Inputs of terrestrial dissolved organic matter enhance bacterial production and methylmercury formation in oxic coastal water

Main hypotheses addressed: 1) MeHg is formed from Hg(II) in oxic waters by natural microbial communities in the absence or low abundance of the hgcAB gene pair; 2) MeHg formation is coupled to the overall bacterial biochemical activity, which is enhanced by the addition of tDOM; 3) A rapid response of bacterial biochemical activity leads to MeHg formation within few hours after the input of Hg(II) to oxic DOM-rich waters.