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 concerns reducing the bioavailability of the pesticides, DDT and dieldrin, in the soil of an old orchard that was contaminated due to historical use of the pesticides. Different organic carbon amendments were mixed with the contaminated soil in a growth chamber pot study. Earthworms were placed in the pots of treated and untreated soils and pesticide bioavailability was assessed. A simple passive sampling approach to assess pesticide bioavailability was also conducted. Comparison of the two approaches indicates that passive sampling simulates uptake by earthworms and two manuscripts have been submitted on this work. 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. Experiments were conducted to examine the effectiveness of different combinations of materials (compost, mulch, gravel, sand, zero valent iron). Initial results suggest that sorption may play a critical role in removing contaminants from ground water. Methods currently under development in this project will be used to support sub-objective 1 of the parent project for measuring the volatile organic compounds in emissions from agricultural operations. Cooperative research activities are being carried out primarily at BARC by University of Maryland graduate students.