| Research Abstract |
The aim of this study was to establish management strategy for the new antifouling compounds alternative to organotins. Compounds used were Irgarol 1051, Diuron, KH 101, Zinc pirithione, Copper Pyrithione, and Sea-Nine 211. Conclusions obtained were as follows :
1) Pollution of Japanese aquatic environment
The highest concentrations of three compounds detected in Japanese ambient waters were as follows ; 0.30 μg/L for Irgarol 1051, 1.9 μg/L for M1, and 3.1 μg/L for Diuron. Three-year survey at two stations indicated the concentrations in higher order as Diuron > Irgarol 1051 > M1, generally.
2) Degradation study
Mercuric ion could catalyze hydrolysis of Irgarol in water to produce M1. Solar irradiation also degraded Irgarol in water to produce M1. Photodegradation rate of Irgarol was accelerated by natural components in water, suggesting photosensitive degradation with humic substances. The origin of Irgarol, M1, and Diuron detected in water was ascertained to commercial antifouling paints available in Japanese market.
3) Ecotoxicity study
Ecotoxicity of Irgarol and M1 was evaluated using environmentally relevant organisms such as marine bacteria, microalgae, seaweed, duckweed, zooplankton, and terrestrial plants. The environmental risk of them was assessed with both the ecotoxicological data and residue concentrations. Toxicity of several new antifouling compounds were evaluated using juvenile fish, suspension-cultured fish cells, fertilized egg of sea urchin, and non-target plant species. The toxicity of metal pyrithiones was high to those species tested, especially zinc pyrithione inhibited sea urchin egg development at femtgram per liter. The metal pyrithiones irradiated with UV-A lamp decreased its toxicity to sea urchin, depending on the duration of light treatment. This suggested that metal pyrithiones could be degraded by solar irradiation.
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