Environmental Engineering Reference
In-Depth Information
ments. Available data on the occurrence and partitioning of these biocides are reviewed and
implications to policies are assessed in the light of presented findings.
Keywords
Antifoulants
·
Fate
·
Organotins
·
Sorption
·
Tr ibut y lt i n
Abbreviations
K
ow
water coefficient
ppb Parts per billion
TBT Tributyltin
TCMS(2,3,5,6-Tetrachloro-4-methylsulphonyl)
TCMTB2-(Thiocyanomethylthio)benzothiazole
Octanol
/
1
Introduction
Antifouling products play an important role in the shipping industry and
are of significant economic importance. It is estimated that, on average, fuel
consumption increases 6% for every 100-
m increase in the average hull
roughness caused by fouling organisms [1, 2]. After 6 months of fouling,
ashipexpends40% extra fuel to maintain a normal speed; other costs include
cleaning, repainting and the loss of revenue due to the time taken for these ac-
tions [3]. Many antifouling systems have been used over the centuries, from
copper and lead sheathing, to the development of paints in the twentieth cen-
tury, containing compounds of copper, lead, arsenic and mercury. Organotins
were first used in the mid-1960s, owing to their acute toxicity to target organ-
isms, with tributyltin (TBT) the most popular compound. Concern over the
effects of organotins used in antifouling paints first arose in France, where
severe problems were encountered in commercial oyster fisheries in areas
where there was intense boating activity and poor tidal exchange [4-6]. Since
then, the distribution, fate and effects of organotins on the marine [7-11]
and freshwater environments [12-16] have been studied extensively. Research
evidence of the damaging effect of triorganotins on the reproduction and
growth of various marine life forms has prompted action by many countries
to regulate or ban their use in antifouling products [17-19]. Following these
legislative controls, TBT contamination of boat harbour water and freshwa-
ters has decreased [20, 21], however a number of studies indicate that even
though regulations were effective in reducing TBT levels, contamination of
sediments by organotin compounds is still widespread and has ecotoxicolog-
ical consequences [22, 23].
TBT products have been superseded by products based on copper, con-
taining organic booster biocides to improve the efficacy of the formulation.
In the absence of the antifouling potency of TBT, a copper compound such
as cuprous oxide (Cu
2
O), copper thiocyanate (CuSCN) or metallic cop-
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