Sedimentary profiles of pollution marker chemicals along a large tributary of Chesapeake Bay (mid-Atlantic USA)

Autor: Thomas B. Huff, Randolph A. McBride, Gregory D. Foster, Cassi L. Walls, Phillip R. McEachern
Rok vydání: 2018
Předmět:
Zdroj: Journal of Soils and Sediments. 19:1511-1526
ISSN: 1614-7480
1439-0108
DOI: 10.1007/s11368-018-2157-2
Popis: Molecular markers in environmental geochemistry include natural product or pollutant chemicals in sediments that are indicative of discharge sources or emission pathways. Four classes of molecular marker compounds, including fatty acids, sterols, PCBs, and PAHs, in surficial sediments (top 2 cm) collected along a downstream transect of the Potomac River within the US mid-Atlantic region were analyzed and correlated with potential pollution discharge sources in close proximity to the sampling sites. Thirty-five surficial sediment samples were collected using a petite Ponar grab sampler along a 320-km longitudinal transect of the Potomac River (mid-Atlantic USA), a major tributary of Chesapeake Bay, ranging from the upland fluvial river to its confluence with the Bay. The sediments were collected along the transect at approximately equidistant points. The marker chemicals were extracted from sediments using microwave-assisted extraction and quantified on a dry weight basis by gas chromatography or gas chromatography-mass spectrometry. Sediment moisture, texture, and organic carbon and nitrogen content were also determined. Fatty acids and sterols were well correlated with ecological factors in the Potomac River, while the sterol ratio epi+brassicasterol/stigmasterol showed moderate spatial correlation with nearby waste treatment plants (WTPs) and city locations, especially in the upland and tidal freshwater river. The fecal sterol coprostanol also showed moderate spatial correlation with some WTPs in both the upland and tidal river. PCB and PAH concentrations were primarily correlated with urban and large military installations. PCBs in sediments appeared to be predominantly derived from Aroclors while PAHs showed a strong pyrogenic origin. Retene and perylene were unique markers for PAHs in sediment and were indicative of aged organic matter in sediments. The marker chemicals had utility in identifying pollution emission sources and pathways in the Potomac River. For PCB pollutants, sediment profiles reflected localized source emissions from industrial sites. PAHs showed a downstream plume effect derived from urban Washington, DC. Fatty acids and sterols were most useful for identifying ecological shifts (i.e., terrestrial versus aquatic origin), but showed spatial correlations with wastewater treatment plants and cities.
Databáze: OpenAIRE
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