Peter Van Voris

Microcosm/field comparison of trace element uptake in crops grown in fly ash-amended soil

Acidic (pH 4.98) precipitator fly ash was mixed with the topsoil of a nearly neutral Crosby silt-loam soil in both laboratory microcosms and field plots. The objective was to evaluate the accuracy and reliability of intact microcosms to predict trace element enrichment in field-grown crops due to fly ash amendment. Laboratory and field experimental units were amended with fly ash at 0, 100, 400, and 700 MT/ha, prior to planting a mixed crop of alfalfa, timothy, and oats. Microcosms accurately predicted the enrichment ratios (ERs) of 22 out of the 25 trace elements analyzed in field-grown alfalfa. Boron was the only element which accumulated in plant tissue at levels reported to be toxic to plants and may have caused the yield declines in all plants at high fly ash treatment levels. Plant uptake of Mo, Se, and As, particularly at the highest fly ash amendment levels, was sufficient to make the crops hazardous as a forage for cattle or sheep. Intact agricultural microcosms are recommended for prediction of potential trace element uptake in the field associated with untested combinations of soil type, fly ash, and plant species.

Evaluate and Characterize Mechanisms Controlling Transport, Fate and Effects of Army Smokes in an Aerosol Wind Tunnel. Transport, Transformations, Fate and Terrestrial Ecological Effects of Fog Oil Obscurant Smokes

Abstract : The terrestrial transport, chemical fate, and ecological effects of fog oil (FO) smoke obscurants were evaluated under controlled wind tunnel conditions. The primary objectives of this research program are to characterize and assess the impacts of smoke and obscurants on: 1) natural vegetation characteristic of U.S. Army training sites in the United States; 2) physical and chemical properties of soils representative of these training sites; and 3) soil microbiological and invertebrate communities. Impacts and dose/responses were evaluated based on an exposure scenario, including exposure duration, exposure rate, and sequential cumulative dosing. Key to understanding the environmental parameters such as relative humidity and wind speed on airborne aerosol characteristics and deposition to receptor surfaces. Direct and indirect biotic effects were evaluated using five plant species and three soil types. Fog oil enhanced the microbial activities in most of the metabolic parameters evaluated. A cumulative dose of fog oil exposure stimulated soil respiration slightly and increased nitro-bacter population in Palouse soil, and greatly increased soil enzyme activity in both Palouse and Burbank soil. Earthworm bioassays indicated no adverse effect of fog oil with exposures up to 800 micrograms/sq. cm soil. In vitro studies, where fog oil was uniformly amended to soil, showed earth- worm survival to be 100% until an exposure of approx. 3600 micrograms/sq. cm (a soil concentration of 285 micrograms FO/g) was reached.