2009 Annual Report
1a.Objectives (from AD-416)
The overall goal of this bridging project is to investigate the potential pollutants and agricultural management practices that affect air quality within the Chesapeake Bay region. Agricultural activities in this region have traditionally been production of corn, soybeans, and specialty crops and some confined animal operations; however, production of bioenergy crops including corn, hulless barley, and switch grass are expected to increase as energy costs rise. Urban encroachment has also become a major concern in this region resulting in increased NOx production which can lead to ozone formation in the presence of VOCs. Objective 1: Identify the major emission sources of agricultural pollutants, such as particulate, pesticide active and inert ingredients and other VOCs, and greenhouse gases within the Chesapeake Bay airshed. Objective 2: Determine the predominant fate processes and atmospheric components that influence the fate of agricultural air-borne pollutants. Objective 3: Estimate the spatial and temporal variability of emissions using a combination of field measurements, remotely-sensed, and land use data. Objective 4: Develop a framework to predict the influence of land use changes and agricultural production practices on air quality for use by policy makers, regulators, and natural resource managers.
1b.Approach (from AD-416)
Rapid detection technologies, such as nano and molecular imprinting technologies, will be developed for measuring agricultural pollutants in air. Using newly-developed and traditional techniques, the emission of air-borne pollutants will be measured in selected subwatersheds. Measurements will be taken over several growing seasons in different land use areas and compared to a previously-identified non-urban area where no agricultural activities have occurred for over thirty years. The fate of identified air borne pollutants will be examined in newly-developed chemical fate models. In areas where urban land use is adjacent to agricultural lands, available NOx and meteorological data will be utilized to predict the potential of agricultural pollutants to form ozone. Predictions will be compared to available ozone concentrations. Measured pollutant concentration data will be combined with land use, physical chemical constants, and meteorological data to produce an estimate of total emissions and potential ozone emission as a function of land use. These data will then be extrapolated to consider the effects of land-use changes and agricultural activity on air quality in the Chesapeake Bay region.
This bridging project utilizes the Choptank River Watershed Conservation Effectiveness Assessment Project (CEAP) located on the Delmarva Peninsula as a platform to investigate the potential pollutants and agricultural management practices that affect air quality within the Chesapeake Bay region. The Choptank River Watershed can be viewed as a microcosm of environmental pressures emerging in agricultural regions across the U.S., i.e., economic influence of bioenergy demand, urban encroachment, and increasing regulatory restrictions. Some of this work draws on results of air and water quality research conducted in other regions of the U.S. Studies concerning the atmospheric fate of pesticides in several regions of the country have demonstrated that a multitude of processes influence emission, transport, and deposition. Furthermore, the fate pathways of pesticides are sometimes similar to the fate pathways of nutrients but often times, pesticides are affected by many more processes. For example, riparian buffers are known to mitigate overland flow from agricultural fields, but these same tree buffers can trap pesticide residues which can be washed off during precipitation events and enter streams and water ways. In the Sierra Nevada Mountains, pesticide residues have been observed in air, water, and biota which have been transported via the air from the adjacent high agricultural areas in the San Joaquin Valley. The obvious relationship of concentration to distance from the source, however, does not apply to all pesticides indicating that other processes are involved. Application of biosolids from municipal waste treatment plants to agricultural lands provides a useful disposal method but also conditions the soil. However, some chemicals are not removed in the waste treatment process and pose a risk to the agricultural lands. Studies in the Mid-Atlantic area have shown that the flame retardants, polybrominated diphenyl ethers (PBDEs), can persist in the soil and may volatilize when the soil is cultivated.
Scientists are participating in and serve on the committee for the development of the report for Section 202(f), Monitoring and Decision Support for Ecosystem Management, of the Executive Order entitled, “Chesapeake Bay Protection and Restoration.” Research gaps were identified and possible approaches considered at several working group meetings for the Maryland Pesticide Network, Pesticides and the Chesapeake Bay Watershed Project. Concepts and strategies were presented to the Director of the U.S. EPA – Office of the Chesapeake Bay Program. CEAP results were presented at the Choptank River Watershed CEAP Field Day for the American Association of Plant Food Control Officials; US EPA Chesapeake Bay Program Office, and Toxic Substances Committee Meeting. Scientists served as coordinators for ARS research on agricultural emissions: assembled and wrote Component 1 on agricultural emissions for the new NP212 Action Plan, proposed and initiated the formation of the ARS Air Quality Working Group; organized a 2-day symposium at the American Chemical Society National Meeting in Washington DC entitled, Managing Agricultural Emissions.
