ASSESSMENT OF HEAVY METAL CONTAMINATION IN SOILS AROUND KREMIKOVTSI SMELTER (BULGARIA)

摘要

Heavy metal contamination of soils by metalliferous activities around metallurgical smelter Kremikovtzi was studied in different distances. Concentrations of Pb, Cd, Cu, Zn, Cr, Ni, As and Hg were determined on 38 soil samples (topsoils and subsoils) in order to assess the distribution of these heavy metals in the soil depth. Soils were analyzed using AAS for Pb, Cd, Cu, Zn, Cr and Ni; CVAAS for Hg; and HGAAS for As. Analysis of pH was also defined by pH meter. Correlation between pH values and heavy metal con-centrations was not established. Higher metal concentrations were determined in the soil samples taken relatively close to the smelter than those taken at 3 km distance. In some samples determined levels of Pb (330 mg/kg) and As (180 mg/kg) exceed considerably the maximum admissible concentrations (MAS) according to the Bulgarian Legislation (MAS of Pb is 130 mg/kg and MAS of As is 40 mg/kg). Determined concentrations of other metals (Cd, Cu, Zn, Cr, Ni, Hg) are below MAS but exceed the background and precautionary values. Determined levels of heavy metals and arsenic in the surface soil layers and these from 30 cm depth were quantified in the same order of magnitude. It was found that metal concentrations decreased with the distance increasing from the smelter. In addition, soil heavy metal contamination may pose a potential health risk to residents in the vicinity of smelter areas. For that reason, the morbidity rate of population living in this region was analyzed and it was found that allergic, respiratory, cardiovascular and endocrine disorders were with higher frequency rate compared with the average data for the city of Sofia.