Use of sediment-trace element geochemical models for the identification of local fluvial baseline concentrations

Abstract

Studies have demonstrated the utility of fluvial bed sediment chemical data in assessing local water-quality conditions. However, estab­ lishing local background trace element levels can be difficult. Reference to published average concentrations or the use of dated cores are often of little use in small areas of diverse local petrology, geology, land use, or hydrolo­ gy. An alternative approach entails the construction of a series of sediment- trace element predictive models based on data from environmentally di­ verse but unaffected areas. Predicted values could provide a measure of lo­ cal background concentrations and comparison with actual measured concentrations could identify elevated trace elements and affected sites. Such a model set was developed from surface bed sediments collected na­ tionwide in the United States. Tests of the models in a small Louisiana basin indicated that they could be used to establish local trace element back­ ground levels, but required recalibration to account for local geochemical conditions outside the range of samples used to generate the nationwide models.