Pyrrole

CAS RN: 109-97-7

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 61(SRC), determined from a log Kow of 0.75(2) and a regression-derived equation(3), indicates that pyrrole is expected to have high mobility in soil(SRC). Volatilization of pyrrole from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 1.8X10-5 atm-cu m/mole(4). The potential for volatilization of pyrrole from dry soil surfaces may exist(SRC) based upon a vapor pressure of 8.35 mm Hg(5). Pyrrole does not readily undergo biodegradation in water unless there exists bacteria that have had previous exposure to pyrrole. Given this need for acclimation, the decomposition of pyrrole may be very slow(6).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 61(SRC), determined from a log Kow of 0.75(2), indicates that pyrrole is not expected to adsorb to suspended solids and sediment in water(SRC). Volatilization from water sources is expected(3) based upon a Henry's Law constant of 1.80X10-5 atm-cu m/mole(4). Volatilization half-lives for a model river and model lake are 42 hrs and 368 hrs, respectively(SRC), using an estimation method(3). According to a classification scheme(5), an estimated BCF of 2(3,SRC) from a log Kow of 0.75(2) suggests the potential for bioconcentration in aquatic organisms is low. Experiments have shown that pyrrole is actually degraded by gasoline-adapted ground water cultures when present as a single substrate. Adaption time was 480 hrs and degradation time was 600 hrs(6). Pyrrole was not degraded in a mixture of compounds in water after 1100-1300 hrs at 10 deg C and at a concentration of 0.2-1 mg/l(6).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), pyrrole, which has a vapor pressure of 8.35 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase pyrrole is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 4 days(SRC) from its rate constant of 1X10-10 cu cm/molecule sec(3). In a comparison of room temperature rate constants and loss rates of selected organics in the presence of 7.2X10+11 molecule/cu cm of ozone, 5X10+5 molecule/cu cm of hydroxyl radicals, and 2.4X10+8 molecules/cu cm of NO3 radicals, pyrrole displayed the following rate constants: 1.6X10-17 cu cm/molecule sec with a loss rate of 1 day, 1.2X10-11 cu cm/molecule sec with a loss rate of 5.2 days, and 4.9X10-11 cu cm/molecule sec with a loss rate of 1000 days, respectively(4).
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