Environmental Engineering Reference
In-Depth Information
3.3
Half-lives of Organotin Compounds in Seawater and Sediment
After the environmental problems of organotin antifouling paints became
evident, the stability of the organotin compounds such as TBT and TPT com-
pounds in terms of the half-lives have been reported in many articles. These
organotins are degraded by hydrolysis in water with sunlight and microor-
ganisms at a room temperature. Hence, data for the half-lives in natural
seawater, in fresh water or in pure water in the laboratory vary with the in-
tensity of light, temperature, types or amounts of organisms, flow rates of
seawater, types or amounts of ions in seawater, and amounts of the organotin
compounds.
In 1983, the degradation of the TBTO as a representative organotin com-
pound in water was reported. Its aqueous solubility at 20
◦
Cis0.7-7 mg L
-1
at pH 5-7 and the vapor pressure is estimated to be 6.4
10
-7
mm Hg. Dis-
solved in water, it neither volatilized nor lost butyl groups over a period of
at least 2 months in the dark at 20
◦
C; in sunlight, however, it underwent
×
Table 8
Degradation of organotin compounds in water [67, 68]
Organotin,
Half life
Comment
Publication Refs.
medium
(days)
(initial concentration)
year
TBT, seawater
4-19
1989
[69]
TBT, seawater
6-7
(0.5
µ
g
/
L)
1989
[70]
open seawater (28
◦
C)
TBT, seawater
17
1986
[71]
TBT, seawater
6-13
in sunlight, San Diego, USA
1996
[72]
TBT, seawater
7-19
in the dark, San Diego, USA
1986
[72]
TBT, seawater
6
in sunlight, San Diego, USA
1988
[73]
TBT, seawater
13
in one location, no degradation
1988
[74]
over 15 days in the dark,
Osaka, Japan
TBT, seawater
4-19
in sunlight, USA
1989
[75]
TBT, seawater
15
Italy
1990
[76]
in the light,
14
CTBT(2
TBT, seawater
6
µ
g
/
L)
[77]
7
in the dark, USA, marina
1988
TBT, seawater
17
open seawater
1996
[71]
at 5
◦
C
TBT, seawater
60
1987
[78]
at 28
◦
C
TBT, estuarine
6-7
1996
[71]
at 22-28
◦
C in the dark
TBT, estuarine
7-14
1988
[74]
TBT, estuarine
7.77
0-39 days
1998
[80]
2.55
for first 10 days
13.4
after 11 to 40 days
TBTO, fresh water
>
89
in sunlight
1983
[66]
TBT, fresh water
26
in winter, in lab window
1992
[81]
