Comparison of sediment metal : aluminum relationships between the eastern and gulf coasts of the United States

Aluminum is often used as a conservative tracer to separate natural from an thropogenic components of metal contamination in marine sediments, but iden tifying uncontaminated sites to develop baseline metal:aluminum relationshi ps can be problematic in populated areas. Here we present a new method for identifying baseline relationships in high population density areas. The me thod involves comparing the residual from the metal:aluminum regression wit h an independent estimate of laboratory measurement error, based on the pre mise that mean square error from the regression must equal laboratory measu rement error for any data set that is free of anthropogenically enriched si tes. The method is applied to data sets from the mid-Atlantic and Gulf coas ts of the United States to test consistency in baseline relationships betwe en these two coasts of geologically different origin. Differences in metal: aluminum relationships between coasts were found to be small and limited to the least abundant trace metals.