DISSIPATION OF PAHs IN SATURATED, DREDGED SEDIMENTS: A FIELD TRIAL

Authors: Smith, Katy; SCHWAB, A - PURDUE UNIVERSITY; BANKS, M - PURDUE UNIVERSITY

Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2008
Publication Date: 6/10/2008
Citation: Smith, K.E., Schwab, A.P., Banks, M.K. 2008. Dissipation of pahs in saturated, dredged sediments: a field trial. Chemosphere. 72:1614-1619.

Interpretive Summary: Sediments dredged from navigable rivers often contain elevated concentrations of recalcitrant, potentially toxic organic compounds such as polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). The presence of these compounds often requires that the sediments be stored in fully contained disposal facilities. A three-year field study was conducted at the Jones Island disposal facility in Milwaukee, Wisconsin to compare bioremediation of PAHs in contaminated dredged sediments in the absence of plants to phytoremediation with Salix nigra (black willow) (SX61), Spartina pectinata (prairie cord grass), Carex aquatalis (lake sedge), Lolium multiflorum (annual rye), and Scirpus fluviatilis (bulrush). Nine PAHs were detected initially in the sediments. Over the three-year experiment, acenaphthene dissipation ranged from 94 to 100%, whereas anthracene, benzo[a]pyrene and indo[1,2,3-cd]pyrene generally had modest decreases in concentration (0 to 30% decrease). The remaining five PAHs ranged in degree of disappearance from 23 to 82%. Planted treatments did not enhance PAH dissipation relative to those without plants, but treatments with high biomass yield and high transpiration plant species had significantly less removal of PAHs than unplanted controls. Significant, negative correlations between nitrogen removal and decreases in PAH concentration suggest that competition for nutrients between plants and microorganisms may have impeded the microbial degradation of PAHs in the rhizosphere of the more rapidly growing plant species.

Technical Abstract: Sediments dredged from navigable rivers often contain elevated concentrations of recalcitrant, potentially toxic organic compounds such as polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). The presence of these compounds often requires that the sediments be stored in fully contained disposal facilities. A three-year field study was conducted at the Jones Island disposal facility in Milwaukee, Wisconsin to compare bioremediation of PAHs in contaminated dredged sediments in the absence of plants to phytoremediation with Salix nigra (black willow) (SX61), Spartina pectinata (prairie cord grass), Carex aquatalis (lake sedge), Lolium multiflorum (annual rye), and Scirpus fluviatilis (bulrush). Nine PAHs were detected initially in the sediments. Over the three-year experiment, acenaphthene dissipation ranged from 94 to 100%, whereas anthracene, benzo[a]pyrene and indo[1,2,3-cd]pyrene generally had modest decreases in concentration (0 to 30% decrease). The remaining five PAHs ranged in degree of disappearance from 23 to 82%. Planted treatments did not enhance PAH dissipation relative to those without plants, but treatments with high biomass yield and high transpiration plant species had significantly less removal of PAHs than unplanted controls. Significant, negative correlations between nitrogen removal and decreases in PAH concentration suggest that competition for nutrients between plants and microorganisms may have impeded the microbial degradation of PAHs in the rhizosphere of the more rapidly growing plant species.