Tracking Persistent Organic Pollutants (POPs) Through Biotic and Abiotic Processes in the EnvironmentEPA Grant Number: R828174
Title: Tracking Persistent Organic Pollutants (POPs) Through Biotic and Abiotic Processes in the Environment
Investigators: Mattina, MaryJane Incorvia , Eitzer, Brian , Simon, Ted
Institution: Connecticut Agricultural Experiment Station
EPA Project Officer: Shapiro, Paul
Project Period: July 1, 2000 through June 30, 2002
Project Amount: $194,622
RFA: Exploratory Research - Engineering, Chemistry, and Physics) (1999) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Air , Engineering and Environmental Chemistry
Over time organic soil contaminants bind to soil particles and resist extraction, microbial degradation, and volatilization. This phenomenon results in the formation of weathered residues, the behavior of which is markedly different from that of freshly applied residues. This proposal will examine the cycling of weathered soil residues between the soil, air, and plant compartments. The following five hypotheses will be tested: (1) Volatilization flux of weathered POPs from soil makes a small but measurable contribution to atmospheric levels of POPs. (Soil-to-air Translocation.); (2) Very low soil concentrations of POPs reflect atmospheric deposition to the site more than they reflect direct application of an agrochemical. (Air-to-soil Translocation.); (3) POPs dose/uptake curves for soil-to-root and air-to-leaf pathways can be established. (Soil-to-root and Air-to-leaf Translocation.); (4) Transpiration flux of POPs from plants makes a small but measurable contribution to atmospheric concentrations. (Leaf-to-air Translocation.); (5) Municipal and commercial compost sources, as well as commercial topsoil and potting soil, contain significant amounts of POPs available for anthropogenic translocation. Cycling of weathered POPs through the biosphere must be clarified before the full impact of POPs on human health can be accurately assessed.
In order to conduct the most appropriate experiments for testing the hypotheses outlined above, we have selected chlordane as the model POP. The commercially available material, technical chlordane, has been shown to be a mixture of 147 different components, the most abundant of which are ~-(or trans)chlordane, ~-(or cis)chlordane, and trans-nonachlor. Both ~-chlordane and ~-chlordane are optically active. The technical chlordane released into the environment is a racemic mixture of the ~-chlordane and ~-chlordane diastereomers, that is, the enantiomeric ratio (ER) for both ~-chlordane and ~-chlordane in technical chlordane is 1. Under abiotic processes such as volatilization, photochemical degradation, and atmospheric transport, enantiomers will behave the same. However, enantiomers behave differently in biotic environments, resulting in an alteration of the ER from a value of 1. Using chiral gas chromatography interfaced to ion trap mass spectrometry, we will exploit the potential of the ER signature to track pesticide movement more definitively than is possible from achiral techniques.
Although the production and use of POPs are restricted in many developed countries, in many third world countries organochlorine insecticides, such as DDT and chlordane, remain primary tools for controlling devastation in the public health and agricultural arenas. Global translocation of POPs, both weathered and freshly applied, will persist into the foreseeable future, making an individual's attendant exposure unknown and unavoidable. This proposal seeks to acquire much of the data necessary to elucidate and possibly minimize the translocation of weathered POPs through biotic and abiotic processes in the biosphere. Health risks to children and adults can only be determined reliably when the magnitude and the length of time of exposure to POPs from food and air are established. Such data are needed for the intelligent formulation of public policy.