Abstract
Sediment management is a fundamental part of reservoir operation, but it is often complicated by metal(loid) enrichment in sediments. Knowledge concerning the sources of potential contaminants is therefore of important significance. To address this issue, the concentrations and the mobile fractions of metal(loid)s were determined in the sediments and the respective catchment areas of six reservoirs. The results indicate that reservoirs generally have a high potential for contaminated sediment accumulation due to preferential deposition of fine particles. The median values of the element-specific enrichment factor (EF) demonstrates slight enrichments of arsenic (EF: 3.4), chromium (EF: 2.8), and vanadium (EF: 2.9) for reservoir sediments. The enrichments of cadmium (EF: 8.2), manganese (EF: 3.9), nickel (EF: 4.8), and zinc (EF: 5.0) are significantly higher. This is enabled by a diffuse element release from the soils into the impounded streams, which is particularly favored by soil acidity. Leaching from the catchment soils partially enriches elements in stream sediments before their fine-grained portions in particular are deposited as reservoir sediment. We assume that this effect is of high relevance especially for reservoirs impounding small streams with forested catchments and weakly acid buffering parent material of soil formation.
Highlights
The investigated reservoir sediments (RS) and stream sediments (SS) have a mostly silty texture and variously pronounced organoleptic characteristics of anoxic conditions. This applies to the sediments of the Einsiedel and Lehnmühle reservoirs, which were drained shortly before sampling
The investigated catchment soils (CS) of terrestrial slope areas were predominantly classified as Dystric Cambisols
In the catchment area of the Steinbach Reservoir, the soil type Dystric Histosol was found in some cases at semi-terrestrial sites
Summary
Reservoirs are increasingly used for energy and drinking water production worldwide. In Germany, are there 371 “larger” dams (defined by either a height ≥ 15 m or a reservoir storage volume ≥ 3,000,000 m3 ), the majority of which were built between. 1900 and 2000 [1] These reservoirs are mainly used for energy production and drinking water supply, and they are operated by private companies or federal states [2,3]. Several reservoirs are used to regulate the water level of rivers and represent important instruments for the operation of federal waterways [4]. Sediment dredging from the reservoir bottom, and other measures that serve to maintain their functionality are necessary works [5] that have to be increasingly carried out in recent years since most of the reservoirs in Germany are older than 80–100 years [2]
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