Samples from tributaries draining known mineralized areas contain considerably more lead than those from the main stream. The unique sediments (i.e. lead rich) from the tributaries are quickly diluted in the main stream to background levels. The lead content of the sediments from the tributaries apparently is controlled by the presence of lead-rich clasts. Sorption of lead by iron oxide coating grains is more significant in the main stream because the unique clasts are diluted. The mineralization also increases zinc and cadmium levels in the sediments. The concentration of calcium is controlled largely by the presence of limestone, whereas the concentrations of Mg, Mn, Co, Cu, Cr and Ni are controlled primarily by the presence of shale fragments and sorption by iron oxide coating clasts.
Bowen, William S. and Steele, Kenneth F.
"Relationship of Lead Mineralization and Bottom Sediment Composition of Streams, Ponca-Boxley District, Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 29
, Article 9.
Available at: http://scholarworks.uark.edu/jaas/vol29/iss1/9