Robert Mason

(Ph.D., University of Connecticut) Professor of Marine Sciences

My current research interests are directed at the fate, transport, and transformation of trace metals, especially mercury (Hg), but also cadmium, lead, and the metalloids (arsenic and selenium) in aquatic systems and the atmosphere. The scope of research includes the open ocean, the coastal zone and estuaries, as well as freshwater systems. The focus of recent research is the important transformation processes, in the sediment, water and air, and at the interfaces (sediment/water and air/sea) for metals and how these impact bioavailability and bioaccumulation into aquatic organisms, primarily those at the base of the food chain (http://mason.mercury.uconn.edu/research-projects/). Mercury inputs come from both natural and anthropogenic sources, and human activities, such as the burning of fossil fuels, and the use of mercury in artisanal gold extraction, have exacerbated the mercury problem globally and locally. Elevated levels of methylmercury (MeHg) in fish are an important human and ecosystem health concern, and as the links between inputs of inorganic Hg and formation of MeHg, and its accumulation into the food chain are complex, and involve many steps, these links have been the focus of much study.

Recent funded research has been connected with the international GEOTRACES Program (https://www.geotraces.org/) and my research group has participated in the most recent US GEOTRACES cruises (GP17-ANT in 2023/24; GP17-OCE in 2022/23; GP15 in 2018) in the Pacific and Southern Oceans, collecting water and atmospheric samples for determining the concentration, form and isotopic signature of Hg. Another current project is focused on air-sea exchange and atmospheric chemistry of mercury and is examining the factors influencing air-sea exchange and its seasonal variability in the North Atlantic near Bermuda on cruises and at the air sampling tower at Tudor Hill. A further project is examining Hg cycling in coastal regions and is focused on the Gulf of Maine and the Penobscot River, which was historically contaminated with Hg. The major objectives of these studies have been to: 1) examine the variation in atmospheric and surface ocean Hg speciation and the primary mechanisms for mercury transformations in seawater and in air; 2) develop a more accurate assessment of the seasonal variability in the air-sea exchange of mercury and to provide better constrained flux estimates at the air-sea interface; 3) examine the sources and cycling of methylated Hg (both MeHg and dimethylmercury); and 4) examine the factors influencing the bioaccumulation of MeHg into plankton. The role of biota, primarily microorganisms, in mediating the chemical transformations of mercury and other metals in the environment has been a recent research focus. Additionally, research is aimed at providing data to constrain and improve ocean and global Hg models, especially those related to assessing the effectiveness of the Minamata Convention, a United Nations Environmental Program (UNEP) effort to reduce Hg inputs to the environment (https://minamataconvention.org/en). To generate sufficient information for modeling requires the development and implementation of novel techniques and research is focused on improving the time resolution of measurement, and in the improvement of flux estimates.

More details of the research programs, which are all funded through the National Science Foundation, and of associated publications, of current and former students, and of other activities at http://mason.mercury.uconn.edu/.

Current Graduate Students

Hannah Inman, Gunnar Hansen and Wes Huffman; MS: Sophia Smith and Melissa Sanchez. Jingjing Yuan is a post-doc.

Recent PhD Graduates

Yipeng He, Patricia Myer and Emily Seelen. See https://mason.mercury.uconn.edu/former-students-post-docs-technicians/

Recent Publications

(see: https://scholar.google.com/citations?user=U6wykfoAAAAJ&hl=en)

