment fractions and organic components of river and reservoir sediments are able to sorb heavy metals [3] [4]
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