Environmental Engineering Reference
In-Depth Information
slow (
t
1
/
2
>
89 days) photolytic decomposition, by stepwise debutylations to
inorganic tin [66].
The half-lives of the organotin compounds in seawater are several days to
several months; however, those in sediment have been reported to be about
1 to 15 years. These data show that the stabilities of the organotin in natural
seawater are surprisingly higher than those previously indicated. In particu-
lar, in sediment the stabilities of the organotins are very high. The data for
the half-lives of organotin compounds including the above data, are shown in
Tables 8, 9 and 10 [66-96].
Lee et al. [97] reported the TBT degradation in low concentrations
(
<
5 ng L
-1
, both radiolabeled and unlabeled) in estuarine waters along the
Georgia coast (USA) with half-lives ranging from 3 to 6 days under light and
from 7 to 13 days in dark conditions. Evidence suggests that microalgae play
important roles in TBT degradation in sunlit coastal water. TBT degradation
rates were high in light as compared with those of degradations in the dark.
Further, after adding nitrate for growth of microalgae, for example
Skele-
Table 9
Degradation of organotin compounds in sediments [67, 68]
Organotin,
Half life
Comment
Publi-
Refs.
medium
(initial
cation
concentration)
year
TBT, sediment
about 2.5 years
Aukland,
1995
[82]
New Zealand
TBT, sediment
about 8.7 years
Vancouver, Canada
1997
[83]
TBT, sediment
2.1 years
1995
[84]
TBT, sediment
1.85 years, first order
Aukland,
1989
[85]
0.375
/
year, estimated from
New Zealand
sediment core data
(TBT: 0.759
ยต
gSn
/
g)
TBT, sediment
>
8-15 years, estimated
Arcachon Bay,
1990
[86]
from sediment core data,
France
TBT, sediment
6.9 years, estimated from
Chinhae Bay,
1998
[87]
sediment core data,
Korea
TBT, sediment
2.1 years, estimated from
Oleron Island,
1995
[88]
sediment core data
France
TBT, sediment
100-800 days, faster under
Japan
1995
[89]
aerobic conditions than
anaerobic conditions
TBT, sediment
460 days
Toba Bay, Japan
1992
[90]
anaeroabic sediment
TBT, sediment
360-775 days
UK
1993
[91]
surfacial sediment
DBT, sediment
1.9 years
1995
[84]
MBT, sediment
1.1 years
1995
[84]
