Increased zinc concentrations in the Canadian Arctic air

Long–term time trends for heavy metals in Canadian arctic surface air were studied recently. Different from the continuing decrease for other metals, such as cadmium and mercury, from 1973 to 2000, zinc concentrations decreased from 1973 to the mid–1980s and then increased again at Resolute (74.7°N, 95.0°W). Its concentrations in the surface air increased from less than 10 ng m-3 in the mid–1980s winters to more than 20 ng m-3 in the late 1990s winters. A sharper increasing trend was found at another arctic site, Coral Harbour (64.2° N, 83.3° W), where Zn increased from about 10 ng m-3 in air in the early 1970s to more than 100 ng m-3 in late 1990s. The increase was also recognized at two sub–arctic sites, Churchill (58.8° N, 94.1° W) and Moosonee (51.3° N, 80.6° W), but not in more southerly sites like Ottawa (45.3° N, 75.7° W) and Windsor (42.3° N, 83.0° W). The possible reasons which led to the Zn increase in the north are discussed in this paper.