The content of heavy metals in the soils of the state protected natural areas in the South-eastern area of the Republic of Moldova

Abstract

Heavy metal (HM) content has been assessed in soils within 10 state protected natural areas (SPNA). The soil samples were collected from the soil layer 0-20 which is in direct relation to all biotic (edaphic and bio-indicatory plant organisms, soil microorganisms) and abiotic (atmospheric and wind deposits, physical-chemical processes, etc.) components responsible for the HM circuit within the ecosystems. Evaluated on the basis of the grading scale of soils of the Republic of Moldova, (Кирилюк, 2006), the content of HM (Zn, Cu, Ni, Co) analysed, for the soil layer studied, was included in the categories of very low - high levels. In the evaluated soil layer, no cases of studied HM pollution were recorded. In some cases, however, there are trends in the accumulation of Zn and Cu, but their contents do not exceed the alert threshold (AT) values (tab. 1). Both for APNA and for other terrestrial ecosystems, increased Cu and sometimes Zn content in environmental components are characteristic, as a result of the intensive processing of surrounding agricultural land and forests with phytosanitary products containing Cu and Zn. After Adriano (1986), copper and zinc fall into the category of microelements with a biologically important role for forest ecosystems, deficiencies (<10 mg/kg) or exceed the AT (>100 mg/kg), can cause reduction of root and shoot growth, inhibition of enzymes, risks that in the case of ecosystems investigated are not attested. In the case of the intervention threshold (IT), the studied HM values do not reach these values after Kloke (1980), which excludes the risk of toxicity, in the studied ecosystems, for plants and soil organisms.