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

Ultraviolet absorbents (UVAs) and industrialantioxidants (IAs) are contaminants of emerging concern. In thisstudy, we investigated the distribution and partitioning of thesecontaminants in surface water, suspended particulate matter(SPM), sediment, and various tissues of lake sturgeon (Acipenserfulvescens) and northern pike (Esox lucius) from the St. LawrenceRiver (SLR), Quebec, Canada. Results indicated that 2,6-di-tert-butyl-1,4-benzoquinone (BHTQ) was the dominant contaminantinthedissolvedphaseofthesurfacewater,withmedianconcentrations of 43, 15, and 123 ng/L for three sampling sites,respectively. Surface water collected downstream of a major cityshowed higher levels of various UVAs, BHTQ, and diphenylaminecompared to the upstream, suggesting the influence of the urbanactivities on the contamination of these emerging contaminants in the SLR. SPM showed greater sorption capacities of most targetcontaminants 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 infish depends on their feeding behavior. Thefield-based tissue-specificbioaccumulation factors (BAFs) for frequently detected contaminants (log BAF 1.5-4.2) were generally comparable to or lowerthan the Estimation Program Interface modeling results (1.4-5.0), indicating that some of these contaminants may be lessbioaccumulative than previously expected.

Automated summary

The study on the St. Lawrence River showed that BHTQ was the dominant contaminant in dissolved water, and sediment had higher sorption capacities for most target contaminants compared to SPM. Different contamination profiles were found in lake sturgeon and northern pike, indicating that the accumulation of UVAs and IAs in fish depends on their feeding behavior.