Humus biodegradability

A preliminary test for the biodegradability of the 3-phenyl- and 3-carbamoyl-2(lH)pyridones was conducted in a barnyard humus suspension. The analysis by HPLC showed some loss, and the fluorescent compounds seemed to be adsorbed onto the solid. The 3-carbamoyl-2(lH)pyridone (II) also hydrolyzed to 3-carboxylic acid-2(lH)pyridone both in the slurry test and in water solutions that had been left standing 1-2 weeks. In preliminary tests both the 3-phenyl- and the 3-carbamoyl-2(lH)pyridones apparently adsorbed to some extent on silica sand columns. In addition, the solubility of both 1-H compounds was somewhat low, 1.3 x 10 M for II, and 1.0 x 10 M for IV. 

Polyaromatic hydrocarbons absorb strongly to humus and other soil components, rendering these contaminants difficult to remove by thermal, physical, or chemical means, and unavailable for biodegradation. To desorb polyaromatic hydrocarbons from soil, surfactant flooding processes and soil-washing processes or treatments to enhance the biodegradation of polyaromatic hydrocarbons have been considered. 

Some compounds, i.e. benzoic and cinnamic acids are not protected against biodegradation to a high degree by linkage and/or absorption on soil constituents such as clay or humus (184), hence they may have a rapid turnover rate in soils. 

Anaerobic conditions often develop in hydrocarbon-contaminated subsurface sites due to rapid aerobic biodegradation rates and limited supply of oxygen. In the absence of O, oxidized forms or natural organic materials, such as humic substances, are used by microorganisms as electron acceptors. Because many sites polluted by petroleum hydrocarbons are depleted of oxygen, alternative degradation pathways under anaerobic conditions tend to develop. Cervantes et al. (2001) tested the possibility of microbially mediated mineralization of toluene by quinones and humus as terminal electron acceptors. Anaerobic microbial oxidation of toluene to CO, coupled to humus respiration, was demonstrated by use of enriched anaerobic sediments (e.g., from the Amsterdam petroleum harbor). Natural humic acids and... 

Hsu, T. S., and R. Bartha, Hydrolyzable and nonhydrolyzable 3,4-dichloroaniline-humus complexes and their respective rates of biodegradation , J. Agric. Food Chem., 24, 118-122 (1976). 

Stott, D. E., Martin, J. P., Focht, D. D. Haider, K. (1983). Biodegradation, stabilization in humus, and incorporation into soil biomass of 2,4-D and chlorocatechol carbons. Soil Science Society of American Journal, 47, 66-70. 

Martin, J. R, and Haider, K. (1980). Microbial degradation and stabilization of 14C-labeled lignins, phenols, and phenolic polymers in relation to soil humus formation In Lignin Biodegradation Microbiology Chemistry and Potential Applications, Vol. II. Kent-Kirk, T., Higuchi, T., and Chang, H., eds., CRC Press, Boca Raton, FL, pp. 77-100. 

A managed process that controls the biological decomposition of biodegradable materials into a humus-like substance called compost The aerobic and mesophilic and thermophilic degradation of organic matter to make compost the transformation of biologically decomposable materials through a controlled process of bio-oxidation... 

Humus The solid organic substance that results from decay of plant or animal matter. Biodegradable plastics can form humus as they decompose. Humus in soil provides a healthy structure within which air, water and organisms can combine. 

Hsu, T. S. and Bartha, R. (1974). Biodegradation of chloroaniline-humus complexes in soil and in culture solutions. Soil Sci. 118, 213-220. 

Mathur, S. P. and Morley, H. V. (1975). A biodegradation approach for investigating pesticide incorporation into soil humus. Soil Sci. 120, 238-240. 

PROBABLE FATE photolysis intramolecular photolysis possible important fate, aqueous photolytic half-life 23-72 hrs, atmospheric photolytic half-life 23-72 hrs, photolytic half-lives in river, bay, and pond waters 2.7, 9.6, 3.7 hr respectively oxidation oxidation could follow adsorption onto clay particles, photooxidation half-life in water 3-33 hrs, photooxidation half-life in air 11.8-118 days hydrolysis not an important process volatilization too slow, therefore not an important process sorption expected to be strongly adsorbed by humus and clay biological processes some bioaccumulation possible, biodegradation very slow... 

PROBABLE FATE photolysis-, intramolecular photolysis is possibly important, atmospheric and aqueous photolytic half-life 17-25 hrs oxidation photooxidation can occur, photooxidation half-life in water 2-17 hrs, photooxidation half-life in air 11.8-118 days, reaetion with photochemically produced hydroxyl radicals has a half-life of 8 hr hydrolysis not an important process volatiiization not expected to be an important transport proeess, relatively slow sorption expected to be strongly sorbed by humus and elay biological processes no data on bioaccumulation, biodegradation very slow... 

PROBABLE FATE photolysis photoreduction could occur if nitrobenzene is adsorbed onto humus particles, atmospheric and aqueous photolytic half-life 67-200 days oxidation only important as method of destroying photoreduction products, photooxidation half-life in water 125 days-22 yrs, photooxidation half-life in air 0.544-5.44 hrs hydrolysis not important volatilization not fast enough to be important, if released to water, some volatilization is expected sorption adsorbed by humus and probably by clay biological processes no bioaccumulation of any significance, biodegradation is relatively slow... 

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