Measurements of mercury stable isotopes during planktonic uptake and photochemical demethylation of methylmercury

Laboratory experiments were performed between 2019 and 2020 to examine how dissolved organic matter (DOM) and phytoplankton (Raphidocelis subcapitata) cells alter mercury (Hg) uptake and isotope fractionation. Experiments were performed at ambient Hg to thiol ratios using natural organic matter isolates received from collaborators at the University of California-Davis. Two types of experiments were performed: (1) one set with SRFA isolates at two concentrations and Hg, termed uptake experiment, and (2) one set with DOM isolates, Hg, and cultured Raphidocelis subcapitata cells, termed sunlight exposure experiment. For additional experimental details, including culturing conditions, experimental set-up, and analysis, refer to the companion publication (Armstrong and others, 2023, TBD).