THE INTERNATIONAL PROJECT ėNAVRUZî IN KAZAKHSTAN.
RESULTS OF INVESTIGATIONS FOR THE PERIOD OF
FALL 2003 - SPRING 2004
K.K. Kadyrzhanov, V.P. Solodukhin, S. Khazhekber, V.L. Poznyak, H.D. Passell*,
G.M. Kabirova, V.V. Smetannikov, R.M. Gabdulin, E.E. Chernykh,
A.D.Musrepov, A.S. Liventsova
Institute of Nuclear Physics NNC, Ibragimov St. 1, Almaty-32, Republic of Kazakhstan, firstname.lastname@example.org.
*Sandia National Laboratories, P.O. Box 5800 MS 1373, Albuquerque, NM 87185-1373, USA.
The main purpose of the project ėNavruzî is research and monitoring of radiation and ecological situation in basins of main rivers of Central Asia -- the Syrdariya and the Amudariya in the territories of Kirghizia, Uzbekistan, Tajikistan and Kazakhstan [1-3]. Of those two rivers, only the Syrdariya and its tributaries flow through Kazakhstan. The present work presents main investigation results of this river basin during the period from fall 2003 to spring 2004 (correspondingly 5th and 6th expeditions).
Figure 1. The scheme of sample points.
Expedition works were carried out according to the layout presented in Fig.1. Monitoring of water and bottom sediments was carried out at 15 permanent control points from KZ 1 to KZ 15. With a view of more intensive investigation of radiation and ecological situation there was carried out sampling of soil, water and bottom sediments at the following additional control points: expedition 5 (KZR 16-30); expedition 6 (KZR 16, 17, 20, 25, 26, 28-40). In the course of expedition works there were determined main chemical-physical parameters of water with the help of "Hydrolab" device: temperature t, С; specific conductivity Ec, mСm/сm; total quantity of dissolved substances TDS, g/l; рН level; reductive-oxidative potential ORP, mV. Prior to sample analysis, water was filtered through membrane filters with 20mm pore. Filters were dried and incinerated in the laboratory environment. Filtered water was fully evaporated. After preparation, samples of soil, bottom sediments, water suspended sediment component (WS) and water-dissolved component (WD), were analyzed by the method of instrumental gamma-spectrometric analysis (radionuclide analysis), as well as by NAA and XRF methods (element analysis). All methods, used in field works and laboratory investigations, are presented in work  in detail.
On the basis of all obtained data there is determined that average content of 238U in soil of the Syrdariya River basin comprises 2.4 mg (29.5 Bq/kg), and 232Th is 9.1mg/g (37.3 Bq/kg). These values evidently exceed average values of uranium concentrations (1mg/g) and thorium (6mg/g) for soils of the whole world . Such conclusion spreads, indeed, to all daughter radioactive and decay products of these elements. Distribution variety of overwhelming majority of studied radionuclides (238U, 234Th, 226Ra, 214Pb, 214Bi; 232Th, 228Ac, 224Ra, 212Pb, 212Bi; 208Tl; 235U; 40K) is relatively low by area and depth of soil stratum at all investigated territories. 210Pb and artificial radionuclide 137Cs are exceptions that for the most part concentrated in upper soil stratum and distributed more contrasting by area. On the basis of data obtained by NAA and XRF methods there is also determined that high contents of Na, K, Ca, Zn, and As are characteristic for investigated territory soils. High concentrations of Sc, Br, Sr, Pb were revealed at various sites. Radionuclide and element composition of bottom sediments corresponds to the soil composition very largely. One can observe that average value of 210Pb concentration, especially, of 137Cs in bottom sediments is noticeably low than in soil. The highest concentrations in soil of natural radionuclides of 238U family were revealed at the border adjacent to Uzbekistan (KZR16); near uranium deposit ėZarechnoeî (KZR18, 19, 20); near uranium deposit ėKaramurunî of Shyili town (KZ 8, 9, 10); in the outlet of the Arys river and downstream of the Syrdariya River (KZR 22, 23, 24); in Kurkeles riverbed (KZR 30); at vicinities of Qyzylorda city and downstream of the Syrdariya (KZ 11, 12; KZR 26). The most high concentrations of natural radionuclides of 232Th family were also revealed at the border adjacent to Uzbekistan (KZR-16); near ėKaramurunî deposit (KZ 8, 9, 10); in Syrdariya riverbed, down Qyzylorda town (KZ 12, 13), at vicinities of Arys river confluence (KZR 23, 24, 35), in Keles (KZ 3, 4; KZR-17) and Kurkeles riverbeds (KZR-30). The most 137Cs concentrations were revealed at sites (KZR 22, 23) located most closely to the underground nuclear explosion ėMeridian-3î. At present there is carried out more detailed investigation at vicinities of this explosion. High concentrations of microelements in soil were revealed at vicinities of large cities as Shymkent at the Badam River (Cr, Zn, As, Sb, Pb); Saryagash at the Keles River (Cr, Zn, Br, Sb, Ba); Qyzylorda at the Syrdariya River (Cr, Zn, Br, Sr, Sb). High concentrations of Br (15-20mg/g), Sr (up to 500mg/g) and Zn (up to 140mg/g) were revealed near ėZarechnoeî deposit (KZR-20). In the area of ėKaramurunî deposit (KZ 8, 9, 10) there were revealed high concentrations of Fe, Zn, Sr, Ba, Pb as well.
The average value for рН in the Syrdariya and its tributaries was 8.0ą0.2, and reductive-oxidative potential (ORP) was 400ą40 mV. During the expeditions a change of Ec and TDS value was revealed in headwaters of the Syrdariya river, where its tributaries exerts a considerable influence. Especially, it is determined that waters of the Keles and Kurkeles rivers are characterized by high physical-and-chemical indicators: TDS up to 2.6 g/l, Ec up to 4000 mSm/cm. Down the last tributary (the Arys river) there were no seasonal changes determined in values of these parameters. On this run of the Syrdariya river average value for Ec is (1620ą80) mSm/cm and for TDS is (1.04ą0.05) g/l.
According to the investigation results of the elemental composition there were revealed high concentrations of Cr, Fe, Co, Ni, Zn, As, La, Ce, Th in bottom sediments of headwaters of the Syrdariya river (above the Shardara reservoir). One can suppose that these microelements come with waters of Keles and Kurkeles tributaries. Specifically, it is determined that concentrations of these microelements in outlet water of the Keles river exceed their average values for the Syrdariya river by 5-8 times. In water of the Kurkeles river there were revealed maximal concentrations of Se at 5.9 mg/l, Sr at 6.8 mg/l and U at 35.5 mg/l.
Maximum concentrations for the majority of microelements in water of the Syrdariya river occurs near Kyzylorda city and Terenozek, Zhusaly towns. Most probably it is connected with hydrological peculiarities of this river.
A high concentration of Ca, Zn, As, Se, Re and other elements has been revealed in waters of the Badam and Arys rivers. Especially, the composition of Re (up to 1.8 mg/l) in these waters exceeds its average value in the Syrdariya river (0.08) more than 20 times. The revealed feature is probably related to industrial activity of Shymkent city.
The obtained results argue that concentrations of many elements along the Syrdariya River essentially exceed (by 10 to 100 times) corresponding world average values. Especially, average 238U concentration equal to 17.7mg/l (218mBq/l) exceeds world average value (1 mg/l) by almost 20 times. Thorium concentration in water of this river is higher than world average value by 15 times. Fe concentration in water of the Syrdariya River, practically along the whole length of it, essentially exceeds (by several times) the sanitary norm of maximum permissible concentrations for drinking water.
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