Primary anaerobic biodegradation

Mirex is a very persistent compound in the environment and is highly resistant to both chemical and biological degradation. The primary process for the degradation of mirex is photolysis in water or on soil surfaces photomirex is the major transformation product of photolysis. In soil or sediments, anaerobic biodegradation is also a major removal mechanism whereby mirex is slowly dechlorinated to the 10-monohydro derivative. Aerobic biodegradation on soil is a very slow and minor degradation process. Twelve years after the application of mirex to soil, 50% of the mirex and mirex-related compounds remained on the soil. Between 65--73% of the residues recovered were mirex and 3-6% were chlordecone, a transformation product (Carlson et al. 1976). 

Ecological and Toxicological Association of the Dyestuffs Manufacturing Industry. Ecological method No. 105. A Screening test for assessing the primary anaerobic biodegradability of water soluble dyestuffs. ETAD, Basel, Switzerland. 

Time, measured in days, from the end of the biodegradation phase until the end of the test. Primary anaerobic biodegradation (ISO 1485)... 

The disappearance of sucrose ester surfactants from river water samples was studied by measuring the consequent increase in surface tension. This showed 100% primary biodegradation within 2 days [70,71]. An advantage of sugar fatty acid esters is their ready anaerobic biodegradation. Complete primary biodegradation within 2 days was also observed under anaerobic conditions [70]. 

Linear primary alcohol sulfates can also be biodegraded under anaerobic conditions but the process seems to be limited to the hydrolysis of the sulfate [407]. 

Brown D, Laboureur P (1993) The degradation of dyestuffs part I primary biodegradation under anaerobic conditions. Chemosphere 12 397 -04... 

Alcohol ether sulfates. Ready aerobic biodegradation of AESs has been described [113], with co/(3-oxidation and cleavage of the sulfate and ether bonds attributed to the process [10]. However, molecular oxygen is not necessary for the two latter steps, and primary and ultimate degradation has been described under both aerobic and anaerobic conditions [114]. 

Ingerslev F, L. Torang, M.L. Loke, B. Halling-Sprensen, and N. Nyholm (2001). Primary biodegradation of veterinary antibiotics in aerobic and anaerobic surface water simulation systems. Chemosphere 44 865-872. 

Dyestuffs in general, and azo dyes in particular, are likely to undergo. substantial primary biodegradation in an anaerobic environment through reductive cleavage of azo bonds into aromatic amines. Lipophilic aromatic... 

Brown D. and P. Laboureur. 1983. The Degradation of dyestuffs Part I—Primary biodegradation under anaerobic conditions. Chemosphere 122, 397-404. 

Persistence in the soil is generally low (half-life under aerobic and anaerobic conditions is 21 and 68 days, respectively). In sterile soil, the half-life is almost 1 year. Azinphos-methyl adsorbs strongly to soil particles and has low solubility in water. Biodegradation and evaporation are the primary routes of elimination from soil but azinphos-methyl is also degraded by ultraviolet light. Degradation is more rapid at higher temperatures. Azinphos-methyl has a short half-life in surface waters (2 days). Hydrolysis is more prominent under alkaline conditions but the compound is relatively stable in water below pH 10. The half-life on crops is 3-5 days under normal conditions. 

---