Spatial-temporal distribution characteristics and source analysis of sediments in Qinghai Lake, China

Sediment is not only an important component of lake ecosystem, but also an important element and interface of geochemical cycle of lake eutrophication. Carrying abundant information of natural environment and mode as well as intensity of human activities on environment, lake sediments are vital to the water environment of lakes. In this paper, nutritive salt and heavy metal elements from different depths of sediments collected from eight representative sites in Qinghai Lake were analyzed, in order to demonstrate the spatial distribution law and accumulation pattern of nitrogen form, phosphorus form, organics, and typical heavy metal elements. Results showed significantly uneven spatial distribution of total nitrogen and organics in the surface sediments in Qinghai Lake, while total phosphorus in the surface sediments presented a relative equilibrium spatial distribution. Vertical distribution of nutritive salt in sediment cores differs from each other. Heavy metals in sediments have relative stable natural source and most heavy metal elements enjoy higher homology, which can be accumulated in sediments through coprecipitation or absorption. The fluctuating vertical distribution of heavy metals may be mainly caused by human activities. This research results can be served as scientific basis for water pollution and heavy metal pollution prevention in sediments in Qinghai Lake.