Monitoring of radionuclide contamination of plants in the western part of Volyn Polissya (Ukraine) during 1994–2007

We present the main results of our more than decade-long monitoring of 137Cs content in berry plants and medical herbs growing in the Shatsk National Natural Park (Volyn Region, Ukraine). It is shown that the 137Cs content for most of the medical herbs has significantly decreased during the monitoring time period and now it meets the demands of Ukrainian sanitary standards (less than 200 Bq/kg d. w.). The decreasing rate is much higher than that for the corresponding soils. This is because the radionuclide available in the soil becomes less accessible for digesting by the plant rootage in the course of time. The 137Cs content in the vegetative and generative organs of bilberry shows essential seasonal variations. The corresponding content for the foliage reveals almost double decrease during the period when the berries ripen and an increase occurring after fructification