新《生活饮用水卫生标准》GB5749-项目解读六氯丁二烯

biodegrade ; thus, HCBD may not biodegrade in anaerobic zones of soil. No information was found about HCBD adsorption to soil. The calculated Koc value for HCBD using equation 4.7 of Lyman et al and a water solubility of 9.77 umole/l is 5181. Thus, HCBD will adsorb strongly to organic material in soils and is not expected to rapidly migrate. However, migration will be more rapid in sandy soils. Dune infiltration studies in the Netherlands indicate that HCBD is mobile in sandy soil. Dune infiltration and effluent HCBD concentrations (respectively) were 0.02 and 0.01 ug/l in 1976 and 0.01 and 0.01 ug/l in 1977(6). Average residence time was 100 days. These results also suggest that degradation of HCBD under these conditions is very slow. AQUATIC FATE: Hexachlorobutadiene (HCBD) may biodegrade in natural waters since 100% HCBD degradation occurred in 7 days in an aerobic batch culture incubated at 25 deg C and inoculated with settled domestic sewage . No information was found on HCBD biodegradation rates in natural waters. Estimated half-lives for HCBD degradation are 3-30 days in river water and 30-300 days in lake and ground waters . No information was found on hydrolysis or photolysis. Because of its relativel high log Kow value (4.90 ), HCBD will sorb to sediments, suspended sediments and biota. The mean bioconcentration factor (BCF) for rainbow trout exposed to 0.10 ng/l and 3.4 ng/l of HCBD was 5800 and 17,000,respectively , which would suggest extensive bioconcentration. The Henry's Law constant for HCBD at 25 deg C is 1.03X10-2 atm-cu m/mole . Another study reports a water/air partition coefficient of 0.97 at 20 deg C (2.4X10-2 atm-cu m/mole). These values indicate that HCBD will rapidly volatilize from water (6). ATMOSPHERIC FATE: In the atmosphere, hexachlorobutane should degrade primarily by addition of photochemically derived hydroxyl radicals with its double bonds. By analogy with tetrachloroethylene one would anticipate a half-life of 2 months. Using a mass balance approach a half-life estimate of 1.6 was obtained for the northerm hemisphere. Therefore HCDB will be long lived in the atmosphere and considerable dispersion would be expected. Drinking Water Impact SURFACE: Hexachlorobutadiene (HCBD) was found at concentrations of 10 and 23 ug/l in water sampled beyond the boundries of two chemical plants . HCBD concentration in an open waste treatment pond was 244 ug/l . Mississippi River water at Baton Rouge, LA contained 1.9 ppb of HCBD . HCBD was found in the Ashtabula River (Ohio) at an unspecified
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