Characterization of selected element concentrations and enrichment ratios in background and anthropogenically impacted roadside areas

Previous research by the National Contaminant Biomonitoring Program found f ish from Manoa Stream, Hawaii, to have the highest concentrations of Pb in the nation. To explore possible source linkages we sampled background (unco ntaminated) soil, roadside soil, and road deposited sediment in Manoa water shed and analyzed them for total and extractable concentrations of Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn. Our concentration and enrichment ratio data ind icate that Al, Co, Fe, Mn, and Ni were controlled by natural source variati ons, and Cu, Zn, and particularly Pb were anthropogenically enhanced. Labil e Pb concentrations, extracted with either dilute HCl or EDTA, reached a ma ximum of 3,560 mg/kg compared to background values of <10 mg/kg. Additional ly, 25% of the 169 contaminated samples analyzed had EDTA-extractable Pb en richment ratios greater than or equal to 11.5, where a value of 1 separates uncontaminated from contaminated media. Given the proximity of most sample s to roadways it is reasonable to conclude that automotive emissions plus v ehicle wear were the primary contributors of trace metals to the roadside s ystem. These data are discussed in context with previous work on the fluvia l bed sediments in this watershed in an attempt to examine the potential li nkage with the biological accumulation of Pb in fish from Manoa watershed.