To acquire advanced information on the processes and the factors that control and govern the fate of pesticides in the soil environment in order to build the relevant and experimental knowledge for a potentially safe, inoffensive, efficient, beneficial, and cost-effective utilization of pesticides.
The project evaluates the abiotic and biotic (through enzymatic catalysis) binding of pesticides on characterized clays, humic materials, and clay-humic complexes. The persistence of free and immobilized pesticides under soil biological activity (bioavailability for indigenous and introduced microorganisms) as well as the abiotic release of pesticides bound to different matrices and their mobility in soils will be tested. Furthermore, the ability of free and immobilized enzymes to intervene in the bioremediation of contaminated soils will be verified.
In the project, particular attention will be devoted to:
- determine a) the adsorption capacity, the specificity or non specificity of the different adsorbents models for certain pesticides; b) the reversibility/non-reversibility of the adsorption/desorption process; c) the effect of the surface properties of adsorbents on the above mentioned processes; d) the type of chemical bonding and the active centres of the surface adsorbents models involved; e) the chemical and thermal stability of the clay-complexes obtained.
- characterize the nature, chemical composition, physico-chemical and surface properties of organo-mineral complexes prepared by using two isolated and characterized humic substances and two clay minerals; identify the preferential disposition of humic macromolecules in the clay-humic complexes.
- purify laccases at high purity degree from select fungal strains; obtain laccase preparations temperature-resistant and active in non aqueous solvents and evaluate the detoxifying activity of laccase preparates, alone or in cooperation with other enzymes, in the task of bound residues.
- prepare pesticide-humic and pesticide-clay-humic complexes by adsorption isotherm techniques, abiotic and biotic binding under selected experimental conditions; describe and quantify the kinetics of adsorption and binding processes.
- analyze the pesticide-complexes by C-13 NMR, massa spectrometry and electronic impact method in order to identify the main components of the humic substances and the predominant type of crosslinking present in the solid state; correlate the changes of structural features and chemical composition obtained by spectroscopic methods and the size of molecular aggregates as obtained by the molecular weight distributions.
- isolate bacterial degraders of pesticides and raise resistant mutants; measure rates and amounts of biodegradation (with and without adsorbents and pesticides complexes) following inoculation and quantify microbial growth rates and yields; identify the responses of the soil indigenous microflore to pesticides and inoculants.
- quantify and determine how various soil environments such as pH, moist-dry cycles, and temperature affect the abiotic release of free and bound pesticides under saturated flow conditions.
Funding SchemeCSC - Cost-sharing contracts
CT2 7NJ Canterbury