Sommari in inglese, francese e tedesco.

The introduction of microorganisms with specific degradative capacities into the soil was shown to be a possible means of ridding the soil of contaminating chemicals. An investigation of the interactions of soil microorganisms and several groups of herbicidal compounds, primarily chlorinated derivatives, was made. In pure culture and in soils the addition of 2,3,5,6-tetrachloroterephthalate (DCPA) had little effect upon bacterial growth, and several microorganisms appeared to use the herbicide as a carbon source. The encouragement of the soil microflora by the addition of nutrient broths resulted in a reduction of toxicity to plants of a number of herbicides. Isopropyl N-phenylcarbamate (IPC) degrading organisms, when added to soil, accelerated the degradation of IPC and related compounds. A membrane 'biologicalilter' device for reducing waterborne biodegradable pollutants was also demonstrated using these organisms.

Pesticide-clay-water interactions; Pesticide organic matter interactions; Movement of pesticides in soil; Movement of pesticides in surface water; Volatilization of pesticides; nonbiological degradation of pesticides; Degradation of pesticides by soil microorganisms; Persistence of pesticides in soil; Effects of soil on the biological activity of pesticides; Plant uptake of insecticides, fungicides, and fumigants from soils; Effects of pesticides on microorganisms in soil and water; Effects of pesticides on nontarget invertebrates in freshwater and soil; Prevention and detoxification of pesticide residues in soil; Removal of organic pesticides from water to improve quality; Extraction and analytical techniques for pesticides in soil, sediment, and water.

Explores the role of biochemical processes in the soil environment, particularly the activity of microorganisms, and the potential application of those processes to environmental biotechnology. The 11 papers also highlight the application of molecular biology and microbial genetics to soil biology a

Experiments were performed in pursuit of understanding of interactions between herbicides and soils, focusing on the effects of heterogeneity within soil organic matter (SOM), and the aggregation of SOM with mineral matter in soils, on equilibrium sorption and sorption rates of herbicides. For this purpose, sorption of three herbicides -- atrazine, metolachlor and napropamide -- was studied on a bulk soil, a bulk peat and three fractions that were chemically isolated from it. Studies were also performed using the well studied polynuclear aromatic hydrocarbon (PAH) phenanthrene to provide a comparison for the herbicides. The sorbents extracted from the soil and peat -- Base extracted fraction (BE), humic acids fraction (HA) and kerogen and black carbon fraction (KB) were characterized with elemental analysis, scanning electron microscopy and surface area measurements and subjected to sorption and desorption equilibrium studies and sorption rate investigations. The herbicides were found to exhibit non linear sorption isotherms on all the sorbents, with HA from both soil and peat showing the least non linear isotherms and fastest sorption rates among all the sorbents. HA fraction also showed the least dependence of equilibrium or time dependent organic carbon normalized sorption capacity (KOC or KOC(t)) on initial aqueous solute concentration. This result was in accordance with the amorphous nature of the HA material and similar to that observed for PAHs. Herbicide atrazine was found to react with HA and was transformed to hydroxyatrazine in its presence. KOC or KOC(t) values for all other sorbents were found to be dependent on initial aqueous solute concentration. High sorption capacity of KB dominated the sorption for all the herbicides, with this capacity being diminished by the aggregation structure of the soil. Significant sorption hysteresis was not observed for the sorption of herbicides on the KB fraction, unlike that observed for phenanthrene, indicating large herbicide molecules do not penetrate nanopores of KB. Hysteresis observed for the bulk soil and BE for atrazine was attributed to chemical interactions between the sorbents and the herbicide. Overall this dissertation found that the herbicides exhibit hydrophobic interactions with soils, similar to PAHs, but owing to their large molecular sizes and polarities may exhibit site specific interactions and lack of hysteresis with soil components that call for changes in existing fate and transport models and further microscopic understanding.