Biodegradation half-life

It is generally accepted that biodegradation half-lives are longer in both seawater and soil/sediment than in fresh water (CEC, 2003). 

The categorization as inherently biodegradable together with the values and other physical properties enabled estimates of biodegradation half-lives in water, soil, and sediment to be made by BUSES. Those for soil and sediment were then reduced to be more consistent with the results of Terytze et al. (2000), as shown in Table 8. 

Table 8 Biodegradation half-lives in fresh water, soils, and sediments.

Ground water t,/2 = 336-1344 h, based on estimated aqueous aerobic biodegradation half-lives (Howard et al. 

Surface Water t,/2 = 168-672 h, based on estimated aqueous aerobic biodegradation half-life (Howard et al. 1991). Ground water t,/2 = 336-8640 h, based on estimated aqueous aerobic and anaerobic biodegradation half-lives (Howard et al. 1991) ... 

Environmental Fate. Di-/ -oct Iphthalate partitions primarily to soils and sediment upon release to the environment. The compound is expected to be strongly sorbed to soil and sediment particulates therefore, it should have limited mobility (EPA 1979, 1992c). Biodegradation half-lives of 1-4 weeks have been estimated for aerobic surface waters and soils. Biodegradation also takes place in sediments half-lives under anaerobic conditions have been estimated to range from of 6 months to 1 year (Howard et al. 1991). The compound may also undergo photolysis in surface waters (estimated half-life of 144 days) and photooxidation in the atmosphere (estimated half-life of about 5-45 hours) (Howard et al. 1991). Di-n-octylphthalate may persist in sediments as a result of its limited rate of biotransformation and preferential partitioning to this medium. 

Acenaphthylene in an unacclimated agricultural sandy loam soil (30.4 mg/kg) was incubated at 10 and 20 °C. After 60 d, acenaphthylene was not detected. The estimated biodegradation half-lives for acenaphthylene in aerobic soil ranged from 12 to 121 d (Coover and Sims, 1987). 

Biological. Using the experimentally determined first-order biotic and abiotic rate constants of chlorpyrifos in estuarine water and sediment/water systems, the estimated biodegradation half-lives were 3.5-41 and 11.9-51.4 d, respectively (Walker et al, 1988). 

Decane is readily degradable in fresh and saline waters. Biodegradation half-lives of decane in... 

Aerobic and Anaerobic Biodegradation Half-lives of Pesticides (Johnson, 1991). 

In ambient air, the primary removal mechanism for acrolein is predicted to be reaction with photochemically generated hydroxyl radicals (half-life 15-20 hours). Products of this reaction include carbon monoxide, formaldehyde, and glycolaldehyde. In the presence of nitrogen oxides, peroxynitrate and nitric acid are also formed. Small amounts of acrolein may also be removed from the atmosphere in precipitation. Insufficient data are available to predict the fate of acrolein in indoor air. In water, small amounts of acrolein may be removed by volatilization (half-life 23 hours from a model river 1 m deep), aerobic biodegradation, or reversible hydration to 0-hydroxypropionaldehyde, which subsequently biodegrades. Half-lives less than 1-3 days for small amounts of acrolein in surface water have been observed. When highly concentrated amounts of acrolein are released or spilled into water, this compound may polymerize by oxidation or hydration processes. In soil, acrolein is expected to be subject to the same removal processes as in water. 

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