Distribution and Fate of Ultraviolet Absorbents and Industrial Antioxidants in the St. Lawrence River, Quebec, Canada.

Ultraviolet absorbents (UVAs) and industrial antioxidants (IAs) are contaminants of emerging concern. In this study, we investigated the distribution and partitioning of these contaminants in surface water, suspended particulate matter (SPM), sediment, and various tissues of lake sturgeon ( Acipenser fulvescens ) and northern pike ( Esox lucius ) from the St. Lawrence River (SLR), Quebec, Canada. Results indicated that 2,6-di- tert -butyl-1,4-benzoquinone (BHTQ) was the dominant contaminant in the dissolved phase of the surface water, with median concentrations of 43, 15, and 123 ng/L for three sampling sites, respectively. Surface water collected downstream of a major city showed higher levels of various UVAs, BHTQ, and diphenylamine compared to the upstream, suggesting the influence of the urban activities on the contamination of these emerging contaminants in the SLR. SPM showed greater sorption capacities of most target contaminants compared to those of the sediment. Different contamination profiles were found in lake sturgeon and northern pike, implying that the accumulation of UVAs and IAs in fish depends on their feeding behavior. The field-based tissue-specific bioaccumulation factors (BAFs) for frequently detected contaminants (log BAF 1.5-4.2) were generally comparable to or lower than the Estimation Program Interface modeling results (1.4-5.0), indicating that some of these contaminants may be less bioaccumulative than previously expected.