Chemistry of snow cover under industrial pressure in the forest ecosystem surrounding the HCM zinc smelter

The industry is the main source of pollutant emissions and is responsible for 63% of Pb emissions and 58% of Cd emissions. One of the oldest and most polluted places related to the mining and processing of non-ferrous metals in Europe is the Silesia-Cracow region (southern Poland). Currently, this region is also the only one where zinc and lead smelting plant are active (HCM) in this part of Europe. Processing of zinc-lead ores and recycled waste materials generates trace elements emission to the environment. Imperial Smelting Process (ISP) used at the HCM zinc smelter generates eg. trace elements, forms of sulfur oxide, and alkali dust. Despite the introduction of protection programs and the implementation of installations preventing the release of pollutants into the environment developed in the last decade by the plant, still, the area surrounding the smelter is characterized by elevated contamination of trace elements.

The work aimed to capture the impact of an industrial plant (HCM zinc and lead smelter) on forest ecosystems, based on physicochemical analyzes of short-term snow cover. The research area was located in the Scots pine (Pinus sylvestris L) stands adjacent to the zinc and lead smelter. The sampling points were selected in directions: N, S, W, and E from the middle point (emitter of HCM) with a 1-kilometer distance interval. There were selected 22 points with distances in values 0-8 km from the middle point. The samples were collected in February 2021. The snow samples were analyzed for pH, EC, SO₄^2-, Cd, Pb, and Zn concentration. Cd ranged from 0.001 to 2.47 mg L^-1, Zn from 12.10 to 0.05 mg L-1, Pb from 2.47 to 0.001 mg L^-1, and SO₄^2- ranged from 1.08 to 19.38 mg L^-1 in the snow. The Cd was concentrated next to the emitter (up to 1 km), similarly to Zn and SO₄^2-, but still high values of Zn and SO₄^2- reached further – up to about 2-3 km from the emitter. The highest Pb pollution was also found near the emitter, but the pollution spread along with the direction of the winds. Pb pollution did not decrease with distance - higher values were found at spots, e.g., about 2 (0.19 mg L^-1) and 4 km (0.13 mg L^-1) away from the emitter on the east. The pH varies from 5.4 to 7.0, and the highest pH occurred just near the emitterand decreased with the direction of the wind.High values of researched pollution in the snow and their distribution indicated the impact of the emitter on the nearest environment, however, these amounts are not harmful to plants, except for point 0 (closest to the emitter). Unorganized emissions (i.e. emissions resulting from technological processes) caused much greater pollution visible at the point closest to the emitter. Organized emission pollution, released through stationary point-sources, i.e.chimneys, discharge air vents, etc., was significantly lower.