Radiation ecological risk for the terrestrial ecosystem in the zone close to the radioactive waste storage facility

At present ecological risk is considered as one of the tools for assessment of the environment response on exposure to the harmful agents. Hazardous effect on the environment is estimated by the response of the most sensitive components of the environment. The lowest level of a pollutant content, at which environmental changes occur, is defined as a critical load. The article presents method for estimating radiation-associated ecological risk with the use of critical loads for terrestrial ecosystems in the area around the radioactive wastes storage site in the north part of the Kaluga oblast. The area was contaminated with radionuclides as a result of leakage of liquid radionuclide wastes from the storage facility. The method for risk assessment used in the study is a modified version of the existing approach to ecologic risk measuring with critical loads for atmotechnogenic pollution. Risk assessment consists of the following 5 stages: identification of harm; identification of reference species and determinants; determination and analysis of critical loads with the use of dose-response relationship; ecological risks assessment and risk functions analysis; analysis of uncertainties. Data of long-term (2010-2015) monitoring were used for determination of the listed input parameters for risk assessment: terrestrial ecosystem is the recipient; factor of ecological hazard, 90Sr, was found due to investigation of chemical and radioactive contaminants; the area contaminated with radionuclides was determined, it was 0.54 hectares, intensity of radiation wastes impact on the recipient was determined; reference species, mollusk, Fruticicola fruticum, and reference determinants, such as its shell height, content of proteins, metallothioneins, in soft tissues of the mollusk, critical loads for every determinants. Values of ecological risk to the ecosystem - recipient assessed for 2 reference determinants, were similar, the risk was acceptable.