Analysis of temporal trends and accumulation potential of cyclic volatile methyl siloxanes in a temperate freshwater lake ecosystem

N as a continuous variable for assessing trophic levels. Trophic dilution was observed for the cVMS in this food web, with trophic magnification factors (TMFs) for D4 and D5 <1.0 (range 0.1 to 0.3), while the detection frequency of D6 was too low to calculate a TMF. For comparison, measured TMF values for PCB-180, a highly-lipophilic chemical known to undergo biomagnification, indicated trophic magnification in this food web. Biota to sediment accumulation factors (BSAFs) calculated for cVMS in mayfly nymphs were below the threshold which would indicate bioaccumulation. In addition, a long-term monitoring project was conducted to examine temporal trends in concentrations of cVMS in aquatic biota and surface sediment from Lake Pepin, based on eight years of data (2011-2016, 2018-2019). Concentrations of D4 in a majority of sediment and biota samples were less than limits of quantification (LOQs), as were concentrations of D6 in biota, precluding temporal trend analysis. Lipid-normalized concentrations of D5 in biota showed log-linear annual changes ranging from -13 % to -11 % with mixed statistical significances (p < 0.05 for mayfly nymphs; p > 0.05 for gizzard shad, and sauger). In sediment, log-linear annual changes for OC-normalized concentrations were similar for D5 and D6, at -10 % and - 11 %, respectively. Collectively, these data demonstrate that trophic magnification of cVMS in the aquatic food web is not occurring and that sediment and biota concentrations of cVMS in this aquatic ecosystem generally decreased over the study period.