Temporal trends of anthropogenic SO₂ emitted by non-ferrous metal smelters in Peru and Russia estimated from Satellite observations

Abstract. We report on satellite observations of atmospheric Sulfur Dioxide (SO₂) emitted from metal smelting industries in Peru, South America and Siberia, Russia. Most of the non-ferrous metal ores are sulfidic and during the smelting process the sulfur is emitted as SO₂. In addition to Norilsk, Russia, Peruvian copper smelters are among the most polluting point sources in the world. We retrieve SO₂ column amounts from spectra of the Global Ozone Monitoring Experiment (GOME) on the Earth Research Satellite 2 (ERS-2) for the years 1996 to 2002 using an algorithm based on differential Optical Absorption Spectroscopy (DOAS). Areas of enhanced SO₂ column amounts are clearly identified on a 7-years mean map of GOME observations over the regions with La Oroya and Ilo copper smelters of Peru and Norilsk smelters of Russia.

Since the instrument sensitivity is highly dependent on surface albedo, SO₂ vertical profile, solar zenith angle (SZA), wavelength, clouds, and aerosol, radiative transfer modelling is used to convert the analysed slant column densities into vertical column densities. In this study, the full spherical Monte-Carlo radiative transport model TRACY-II is used for SO₂ AMF calculation.

GOME data is analysed in further detail by calculating time series over these regions. For the different locations, the results demonstrate both, increasing and decreasing trends in the SO₂ column amounts over the time period of 1996–2002. The decreasing trend for the Ilo copper smelter is in good agreement with implemented measures for emission reductions. However, even for the cases with decreasing trends, these point sources are still a dominant source of anthropogenic SO₂ emissions in their region. For the smelters in Peru, the potential influence due to SO₂ emission by the nearby volcanoes is investigated and found to be negligible.