Response to Comment on 'Fate of Octyl- and Nonylphenol Ethoxylates and Some Carboxylated Derivatives in Three American Wastewater Treatment Plants'

摘要

In their comment (1) on our paper on the fate of alkylphenol ethoxylates (APEO) in wastewater treatment plants (2), Dhaliwal and Craig suggest that the alkylphenoxyethoxy carboxylate (APEC) concentrations in influents and effluents were reversed because wastewater treatment plants (WWTPs) cannot be "such a significant source of APECs". However, APEC formation in WWTPs has been reported in the literature from the early studies on APEO degradation (3-5), and we did not emphasize it in our paper precisely because it is a widespread phenomenon (6, 7). APEC concentrations have been shown to constitute a predominant fraction of APEO-related compounds in WWTP effluent (4, 5), and the concentrations we reported were within the range found by other groups (4-6, 8). Additionally, we find no reason to question our analytical results; although we calculated APEC concentrations using an external standard approach, we verified some of these measurements using standard additions and we found little deviation from the original results (9). Therefore, we stand by the APEC data and conclusions we derived from them.