1a.Objectives (from AD-416)
Examine the use of recycled organic and inorganic materials in lower cost remediation approaches for sites contaminated with persistent organic pollutants.
1b.Approach (from AD-416)
Research will focus on two contaminated sites at the Beltsville Agricultural Research Center. The first is an area contaminated with the chlorinated insecticides DDT and dieldrin from historical use. Bench scale pot studies will be carried out with representative soils from the site to examine the effectiveness of different organic matter amendments and growing plants on reducing the bioavailability of the pollutants to earthworms. Results of the small scale experiments will be used to design a treatment for the contaminated site. Field scale trials will be carried out as a second phase of this work. The second site is a former landfill where trichloroethene (TCE) contamination has been discovered in groundwater seepage. A potential treatment approach is to install a biowall (permeable reactive barrier) down gradient of the contaminated area. Bench-scale experiments will be conducted that incorporate organic and inorganic materials in a hardwood mulch-based biowall. In addition, we will characterize the effects of the column biowall matrices on microbial community changes. Results of the column microcosm biowall tests will be used to design a site implementation plan using the best remediation biowall matrx treatment at the contaminated site at BARC. Field-scale trials of the most effective materials will be carried out in later stages of this project.
This specific cooperative agreement was created to support two separate but related projects. Each project seeks to implement sustainable remediation methods for contaminated sites at the Beltsville Agricultural Research Center (BARC). The first project is centered on reducing the bioavailability of the pesticides dichlorodiphenyldichloroethane (DDT) and dieldrin in soils of an old orchard field that is contaminated from historical use. Different organic carbon amendments are being tested with the contaminated soil in a growth chamber pot study. Earthworms are to be inserted in treated and untreated soils and exposed to observe differences in pesticide bioavailability. A simple passive sampling approach is also being tested for the assessment of bioavailability in comparison with the earthworms. Initial results using this simple method are very promising and can likely be used in support of subobjective 3 of the parent project for measuring the emission potential of less volatile residues in soil. The second project focuses on the development of an underground, permeable biowall to treat off-site movement of a chlorinated solvent from an old landfill at BARC. The biowall should facilitate degradation of the solvent and prevent movement of the contaminant into a nearby stream. Initial experiments will test the effectiveness of different combinations of materials (compost, mulch, gravel, sand, zero valent iron). Methods currently under development in this project will be used to support subobjective 3 of the parent project for measuring the emission potential of volatile organic compounds in soil. Monitoring of project activities has been carried out through multiple planning meetings of all participating groups and frequent email communications to facilitate progress towards project objectives.