Ma, Yingqun and Lu, Wenzhou and Lin, Chuxia (2011) Downstream patterns of bed sediment-borne metals, minerals and organic matter in a stream system receiving acidic mine effluent: a preliminary study. Journal of Geochemical Exploration, 110 (2). pp. 98-106. ISSN 0375-6742
Abstract
Different downstream variation patterns were observed for a range of bed sediment-borne metals (aqua regia-extractable fraction) in a subtropical stream system receiving acid mine drainage. Mine-originated Fe tended to be deposited in the acidic (mean pH b4.9) upstream reach in forms of goethite and/or hematite. In contrast, other metals tended to be transported farther downstream and settled in a low-gradient reach with high pH (mean pH N5.6). The peak of sediment-borne Al, Be, Ca, Cd, Co, Cu, La, Mn, Ni and Zn corresponded very well with the peak of the sediment-borne organic matter, suggesting a close association between the
water-borne organic colloids and the inorganic metal oxides/hydroxides during their transport. The marked
increase in the sediment-borne Al and Pb started more upstream than the other metals, suggesting that the
water-borne Al and Pb were more susceptible to pH rise-induced precipitation, as compared to the other
metals. It appeared that the organic colloids played no important role in Pb transport and settlement. The iron
precipitates had a limited role to play in affecting the transport and fates of other metals since they were
predominantly formed and deposited in the acidic reach, which made them incapable of scavenging cationic metals by co-precipitation or adsorption.
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