Dichloromethane

75-09-2

Solvent. 
Aerosol propellant, paint remover, metal degreaser and
a urethane foam blowing agent. 
(Chem Mark Report 1983).

84.93

Relative volatility (nBuAc=1) = 27.5

Dichloromethane has a high Henry's Law coefficient and will
evaporate rapidly from water. 
Half-lives for the evaporation
from water of 3 - 5.6 hours have been determined at moderate
mixing conditions (Lyman et al. 1987, Rathbun & Tai 1981).

When dichloromethane released into an estuarine bay, all the
chemical dissipated within 4 km of the release point in the
spring and within 8 km in the winter under ice (Howard 1990).

Due to high vapor pressure of dichloromethane, it will
evaporate rapidly from near-surface soil (Howard 1990).

94.57 % (air), 5.39 % (water), 0.04 % (sediment).

log Kom 1.44 (Sabljic 1984)

log Koc 1.68 (calc.) 
(Lyman et al. 1987)

Dichloromethane is adsorbed strongly to peat moss, less
strongly to clay, only slightly to dolomite limestone and not
at all to sand (Dilling et al. 1975).

Since dichloromethane does not absorb light >290 nm, it will
not degrade by direct photolysis in the troposphere (Hubrich 
& Stuhl 1980).

Dichloromethane released into the atmosphere will degrade by
reaction with hydroxyl radicals with a half-life of several
months. 
A small fraction of the chemical will diffuse to the
stratosphere where it will rapidly degrade by photolysis and
reaction with chlorine radicals (Howard 1990).

Biodegradation:
5-26% by BOD
period: 28d
substance: 100 mg/l
sludge: 30 mg/l
(MITI 1992)

Degradation of dichloromethane:
*------------------------------------------------------------*
ENVIRONMENT  INIT.CONC   REDOX-       TEMP    DEGRADATION  REF.
             mg/l        COND.        °C      %/day
*--------------------------------------------------------------*
water (adapted)   17     aerobic       30      100/0.5        a
water             17     anaerobic     30       60/0.5        a
water (deion.)     1     aerobic       25    t 1/2 = 540 d    b
water (adapted)  840     aerobic        -      100/0.75       c
water (adapted)  840     aerobic        -       80/30         c
water (abiotic)    -        -          25    t 1/2 = 700 yr   d
water (adapted)  5 - 10  aerobic       25      100/7          e
sandy soil         0.2   aerobic + natural gas t 1/2 = 0.04 d f
*--------------------------------------------------------------*
a) Brunner et al. 1980           d) Schwarzenbach 1985
b) Dilling et al. 1975           e) Tabak et al. 1981
c) Kästner 1986                  f) Anon. 1987b
(Anon. 1987b).

Dichloromethane biodegrades completely under aerobic conditions
with sewage seed or activated sludge between 6 hours to 7 days
(Howard 1990).

86 - 92 % conversion to CO2 will occur after a varying
acclimation period using anaerobic digestion in wastewater
(Gossett 1985).

Confirmed to be non-accumulative or low accumulative
(Anon. 1987).

EC50 = 1000 mg/l, 15 min, Photobacterium phosphoreum,
EC50 = 2880 mg/l, 15 min, Photobacterium pho sphoreum
(Anon 1986b).

Pimephales promelas, 82.5 mg/l, 28 d, measurable change in
length and/or weight (Dill et al. 1987).

50 % pht inhibition = 1480 mg/l, Chlamydomonas angulosa,
50 % pht inhibition = 2300 mg/l, Chlorella vulgaris,
EC5 = > 8000 mg/l, 48hr, pH 6,9, Chilomonas paramaecium,
EC5 = > 8000 mg/l, 72hr, pH 7, Entosiphon sulcatum
EC5 = > 16000 mg/l, 20hr, pH 7, Uronema parduczi
(Anon 1986b).