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Researchers from the North Carolina State University investigated the concentrations of precipitation and ammonia emissions at the National Atmospheric Deposition Program/National Trends Network site NC35 in North Carolina.

Researchers from North Carolina used a 610 m tall shower to measure the vertical distribution of ozone in the atmospheric boundary layer and to predict ozone concentrations on the ground zone level.

The transport and fate of gaseous hydrogen peroxide into needles of red spruce saplings were investigated using a continuous-flow, well-mixed exposure chamber. The experiment was conducted as part of a study to determine foliar uptake by plants as a sink for air pollutants, and to determine whether hydrogen peroxide is injurious to red spruce. The results indicate that hydrogen peroxide uptake by red spruce is limited to surface deposition.

A gas transport model of the multicomponent transport of gases into the needles of red spruce was developed. The model incorporates the detailed physiology of the stomatal zone, and fundamental equations for multicomponent gas diffusion are used to describe diffusion through the atmospheric boundary layer, wax-filled antechamber, stomate and substomatal cavity. Analysis of the results of experiments exposing red spruce to hydrogen peroxide (H2O2) or a combination of H2O2, SO2 and O3 showed that the model is sensitive to various parameters of gas transport.

Hydrogen sulfide (H2S) emissions were determined from an anaerobic lagoon at a swine concentrated animal feeding operation (CAFO) in North Carolina. Measurements of H2S were made continuously from an anaerobic lagoon using a dynamic flow-through chamber for ~1 week during each of the four seasonal periods from June 2007 through April 2008. H2S lagoon fluxes were highest in the summer with a flux of 3.81 ± 3.24 μg m-2 min-1 and lowest in the winter with a flux of 0.08 ± 0.09 μg m-2 min-1. An air-manure interface (A-MI) mass transfer model was developed to predict H2S manure emissions. The accuracy of the A-MI mass transfer model in predicting H2S manure emissions was comprehensively evaluated by comparing the model predicted emissions to the continuously measured lagoon emissions using data from all four seasonal periods. In comparison to this measurement data, the A-MI mass transfer model performed well in predicting H2S fluxes with a slope of 1.13 and an r² value of 0.60, and a mean bias value of 0.655 μg m-2 min-1. The A-MI mass transfer model also performed fairly well in predicting diurnal H2S lagoon flux trends. [ABSTRACT FROM AUTHOR]

Scientific assessments of agricultural air quality, including estimates of emissions and potential sequestration of greenhouse gases, are an important emerging area of environmental science that offers significant challenges to policy and regulatory authorities. Improvements are needed in measurements, modeling, emission controls, and farm operation management. Controlling emissions of gases and particulate matter from agriculture is notoriously difficult as this sector affects the most basic need of humans, i.e., food. Current policies combine an inadequate science covering a very disparate range of activities in a complex industry with social and political overlays. Moreover, agricultural emissions derive from both area and point sources. In the United States, agricultural emissions play an important role in several atmospherically mediated processes of environmental and public health concerns. These atmospheric processes affect local and regional environmental quality, including odor, particulate matter (PM) exposure, eutrophication, acidification, exposure to toxics, climate, and pathogens. Agricultural emissions also contribute to the global problems caused by greenhouse gas emissions. Agricultural emissions are variable in space and time and in how they interact within the various processes and media affected. Most important in the U.S. are ammonia (where agriculture accounts for ∼90% of total emissions), reduced sulfur (unquantified), PM2.5 (∼16%), PM10 (∼18%), methane (∼29%), nitrous oxide (∼72%), and odor and emissions of pathogens (both unquantified). Agriculture also consumes fossil fuels for fertilizer production and farm operations, thus emitting carbon dioxide (CO2), oxides of nitrogen (NOx), sulfur oxides (SOx), and particulates. Current research priorities include the quantification of point and nonpoint sources, the biosphere-atmosphere exchange of ammonia, reduced sulfur compounds, volatile organic compounds, greenhouse gases, odor and pathogens, the quantification of landscape processes, and the primary and secondary emissions of PM. Given the serious concerns raised regarding the amount and the impacts of agricultural air emissions, policies must be pursued and regulations must be enacted in order to make real progress in reducing these emissions and their associated environmental impacts. [ABSTRACT FROM AUTHOR]

Presents the measurement of fluxes and deposition velocities of gas-phase hydrogen peroxide to red spruce saplings in well-mixed, controlled environment, exposure chambers. Wall losses; Fluxes; Rate constants; Deposition velocity; Comparison to other measurements; Surface versus stomatal deposition.