Assessment of geogenic input into Bilina stream sediments (Czech Republic).

Over the past 100 years, the area along the River Bílina has been influenced by open-cast brown-coal mining, coal processing, petroleum refineries, and chemical plants. As a result, the extensive industrial activity has changed the overall character as well as the morphology of the landscape. A survey was underway to investigate the occurrence and distribution of various elements in the sediments of the River Bílina-a tributary of the River Elbe, a watercourse running through the Czech Republic and Germany-in order to discern the natural background from anthropogenic pollution. The study evaluated the content of selected elements (As, Zn, Pb, Cr, Ni, V, and Cu) in stream sediments of the River Bílina. Samples were taken at 20 sampling sites throughout the 82-km-long watercourse. For all the samples, the content of the elements was determined using ICP-MS after each of the sample was digested using HF and HNO3 . The results of analyses of elemental composition of stream sediments were compared with those found through such analyses made within the surrounding geological units-more specifically, Proterozoic crystalline, Tertiary volcanic, Quaternary loess, Neogene sediments, and Neogene coal. All the samples of the stream sediments examined revealed increased amounts of As, V, Ni, Cr, and Pb. Using the enrichment factor established on the basis of the regional geological background values proved that elevated levels of elements in stream sediments are not always the result of industrial contamination.