The Interaction of Mercury and Methylmercury with Reduced Sulfur: Implications for the Transformation of Mercury and Methylmercury in the Environment

• Other Authors: Mazrui, Nashaat M. (Creator), Mason, Roert (Major Advisor), Zhao, Jing (Associate Advisor), Vlahos, Penny (Associate Advisor), Hren, Michael (Associate Advisor), Selampina, Fatma (Associate Advisor), University of Connecticut (Degree grantor)
• Format: Text
• Language: unknown
• Published: University of Connecticut 2016
• Subjects: Long Island; Long Island Sound; North Atlantic
• Online Access: http://hdl.handle.net/11134/20002:860652832; https://digitalcollections.ctstatelibrary.org/islandora/object/20002%3A860652832/datastream/TN/view/Interaction%20of%20Mercury%20and%20Methylmercury%20with%20Reduced%20Sulfur%3A%20Implications%20for%20the%20Transformation%20of%20Mercury%20and%20Methylmercury%20in%20the%20Environment.jpg

The formation of mercury sulfide nanoparticles (β-HgS(s)nano) from inorganic mercury (HgII), dissolved sulfide, and marine DOM extracted from: Eastern Long Island Sound, Western Long Island Sound and at the shelf break of the North Atlantic Ocean was studied. All the DOM used led to the formation of stable β-HgS(s)nano however, DOM extracted from the shelf break was less effective at inhibiting growth of β-HgS(s)nano relative to coastal DOM. It is also shown that the β-HgS(s)nano are stable in the dark and in the absence of oxygen, but that they slowly aggregate in the presence of light and oxygen. Aside from the precipitation of β-HgS(s)nano from dissolved species, we also show that Hg containing nanoparticles can form in the environment from the interaction of HgII with metal sulfide nanoparticles. Using steady-state and time-resolved fluorescence measurements we show that HgII forms a strong complex with CdS(s) quantum dots. We further demonstrate that HgII added to sediment slurries as β-HgS(s)nano was methylated by Hg methylating bacteria more than when HgII was added to the sediment as microparticles of β-HgS(s). Thus, contrary to popular belief, the precipitation of β-HgS(s) in sediments does not always limit the availability of HgII to methylating bacteria. We also found that HgII added to sediment slurries as HgII complexed to thiol groups on DOM is more bioavailable for methylation than other complexes of HgII with reduced sulfur that are commonly found in the environment, and at least 2 times more than HgII added to the sediment slurries as Hg(aq). The enhanced availability of HgII-DOM complexes in sediment slurries, shown here, has not been demonstrated before. Lastly, we show that methylmercury (MeHg) is converted to dimethylmercury (DMeHg) from the adsorption or complexation of MeHg on metal sulfide surfaces or on low molecular weight thiols, respectively. Based on the measured production rates of DMeHg in our experimental solutions and on the saturation level of surface sites of mackinawite, we ...