Every spring, a haze forms over the once pristine Arctic. This haze contains gaseous species like SO2 and NOx, as well as aerosols, containing SO4-2, H +, NH4+2 and metals. The primary source for these pollutants is thought to be mid-latitude Eurasian industry. However, major sources within the Arctic are not well quantified.
Among the largest point sources of pollutants within the Arctic are Russian metal smelters. It is known that they release large quantities of sulfur dioxide. They are also suspected to emit heavy metals, but these emissions are poorly characterized and quantified. We have investigated one such smelter to determine the magnitude of its metal emissions; the Severonikel Copper-Nickel smelter in the city of Monchegorsk, Kola Peninsula, Russia.
Investigating the emissions of an industrial plant should be a straight-forward project. Working in the former Soviet Union, however, puts unusual constraints on the experiments that can be conducted. For our study, it was impossible to obtain permission to sample within the stack exhaust or to sample on the grounds of the complex. Therefore, we developed a method of obtaining an estimate of emissions from sites several kilometers downwind of the smelter.
The data set consists of two parts; sulfur dioxide measurements and size segregated metals aerosol measurements. Samples were collected at several sites, all within 10 kilometers of the source. SO2 measurements were made simultaneously at several sites. Size segregated aerosol samples were collected at two sites daily and analyzed for copper, nickel, arsenic, lead and cadmium.
There are two main pieces of information we can learn from this data set. First, the size segregated aerosols can tell us which metals are likely to have the most long range impact. Smaller particles stay airborne much longer than larger particles. Therefore, because arsenic and lead were found to be in smaller size range particles as compared to copper and nickel, they will be disproportionally represented in the emissions of the smelter that are transported great distances.
The second valuable piece of information that can be determined from this data set is an estimate of the emissions of the smelter. Since relatively reliable annual SO2 emissions are published each year, a ratio between airborne concentrations of SO2 and each metal was established. Multiplying the SO2 annual emissions by the established ratio gives an estimate of the metal emissions of plant.
The best ratios of metals to sulfur dioxide are shown in Table 1. Using an average annual emission of 200,000 metric tons of SO2, metals emissions are estimated to be 2000 ± 600 tons per year of copper, 1300 ± 500 tons per year of nickel, 170 ± 50 tons per year of arsenic and 300 ± 90 tons per year of lead. The quantity of copper agrees with previous estimates but the nickel quantity is a factor of two lower than previously reported values. Arsenic and lead emissions have not been previously reported.
These emissions estimates give a new understanding of the technology used in the former Soviet Union. We hope that future Arctic pollution studies can benefit from these new numbers that are more accurate than previous estimates. Transport models can take into account the size distributions of the emissions to better assess the global impact of these Russian sources.
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