7091 - Laserfiche WebLink

Home Browse Search

BACKGROUND CONCENTRATIONS GENERAL In aquatic environments, organotin concentrations were elevated in sediments, biota, and surface water microlayers collected near marinas, aquaculture rearing pens, and other facilities where organotin-based antifouling paints were used. In some cases, organotin concentrations in the water column were sufficiently high to pose a substantial risk to sensitive species. Data are now extremely limited on background concentrations of organotins in all environmental samples, especially in terrestrial ecosystems, and this may be attributed, in part, to limitations in routine chemical analytical capabilities. NONBIOLOGICAL Tin concentrations in water, air, soils, sediments, and other nonbiological materials are documented but information is scarce except for aquatic systems (Table 6). In aquatic systems, several trends were evident. First, tin and organotin compounds tend to concentrate in surface microlayers by factors up to 10,000X relative to subsurface water; in the case of organotins, this may be due to partitioning into the film of petroleum hydrocarbons commonly present on water surfaces (Maguire et al. 1982; Cleary and Stebbing 1987; Hall et al. 1987). Second, organotin concentrations, especially tributyltins, were highest in the vicinity of marinas and harbors, and this is consistent with its use as an antifouling agent in some paints for boats, ships, and docks (Chau et al. 1984; Maguire et al. 1986; Randall et al. 1986; Valkirs et al. 1986). Peak tributyltin concentrations occurred in late spring and early summer in association with postwinter launching of freshly painted boats (Hall et al. 1987). Third, organotin levels throughout the water column of marinas in numerous freshwater and marine locations were sufficiently elevated to cause chronic toxic effects in sensitive organisms including algae, copepods, oysters, mussel larvae, and fish (Maguire et al. 1982, 1986; Waldock and Thain 1983; Chau et al. 1984; Maguire and Tkacz 1985; Beaumont and Newman 1986; Cardwell and Sheldon 1986; Thain and Waldock 1986; Cleary and Stebbing 1987; Hall et al. 1987; Stromgren and Bongard 1987). Fourth, methyltin species were infrequently detected. Their occurrence was positively correlated with the presence of relatively high concentrations of inorganic tin and was due primarily to biotic and abiotic methylation of both organotin and inorganic tin compounds (Chau et al. 1984; Maguire et al. 1986). Finally, butyltin species were detected in harbor sediments at 20