Quaternary Ammonium Compounds in Urban Estuarine Sediment Environments - A Class of Contaminants in Need of Increased Attention?

The distributions of wastewater-derived quaternary ammonium compounds (OACs) were determined in surficial sediments (n = 47) collected from the urbanized lower Hudson River basin. The most abundant class of OACs were dialkyldimethylammonium compounds (DADMACs, with C8 to C18 carbon chain lengths; median Sigma DADMAC = 26 mu g/g), followed by benzylalkyldimethylammonium compounds (BAC, C12-C18; 1.5 mu g/g), and alkyltrimethylammonium compounds (ATMAC, primarily C16 and C18; 0.52 mu g/g). The concentrations of total OACs are higher than those of other conventional organic contaminants determined on the same samples (e.g., median Sigma PAH level of 2.1 mu g/g). Comparatively high concentrations, correlations with sewage derived contaminants, and the relatively constant compositions of OACs observed over large areas suggest that many sediment-sorbed GACs can be relatively persistent in receiving waters. Unusually large concentration-dependent sorption is considered as a mechanism that likely affects persistence of these intrinsically biodegradable chemicals under field conditions. There has been comparatively little field-based research on these classes of cationic surfactants; given the levels of OACs observed here, it is suggested that further investigation is warranted.