Water vapor adsorption alone may be insufficient to raise the soil-water content above the threshold water content. A numerical model was developed to simulate pesticide transport in both wet and dry soils. The calculated and measured results agree well. We have completed this stage of the research and have submitted three manuscripts for publication. Nitric oxide is a precursor to nitric acid, and plays a central role in photochemical reactions, which regulate levels of tropospheric ozone.
Ozone can have detrimental effects on plants upon extended exposure at fairly low levels.
Ozone damage to forests in the Sierra Nevada mountains are considered to be one of the stressors potentially causing premature tree death. Laboratory experiments were conducted with three agricultural soils to examine substrate and process controls over temporal variability of NO and N 2 O production during nitrification, and to quantify the kinetics of HNO 2 -mediated chemical reactions. These measurements indicate that control of soil acidity may be an important strategy for minimizing gaseous N losses from fertilized soils, and possibly for improving air quality in rural areas. Our future work will include two components. One will be to develop modeling approaches for use in ecotoxicological exposure assessments in terrestrial ecosystems.