PROJECT RESULTS

The catastrophic failure of tailings pond No.2 in 1964 actually predetermined the environmental situation in the Kichi-Kemin river valley from the Ak-Tyuz village down stream to the state border with Kazakhstan and probably even further. The analyses of samples collected showed that stream sediment and heavy mineral surveys, soil geochemistry and gamma spectrometry are methods which can provide reliable information, and relics of radioactive tailings also containing heavy metals to be identified and mapped so that their areal extent can be defined. Progressive increase in contamination of sediments by some elements below the village of Ak-Tyuz (tailings pond No.2) was confirmed. These elements are characteristic of mineral assemblages contained in ores extracted from the local mineral deposit. They include Pb - Zn, La - Y, Th and some others, such as Zr, W and Be. High contents continue to occur through the villages of Kichi-Kemin and Boroldoy as far as the border with Kazakhstan. Considerable variations in the concentrations of individual elements (sudden alternation of high and low contents) are characteristic and seem to reflect changes in the proportion of wastes in stream sediments. On the other hand, contents of single elements upstream from the village of Ak-Tyuz are mostly uniform and most probably reflect the natural background derived from the local rocks.

 

A similar trend can be seen in the distribution of Th in concentrates of heavy minerals.

 

Soil geochemistry at the Ak-Tyuz site. Altogether 85 soil samples on 9 profiles based on a 250 x 50 m grid were collected. The whole territory of the village at a distance of ca 2 km from the abandoned concentrator in the SW as far as the cemetery on the NE edge of the area investigated, which is already outside the settlement, was covered by soil geochemistry. All sampling sites were also measured using surface dosimetry and gamma spectrometry (Th, U, K). The survey was designed to determine the level of contamination of soils by heavy metals and radionuclides.

The distribution of selected contaminant metals, specifically As, Be, Cu, Mo, Pb and Zn appears to be homogeneous. Marked anomalies of these elements were detected in the SW part of the village in the area immediately linked with the former concentrator and tailings pond No.1 (unambiguous source of contamination). These anomalies become gradually less pronounced towards the north-west with increasing distance from the tailings pond and finally vanish at the NE margin of the area surveyed (profiles 1 and 2).

 

As follows from maps of element distribution, arsenic and lead are the major pollutants. High concentrations exceeding the safe limits set for sites of housing development are found over large areas posing significant risks to the health of the local population.

 

Radioactive elements measured by gamma ray spectrometry show a pattern of distribution similar to that shown by heavy metals. Enhanced contents of radioactive elements again tend to extend from SE to NW across the Ak-Tyuz settlement and their concentrations decrease in the same direction. However, the slightly anomalous values depicted in the dosimetric map do not exceed the safe standard equal to 50uR/hr.

 

Based on the spatial distribution and the trends in increased and anomalous contents of elements it can be assumed that the migration of heavy metals in the area of Ak-Tyuz village is likely to have been caused by aeolian transport of dust from the concentrator, open cast mine workings and from tailings ponds.

 

2) Remediation of radioactive contamination – former storehouse of Th-REE concentrate

The remediation of this small source of radioactive element contamination was undertaken in the years 2004-2005.

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Jihlava, 2006

Project manager: RNDr. Miloš Abraham, phone. +420 567161258, E-mail: abraham@geomin.cz