Abstract

Suspended material samples were collected from eastern Kansas rivers during several floods. The samples were examined for qualitative mineralogy, sediment size, and the concentrations and locations of selected trace metals (Fe, Mn, Zn, Ni, Cu, Co). Illite, interlayered material with montmorillonite, kaolinite, quartz, and potassium feldspar were detected in samples from all rivers. Vermiculite was significant in samples from rivers draining Pleistocene glacial deposits. The size distributions were similar for all rivers. The suspended materials were chemically separated into three extracts: 1) manganese oxides, carbonates and organics, 2) iron oxides, other metal oxides, and leached iron from iron minerals, and 3) crystalline sediments. Manganese concentrations were highest in extract 1). Iron and zinc concentrations were highest in extracts 2) and 3). Trace metal concentrations in flood sediment samples were lower than those collected during average river discharge. The lower chemical concentrations are due to dilution of the suspended materials by leached soils, transported to the rivers by sheet wash. Although floods transport greater than 90 percent of the annual sediment load in Kansas rivers (Mundorff and Scott, 1964), a higher trace metal concentration is transported during average discharge than during flooding.

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