Biodegradation in soil

Phthalate Biodegradation, percent Half-life, days 

Diallyl phthalate, dihexyl phthalate, diisobutyl phthalate, diisodecyl phthdate, diisononyl phthalate, diisooctyl phthalate, dinonyl phthalate, di-(2-ethylhexyl) adipate, di-n-octyl adipate, acetyl tributyl citrate, and tricresyl phosphate Expected in soil and sediments (5) based on biodegradation studies with non-soil systems, but too few data for quantitative generalizations 

Tri-(2-ethyUiexyl) trimelhtate and di-(2-ethylhexyl) sebacate Expected to be slow (5) 

Ditridecyl phthalate, diundecyl phthalate, di-(2-ethyUiexyl) azelate, and dibutyl sebacate No information located on biodegradation potential 

Ten of the 23 plastieizers can be expected to biodegrade in soil and sediments to some extent, bnt there were too few data available to make quantitative generahzations. Limited studies suggested that tri-(2-ethylhexyl) trimelhtate and di-(2-etliylhejqrl) seba-cate may be relatively persistent in soil. The biodegradation of ditridecyl phthalate, diun- 

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Racke KD, DA Laskowski, MR Schultz (1990) Resistance of chloropyrifos to enhanced biodegradation in soil. J Agric Eood Chem 38 1430-1436. 

Hexachloroethane may biodegrade in soil, but abiotic degradation processes are not expected to be significant. Hexachloroethane is biotransformed in soil under both aerobic and anaerobic conditions, but proceeds more rapidly in anaerobic soils (Spanggord et al. 1985). Loss of 99% of hexachloroethane was reported after 4 days of incubation anaerobically and after 4 weeks under aerobic conditions. Volatilization contributed to aerobic losses. 

Available data indicate that phenol biodegrades in soil under both aerobic and anaerobic soil conditions. The half-life of phenol in soil is generally less than 5 days (Baker and Mayfield 1980 HSDB 1997), but acidic soils and some surface soils may have half-lives of between 20 and 25 days (HSDB 1997). Mineralization in an alkaline, para-brown soil under aerobic conditions was 45.5, 48, and 65% after 3, 7, and 70 days, respectively (Haider et al. 1974). Half-lives for degradation of low concentrations of phenol in two silt loam soils were 2.70 and 3.51 hours (Scott et al. 1983). Plants have been shown to be capable of metabolizing phenol readily (Cataldo et al. 1987). 

A project at the University of California at Riverside (FEDRIP 1996) will study factors affecting the biodegradation in soils of several pesticides and halogenated organics by such microbes as Methano-bacterium thermoautotrophicum. This anaerobic bacterium shows the potential for very rapid oxidation of... 

Soil. Methylene chloride undergoes biodegradation in soil under aerobic and anaerobic conditions. Under aerobic conditions, the following half-lives were reported 54.8 d in sand (500 ppb) 1.3, 9.4, and 191.4 d at concentrations of 160, 500, and 5,000 ppb, respectively, in sandy loam soil 12.7 d (500 ppb) in sandy clay loam soil 7.2 d (500 ppb) following a 50-d lag time. Under anaerobic conditions, the half-life of methylene chloride in clay following a 70-d lag time is 21.5 d (Davis and Madsen, 1991). The estimated volatilization half-life of methylene chloride in soil is 100 d (Jury et al., 1990). 

Arthur, M.F. and Frea, J.I. 2.3.7.8-Tetrachloro-p-dioxin aspects of its important properties and its potential biodegradation in soils, / Environ. Qual, 18(1) 1-11, 1989. 

The hydrochloric acid salt of 3,3 -dichlorobenzidine readily photolyses in water exposed to natural sunlight, but may not readily biodegrade in soil and aeelimated sludges. It has a strong tendency to partition to soils and sediments, a property which reduces the potential for human exposure (Boyd et al. 1984 Chung and Boyd 1987 Sikka et al. 1978). Once partitioned to soil, the compound apparently binds further with humie substances to form humie-like materials that presumably would be non-hazardous (Sikka et al. 1978). However, in a recent paper, Nyman et al. (1997) stated that dehalogenation of 3,3 -dichlorobenzidine to form benzidine (also a toxie substance) occurs in sediment/water mixtures under anaerobic conditions. 

