The current air pollution by SO2 due to anthropogenic pressure in Poland was assessed based on sulfur concentrations in pine needles (Pinus sylvestris L.). On 308 monitoring sample plots located in pine stands distributed across Poland, measurements were conducted in mineral soil layers (0-10 cm, 10-40 cm, 40-100 cm) and in the soil organic layer (+5-0 cm). Samples of Scots pine foliage (current-year needles) were then collected, and the sulfur concentration in these needles was determined. Based on these data, a map of the spatial variability of sulfur concentrations in pine needles was drawn. The mean sulfur concentration in the pine needles was 854.8 mg kg-1 in dry mass. Higher SO2 emissions were noted in regions influenced by industry, such as the Upper Silesia and regions under strong urban pressure. Sulfur concentrations in Scots pine needles were related to the stands' degrees of defoliation. A comparison of the current sulfur concentrations in pine needles from biomonitoring in 2015-2016 with those from previous biomonitoring (in 1983-1985, by Dmuchowski and Bytnerowicz (1995) showed that air quality has improved and SO2 emissions have decreased.
Keywords: Air quality; Bioindication; Defoliation; Sulfur dioxide.
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