Soil degradation

Additional chronic toxicity Additional environmentally dangerous properties Toxicity to birds Long-term toxicity in water and soil Degradability simulation tests Additional abiotic degradability Mobility in water, soil and air cumulative... 

An analytical method for the following soil degradates was developed. 

Owing to its low water solubility and high octanol/water partition coefficients, dinitroaniline herbicides adsorb and bind to soil macromolecules and show minimal leaching potential. Dinitroanilines herbicides show good soil residue activities with soil half-lives ranging from 30 days for benfluralin and oryzalin to 6-7 months for trifluralin. Al-Dealkylation (aerobic conditions) and reduction of the nitro group to an amino moiety (anaerobic conditions) have been reported as major soil degradation pathways. 

Dinitroaniline herbicides are generally stable in soil. Residue methods were developed for both the parent molecule and selective soil degradates. 

The photolysis and soil degradation constants must be realistic for the compound in question. Laboratory or field studies are usually needed to confirm these numbers. 

Soil Type Kd Photolysis Half-Life (Days) Soil Degradation (Days 1) % Onto Soil Rainfall Intensity Rainfall in CGA-72662 Run-off lbs. ai/A... 

Concerns regarding progressive soil degradation and the long-term sustainability of current agricultural practices have lead to the study and assessment of soil quality (Karlen et al. 1997). Soil organic matter is an extremely important attribute of soil quality since it profoundly influences... 

Diflubenzuron breakdown by hydrolysis, soil degradation, or plant and animal metabolism initially yields 2,6-difluorobenzoic acid and 4-chlorophenylurea. Ultimately, the end products are... 

Keywords Fanning system Indigenous soil knowledge Scientific soil knowledge Soil characteristics Soil degradation Soil restoration Sustainable agriculture Traditional soil knowledge... 

Table 11.2 Indigenous knowledge of soil degradation in Asia (Ali 2003 Handayani et al. 2006)...

Overcultivation Syndrome Overcultivation of marginal land Destabilization of ecosystems, loss of biodiversity, soil degradation, desertification, threats to food security, marginalization, rural exodus... 

Military Activities Syndrome Environmental destruction through war and military action Loss of biodiversity due to chemical warfare agents, permanent soil degradation due to mining, contamination caused by fuels and explosives, health hazards, greater flows of refugees... 

Core problems Climate change Loss of biodiversity Soil degradation Scarcity and pollution of freshwater i Threats to world health Threats to food security Population growth and distribution Man-made disasters Over exploitation and pollution of the world s oceans Global disparities in development... 

Incubations of heptachlor with a mixed culture of soil microorganisms for 12 weeks showed conversion of heptachlor to chlordene, 1-exohydroxychlordene, heptachlor epoxide, and chlordene epoxide. A mixed culture of soil microorganisms, obtained from a sandy loamy soil, degraded heptachlor epoxide to the less toxic 1-exohydroxychlordene. Conversion was about 1% per week during the 12-week test period (Miles et al. 1971). 

Biological. Four Pseudomonas sp., including Pseudomonas putida (ATCC culture 29607) isolated from soil, degraded chloropicrin by sequential reductive dechlorination. The proposed degradative pathway is chloropicrin -> nitrodichloromethane nitrochloromethane nitromethane + small amounts of carbon dioxide. In addition, a highly water soluble substance tentatively identified as a peptide was produced by a nonenzymatic mechanism (Castro et al., 1983). 

Microorganisms isolated from a loamy sand soil degraded lindane and some of the metabolites identified were pentachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, y-PCCH, y-TCCH and p-3,4,5,6-tetrachloro-l-cyclohexane (p-TCCH) (Tu, 1976). y-PCCH was also reported as a metabolite of lindane in an Ontario soil that was pretreated with jo,//-DDT, dieldrin, lindane, and heptachlor (Yule et ah, 1967). The reported half-life in soil is 266 d (Jury et al., 1987). 

A species of Pseudomonas, isolated from creosote-contaminated soil, degraded 4-methylphenol into 4-hydroxybenzaldehyde and 4-hydroxybenzoate. Both metabolites were then converted into protocatechuate (O Reilly and Crawford, 1989). In the presence of suspended natural populations from unpolluted aquatic systems, the second-order microbial transformation rate constant determined in the laboratory was reported to be 2.7 + 1.3 x 10 ° L/organism-h (Steen, 1991). 

Soil. A Pseudomonas sp. (ATCC 29354), isolated from parathion-amended treated soil, degraded 4-nitrophenol to 4-nitrocatechol, which was recalcitrant to degradation. In an unsterilized soil, however, p-nitrocatechol degraded to nitrites and other unidentified compounds (Sudhakar-Barik et al, 1978a). Pseudomonas sp. and Bacillus sp., isolated from a parathion-amended flooded soil, degraded 4-nitrophenol (parathion hydrolysis product) to nitrite ions (Siddaramappa et al, 1973 Sudhakar-Barik et al., 1976) and carbon dioxide (Sudhakar-Barik et al., 1976). 

CASRN 510-15-6 molecular formula C16H14CI2O3 FW 325.21 Biological. Rhodotomla gracilis, a yeast isolated from an insecticide-treated soil, degraded chlorobenzilate in a basal medium supplemented by sucrose. Metabolites identified by this decarboxylation process were 4,4 -dichlorobenzilic acid, 4,4 -dichlorobenzophenone, and carbon dioxide (Miyazaki et al., 1969, 1970). 

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