Honors & Awards


  • Dean Scholarship, Trent University (2007-2014)
  • Commonwealth Scholarship, Canadian Foreign Affairs and Canadian Nureau for International Education (2005-2008)
  • Graduate Entrance Scholarship, University of Guelph (2005)

Education & Certifications


  • Ph.D., Trent University, Environmental and Life Sciences (2014)
  • M.Sc., University of Guelph, Environmental Engineering (2007)

All Publications


  • Mercury speciation and mercury stable isotope composition in sediments from the Canadian Arctic Archipelago SCIENCE OF THE TOTAL ENVIRONMENT Strok, M., Baya, P., Dietrich, D., Dimock, B., Hintelmann, H. 2019; 671: 655–65

    Abstract

    Total mercury (THg) and monomethylmercury (MMHg) concentrations as well as mercury (Hg) isotope ratios were determined in sediment cores sampled from six locations from the Canadian Arctic Archipelago (CAA). At most sites, THg concentrations showed a decreasing trend with depth, ranging from 5 to 61 ng/g, implicating possible increased Hg deposition and/or riverine inputs in top sediment layers. MMHg values showed large oscillations within the top 10 cm of the cores. This variability decreased at the bottom of the cores with MMHg concentrations ranging from less than12 to up to 1073 pg/g. Average concentrations of THg and MMHg in the top 10 cm were linearly correlated, whereas no correlation was observed with organic matter (loss on ignition). Mercury isotope ratios showed negative values for both δ202Hg (-1.59 to -0.55‰) and Δ199Hg (-0.62 to -0.01‰). δ202Hg values became more negative with depth, while the opposite was observed for Δ199Hg. The former is consistent with predicted historical atmospheric Hg trends as a result of increased coal burning worldwide. Hg isotope ratio measurements in CAA sediments offer additional opportunities to trace Hg processes and sources in the Arctic.

    View details for DOI 10.1016/j.scitotenv.2019.03.424

    View details for Web of Science ID 000466090500069

    View details for PubMedID 30939318

  • A Model of Mercury Distribution in Tuna from the Western and Central Pacific Ocean: Influence of Physiology, Ecology and Environmental Factors ENVIRONMENTAL SCIENCE & TECHNOLOGY Houssard, P., Point, D., Tremblay-Boyer, L., Allain, V., Pethybridge, H., Mashou, J., Ferriss, B. E., Baya, P. A., Lagane, C., Menkes, C. E., Letourneur, Y., Lorrain, A. 2019; 53 (3): 1422–31

    Abstract

    Information on ocean scale drivers of methylmercury levels and variability in tuna is scarce, yet crucial in the context of anthropogenic mercury (Hg) inputs and potential threats to human health. Here we assess Hg concentrations in three commercial tuna species (bigeye, yellowfin, and albacore, n = 1000) from the Western and Central Pacific Ocean (WCPO). Models were developed to map regional Hg variance and understand the main drivers. Mercury concentrations are enriched in southern latitudes (10°S-20°S) relative to the equator (0°-10°S) for each species, with bigeye exhibiting the strongest spatial gradients. Fish size is the primary factor explaining Hg variance but physical oceanography also contributes, with higher Hg concentrations in regions exhibiting deeper thermoclines. Tuna trophic position and oceanic primary productivity were of weaker importance. Predictive models perform well in the Central Equatorial Pacific and Hawaii, but underestimate Hg concentrations in the Eastern Pacific. A literature review from the global ocean indicates that size tends to govern tuna Hg concentrations, however regional information on vertical habitats, methylmercury production, and/or Hg inputs are needed to understand Hg distribution at a broader scale. Finally, this study establishes a geographical context of Hg levels to weigh the risks and benefits of tuna consumption in the WCPO.

    View details for DOI 10.1021/acs.est.8b06058

    View details for Web of Science ID 000458220600040

    View details for PubMedID 30672293

  • Mercury contamination level and speciation inventory in Lakes Titicaca & Uru-Uru (Bolivia): Current status and future trends ENVIRONMENTAL POLLUTION Guedron, S., Point, D., Acha, D., Bouchet, S., Baya, P. A., Tessier, E., Monperrus, M., Molina, C. I., Groleau, A., Chauvaud, L., Thebault, J., Amice, E., Alanoca, L., Duwig, C., Uzu, G., Lazarro, X., Bertrand, A., Bertrand, S., Barbraud, C., Delord, K., Gibon, F. M., Ibanez, C., Flores, M., Fernandez Saavedra, P., Ezpinoza, M. E., Heredia, C., Rocha, F., Zepita, C., Amouroux, D. 2017; 231: 262–70

