Arsenic, Cadmium and Thallium Content In Plants Growing In Close Proximity to a Zinc Works – Long-Term Observations

摘要

The paper comprises an analysis of As, Cd, and Tl content in two plant species (Agrostis capillaris and Betula pendula) commonly growing in the vicinity of the Miasteczko Śląskie Zinc Works, in the period of 1998–2018. In 2018, the As, Cd, and Tl content (in mg/kg) in the grasses was 1.10–1.68, 3.14–19.05, and 0.53–5.96, respectively, i.e. lower by 50–70%, compared to the year 1998. In birch leaves, the As, Cd, and Tl content (in mg/kg) at the same time point was 0.74–1.54, 4.65–32.44, and 0.80–7.57, respectively, i.e. lower by 10–80%, compared to values found 20 years before. In all grass and birch leaf samples collected in 1998 and 2018, the content of the studied elements exceeded the so-called “natural levels”.The 1998 content of As, Cd, and Tl in the plants was due to the settling of dust containing industrial pollutants in 77–96%. After 20 years, the contribution of this source of pollution was considerably lower, 63–79%. The performed analyses demonstrated the following mean contents of the analyzed elements in dust: 243 mg As/kg, 1113 mg Cd/kg, and 44 mg Tl/kg, which confirms the hypothesis on the major role of dust in the current soil and plant pollution. In all the habitats analyzed, a significant decrease of the transfer factor (TF) was found for As and Cd in 2018, compared to 1998. For Tl, a different observation was made. In three out of four analyzed habitats, TF decreased over the two decades studied, whereas in the remaining habitat, TF was higher in 2018 than in 1998 both for the grasses and for the birch leaves. Over the past 20 years, the most polluted area also changed, from the land located closest to the zinc works, in the direction aligned with the most common winds, to areas subject to the most intense settling of pollutants carried by wind from unsecured heaps and industrial waste storage areas.