RESUMO
This study discusses contamination of soils and sediments with trace elements such as Mn, Ba, W, V, Co, Cr, Zn, Ni, As, Sb Hg as well as Th and U, the influence of natural and anthropogenic factors on the distribution of elements and the ecological state of the Zarafshon Valley. The elemental composition of 116 soil and sediment samples were analyzed by the neutron activation analysis. The calculation of the geoaccumulation index (Igeo), contamination factor (CF) and pollution load index (PLI) showed that some places in the investigated region with developed the industrial zones (around mining and processing plants of "Anzob", "Konchoch", "Kumargi bolo" and "Mogiyon") are mostly polluted by As, Sb, Hg, and in rare cases, the high concentration of W and V were determined. In addition, they were considered the distribution of radioactive elements-thorium and uranium and their ratio in the soil and sediments. Moreover, in the investigated area, strong anomalies of Th and U were not found. It turned out that the content of Th and U are local in nature and do not have a noticeable effect on the environment.
RESUMO
The study was performed in a mountainous area of approximately 7000 sq. km of Western Tajikistan, i.e., Turkestan, Zeravshan, Hissar, and Karateghin ridges that are characterized by complex geological settings. Moss biomonitoring was used to assess the concentration level of trace and major elements in atmospheric deposition of the study area. Hylocomium splendens (Hedw.) Schimp. moss was used as biomonitor in this study. 43 major and trace-elements were determined by Epithermal Neutron Activation (ENAA) and Atomic Absorption Spectrometry (AAS). GIS maps of the 43 elements showed that the distribution of Mo, Cd, REE, Th, and U could be most probably associated with the Odjuk pegmatite field. Zr, Hf, and W contents are significantly increased in the vicinity of the Sarbo River washout while Cr, Co, Ni, and As showed a maximum content near Kanchoch gold field. The global pollution index based on the local content of presumed pollutants Cr, Ni, Cu, Zn, As, Cd, Sb, and Pb in some places exceeded the threshold limits for a pristine, unpolluted environment. At the same time, the distribution of incompatible Sc, La, Yb, and Th suggested for the airborne material deposited on mosses a continental component, enriched in few places in felsic components.