Role of green spaces for migration and setting of heavy metals (as illustrated by Holosiivskyi National Nature Park, Kyiv)

Abstract

Air pollution by heavy metals in the urbanized surroundings presents a serious threat to human health and the environment. Road dust is distinguished as a high-level pollutant and characterized by a significant content of heavy metals. Green spaces play a leading role when it comes to improving the quality of atmospheric air in megalopolises. They trap pollutants. Most of them settle on the surfaces of plant leaves, but some can be also absorbed through the stomata. As a result of these processes, pollutants, along with fallen leaves, can later migrate to other components of the ecosystem. An important component of this system is forest litter that plays a kind of trigger role by regulating the directions of substance flows in the “leaves-litter-soil” system, keeping chemical elements from leaching out and evenly distributing their inflows. Thus, forest litter functions as a sort of biogeochemical barrier and plays a leading role in the ability of ecosystems to self-regulate.
 Thus, the purpose of this work was to assess the role of green spaces in improving the quality of atmospheric air in the urban surroundings and to conduct a preliminary assessment of the features of the processes of heavy metals transformation within the forest litter. The model site of research is located within the territory of Holosiivskyi forest, a part of the Holosiivskyi National Nature Park (Kyiv). The content of heavy metals in the forest litter was determined using the methods of atomic absorption spectrophotometry. The results of the study of Cu, Ni, Pb, Cd, Cr and Zn content annual dynamics within the forest litter of the hornbeam forest of the Holosiivskyi National Nature Park show that the maximum concentrations are typical for the summer period, when the litter reserves sharply decrease, and the minimum ones – for the autumn-winter period during their accumulation. Comparison of the distribution of heavy metals content within the leaf and fermented layers showed that, under the conditions of the model area, Zn, Cu, and Ni are predominantly accumulated right in the leaf layer of the forest litter. Moreover, it was revealed that the processes of leaf litter mineralization lead to migration of Cu, Ni, Pb, Cd and Cr, and setting of Zn.