USE OF HYDROGEN CONCENTRATIONS IN A WETLANDS NATURAL ATTENUATION EVALUATION

摘要

Hydrogen concentration data was used to evaluate the efficacy of natural attenuation of a chlorinated solvent plume near, and in, a wetland environment in Coastal North Carolina. Chlorinated solvents of interest included trichloroethene (TCE) and daughter products from multiple releases. An extensive soil and groundwater sampling program was conducted in several phases to determine the areas of highest contamination and evaluate the potential for natural biodegradation in the aquifer and wetlands system. Three rounds of groundwater sampling were conducted over a seven-month period from five well clusters along the plume centerline as well as four flanking well clusters. Analysis was conducted on samples from 34 wells per round and included the contaminants of concern and natural attenuation parameters (including dissolved oxygen, oxidation-reduction potential [ORP], ethene, ethane, methane, nitrate, ferrous iron chloride, sulfate, sulfide, total organic carbon [TOC]). Samples were collected for hydrogen analysis during the second and third rounds. Analysis indicates that the hydrogen data is spatially and temporarily variable; but when analyzed with other natural attenuation parameters, indicates that dechlorination is occurring predominantly through sulfate reduction to methanogenesis.