PROJECT OUTLINE AND METHODS OF INVESTIGATION

The work on the project was carried out during the period of July 22 – October 8, 2004 and June 30 – September 30, 2005. Preparatory and reconnaissance stages were undertaken in 2004, in order to become acquainted with the local situation and to test and verify the procedures for sampling and implementation of the work involved in removing the radioactive contamination of the warehouse in which concentrates were formerly stored at the Ak-Tyuz site. In 2005, this preparatory work was followed by systematic geoenvironmental surveys in the Kichi-Kemin river valley. The former storehouse was also decontaminated and reclaimed.

 

1) Geoenvironmental survey of the Kichi-Kemin river valley
The survey involved geophysical measurements combined with geochemical sampling and analysis of several components of the environment. The objective of the work was to define the areal extent and level of anthropogenic contamination caused by the mining and mineral processing complex of Ak-Tyuz and the impacts of the catastrophic failure of the dam of tailings pond No.2 that occurred in 1984. Dosimetry. This method was used continuously during the field operations and at all sampling sites where stream sediments and samples of industrial residues were collected. The method was also applied to soil samples taken on several profiles. The instrument used was an EXPLORANIUM Company, model GR 130, and measurements were made at two- second intervals, measurements being recorded as units of uR/hr. Gamma spectrometry. This method followed the dosimetric measurements using the GR 130 instrument (time of measurements 300 seconds). Contents of Th (ppm), U (ppm), K (%) and total gamma activity were established. Magnetic susceptibility measurements were applied as a supplementary method to establish susceptibility in soils and stream sediments. The tailings from ore treatment processes are rich in magnetite that is reflected in enhanced magnetic susceptibility. Consequently, remains of tailings in the Kichi-Kemin river valley can be detected using magnetic susceptibility as well as by conventional radiometry. A kappameter KT 9 produced by the Canadian Company EXPLORANIUM was used for the field measurements. The recorded value of magnetic susceptibility was based on an average of 5 measurements at a site 1 m in diameter. Stream sediments. Samples were collected from the river Kichi-Kemin and its tributaries, the sampling interval was ca 500 m. Fine muddy-clayey sediment of a mass of ca 1-1.5 kg was sampled whenever possible.

 

Other stream sediment samples were collected in the river Chu catchment to find out whether irrigation water from the river Kichi-Kemin carries any heavy metals to pollute the Chu river basin. Heavy mineral concentrates. Samples of an initial volume of 10 l of alluvial material were collected at ca 2 km intervals and washed to obtain a heavy mineral concentrate. Soil samples. Samples weighing ca 1-1.5 kg were taken from the soil profile below humic layer using a spade. Sampling was done in a grid with variable spacing on single profiles and sampling sites (altogether 48 profiles).

 

Soil sampling on 9 profiles using a grid of 250 x 50 m was carried out in the Ak-Tyuz village. Short profiles across the Kichi-Kemin river bed in its middle and lower reaches (sampling sites 50 m apart) were combined with reconnaissance profiles covering a broad stretch of the river towards the Chui river basin (sampling sites mostly 200 – 250 apart).

 

Technological samples. These samples consisting of tailings from mineral processing were taken from tailings ponds Nos. 1, 3 and 4 and from dumping grounds located on the Kichi-Kemin river bank. Water samples. Water flowing out from tailings ponds and also water from a few sites on the Kichi-Kemin river was collected. One part of each sample (sample was buffered by nitric acid) was analyzed using the ICP-AES method for 33 elements. Radioactivity in the other part of the same sample was also measured. Five samples were completely analyzed for cations and anions. Type and number of samples, type of analysis and the laboratory responsible are summarized in the Table below