Assessment of the impact of radio-ecological conditions on the rate of decomposition of plant organic matter in forests and waters of the Exclusion Zone

Client: State Agency of Ukraine of the Exclusion Zone Administration (SAEZ)
Period: 2011-2012

The object of research was to evaluate the rate of plant organic decay (leaves of trees) in terrestrial and aquatic forest ecosystems, depending on the levels of radioactive contamination.
The experiment included the placement of “standard” plant organic material in the horizon of plant residues or near the bottom of ponds in the areas of the Exclusion Zone, which have similar general ecological conditions and excellent radiation, exposure of it over particular period of time and assessment of the decay ratio. As a “standard” material fresh autumn litter of leaves from trees of two species were selected: alder ( Alnus glutinosa) and birch ( Betula pendula), which were collected in relatively “clean” radiation areas: near the settlements Nezamozhnya and Mekshunovka in Chernigiv region. The leaves were dried at room temperature to the stable weight.
The complex of works, which was performed actually by IRL experts, included:

1. choice of test sites and description of radio-ecological conditions;
2. collection of fallen leaves and training;
3. placing of leaves in the form of transparent microcosms (plastic mesh bags) for biota activities in the Exclusion Zone areas;
4. microcosm collection over particular period of time and determination of the organic mass, which remains (estimation of decay coefficient).

The complex of works, which was performed by the participation and support of IRSN, included:

1. characterization of reservoirs and soil-plant systems;
2. assessment of radionuclides (90Sr, 137Cs, 241Am, 238-240Pu, 234,238U) in soil samples and sediments, selected in areas where microcosm was laid (the works were performed in IRL with IRSN funding);
3. assessment of diversity and activity level of biota (bacteria, fungi, nematodes, macropodus) on experimental plots;
4. assessment of radiation dose using thermoluminescent dosimeters.

Complex of works was carried out by two groups: IRL ChC and together with specialists from Institute of Radiation Protection and Nuclear Safety (IRSN, France) – and, accordingly, was funded from two sources: budget program of Ukraine (KPKV 3202110, item 2) and IRSN (agreement #1, Work package 2). The works were carried out in accordance with the program of joint activities of the Chornobyl Center and Institute of Radiation Protection and Nuclear Safety (IRSN, France), which was agreed by Ministry of Emergency Situations of Ukraine.

Contact:
Deputy Director General of IRL in science
Head of Radioecological Research Department
Gaschak Sergei Petrovich
Tel. +38 (04579) 6 15 62
Fax: +38 (04579) 6 15 62
e-mail: sgaschak@chornobyl.net