Environmental Engineering Reference
In-Depth Information
Legislation to ban the use of the organotins for small boats was first intro-
duced in France in 1982 and followed by the UK in 1987. Similar legislations
have been introduced worldwide since then, and led to a significant fall in the
concentrations of organotins in seawater.
The “International Convention on the Control of Harmful Antifouling Sys-
tems on Ships” adopted on 5 October 2001 by the International Maritime
Organization (IMO) stated that: (1) by 1 January 2003, a ban on the applica-
tion of TBT-based antifouling paints should be introduced; and (2) 1 January
2008 is the last date for having a TBT-based antifouling paint on a vessel. In
addition, the MEPC also proposed that the IMO promotes the use of environ-
mentally safe antifouling technologies to replace TBT [1].
However, by November 2005, two years later, there were only 12 countries
including Antigua & Barbuda, Bulgaria, Denmark, Japan, Latvia, Nigeria,
Norway, Poland, Romania, Saint Kitts and Nevis, Spain and Sweden, who had
ratified this control. Since at least 25 countries are required to ratify the con-
trol it has not become effective yet.
There are three issues regarding the control: The first is that the organotin
antifouling paints have too high a performance, as some researchers suggest
that organotin antifouling paints have ten years of life and they are too cost
effective. The second is that alternative antifouling paints do not inspire con-
fidence in providing high antifouling activity and environmental problems
yet. The third is that many articles have reported that concentrations of the
organotins in marinas decreased after regulation of small vessels.
Although the control was approved in 1999—by the IMO conference—by
2005 it had still not come into effect. It has been stated that world opinion is
gradually changing from supporting organotin antifouling paints to support-
ing alternative antifouling paints. Hence, if good alternative antifouling paints
were to be found, organotin antifouling paints would be easily and com-
pletely replaced by the alternative antifouling paints. However, at this time,
the best alternative antifouling paints have not been determined. Hence, there
is a need for reliable data regarding both the fate of organotin compounds
and the performance of the most cost-effective and environmentally friendly
alternative antifouling paints.
2
Organotin Compounds and Their Properties
2.1
Organotin Compounds
There are two kinds of organotin compounds, i.e., bivalent compounds and
tetravalent compounds. The bivalent compounds, which have two organic
groups and one lone pair of electrons, are shown in structural formula 1.
