To investigate relationshi.Qs between mercury speciation and site-specific factors in temperate freshwaters, we measured the concentration of seven Hg species along with 18 environmental variables in the surface waters of 23 northern Wisconsin lakes during spring and fall. The lakes spanned relatively wide gradients in Hg (0.15-4.8 ng liter ') and methylmercury (MeHg: 0.04-2.2 ng liter-I). Over the range ofmeasured variables, Hg and MeHg were most strongly correlated with each other (r2 = 0.83-0.88) and with dissolved organic C (DOC) (r2 = 0.64-0.92). Multiple regression models containing DOC and a (DOC x pH) interaction term accounted for 85-90% of the variability in Hg and MeHg between lakes.Observed differences between lakes reflected internal cycling processes and external transport pathways. Internally, high DOC and low pH favored Hg methylation and retention over Hg evasion across the airwater interface. Externally, watershed mapping suggested that the cotransport of DOC, Hg, and MeHg from riparian wetland was also a potentially important process. Observed seasonal differences indicated a 30% increase in MeHg across lakes during summer due to internal or external processes.The effects of DOC on bioaccumulation may be twofold and antagonistic. Although waterborne Hg and MeHg increased with DOC, seston-water partition coefficients tended to decrease, indicating disproportionately more Hg in the dissolved phase. These observations are consistent with previous data on bioaccumulation factors for zooplankton and fish.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.