Distribution, Fate, and Behavior of Nonylphenol Ethoxylates and Degradation Products in the Dispersion Plume of a Major Municipal Wastewater Effluent

Abstract

The aim of this study was to estimate the distribution, fate, and behavior of p-nonylphenols (p-NPs: p-n-nonylphenol and its isomers), nonylphenol ethoxylates (NP_1–17EOs), and nonylphenol carboxylic acids (NP_1–2ECs) in the municipal wastewater effluent (MWWE) of the City of Montreal, Canada, and in the receiving waters of the St. Lawrence River. The MWWE was sampled at the Montreal wastewater treatment plant, while surface water was sampled at sites located upstream and downstream of the effluent outfall. Twenty-four hour composite samples were obtained at the treatment plant on three nonconsecutive days during the summer of 2002. Water samples were filtered, then particulate and dissolved phases were extracted using Soxhlet and solid-phase extraction techniques, respectively, prior to LC/MS/MS analysis for the compounds of concern. The effluent contained essentially dissolved (75.4%, 375 kg/day) and particulate (23.7%, 118 kg/day) NP_1–17EOs. By contrast, the surface water downstream of the outfall contained p-NPs at an average of 9.8% and dissolved NP_1–2ECs (1.3%), as well as dissolved NP_1–17EOs (86.7%) and a small fraction of particulate NP_1–17EOs (2.1%). All NP_nEOs and their degradation products were present in higher amounts in the dissolved phase (particulate/dissolved ratio < 1) than in the particulate phase in both the wastewater and surface water. In the surface waters downstream of the effluent outfall, an average of 89% of the particulate NP_1–17EOs was rapidly released (within 1.5 h) into the dissolved phase during the physical exchange, and there were variances in changes in the phase distribution among the compounds being studied. Following this relatively fast phase transfer in the receiving waters, 30% of total NP_1–17EOs were lost, 25% of p-NPs and NP_1–2ECs were formed by the degradation of a fraction (6%) of NP_1–17EOs, and 24% of NP_1–17EOs loss remains unexplained.

Keywords:

• municipal wastewater effluent
• endocrine-disrupting compounds
• hormone-mimicking substances
• nonionic surfactants
• nonylphenol isomers

Acknowledgments

The authors thank P. Cejka and Y. Lafleur for sampling of the Montreal municipal wastewater effluent. They are also grateful to M. Arseneau, G. Brault, K. Dohrendorf, and G. Côté for the excellent field and laboratory work, F. Boudreault and P. Gagnon for drafting the map and figures, and P. Potvin for manuscript editing. This research was funded by the St. Lawrence Centre of Environment Canada.

Notes

*Do not include p-n-NP.

*Difference (in μ g/L) for p-NPs, for example, is calculated as follows: measured value for p-NPs − calculated value for p-NPs.

**Difference (in %) for p-NPs, for example, is calculated as follows: (measured value for p-NPs − calculated value for p-NPs)/calculated value for p-NPs × 100. Note: measured values are given in Table 3 (values for surface water downstream the outfall).