Geochemistry of metals in sediments from the mainstem of the Yellow River, China

Sediment samples at 10 locations in the mainstem of the Yellow River were taken in 1994. Five forms (exchangeable, carbonate, organic, Fe/Mn oxide and residual) of metals were extracted by the Tessier method. The total contents and contents of the five forms of 16 metal elements (Li, Na, K, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Al) were determined by ICP-AES. In sediments of the Yellow River, except for Na, mobile elements (such as K, Ca) do not show a negative correlation with the immobile elements. Alkaline metals (Li, Na, and K), Ti, and Al exist mainly in the residual form. The exchangeable forms of alkaline-earth elements (Ca, Sr, and Ba) are the highest, and their residual forms go up with the increase of the period in the periodic table of elements. Half of Mn exists in the residual form, and its non-residual forms exist mainly in carbonate and oxide forms. Except Mn, the iron group elements (Fe, Co, Ni, V, Cr) mainly exist in the residual and oxide forms. High carbonate content of Ca does not cause high contents of other elements in carbonate form, showing that chemical weathering is not strong in the area.