Water Resources Research Act Program

Details for Project ID 2003NC25B

The Role of Flood Flows on the Lead Isotopic Composition of Stream Waters, Suspended Sediments, and Rainbow Trout Downstream of Lead Contaminated Soils in Barber's Orchard

Institute: North Carolina
Year Established: 2003 Start Date: 2003-03-01 End Date: 2004-06-01
Total Federal Funds: $39,084 Total Non-Federal Funds: $78,166

Principal Investigators: Jerry Miller, Peter Galbreath

Project Summary: Recent studies demonstrate that Pb isotopes are excellent tracers of metal contamination because the isotopic abundances found in ore deposits from which Pb in industrial products is derived, differ from those contained in other rock types that generally serve as the natural source of Pb in the environment. Moreover, Pb isotopes are not fractionated during biological uptake, theoretically allowing a determination of the relative contributions of Pb in biota from different Pb sources. This investigation will determine the effectiveness of using Pb isotopes to track the movement of lead arsenate, an extensively used pesticide, through biotic and abiotic components of an aquatic ecosystem. More specifically, four hypotheses generated from our previous studies of Richland Creek, which drains the Barbers Orchard Superfund site, will be tested. These hypotheses include (1) that short-term shifts in the isotopic composition of water occurs within Richland Creek during flood events as a result of the erosion and transport of contaminated soils from Barbers Orchard, (2) that Pb is sequestered in the bone of fish (as a replacement element for calcium), whereas it is readily excreted by fleshy tissues, (3) that bone reflects the isotopic signature of contaminant Pb because of the bioavailability and concentrations of Pb to which the fish are subjected during flood events, and (4) that fish bone provides a long-term biomarker of Pb loadings to the aquatic system, whereas soft tissues such as liver and muscle reflect the isotopic composition of the water within a few days of sampling. Analysis of these hypotheses will involve the collection of geochemical and hydrologic data from Richland Creek, and the assessment of Pb isotopic partitioning in rainbow trout within the laboratory where concentrations, duration, nature of exposure, and the isotopic fingerprint of the contaminating materials (lead nitrate) can be controlled. To our knowledge, this is the first study to apply Pb isotopic fingerprinting to the transport and fate of lead arsenate in stream systems. It is important to recognize, however, that the study results are not only important to the fingerprinting of lead arsenate, but Pb contaminants in general.