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The toxicity and persistence of antifouling booster biocides are of major concern. This study reports the occurrence of Irgarol 1051 and its degradation product M1, in coastal waters of Southern England, during 2004-2005. The highest concentrations of Irgarol 1051 were 89 ng/L in water and 45 ng/g dry weight in sediments, with an overall mean (n=108) of 13 ng/L and 16 ng/g in water and sediments, respectively. As the degradation product of Irgarol 1051, M1 was less widespread, with the highest concentration of 30 ng/L in water and 14 ng/g in sediments, with an overall mean (n=108) of 5 ng/L and 4 ng/g in water and sediments, respectively. Overall, the concentration of Irgarol 1051 and M1 decreased significantly during the sampling period and in comparison to earlier studies during 2000 to early 2004, indicating that control measures by restricting the use of Irgarol 1051 are effective in reducing its concentrations in coastal waters. The distribution of Irgarol 1051 between sediments and water was significantly related to sediment organic carbon content. In addition, significantly higher concentrations of Irgarol 1051 were detected in paint particles than in sediment. The rate of release of Irgarol 1051 from paint residues is very slow, with a half life of approximately 1 y. Two important findings are emerging, first the importance of organic rich sediments and paint residues as major sites of storage for Irgarol 1051, and secondly Irgarol 1051 may be classified as a persistent organic pollutant due to its long half life.

The sorption of seven endocrine disrupting chemicals (EDCs) to aquatic colloids was determined by cross-flow ultrafiltration (CFUF) followed by gas chromatography-mass spectrometry (GC-MS). Results show that the colloidal organic carbon normalized sorption coefficient (Kcoc) of EDCs to different aquatic colloids varies by a factor of 6-12 because such colloids are of different origin. Through characterization of colloidal samples, a significant relationship was established between Kcoc values and the molar extinction coefficient of colloids at 280 nm, whereas no other colloidal properties such as elemental ratios were correlated with Kcoc values. The results are consistent with other reports of the importance of the quality of sorbents such as their aromatic carbon content in sorbing various organic pollutants. The presence of a surfactant was found to increase Kcoc values for estrone (El) and 17alpha-ethynylestradiol (EE2). The method was subsequently applied for determining EDC concentrations in field samples, where both conventional and truly dissolved EDCs showed higher concentrations close to sewage outfalls than either upstream or downstream, confirming the sourceconcentration relationship. In addition, the truly dissolved EDC concentrations were lower than the conventional dissolved concentrations, confirming that there were interactions between aquatic colloids and EDCs. It is estimated that between 10 and 29% of EDCs are associated with aquatic colloids. As colloids are highly abundant in rivers and ocean, they will therefore play a significant role in the environmental behavior and fate of EDCs.