An inventory of historical mercury emissions in Maritime Canada: implications for present and future contamination

Mercury is a longstanding concern in Maritime Canada due to high levels of contamination in a number of fish and bird species. The recycled component of past releases of anthropogenic mercury may be a significant source of on going pollution in many areas. Historical information on mercury releases c an be used to quantify past and present anthropogenic contamination. We pre sent an inventory of historical mercury emissions from anthropogenic source s in Maritime Canada for the years 1800-1995. Long-term trends in mercury e missions and the significance of the cumulative burden of mercury released from local sources are discussed. Emissions are calculated using both histo rical monitoring data and the application of emission factors. The nature o f current anthropogenic sources of mercury is quite different than it was s everal decades ago when many of the existing policies governing mercury pol lution were created. Our inventory illustrates that many of the most signif icant sources in the past such as the chlor-alkali industry, paint containi ng mercury additives, and pharmaceuticals, have been largely phased out wit h fossil fuel combustion and waste disposal remaining as the most significa nt modern sources. Atmospheric emissions in Maritime Canada peaked in 1945 (> 1750 kg year(-1)), and again between 1965 and 1970 (> 2600 kg year(-1)). Cumulative releases of mercury from anthropogenic sources for the years 18 00-1995 were between 115 and 259 t to the atmosphere alone, and 327-448 t w hen discharges to wastewater and effluents were included. Assuming that onl y 0.2% (Nriagu, 1994.) of these releases become part of the recycled fracti on of current fluxes, we estimate that between 570 and 900 kg Hg year(-1) i s deposited in Maritime Canada from past anthropogenic sources. Modern sour ces within Maritime Canada contribute at least 405 kg year(-1) to the total annual deposition of 1.71 t over the provinces of New Brunswick, Nova Scot ia and Prince Edward Island, leaving similar to 735 kg year(-1) from natura l sources and long-range contamination. Further study is needed to verify t hese estimates and clarify the significance of natural and long-range sourc es of mercury in Maritime Canada. (C) 2000 Elsevier Science B.V. All rights reserved.