Conducts research on the organic carbon cycle, the hydrological cycle and contaminant cycling in the coastal and open ocean, lakes and rivers of Canada's west coast and the Canadian Arctic. Trends and the effects of change are investigated using water column data and sediment core records.
Current research and/or projects
Dr. Macdonald studies environmental pathways of organic carbon in Canada's Arctic waters including the Beaufort Sea, the Canadian Arctic Archipelago, Hudson Bay and coastal British Columbia. Within the context of organic carbon and hydrological pathways, Dr. Macdonald studies a number of contaminants including Hg and other metals, organochlorine compounds (e.g., PCBs, PBDEs, DDT) and hydrocarbons (e.g., PAHs, alkanes). Most of the research is conducted coastal waters and over shelves. He determines temporal trends and the behaviour of contaminating substances in the context of natural cycles of organic matter and fresh water bringing to bear such tools as water-mass analysis, transient and steady state tracers, stable isotope analyses (oxygen, carbon and lead), the determination of particle fluxes and sedimentation rates, multivariate statistics and modeling. Most of the major contaminant groups have been studied including PAH, metals, radionuclides, organochlorines, and other synthetic organic compounds like the nonylphenol ethoxylates.
Dr. Macdonald focuses on site-specific contaminant sources and broader contaminant issues such as long-range atmospheric transport of semi-volatile contaminants to the Arctic Ocean and Georgia Basin. Contaminants are studied according to how they enter and leave natural water bodies and how they impinge on natural biogeochemical cycles. Multivariate statistical techniques as well as dated sediment cores are used to distinguish between anthropogenic contaminants and their natural counterparts. Often, more than one anthropogenic source contributes to contaminant loadings, in which case the same techniques are used to work out the relative strength of each source. Insight and data developed through these studies is incorporated into national and international environmental assessments.
Research and/or project statements
Dr. Macdonald presently collaborates with a number of colleagues working on organic pathways in Hudson Bay, inorganic contributions from small rivers in the Canadian Arctic Archipelago, and carbon & contaminant cycling in the Strait of Georgia. Historical data are also being developed into journal articles and reviews.
Professional activities / interests
Writing topical papers using archived data, and collecting new data as a co-investigator on a number of projects. Collaborating with and mentoring students and colleagues.
Education and awards
BSc (Hons) Chemistry, Dalhousie University, 1968
PhD Chemistry, Dalhousie University, 1972
The Polar Medal (2016)
Northern Science Award and Centenary Medal (2014)
Fellow the Royal Canadian Geographical Society (2013)
Fellow of the American Geophysical Union (2010)
Co-Recipient RCGS Gold Medal (2010)
Fellow-International, Explorers Club (2007)
Miroslaw Romanowski Medal (RSC) (2005)
Fellow of the Royal Canadian Geographical Society (2004)
Co-recipient, Head of the Public Service Award (2002)
President's Prize (CMOS) (2000)
Fellow of the Chemical Institute of Canada (1989)
International experience and/or work
Under programs like the Arctic Monitoring and Assessment Programme have widely collaborated with the the international community studying contaminants, climate change, organic carbon cycling and freshwater pathways. This has included participation in a number of Arctic Assessments.
Selected Recent Publications (a full list is publicly available at Google Scholar)
Alkire, M.B., Jacobson, A., Macdonald, R.W. and Lehn, G. (2019) Assessing the contributions of atmospheric/meteoric water and sea ice meltwater and their influences on geochemical properties in estuaries of the Canadian Arctic Archipelago. Estuaries and Coasts in press.
Brown, T.M., Macdonald, R.W., Letcher, R.J. and Muir, D.C.G. (2018) The distribution and trends of persistent organic pollutants and mercury in marine mammals from Canada's Eastern Arctic. Science of the Total Environment 618, 500-517.
Johannessen, S.C. and Macdonald, R.W. (2018) Reply to Macreadie et al comment on ‘Geoengineering with seagrasses: is credit due where credit is given?’. Environmental Research Letters 13, 028001.
Johannessen, S.C. and Macdonald, R.W. (2018) Reply to Oreska et al. comment on 'Geoengineering with seagrasses: is credit due where credit is given? Environmental Research Letters 13, 038002.
Johannessen, S.C., Macdonald, R.W. and Wright, C.A. (2019) Rain, runoff and diatoms: the effects of the North Pacific 2014-2015 warm anomaly on particle flux in a Canadian west coast fjord. Estuaries and Coasts 42, 1052-1065.
Pomerleau, C., Matthews, C.J.D., Gobeil, C., Stern, G.A., Ferguson, S.H. and Macdonald, R.W. (2018) Mercury and stable isotope cycles in baleen plates are consistent with year-round feeding in two bowhead whale (Balaena mysticetus) populations Polar Biology 41, 1881-1893.
