| 環境中動態 | TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 1120(SRC), determined from a structure estimation method(2), indicates that p-cymene is expected to have low mobility in soil(SRC). Volatilization of p-cymene from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 0.011 atm-cu m/mole(SRC), derived from its vapor pressure, 1.50 mm Hg(3), and water solubility, 23.4 mg/L(4). However, adsorption may attenuate this process. p-Cymene is expected to volatilize from dry soil based on its vapor pressure(4). p-Cymene, present at 100 mg/L, reached 83-95% of its theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L with the Japanese MITI test(5,6) which classifies p-cymene as readily biodegradable(6).AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 1120(SRC), determined from a structure estimation method(2), indicates that p-cymene is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 0.011 atm-cu m/mole(SRC), derived from its vapor pressure, 1.50 mm Hg(4), and water solubility, 23.4 mg/L(5). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 3.5 hours and 4.6 days, respectively if adsorption is ignored(SRC). The volatilization half-life from a model pond is estimated as 30 days if adsorption is considered(6). According to a classification scheme(7), an estimated BCF of 236(SRC), from its log Kow of 4.10(8) suggests the potential for bioconcentration in aquatic organisms is high. p-Cymene, present at 100 mg/L, reached 83-95% of its theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L with the Japanese MITI test(9,10) which classifies p-cymene as readily biodegradable(10). p-Cymene is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(3).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), p-cymene, which has a vapor pressure of 1.50 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase p-cymene is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and nitrate radicals(SRC)the half-life for the reaction with hydroxyl radicals is estimated to be about 1 day(SRC), calculated from its measured rate constant of 1.51X10-11 cu cm/molecule-sec at 22 °C(3). The half-life for the reaction with nitrate radicals is estimated to be 34 days(SRC), calculated from its rate constant of 9.9X10-16 cu cm/molecule-sec at 25 °C(3). p-Cymene's detection in snow(4) suggests that removal from air by wet deposition occurs(SRC). |
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