  1. He, Y., Inman, H., Kadko, D., Stephens, M., Hammond, D., Landing, W., Mason, R.P. 2024. Elevated methylmercury in Arctic rain and aerosol linked to air-sea exchange of dimethylmercury. Scientific Reports, in review.
  2. Liu, M., Bianchi, T.S., Mason, R.P., Taylor, M., Raymond, P. 2024. Climate and human-induced perturbations are remobilizing the largest marine mercury sinks. Nature Geosciences, in revision.
  3. He, Y., Mason, R.P. 2024. Improving a continuous mercury analyzer with circulated carrier gas: economic and operational advancements. Environ., in review.
  4. Gustin, M.S., Dunham-Cheatham, S.M., Lyman, S., Horvat, M., Gay, D.A., Gačnik, J., Gratz, L., Kempkes, G., Khalizov, A., Lin, C-J., Lindberg, S., Lown, L., Martin, L., Mason, R.P., MacSween, K., Nair, S.V., Nguyen, L.S.P., O’Neil, T., Sommar, J., Weiss-Penzias, P.,  Zhang, L., Živković, I. 2024. Measurement of Atmospheric Mercury: Current Limitations and Suggestions for Improvements. Sci. Technol. DOI: 10.1021/acs.est.4c06011.
  5. Gosnell, K., Mazrui, N., Mason, R.P. 2024. Properties Influencing Algae Uptake of Mercury and Methylmercury from Estuarine Sediments. Poll. 346: Art. # 123604.
  6. Hansen, G., Shumway, S.E., Mason, R.P., Baumann, Z. 2024. A comparative study of mercury bioaccumulation in bivalve molluscs from a shallow estuarine embayment. Environ. Contam. Toxicol. 86: 262-273.
  7. Liu, M., Mason, R.P., Vlahos, P., Whitney, M.M., Zhang, Q., Warren, J.K., Wang, X., Baumann, Z. 2023. Riverine discharge fuels the production of methylmercury in a large temperate estuary. Sci. Technol. DOI: 10.1021/acs.est.3c00473.
  8. Barrett, L.J., Vlahos, P., Hammond, D.E., Mason, R.P. 2023. Sediment-water fluxes of inorganic carbon and nutrients in the Pacific Arctic during the sea ice melt season. Continental Shelf Research 268: Art. # 105116.
  9. Seelen, E.A., Liem-Nguyen, V., Wünsch, U., Mason, R.P., Skyllberg, U., Björn, E. 2023. Thiol content of dissolved organic matter controls methylmercury bioavailability across the terrestrial-marine aquatic continuum. Nature Communications 14: Art. # 6728.
  10. Fisher, J.A., Fostier, A.H., Guerrero, S., Guimares, J.R.D., Labuschagne, C., Leaner, J.J., Martin, L.G., Mason, R.P., Somerset, V.S., Walters, C. 2023. A synthesis of mercury research in the Southern Hemisphere, Part 2: Anthropogenic perturbations. Ambio DOI: 1007/s13280-023-01840-5.
  11. Schneider, L., Fisher, J.A., Dieguez, M.C., Fostier, A.H., Guimares, J.R.D., Leaner, J.J., Mason, R.P. 2023. A synthesis of mercury research in the Southern Hemisphere, Part 1: Natural processes. Ambio DOI: 1007/s13280-023-01832-5.
  12. Mason, R.P., Buckman, K.L., Seelen, E.A., Taylor, V.T., Chen, C.Y. 2023. An examination of the factors influencing the bioaccumulation of methylmercury at the base of the estuarine food web. Tot, Environ. 866: Art. # 163996.
  13. Despins, M.C., Mason, R.P., Aguilar-Islas, Hammerschmidt, C.R., Newell, S.E. 2023. Linked mercury methylation and nitrification across oxic sub-polar regions. Frontiers in Environ. Chem., DOI: 10.23389/fenvc.2023.1109537.
  14. Chen, C.Y., Mason, R.P., Lohmann, R., Muir, D. 2023. Chemical pollution and the ocean. In: Oceans and Human Health: Opportunities and Impacts, 2nd,, Fleming, L.E. et al. (Eds.), Chapter 13, Elsevier, 351-426.
  15. Jonsson, S., Michelle G. Nerentorp Mastromonaco, Gardfeldt, Mason, R.P. 2022. Distribution of total mercury and methylated mercury species in central Arctic Ocean Water and Ice. Marine Chemistry 242: Art. # 104105.
  16. Blanchfield, P.J., Rudd, J.W.M., Hrenchuk, L.E., Amyot, M., Babiarz, C.L., Beaty, K.G., Bodaly, R.A., Branfireun, B.A., Gilmour, C.C., Graydon, J.A., Hall, B.D., Harris, R.C., Heyes, A., Hintelmann, H., Hurley, J.P., Kelly, K.A., Krabbenhoft, D.P., Lindberg, S.E., Mason, R.P., Paterson, M.J., Podemski, C.L., Sandilands, K.A., Southworth, G.R., St. Louis, V.L., Tate, L.S., Tate, M.T. 2022. Experimental evidence for the recovery of mercury-contaminated fish. Natureorg/10.1038/s41586-021-04222-7.
  17. Dastoor, A., Angot, H., Bieser, J., Christensen, J., Douglas, T., Heimbürger-Boavida, L-E., Jiskra, M., Mason, R.P., McLagan, D., Obrist, D., Outridge, P., Petrova, M., Ryjkov, A., St. Pierre, K., Schartup, A., Sørensen, A., Travnikov, O., Toyota, K., Wilson, S., Zdanowicz, C. 2022. Arctic Mercury Cycling. Nature Reviews – Earth & Environment 3(4): 270-286.
  18. Mason, R.P, Coulibaly, M., Hansen, G., Inman, H., Myer, P.K, Yao, K.M. 2022. An examination of the mercury levels in the coastal environment and fish of Cote d’Ivoire. Chemosphere 300: Art. #134609.
  19. He, Y., Shi, X., Huffman, W.W., Lamborg, C.H., Mason, R.P. 2022. Description of a dimethylmercury automatic analyzer for the high-resolution measurement of dissolved gaseous mercury species in surface ocean waters. Sci. Technol. 56(18): 13076-13084.
  20. He, Y., Mason, R.P. 2021. Comparison of reactive gaseous mercury measured by KCl-coated denuders and cation exchange membranes during the Pacific GEOTRACES GP15 expeditio. Atmospheric Environment 244: Art # 117973.
  21. Seelen, E.A., Chen, C.Y., Balcom, P.H., Buckman, K.B., Taylor, V.F., Mason, R.P. 2021. Historic contamination alters mercury sources and cycling in temperate estuaries relative to uncontaminated sites. Res. 190: Art. # 116684.
  22. Buckman, K.B., Mason, R.P., Seelen, E.A., Buckman, K.B., Taylor, V.F., Balcom, P.H., Chipman, J., Chen, C.Y. 2021. Patterns in forage fish mercury concentrations across Northeast US estuaries. Res. 194, Art. # 110629. DOI: 10.1016/j.envres.2020.110629.
  23. Coulibaly, M., Mazrui, N., Jonsson, S., Mason, R.P. 2021. Abiotic reduction of mercury(II) in the presence of sulfidic mineral suspensions. Frontiers in Environmental Chemistry, 2, Art. # 660058.
  24. , K., Dam, H.G., Mason, R.P. 2021. Mercury and methylmercury uptake and trophic transfer from marine diatoms to copepods and field collected zooplankton. Marine Environmental Research 170 Art. # 105446.
  25. Shi, X., Zhao, J., Wang, Y., Mason, R.P. 2021. The transformation of inorganic and methylmercury in the presence of L-cysteine capped CdSe nanoparticles. Frontiers in Environmental Chemistry # 762052; DOI: 10.3389/fenvc.2021.762052.
Chem06-RobMason
Contact Information
Emailrobert.mason@uconn.edu
Phone860-405-9129
Fax860-405-9153
Linkhttp://mason.mercury.uconn.edu/