Premium
Ecosystem Controls on Methylmercury Production by Periphyton Biofilms in a Contaminated Stream: Implications for Predictive Modeling
Author(s) -
Schwartz Grace E.,
Olsen Todd A.,
Muller Katherine A.,
Brooks Scott C.
Publication year - 2019
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.4551
Subject(s) - periphyton , methylmercury , zoology , chemistry , mercury (programming language) , environmental chemistry , environmental science , nutrient , biology , bioaccumulation , organic chemistry , computer science , programming language
Periphyton biofilms produce a substantial fraction of the overall monomethylmercury (MMHg) flux in East Fork Poplar Creek, an industrially contaminated, freshwater creek in Oak Ridge, Tennessee. We examined periphyton MMHg production across seasons, locations, and light conditions using mercury stable isotopes. Methylation and demethylation rate potentials ( k m, trans av and k d, trans av , respectively) were calculated using a transient availability kinetic model. Light exposure and season were significant predictors of k m, trans av , with greater values in full light exposure and in the summer. Season, light exposure, and location were significant predictors of k d, trans av , which was highest in dark conditions, in the spring, and at the upstream location. Light exposure was the controlling factor for net MMHg production, with positive production for periphyton grown under full light exposure and net demethylation for periphyton grown in the dark. Ambient MMHg and k m, trans av were significantly correlated. Transient availability rate potentials were 15 times higher for k m and 9 times higher for k d compared to full availability rate potentials ( k m, full av and k d, full av ) calculated at 1 d. No significant model for the prediction of k m, full av or k d, full av could be constructed using light, season, and location. In addition, there were no significant differences among treatments for the full availability k m, full av , k d, full av , or net MMHg calculated using the full availability rate potentials. k m, full av was not correlated with ambient MMHg concentrations. The present results underscore the importance of applying transient availability kinetics to MMHg production data when estimating MMHg production potential and flux. Environ Toxicol Chem 2019;38:2426–2435. © 2019 SETAC