Isotope Biogeochemistry of Polycyclic Aromatic Hydrocarbons in Riverine Sediments (With Application to St. Lawrence and Hudson River)

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

0073912 Abrajano The molecular and stable isotopic compositions (C and H) of polycyclic aromatic hydrocarbons (PAH) and other particle-associated organic contaminants in riverine sediments reflect the combined effects of the (1) nature of contaminant sources, (2) biotic and abiotic transformation during transport, (3) dynamics of particle association and source mixing, (4) depositional history and (5) post-depositional diagenetic reactions. This multiplicity of possible sources and processes affecting particle-associated organic contaminants in large river systems requires a complete understanding of specific processes or sources on the molecular and isotopic chemistry of the contaminant. This in turn requires the availability of multiple hydrogeochemical vectors that are able to uniquely identify or seriously constrain specific contaminant sources and/or pathways. Our primary goal is to enhance existing approaches to evaluating the sources and fate of particle-associated organic contaminants in surface water systems. We will focus on the development of compound-specific 13C/12C and molecular organic measurements. The proposed work will examine the source discrimination potential of D/H ratios as well as D/H-specific transformation reactions involving hydrocarbons. Specifically, the impact of volatilization, photodegradation, sorption, and biodegradation on the D/H ratios of individual PAH compounds will be examined under a range of expected near-surface conditions. The proposed research will also examine the utility of the D/H technique for elucidating the sources and fate of PAH in the sediments of the St. Lawrence River (SLR) and Hudson River (HR) basins. These systems exemplify the multiplicity of natural and anthropogenic hydrocarbon sources in this region and elsewhere, and the long history of human use of these two rivers offers some of the most extensive records of anthropogenic hydrocarbon deposition and storage in river sediments.