Ecological standardization of permissible radionuclide pollutions of fresh water ecosystems on the basis of theory and models of radiocapacity

Taras Schevchenko National Kiev State University, Department of Radiobiology and Radioecology, 01004 Kiev, Ukraine

Abstract

In the case of radionuclide releases and disposal into the environment it is important to assess the maximum admissible values of income of radionuclides into an ecosystem, where there are no yet noticeable biological changes as the result of ionising radiation. The natural boundary for estimation of maximum permissible disposal of radionuclides into ecosystems is the dose commitment or the annual absorbed dose rate. G. Polikarpov and V. Tsytsugina have proposed a scale of dose commitments to ecosystems consisting of four basic dose limits. From the given scale it follows that the real dose limit for release and accidental "disposal" of radionuclides in ecosystems and their components is the dose rate that exceeds 0.4 Gy y^-1 for terrestrial animals and 4 Gy y^-1 for hydrobionts and terrestrial plants. At such dose rates it is possible to expect a development of evident ecological effects in ecosystems. Dose commitments from α^-, β^-, γ-radiation are not difficult to assess for the radionuclides composition of the Kyshtum and the Chernobyl releases. According to our assessments the calculated total dose of 0.4 Gy y^-1 to 4 Gy y^-1 (as given by Amiro, [4]) correspond to respective concentration of ¹³⁷Cs of about 100 and 1000 kBq l^-1(kg^-1) in ecosystem or in its elements (terrestrial plants and hydrobionts). The total dose 4 Gy y^-1 corresponds to ¹³⁷Cs concentration of about 1000 kBq l^-1(kg^-1) for a fresh water ecosystem. The maximum permissible releases of radionuclides into the ecosystems could be assessed on the basis of the above mentioned models and equations, using an assessment of maximum permissible concentration of radionuclides in the components of the ecosystem.