Flame retardant chemicals can persist in biosolids-amended agricultural soils. Biosolids, generated during wastewater treatment are materials, high in organic carbon and nutrient content are often used as soil conditioners on agricultural lands. Concerns exist over the persistence and potential toxicity of flame retardant chemical residues, polybrominated diphenyl ethers (PBDEs), present in biosolids as a result of their use in consumer products. Surface soil samples were collected from farms in the Mid-Atlantic region of the U.S. Results indicated that transfer from the biosolids to soil or air may be a critical factor controlling the fate and availability of PBDEs and that volatilization is likely to continue even after the biosolids are completely incorporated to the soil with loss rates changing with temperature. The loss processes controlling the fate of these chemicals are not fully understood and the degradation and emission rates could vary widely depending on soil properties and meteorological conditions. These results indicate that PBDEs are relatively persistent in soils, but further research is required to examine the potential risks to wildlife and human populations.
Atmospheric transport of pesticides to the Sierra Nevada mountains is not just dependent on distance from the source. Atmospheric transport of pesticides in the Sierra Nevada mountains of California have been implicated as a factor adversely affecting biological resources such as amphibians and fish. Studies were conducted to examine the pesticide distribution in the high-elevations of the Sierra Nevadas and the relationship of concentration to distance from the adjacent, high-agricultural use, San Joaquin Valley. Although most sites received the same set of compounds, the concentrations for some pesticides were very much related to distance from the Valley and in other cases no relationship to distance was observed. These results suggest that atmospheric transport process are important but that other on-site characteristics or processes may be just as important or more so in explaining the differences in chemical concentrations among high-elevation sites. Defining these processes is important so that mitigation strategies can be developed to decrease the unintended release of chemicals to the atmosphere.
Forested areas affect pesticide and nutrient fate differently in Choptank River subwatersheds. Farmers utilize conservation practices such as tree or grass buffers or cover crops to protect water resources from nutrient and sediment contamination. In the Choptank River Watershed project, stream water from 15 small watersheds with differing amounts of agriculture and conservation practices were compared for nutrient and pesticide contamination throughout the year. The lowest concentrations of nutrients were found in watersheds with the largest amount of forested areas and did not vary widely during the year; however, pesticide concentrations were highest in spring just after application. Pesticide residues varied by the two hydromophological regions in the Choptank River watershed, the well drained uplands (WDU) and the poorly drained uplands (PDU). In the WDU, where forested lands surround much of the streams, the highest pesticide concentrations were observed in the subwatersheds with the highest forested area; however, the PDU subwatersheds are highly ditched and no single land use/characteristic correlated with presence of pesticide residues. This work supports the concept that nutrients are delivered primarily by groundwater in this region and movement of pesticides to streams is more complicated as delivery can occur via leaching, overland flow, and atmospheric delivery to riparian corridors via drift and/or volatilization.
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McCarty, G.W., McConnell, L.L., Sadeghi, A.M., Hapeman, C.J., Graff, C., Hively, W.D., Lang, M.W., Fisher, T.R., Jordan, T., Rice, C., Whitall, D., Lynn, A., Keppler, J., Fogel, M.L. 2008. Overview of the Choptank River watershed conservation effectiveness assessment project. Journal of Soil and Water Conservation. 63:461-474.
Stevens, M.D., Black, B.L., Lea-Cox, J.D., Sadeghi, A.M., Harman-Fetcho, J., Pfeil, M., Downey, P.M., Hapeman, C.J. 2009. A Comparison of Three Cold-Climate Strawberry Production Systems: Environmental Effects. Journal of the American Society for Horticultural Science. 44(2):298-305.