Registration Dossier

Environmental fate & pathways

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If released to air, a vapor pressure of 35.3 mm Hg at 25oC indicates dibromomethane will exist solely as a vapor in the ambient atmosphere. This tendency is predicted by Level III Fugacity Model:

 

Mass Amount (%)

Emissions (kg/hr)

Air

97.3

1000

Water

2.33

0

Soil

0.378

0

Sediments

0.00638

0

If released to soil, dibromomethane is expected to have very high mobility based upon an estimated Koc of 29.86. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 8.22X10-4atm m3/mole. Dibromomethane may volatilize from dry soil surfaces based upon its vapor pressure. This tendency is predicted by Level III Fugacity Model:

 

Mass Amount (%)

Emissions (kg/hr)

Air

27.5

0

Water

4.86

0

Soil

67.6

1000

Sediments

0.0133

0

 If released into water, dibromomethaneis not expected to adsorb to suspended solids and sediment in water based upon the Koc and by Level III Fugacity Model. Volatilization from water surfaces is expected to be a significant transport mechanism based upon Henry's Law constant and estimated volatilization half-lives for a model river and model lake are 2 hours and 6 days, respectively. On the other hand, Level III Fugacity Model predicted 84% of the substance remains in water and thus, dibromomethane can be available to biotic and abiotic degradations processes in water.

 

Mass Amount (%)

Emissions (kg/hr)

Air

15.6

0

Water

84.2

1000

Soil

0.0605

0

Sediments

0.231

0

 If released to air soil and water dibromomethane is tending to distribute among these three compartments almost equally as predicted by Level III Fugacity Model:

 

Mass Amount (%)

Emissions (kg/hr)

Air

33.9

1000

Water

35.9

1000

Soil

30.1

1000

Sediments

0.0983

0

As predicted by Level III Fugacity Model dibromomethane is tending to distribute among water soil and air compartments almost equally. Thus, dibromomethane is expected to undergo biotic and abiotic degradation processes in each of these three compartments.