Biomonitoring of Environmental Pollution Using Forest Tree Foliage Chemistry at Extremely Contaminated, Post-Industrial Sites

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Biomonitoring based on foliage chemistry was used to study the effects of environmental sulfur (S) pollution on forest stands. The foliage samples were collected in two forest ecosystems exposed to industrial emissions: a zinc (Zn) and lead (Pb) smelter plant in Silesia (HCM) and a reclaimed forest on the site of the former borehole S mine Jeziórko (FJSM), in the Tarnobrzeg S deposit region (southern Poland). Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) foliage chemistry was analyzed: S (using a TruMac CNS analyzer, Leco Corporation, Saint Joseph, MI, USA), N, P, K Ca, and Mg, and trace elements (Zn, Cd, Pb, Al, Fe, Mn, Cu) using an ICP OES ICAP 6000 spectrometer, Thermo Fisher Scientific, Waltham, MA, USA),. At the HCM site, 20 monitoring points were located in the forest at different directions and at varying distances from the smelter plant. At the FJSM site, 16 sampling points were distributed depending on vegetation type and tree species abudance. The S content in foliage was generally high at both sites. However, at the HCM site, the highest S content was found in areas close to the smelter plant (1664 mg kg−1) and decreased linearly according to the direction of the dominant wind to the east (; 1098 mg kg−1). S was correlated with Zn, Cd, and Pb (the main elements produced in the smelter plant). At the FJSM site, high S concentrations were observed in degraded soil areas (4816 mg kg−1 in birch, 1563 mg kg−1 in pine). These areas were hot spots that had the highest amount of S in the soil. These results indicate high biosorption of the pollutant by trees. The S concentration was also higher in birch (B) than in pine (P) foliage (regular forest: 1954 mg kg−1 in B, 1272 mg kg−1 in P; degraded area: 4816 mg kg−1 in B, 1563 mg kg−1 in P), and the differences were significant in the degraded areas. At the FJSM site, S was also correlated with Zn and, to a lesser extent, with Cd and Pb. S also influenced nutrient element supply status, in particular Mg. We confirmed that tree foliage chemistry reflects the state of the environment in highly polluted areas, so biomonitoring should be used to assessment of environmental pollution.