Pućko, M., Stern, G.A., Burt, A., Jantunen, L.M., Bidleman, T.F., Macdonald, R.W., Barber, D.G., Geilfus, N.-X., Mundy, C.J. and Rysgaard, S. (2017) Use Pesticide (CUP) and legacy organochlorine pesticide (OCP) dynamics at the ocean-sea ice-atmosphere (OSA) interface in Resolute Passage, Canadian Arctic, during winter-summer transition. Science of the Total Environment 580, 1460-1469.
Wang, K., Munson, K.M., Beaupré-Laperrière, A., Mucci, A., Macdonald, R.W. and Wang, F. (2018) Subsurface seawater methylmercury maximum explains biotic mercury levels in the Canadian Arctic. Scientific Reports 8, 14465.
Li, Y.-F., Qiao, L.-N., Ren, N.-Q., Sverko, E., Mackay, D., Macdonald, R.W., 2017. Decabrominated diphenyl ethers (BDE-209) in Chinese and global air: Levels, gas/particle partitioning, and long-range transport: Is long range transport really governed by the movement of particles? Environmental Science and Technology 51, 1035-1042.
Alkire, M.B., Jacobson, A.D., Lehn, G.O., Macdonald, R.W., Rossi, M.W., 2017. On the geochemical heterogeneity of rivers draining the Canadian Arctic Archipelago. Journal of Geophysical Research Biogeosciences 122.
Denman, K.L., Macdonald, R.W., 2017. Ocean Acidification in Canada’s Coastal Waters: Climate Change, Processes and Impacts. Canadian Climate Forum, Issue Paper #6, 12pp.
Ianson, D., Allen, S.E., Moore-Maley, B.L., Johannessen, S.C., Macdonald, R.W., 2016. Vulnerability of a semi-enclosed estuarine sea to ocean acidification in contrast with hypoxia Geophysical Research Letters 43, 9.
Johannessen, S.C., Macdonald, R.W., 2016. Geoengineering with seagrasses: is credit due where credit is given? Environmental Research Letters 11, 113001.
Kuzyk, Z.A., Gobeil, C., Macdonald, R.W., 2017. Early Diagenesis and Trace Element Accumulation in North American Arctic Margin Sediments. Geochimica et Cosmochimica Acta 203, 175-200.
Ma, J., Hung, H., Macdonald, R.W., 2016. The influence of global climate change on the environmental fate of persistent organic pollutants: A review with emphasis on the Northern Hemisphere and the Arctic as a receptor. Global and Planetary Change 146, 89-108.
Abbott, B.W. et al., 2016. Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment. Environmental Research Letters 11, 034014.
Heikkilä, M., Pospelova, V., Forest, A., Stern, G.A., Fortier, L., R.W., M., 2016. Dinoflagellate cyst production over an annual cycle in seasonally ice-covered Hudson Bay. Marine Micropaleontology 125, 1-24.
Drevnick, P.E. et al., 2016. Spatiotemporal patterns of mercury accumulation in lake sediments of western North America. Science of the Total Environment 568, 1157-1170.
Johannessen, S.C., Macdonald, R.W., van Roodselaar, A., Bertold, S., 2015. Local environmental conditions determine the footprint of municipal effluent in coastal waters: A case study in the Strait of Georgia, British Columbia Science of the Total Environment 508, 228-239.
Yunker, M.B., Macdonald, R.W., Ross, P.S., Johannessen, S.C., Dangerfield, N., 2015. Alkane and PAH provenance and potential bioavailability in coastal marine sediments subject to a gradient of anthropogenic sources in British Columbia, Canada Organic Geochemistry 89-90, 80-116.
Vonk, J.E., et al. 2015. Spatial variations in geochemical characteristics of the modern Mackenzie Delta sedimentary system. Geochimica et Cosmochimica Acta 171, 100-120.
Anderson, L.G., Macdonald, R.W., 2015. Observing the Arctic Ocean carbon cycle in a changing environment. Polar Research 34, 26891.
Feng, X., et al., 2015. Multi-molecular tracers of terrestrial carbon transfer across the pan-Arctic: 14C characteristics of sedimentary carbon components and their environmental controls. Global Biogeochemical Cycles 29, 1855-1873.
Johannessen, S.C., Masson, D., Macdonald, R.W., 2014. Oxygen in the deep Strait of Georgia, 1951-2009: The roles of mixing, deep-water renewal, and remineralization of organic carbon. Limnology and Oceanography 59, 211-222.
Riche, O., Johannessen, S.C., Macdonald, R.W., 2013. Why timing matters in a coastal sea: trends, variability and tipping points in the Strait of Georgia, Canada. Journal of Marine Systems 131, 36-53.
Timothy, D.A., Wong, C.S., Barwell-Clarke, J.E., White, L.A., Page, J.S., Macdonald, R.W., 2013. Climatology of sediment flux and composition in the subarctic Northeast Pacific Ocean with biogeochemical implications. Progress in Oceanography 116, 95-129.
Adjunct professor at the University of Manitoba