CHAPTER 8 • Quality Status, Appropriate Monitoring and Legislation of the North Sea
169
remobilized during the winter gales and likely to be carried further north and finally
deposited in the Norwegian Trench (Skei 1981).
Data from Wild and Jones (1995) show that 11% of PAH inputs to the atmosphere
are from motor vehicles, and correlations between PAHs and lead in North Sea aerosol samples suggest a source related to road transport (Preston et al. 1992; Chester
et al. 1994). They propose the relationship of PAHs with lead, as a tracer of anthropogenic influence, could be used to follow changes due to the adoption of lead-free petrol
and the decreasing use of leaded petrol. Airborne contantinant inputs to the northern
North Sea are only 50% of those to the southern North Sea (QSR 1993) due to greater
urbanisation and industrialisation.
Among the most comprehensive study of estuarine PAHs was that conducted by
Readman et al. (1987) for the R. Tamar. They established that PAHs appear to be stable
in anoxic sediments, such that PAH concentrations at dated levels in a sediment core
reflect inputs to the sediments when they were laid down. He concluded that the exponential increases from 1960-1980 in PAHs and some metals (Cu, Zn, Pb), typical of other
UK estuaries, suggests inputs from motor vehicles and road run-off.
Elevated nearshore PAH concentrations also provided the dominant pollutant in the
effects observed by Widdows et al. (1995). They conclude that" ... at the majority of NOIith
Sea coastal (26) sites toxic hydrocarbons are at concentrations capable of inducing significant inhibition of SFG and forming a major component of the overall reduction in
SFG". In some instances this accounted for up to 90% of the reduction in SFG.
When considering the effects of North Sea contaminants the QSR (1993) reports that
"Information on the occurrence of these compounds in the North Sea is rather scarce
and almost no information on inputs is available". Since then preliminary analyses of
water samples have been conducted as part of the UK National Monitoring Programme
(Law et al. 1997). They show elevated concentrations in industrialized estuaries with
levels as high as 1O.7jlg 1-', and 15% of samples exceed sublethal toxicity thresholds.
PAHs provide another example (see Section 8.2) where biological techniques are
highlighting the importance of a class of compounds which a predominately chemical
approach has, until recently, overlooked.
8.5.2
Organotins
The most significant individual contaminant known in recent years to depress coastal
water quality is tributyl tin (TBT); the biocide used in antifouling paints. The significance of TBT was first detected by its effect on non-target organisms: shell thickening
in oysters and a failure of their larvae to grow to metamorphosis (Alzieu et al. 1982).
Subsequently it was found to disrupt the endocrine system in the dog whelk (Nucella
lapillus), causing infertility by inducing females to become male (imposex) (see review
by Gibbs and Bryan 1996). TBT is now known to induce imposex in about 30 species
of gastropod, and has been established as a specific index of TBT pollution. TBT constitutes a unique ecotoxicological case study illustrating the complete action cycle, from
the problem detected, to causality established, legislation introduced and recovery
monitored (Abel 1996; see Champ and Seligman 1996 for a full account).
The impact of TBT is sometimes trivialized as only causing imposex in dog whelks
and shell thickening in cultivated Japanese oysters.Jt is therefore overlooked that TBT
169
remobilized during the winter gales and likely to be carried further north and finally
deposited in the Norwegian Trench (Skei 1981).
Data from Wild and Jones (1995) show that 11% of PAH inputs to the atmosphere
are from motor vehicles, and correlations between PAHs and lead in North Sea aerosol samples suggest a source related to road transport (Preston et al. 1992; Chester
et al. 1994). They propose the relationship of PAHs with lead, as a tracer of anthropogenic influence, could be used to follow changes due to the adoption of lead-free petrol
and the decreasing use of leaded petrol. Airborne contantinant inputs to the northern
North Sea are only 50% of those to the southern North Sea (QSR 1993) due to greater
urbanisation and industrialisation.
Among the most comprehensive study of estuarine PAHs was that conducted by
Readman et al. (1987) for the R. Tamar. They established that PAHs appear to be stable
in anoxic sediments, such that PAH concentrations at dated levels in a sediment core
reflect inputs to the sediments when they were laid down. He concluded that the exponential increases from 1960-1980 in PAHs and some metals (Cu, Zn, Pb), typical of other
UK estuaries, suggests inputs from motor vehicles and road run-off.
Elevated nearshore PAH concentrations also provided the dominant pollutant in the
effects observed by Widdows et al. (1995). They conclude that" ... at the majority of NOIith
Sea coastal (26) sites toxic hydrocarbons are at concentrations capable of inducing significant inhibition of SFG and forming a major component of the overall reduction in
SFG". In some instances this accounted for up to 90% of the reduction in SFG.
When considering the effects of North Sea contaminants the QSR (1993) reports that
"Information on the occurrence of these compounds in the North Sea is rather scarce
and almost no information on inputs is available". Since then preliminary analyses of
water samples have been conducted as part of the UK National Monitoring Programme
(Law et al. 1997). They show elevated concentrations in industrialized estuaries with
levels as high as 1O.7jlg 1-', and 15% of samples exceed sublethal toxicity thresholds.
PAHs provide another example (see Section 8.2) where biological techniques are
highlighting the importance of a class of compounds which a predominately chemical
approach has, until recently, overlooked.
8.5.2
Organotins
The most significant individual contaminant known in recent years to depress coastal
water quality is tributyl tin (TBT); the biocide used in antifouling paints. The significance of TBT was first detected by its effect on non-target organisms: shell thickening
in oysters and a failure of their larvae to grow to metamorphosis (Alzieu et al. 1982).
Subsequently it was found to disrupt the endocrine system in the dog whelk (Nucella
lapillus), causing infertility by inducing females to become male (imposex) (see review
by Gibbs and Bryan 1996). TBT is now known to induce imposex in about 30 species
of gastropod, and has been established as a specific index of TBT pollution. TBT constitutes a unique ecotoxicological case study illustrating the complete action cycle, from
the problem detected, to causality established, legislation introduced and recovery
monitored (Abel 1996; see Champ and Seligman 1996 for a full account).
The impact of TBT is sometimes trivialized as only causing imposex in dog whelks
and shell thickening in cultivated Japanese oysters.Jt is therefore overlooked that TBT