Environmental Engineering Reference
In-Depth Information
data are available for Irgarol [43-46], while of the other booster biocides, di-
uron, chlorothalonil, dichlofluanid and Kathon
Sea-Nine have received the
most attention. Since almost all of these compounds have agricultural uses
their presence in the aquatic and estuarine environments cannot be attributed
solely to the use of antifoulants [47].
There are many factors that influence the degradation and persistence of
these biocides in the marine environment. These include their chemical and
physical properties as well as ecosystem-specific parameters such as the na-
ture and concentration of microbial populations, dissolved and suspended
material and temperature. For example, in a study investigating biodegrad-
ability in seawater, the breakdown of four biocides (diuron, Irgarol, Kathon
and chlorothalonil) was monitored over 8 weeks by bioassay using
Amphora
coffeaeformis
(a ship-fouling diatom). The results demonstrated that abiotic
pathways were unlikely to be a major route for degradation of these sub-
stances in the sea, although photolysis may be significant in the upper layers
of water [48].
/
2.1
Irgarol
A number of studies on the occurrence of Irgarol in coastal waters [41, 43,
45, 46, 49-59] and freshwaters [44, 51, 60] indicate its widespread occurrence
in aquatic environments. Irgarol is the most frequently detected antifouling
biocide worldwide [31].
Water samples collected from marinas, estuaries and coastal waters along
the UK south coast and sediment samples from the Hamble estuary in the UK
showed that Irgarol residues were present in most marine and estuarine sam-
ples, although not in freshwaters [45]. The highest concentrations were found
in areas of high boating activity, particularly marinas and the Hamble estu-
ary, indicating a correlation with its use in antifouling paints. Monitoring of
water samples taken from Plymouth Sound (UK) showed Irgarol at all sam-
pling sites. The highest levels were found in close proximity to areas of high
boat density, especially where water flow was restricted within marinas; the
highest detected value was 127 ng L
-1
[46]. Monitoring of subsurface waters
from the French Mediterranean (Côte d'Azur) coastline showed substantial
levels of Irgarol in all marinas, with concentrations reaching 640 ng L
-1
[61].
Assessment of the contamination of different compartments of Lake Geneva
(water, sediments, zebra mussels, macrophytes and algae) over a period of
9 months found concentrations comparable to those observed in marine stud-
ies [44].
The highest concentrations of Irgarol have been associated with marinas,
while ports tend to have lower concentrations. Irgarol was also detected at
high concentrations in fishery harbours in one study in Japan [51]. The re-
strictions on the use of Irgarol on small boats may change this distribution.
