2011 Annual Report
1a.Objectives (from AD-416)
Discern the chemical nature, fate, and transport of critical agricultural pollutants emitted to the atmosphere and consider the potential risks posed by reactivity and/or deposition of these chemicals to sensitive ecosystems. Disseminate results to customers concerning the effects of atmospheric agricultural pollutants on environmental quality.
1b.Approach (from AD-416)
Measure ambient concentrations of agricultural pollutants in soil and in air across the agriculture-urban transect of the Chesapeake Bay watershed. Compare volatile organic compound and particulate matter emissions from poultry production under different ammonia management practices. Test novel approaches to fingerprint particulate matter sources chemically and evaluate the fate and transport of critical agricultural pollutants for estimating potential risks using regional-scale atmospheric transport and deposition modeling tools.
Significant progress has been achieved in initiating the core planned activities. In addition, new opportunities for fruitful collaborations have emerged to increase the impact of existing research efforts. Under subobjective 1, new atmospheric particulate samplers were fabricated in collaboration with scientists from Oklahoma State University (1265-12610-001-03S) and ARS-Mesilla Park, NM. Air samplers were deployed at the master station in Beltsville and preparations for deployment at two additional sites is ongoing. Experiments described in subobjective 2 to investigate air quality parameters within and downwind of poultry facilities have been delayed. However, in related work, ARS-Beltsville was asked by scientists from the USDA Natural Resource Conservation Service (NRCS), National Plant Materials Center (Beltsville, MD), to collaborate in studies to examine the efficiency and ruggedness of vegetative environmental buffers (VEBs) in controlling emissions from poultry facilities. ARS-Beltsville will provide expertise in air pollutant measurement and modeling. Identification of the most appropriate farm location(s) to conduct initial small-scale experiments in Fall 2011 or Spring 2012 is ongoing. Additional resources are being sought through competitive grants to support expansion of this work. Ultimately, results will be used to develop criteria concerning the design and implementation of VEBs for inclusion in a new NRCS National Conservation Practice Standard. The NRCS Air Quality and Atmospheric Change Technology Development Team have identified VEBs as having considerable promise in addressing air quality concerns from livestock operations. They are very much interested in the outcomes of this study. Subobjective 2 also includes development and refinement of an atmospheric particulate fingerprinting methodology. The approach combines acquired Raman spectra of single particles with advanced statistical analysis methods. As described, this work was to be conducted using particles captured at poultry facilities, but particles from a large cattle feedlot were utilized instead. These samples were collected in a collaborative study with Kansas State University, ARS-Ames, IA, and ARS-Florence, SC, which was partially funded by an Agriculture and Food Research Initiative grant (1265-12610-001-01R). Initial results are extremely promising and will likely be useful in examining the transport of particles from different agricultural sources under a variety of scenarios. A new collaboration with University of Maryland has led to the development of methods that will be utilized in subobjective 3 (1265-12000-040-20S). A novel and inexpensive method is being tested to discern the availability of pollutant residues in soils. It is expected that this approach will be used to estimate the emission potential of semi-volatile organic contaminants observed in soils collected across the Chesapeake Bay region. Progress has been achieved in calibrating the Pesticide Emission Model using existing datasets of pesticide volatilization measured in Beltsville as part of subobjective 3 and in developing inventories on land use data and for use in subobjective 4.
Herbicide metabolite reveals agricultural nitrogen fate and transport pathways at watershed scales. Nearly half of U.S. water bodies and waterways are deemed impaired by the Clean Water Act criteria with nonpoint source pollution from croplands being a major contributor. Innovative monitoring and modeling strategies are needed to account for pollutant-matrix interactions, climatic conditions, and landscape complexity, especially for nitrate and ammonia delivered to surface waters via groundwater and atmospheric deposition, respectively. ARS researchers at Beltsville have discovered that a metabolite of an extensively-used herbicide is an ideal nitrate tracer because it is highly stable, is water soluble like nitrate, and is delivered to the groundwater in a manner similar to nitrate. Exploiting this fortuitous correlation will allow researchers to discern the contributions of the various processes to the overall nitrogen load in waterways. In addition, policy makers and land managers will be able to identify more readily the areas where conservation and mitigation practices will be most effective at curbing agricultural nutrient pollution.
Recommendations provided to improve ozone formation potential estimates for pesticide formulations. Volatile organic compounds (VOCs) can be precursors to ozone pollution at ground level. California experiences some of the worst ozone episodes in the United States and has deemed that all sources of VOC emissions, which include pesticide application by farmers and producers, must be reduced to alleviate this problem. The California Department of Pesticide Regulation has determined that VOC emissions from pesticides must be reduced by 10% and currently uses an experimental method known as thermogravimetric analysis to determine VOC emissions from pesticides. ARS researchers at Beltsville, Maryland, have demonstrated that this method does not consider how VOCs react in the atmosphere (ozone formation potential) nor does it account for the ability of the VOC to transition from a liquid to a vapor at typical field temperatures (volatility). They tested and provided critical analysis of several alternative approaches to estimate the volatility and the ozone formation potential of pesticide products. Future research needs were also recommended so that more effective air quality management practices can be developed. The California Department of Pesticide Regulation is currently changing their approach for estimating VOC emissions to include reactivity of the VOC.
Bradford, D.F., Knapp, R.A., Sparling, D.W., Nash, M.S., Stanley, K., Tallent-Halsell, N.G., Mcconnell, L.L., Simonich, S.M. 2011. Pesticide distributions and population declines of California alpine frogs, Rana muscosa and Rana sierrae. Environmental Toxicology and Chemistry. 30:682-691.
Zeinali, M., Mcconnell, L.L., Hapeman, C.J., Nguyen, A., Schmidt, W.F., Howard, C. 2011. Volatile organic compounds in pesticide formulations: Assessing methods to predict contributions to ground-level ozone. Atmospheric Environment. 45:2404-2412.
Trabue, S.L., Scoggin, K.D., Mcconnell, L.L., Maghirang, R., Hatfield, J.L. 2011. Identifying and tracking key odorants from cattle feedlots. Atmospheric Environment. 45:4243-4251.