Harold E. Welch

Magnification of atmospheric mercury deposition to polar regions in springtime: The link to tropospheric ozone depletion chemistry

Mercury—in the chemical/physical forms present in the biosphere—is a persistent, toxic, bioaccumulative pollutant that is dispersed throughout the environment on a global scale, mainly via the atmosphere. It is among the “heavy metals” for which the natural biogeochemical cycle has been perturbed by a wide range of human activities, including fossil-fuel combustion and waste incineration. Results of our recent measurements of gaseous elemental mercury (GEM), as well as total particulate-phase mercury (TPM) concentrations in Arctic air, ‘total Hg’ concentrations in Arctic snow, and tropospheric BrO concentrations from an earth-orbiting-satellite platform are presented and discussed. Findings of our research, and the conclusions derived therefrom, are important for environmental protection as well as the health and well-being of aboriginal people in Arctic circumpolar nations.

ATMOSPHERIC CHANGE AND BIODIVERSITY IN THE ARCTIC

The Canadian Arctic is characterized by a high variation in landform types and there are complex interactions between land, water and the atmosphere which dramatically affect the distribution of biota. Biodiversity depends upon the intensity, predictability and scale of these interactions. Observations, as well as predictions of large-scale climate models which include ocean circulation, reveal an anomalous cooling of northeastern Canada in recent decades, in contrast to the overall significant increase in average annual temperature in the Northern Hemisphere. Predictions from models are necessary to forecast the change in the treeline in the 21st century which may lead to a major loss of tundra. The rate of change in vegetation in response to climate change is poorly understood. The treeline in central Canada, for example, is showing infilling with trees, and in some locations, northerly movement of the boundary. The presence of sea ice in Hudson Bay and other coastal areas is a major factor affecting interactions between the marine and terrestrial ecosystems. Loss of ice and therefore hunting of seals by polar bears will reduce bear and arctic fox populations within the region. In turn, this is likely to have significant effects on their herbivorous prey populations and forage plants. Further, the undersurface of sea ice is a major site for the growth of algae and marine invertebrates which in turn act as food for the marine food web. A rise in sea-level may flood coastal saltmarsh communities leading to changes in plant assemblages and a decline in foraging by geese and other consumers. The anomalous cooling in the eastern Arctic, primarily in late winter and early spring, has interrupted northern migration of breeding populations of geese and ducks and led to increased damage to vegetation in southern arctic saltmarshes as a result of foraging. It is likely that there has been a significant loss of invertebrates in those areas where the vegetation has been destroyed. Warming will have major effects on permafrost distribution and on ground-ice resulting in a major destabilization of slopes and slumping of soil, and disruption of tundra plant communities. Disruption of peat and moss surfaces lead to loss of insulation, an increase in active-layer depth and changes in drainage and plant assemblages. Increases of UV-B radiation will strongly affect vulnerable populations of both plants and animals. The indigenous peoples will face major changes in life style, edibility of food and health standards, if there is a significant warming trend. The great need is for information which is sensitive to the changes and will assist in developing an understanding of the complex interactions of the arctic biota, human populations and the physical environment.

Seasonal distribution of sympagic amphipods near Chesterfield Inlet, N.W.T., Canada

Abstract The seasonal distribution of sympagic amphipods was investigated in the Chesterfield Inlet area of northwestern Hudson Bay (63°30′N). Amphipod abundance was measured by photographic samples and species composition was determined by sweep net samples. Twelve species of amphipods were collected, the most common being Ischyrocerus anguipes, Pontogeneia inermis, Apherusa megalops and Weyprechtia pinguis. The major environmental variable affecting amphipod distribution was water depth. Amphipod abundance was highest near 20 m and near zero past 50 m. The maximum recorded abundance was 1367 m−2. A minor factor affecting the distribution of amphipods was snow depth, through its modifying effect on light and thereby the growth of ice algae. Amphipods began to inhabit the sea ice shortly after its formation. From the beginning of March, the number of amphipods on the ice increased steadily to about the 3rd week of April, after which numbers declined. This pattern coincided with the seasonal ice algae abundance. Amphipods reduced ice algal biomass over 20-m depth by 63%. No evidence of diurnal changes in abundance was observed.

Identification of in situ Canadian Arctic bivalves using underwater photographs and diver observation

SummaryIn situ bivalves in the Barrow Strait region of the Canadian Arctic can be identified accurately to genus from siphon characteristics or general appearance. Identification characteristics are described for seven taxa found in the area including Mya truncata, Serripes groenlandicus, Hiatella arctica, Musculus spp., Astarte spp., Macoma spp. and Delectopecten greenlandicus.

Uranium-Series Nuclides in Sediment, Water, and Biota of Saqvaqjuac Inlet, a Subarctic Estuary, N.W. Coast Hudson Bay

Saqvaqjuac Inlet (63°39′N., 90°39′W.) is a fjord-like estuary of the Saqvaqjuac River on the northwest coast of Hudson Bay. Surface water salinities vary from 5–30‰, and deeper water is 33–34‰ and sometimes anaerobic. Isolated and shallow-silled small bays of the inlet have anaerobic, hypersaline (up to 100‰) deep waters. River discharge and atmospheric deposition are major sources of Pb-210 and Po-210, and these nuclides are inversely related to salinity. Sea water inputs from the tides, and sediment diagenesis appear to be sources of U-238, Ra-226, and Th-230, and they are positively related to salinity. Hypersaline anaerobic waters are usually depleted in U and Ra, and enriched in Pb-210 and Po-210. Bioconcentration factors for these nuclides in estuarine biota will be given, and the highest factors (105 to 106) were found for Pb-210 and Po-210 in hepatopancreas of crabs and pyloric caecae of Greenland cod.