Distribution and toxic potential of alkylphenols, nonylphenol ethoxylates, and pyrethroids in Minnesota, USA lake sediments

Abstract

This study provided the first assessment of pyrethroids and pyrethrins in Minnesota, USA lake sediments, and the second one for alkylphenols (APs) and nonylphenol ethoxylates (NPEs). Surficial sediments were collected in 2017 from 30 small to medium-sized lakes, encompassing a variety of watershed land uses and ecoregions. These lakes were targeted from a pool of 50 randomly selected lakes included in the National Lakes Assessment (NLA) study. Sixty percent of the study lakes ( n = 18) had at least one detection of a contaminant of emerging concern (CEC). 4-Nonylphenols (4-NP) had the highest detection frequency (46.7%), followed by 4-nonylphenol monoethoxylates (4-NP1EO; 26.7%), bifenthrin (26.7%), 4-nonylphenol diethoxylates (3.3%), and resmethrin (3.3%). The prevalence of 4-NP was consistent with the degradation of high production NPEs in the environment. All other CECs and pyrethrins were not detected. No CECs were detected in the three most remote lakes, located in forested northeastern Minnesota, where atmospheric deposition would be the most likely source of contamination. The concentrations of detected CECs were below levels of concern to benthic invertebrates. Lakes associated with crop land use and the Upper Midwest ecoregion had the highest number of detections for 4-NP, 4-NP1EO, and bifenthrin. Lakes impacted by development had significantly higher ( p < 0.05) 4-NP and 4-NP1EO concentrations than lakes with other watershed land uses, while there was no significant difference ( p > 0.05) between land use categories for bifenthrin. For the first time, ambient background threshold values were calculated for 4-NP, 4-NP1EO, and bifenthrin to provide an indication of ambient sediment quality conditions represented by diffuse anthropogenic sources. This study demonstrated the benefit of analyzing CECs in sediments from small to medium-sized lakes, for which the random sampling design of future NLA studies could be utilized to fully assess the distribution and toxic potential of select CECs nationwide. • CECs have not been well studied in bed sediments from small to medium-sized lakes. • Alkylphenols, nonylphenol ethoxylates, and pyrethroids are CECs of interest. • These CECs were analyzed in surficial sediments collected from 30 Minnesota lakes. • CEC concentrations were below levels of concern to benthic invertebrates. • Watershed land uses affected the distribution of some CECs, but not for bifenthrin.