Sorption of small metabolites of nonylphenol polyethoxylates in single and complex systems on aquatic suspended particulate matter.

Sorption of nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) as well as their binary and ternary mixtures were studied and compared on three simulated suspended particulate matters (SPMs). Sorption dynamics of NP on the three SPMs could be divided into two phases, the rapid sorption phase and the slow sorption phase. A third phase, 'apparent desorption' occurred before the slow sorption phase for NP1EO and NP2EO as well as for all mixtures. Initial sorption rate increased with the OC% content of the SPMs. At low concentration, the sorption of NP, NP1EO and NP2EO (only at low concentration for 3# SPM) followed linear isotherm on the three SPMs. The linear Kd value of NP or NP1EO increased with the OC% content of SPM. In mixtures, sorption of NP, NP1EO and NP2EO increased significantly, and a 'critical point', after which sorption increased significantly, was observed in certain sorption isotherms.