P-CD was also reported to improve the biodegradation of a single hydrocarbon (dodecane) (15). y-CD, HPBCD, and RAMEB were effective in the intensihcation of PCB biodegradation in soils (10, 16). Especially remarkable bioavailability-enhancing properties were exhibited by RAMEB in hydrocarbon-polluted soils (17). Because soil bioremediation needs months to years depending on type and concentration of the contaminants, soil properties, and microflora, an additive that degrades slowly in the soil is required. RAMEB meets this requirement. Its half-life time is about 1 year in a soil contaminated with motor oil (18), while HPBCD is decomposed rapidly (19). (Adapted from Jozefaciuk et ah, 2003)... 

Since Bionolle is biodegradable, it should spontaneously decompose and revert to soil when left in soil. Given these characteristics, we assume complete biodegradation in soil rather than recovery and disposal. 

Emission of carbon contained in Bionolle drawn from fossil resources must be accounted for as CO2. However, there has been no study mentioning the ratio of carbon components discharged into the open air after biodegradation in soil. Instead, it is assumed that the entire component will be emitted into the open air as CO2. 

For this reason, additional studies on carbon tetrachloride flux rates into and out of surface water, as well as refined quantitative estimates of aquatic fate processes would be valuable. The chemical is expected to evaporate rapidly from soil due to its high vapor pressure and may migrate into groundwater due to its low soil adsorption coefficient. No data are available on biodegradation in soil. Additional studies to determine degradation rates and the extent to which adsorption has occurred would be useful. These data are also useful in evaluating the impact of carbon tetrachloride leaching from hazardous waste sites. 

Graves, D. Leavitt, M. (1991). Petroleum biodegradation in soil the effect of direct application of surfactants. Remediation, 2, 147-66. 

In summary, bioavailability strongly affects CP biodegradation in soil and sediments. The partitioning of CPs to water-saturated subsurface solids also affects groundwater bioremediation. The organic content of the solid matrix increases the unavailability of CPs to biodegradation. 

Biodegradation in soil) 3400 304A 3300 lowk 100% soil 14C Calc. 

Environmental Fate. Information on biodegradation in soil under aerobic conditions exists, but degradation products were not identified. Anaerobic biodegradation, as might occur in river bottoms and in Superfund sites, has not been studied and would be valuable. Emissions from waste lagoons have been modelled and measured in bench-top experiments and are measured as part of many Superfund Remedial Investigation/Feasibility studies, but those were not located. 

Triazine biodegradation in soil is dependent on a number of factors, most importantly the presence, population, and activity of triazine-degrading microorganisms. Therefore, factors that affect soil microbial populations and activity... 

Soil t,/2 < 28 d for 10 pg/mL to biodegrade in soil-water suspension (Rueppel et al. 1977 quoted, Muir 1991) estimated first-order t,2 = 7 d from biodegradation rate constant k = 0.1 d 1 from soil incubation die-away studies (Rao davidson 1980 quoted, Scow 1982) moderately persistent in soil with t,/2 = 20-100 d (Willis McDowell 1982) average t,/2 < 60 d (Hartley Kidd 1987 Herbicide Handbook 1989 quoted, Montgomery 1993) selected t,/2 = 47 d (Wauchope et al. 1991 quoted, Dowd et al. 1993 Halfon et al. 1996). 

Biodegradation in soil, microbial degradation occurs rapidly, t,/2 = 2.1 months for aerobic and t,/2 = 10 d for anaerobic metabolism (Tomlin 1994). 

Biodegradation in soil, fairly rapid degradation by microbial activity, with an average t1/2 = 46 d depending on soil and climatic conditions (Spencer 1982 Tomlin 1994) aerobic rate constant, k = 9.03 x 10 Ir1 (Armbrust 2000). 

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