Anaerobic Biodegradation and Hydrogeochemical Controls on Natural Attenuation of Trichloroethene in an Inland Forested Wetland

Authors: Lorah, Michelle M.¹; Dyer, Linda Jo¹; Burris, David R.²

Source: Bioremediation Journal, Volume 11, Number 2, April 2007 , pp. 85-102(18)

Publisher: Taylor and Francis Ltd

Abstract:

A field and laboratory investigation of natural attenuation, focusing on anaerobic biodegradation, was conducted in a forested wetland where a plume of trichloroethene discharges from a sand aquifer through organic-rich wetland and stream-bottom sediments. The rapid response of the wetland hydrology to precipitation events altered groundwater flow and geochemistry during wet conditions in the spring compared to the drier conditions in the summer and fall. During dry conditions, partial reductive dechlorination of trichloroethene to cis-1,2-dichloroethene occurred in methanogenic wetland porewater. Influx of oxygenated recharge during wet conditions resulted in a change from methanogenic to iron-reducing conditions and a lack of 1,2-dichloroethene production in the wet spring conditions. During these wet conditions, dilution was the primary attenuation mechanism evident for trichloroethene in the wetland porewater. Trichloroethene degradation was insignificant in anaerobic microcosms constructed with the shallow wetland sediment, and microbiological analyses showed a low microbial biomass and absence of known dehalorespiring microorganisms. Despite the typically organic-rich characteristic of wetland sediments, natural attenuation by anaerobic degradation may not be an effective groundwater remediation for chlorinated solvents at all sites.

Keywords: biodegradation; chlorinated solvents; groundwater contamination; natural attenuation; trichloroethene; wetlands

Document Type: Research article

DOI: http://dx.doi.org/10.1080/10889860701429294

Affiliations: 1: U.S. Geological Survey MD-DE-DC Water Science Center, Baltimore, Maryland, USA 2: Air Force Research Laboratory, Tyndall Air Force Base, Florida, USA

Publication date: 2007-04-01

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