    Abstract

    Aquatic ecosystems of the Bolivian Altiplano (∼3800 m a.s.l.) are characterized by extreme hydro-climatic constrains (e.g., high UV-radiations and low oxygen) and are under the pressure of increasing anthropogenic activities, unregulated mining, agricultural and urban development. We report here a complete inventory of mercury (Hg) levels and speciation in the water column, atmosphere, sediment and key sentinel organisms (i.e., plankton, fish and birds) of two endorheic Lakes of the same watershed differing with respect to their size, eutrophication and contamination levels. Total Hg (THg) and monomethylmercury (MMHg) concentrations in filtered water and sediment of Lake Titicaca are in the lowest range of reported levels in other large lakes worldwide. Downstream, Hg levels are 3-10 times higher in the shallow eutrophic Lake Uru-Uru than in Lake Titicaca due to high Hg inputs from the surrounding mining region. High percentages of MMHg were found in the filtered and unfiltered water rising up from <1 to ∼50% THg from the oligo/hetero-trophic Lake Titicaca to the eutrophic Lake Uru-Uru. Such high %MMHg is explained by a high in situ MMHg production in relation to the sulfate rich substrate, the low oxygen levels of the water column, and the stabilization of MMHg due to abundant ligands present in these alkaline waters. Differences in MMHg concentrations in water and sediments compartments between Lake Titicaca and Uru-Uru were found to mirror the offset in MMHg levels that also exist in their respective food webs. This suggests that in situ MMHg baseline production is likely the main factor controlling MMHg levels in fish species consumed by the local population. Finally, the increase of anthropogenic pressure in Lake Titicaca may probably enhance eutrophication processes which favor MMHg production and thus accumulation in water and biota.

    View details for DOI 10.1016/j.envpol.2017.08.009

    View details for Web of Science ID 000414881000026

    View details for PubMedID 28806691

  • The mercury isotope composition of Arctic coastal seawater COMPTES RENDUS GEOSCIENCE Strok, M., Baya, P., Hintelmann, H. 2015; 347 (7-8): 368–76
  • Determination of Monomethylmercury and Dimethylmercury in the Arctic Marine Boundary Layer ENVIRONMENTAL SCIENCE & TECHNOLOGY Baya, P. A., Gosselin, M., Lehnherr, I., St Louis, V. L., Hintelmann, H. 2015; 49 (1): 223–32

    Abstract

    Our understanding of the biogeochemical cycling of monomethylmercury (MMHg) in the Arctic is incomplete because atmospheric sources and sinks of MMHg are still unclear. We sampled air in the Canadian Arctic marine boundary layer to quantify, for the first time, atmospheric concentrations of methylated Hg species (both MMHg and dimethylmercury (DMHg)), and, estimate the importance of atmospheric deposition as a source of MMHg to Arctic land- and sea-scapes. Overall atmospheric MMHg and DMHg concentrations (mean ± SD) were 2.9 ± 3.6 and 3.8 ± 3.1 (n = 37) pg m(-3), respectively. Concentrations of methylated Hg species in the marine boundary layer varied significantly among our sites, with a predominance of MMHg over Hudson Bay (HB), and DMHg over Canadian Arctic Archipelago (CAA) waters. We concluded that DMHg is of marine origin and that primary production rate and sea-ice cover are major drivers of its concentration in the Canadian Arctic marine boundary layer. Summer wet deposition rates of atmospheric MMHg, likely to be the product of DMHg degradation in the atmosphere, were estimated at 188 ± 117.5 ng m(-2) and 37 ± 21.7 ng m(-2) for HB and CAA, respectively, sustaining MMHg concentrations available for biomagnification in the pelagic food web.

    View details for DOI 10.1021/es502601z

    View details for Web of Science ID 000347589300025

    View details for PubMedID 25437177

  • Evaluation and optimization of solid adsorbents for the sampling of gaseous methylated mercury species ANALYTICA CHIMICA ACTA Baya, P. A., Hollinsworth, J., Hintelmann, H. 2013; 786: 61–69

    Abstract

    This study evaluates the suitability of commercially available adsorbents for the measurement of gaseous organic mercury species namely monomethylmercury (MMHg) and dimethylmercury (DMHg). Bond Elut ENV (BE), a new generation of divinylbenzene (DVB), is evaluated the first time for simultaneous sampling and quantification of ultra-trace levels of MMHg and DMHg in air and its performance compared against Carbotrap(®) B (CB) and Tenax(®) TA (TA), two commonly used adsorbents for mercury solid phase adsorption. The suitability of TA as an absorbent for MMHg (recovery 100±8.1%) but less so for DMHg (recovery 64±17.3%) was confirmed while the reverse was observed for CB with an average recovery of 100±0.3% for DMHg but only 61±32.5% for MMHg. BE is the only adsorbent that showed excellent performance for trapping both Hg species with recoveries of 98±9.2% and 95±8.1% for MMHg and DMHg, respectively. Furthermore, BE exhibited much higher sampling capacities (>100L at 4°C) and preservation of sample integrity (>1 month at -20°C in the dark). Overall, BE proves to be the most suitable adsorbent for simultaneous trapping of organic Hg species with high sampling capacity and sample stability but also very good chromatographic properties which are desirable characteristics for both collection traps and analytical traps. Bond Elut ENV is proposed as an alternative to both Tenax(®) TA and Carbotrap(®) B with additional advantages of offering more versatility and sampling options.

    View details for DOI 10.1016/j.aca.2013.05.019

    View details for Web of Science ID 000320852300010

    View details for PubMedID 23790293

  • Assessing the trends and effects of environmental parameters on the behaviour of mercury in the lower atmosphere over cropped land over four seasons ATMOSPHERIC CHEMISTRY AND PHYSICS Baya, A. P., Van Heyst, B. 2010; 10 (17): 8617–28