Distribution of degradation products of alkylphenol ethoxylates near sewage treatment plants in the lower Great Lakes, North America

Degradation of alkylphenol ethoxylate (APEO) surfactants in the environment leads to the formation of relatively hydrophobic compounds such as nonylph enol (NP), octylphenol (OF), nonylphenol monoethoxylate (NPIEO), and nonylp henol diethoxylate (NP2EO) that have been shown to have estrogenic activity . Previous studies have shown that sewage treatment plants (STPs) are point sources for these compounds in the aquatic environment. We collected sedim ent samples at several sites in the vicinity of STPs in Hamilton Harbour an d in the Detroit River to determine the spatial distribution of the degrada tion products of APEOs. In addition, we deployed semipermeable membrane dev ices (SPMDs) and caged freshwater mussels (Elliptio complanata) at these lo cations to determine the distribution of these compounds in the dissolved p hase and their potential to bioaccumulate in aquatic organisms. The NP, OF, NP1EO, and NP2EO were found at mu g/g (dry wt.) concentrations in sediment s and accumulated to ng/g (wet wt.) concentrations in caged mussels near th e STPs. However, in the Detroit River, the concentrations of these compound s declined to near background levels in the sediments, water column (i.e., SPMDs), and biota at stations about I km downstream from STPs. At stations in Hamilton Harbour, concentrations of APEO degradation products also decli ned markedly in sediments and SPMDs located a few hundred meters from the S TP. These data indicate that degradation products of APEOs can be accumulat ed by biota near STPs. However, the environmental distribution of these com pounds is localized to areas close to the point of discharge.