The occurrence and geographic distribution of major metals and trace elements was assessed in the lower Kansas River Basin of Kansas and Nebraska by studying the concentrations of metals and nonmetallic elements in the less-than 63-micrometer-sized fraction of streambedsediment samples from 422 sites on first- and second-order streams. Median concentrations were the same order of magnitude as the geometric mean concentrations in soils of the western United States. Either threshold concentrations or upper percentile classes (greater than 50 percent of concentrations) were determined for 14 metals, arsenic, and phosphorus. Threshold concentrations were determined as the point that the slope of a normal-probability plot increases, indicating data from two different populations. Samples with a concentration greater than the threshold concentration indicated possible enrichment with respect to that particular element. Concentrations of the transition metals, which included chromium, cobalt, copper, manganese, nickel, and vanadium, generally were larger in the southeastern part of the study unit where Permian and Pennsylvanian shale and limestone predominate.
The largest concentrations of the alkali metals, potassium and sodium, mainly were in the northwestern part of the study unit, which is an area of Quaternary loess deposits irrigated with ground water. Large concentrations of the alkaline-earth metal, barium, also were in the northwestern part of the study unit. Concentrations of the other alkaline-earth metals, calcium, magnesium, and strontium, were larger in the southern part of the basin, which is underlain by Permian and Pennsylvanian shale and limestone. The largest concentrations of arsenic and lead were mainly in the southeastern part of the study unit, an area of Permian and Pennsylvanian shale. Large concentrations of phosphorus in the northwestern part of the study unit probably were due to runoff from irrigated agricultural lands.
