Radioecological monitoring of Syrdarya and Amudarya rivers

 

B.S.Yuldashev, U.S.Salikhbaev, R.I.Radyuk, E.D.Vdovina, A.A.Kist, E.A.Daniljva, S.V.Artemov, G.A.Radyuk, E.A.Zaparov

 

Institute of Nuclear Physics AS RU

 

Water is a precious gift of nature; life is not possible without water. There is a necessity to control water resources of earth. The total stock of water in Central Asia is 136.5 km3/year (Amudarya -87 km3/year, Syrdarya - 49.3 km3/year).

The transboundary nature of water resources demands transboundary approach to their monitoring and management.

The Navrus project addresses three main goals: to help increase capabilities in Central Asian nations for sustainable water resources management; to provide a scientific basis for supporting nuclear transparency and non-proliferation in region; and to help reduce the threat of conflict in Central Asia over water resources, proliferation concerns, or other factors.

 

The Central Asia Cooperative Monitoring Experiment (CME) began with the construction of a sampling and analysis plan /1/. This plan was referred to as an instruction manual for participants on sample collection activities, sample equipment operations and procedures, sample handling, laboratory analysis, detection limits, sample preparation, and instrument procedures. Data obtained in the project are shared among all participating countries and the public through an Internet web site and are available for use in further studies and in regional transboundary water resource management efforts.

 

         The Hydrolab instrument was used during sampling to measure the following parameters: water temperature, specific conductivity, oxidation-reduction potential, pH, dissolved oxygen, salinity and total dissolved solids.

The pH of water at all sampling points is equal to approximately 8.0. This value is between permissible levels (6.0 - 9.0). The specific conductivity (capacity of water to conduct electricity) changes from 200 to 3000 mS/cm. It is connected with increasing water salinity, especially in the springtime. Oxidation -reduction potential is an important factor for chemical reactions involving metals in water, and this value equals 300-400 mV for all samples. Dissolved oxygen is an important factor for many biological and chemical reactions in surface water. This parameter varied between 0.8-12 mg/l. Increasing dissolved oxygen is connected with increasing quality of fertilization in river water.

A flow meter was used to measure velocity of flow and discharge of water for rivers of Uzbekistan. The discharge of water for the spring period is higher than for fall. There is a very small water discharge from the Zaravshan River especially for fall period.

 

The study of waterborne radionuclides and metals concentration in Syrdarya and Amudarya rivers is of particular interest in the region because of the history of nuclear materials mining, fabrication, transport and storage. This development left a legacy of radionuclides and metals contamination in Basin this rivers, which poses a clear health hazard to populations who rely heavily upon surface water for cropland irrigation and direct domestic consumption.

 

         Thirty sampling location have been identified in Uzbekistan. Sampling was occurred in different media. The four different media are water (dissolved); bottom sediment; aquatic vegetation; soils.

 

         Measured parameters are:

- Radionuclides parameters - alpha activity, beta activity, radionuclides. (40K, 208Tl, 212Bi, 214Bi, 212Pb, 214Pb, 226Ra, 232Th, 235U, 238U);

- metals parameters - Al, Ag, As, Ba, Ca, Co, Cr, Cu, Fe, Hg, Mg, Mn, Zn e.t.c.)

 

           Thus, estimation of radioecological situation was made with helping of this results and peculiarities of distribution of radionuclides and metals on the rivers Amu Darya and Syr Darya were shown.

 

Reference

 

1. ÓNavrusÓ. Central Asia Cooperative Radionuclide Monitoring Experiment. Sampling and Analysis Plan. August,2001, Sandia National Laboratories of USA, 127p.