MIGRATION OF RADIONUCLIDES IN ARABLE LAND OF LITHUANIA

Abstract

The paper presents the investigation data on soil contamination by Cs and Sr during the period 1974–2000 in various climatic zones and geographical locations for various granulometric and mineralogic composition of the soil and also for different mineralogical rock composition. The data concerning the accumulation of these elements, their perpendicular distribution before and after the Chernobyl Atomic Power Plant (ChAPP) accident. Besides, the influence of long term fertilization by various NPK rates on the amounts of radionuclides in the soil is presented. It is determined that before the ChAPP accident an average activity of 137Cs and 90Sr was 6,8±1,8 Bq·kg−1 and 5,3±1,2 Bq·kg−1, respectively. The radioactivity of peat soils was 2–5 times larger than that of mineral soils. After the accident in the ChAPP the amount of 90Sr in control plots, in the layer of 0–20 cm has not changed. In some fields an average amount of 137Cs is 6,7–28,5 Bq·kg−1. Larger concentrations of radionuclides were detected in the southeastern, southern and western regions of Lithuania. The amount of 137Cs in the upper soil layer in the western region of Lithuania was 1,1–1,2 times larger than in the layer of 5–20 cm, and 1,3–2,5 times larger than in the layer of 20–40 cm. Distinction is not so noticeable in the middle and eastern regions of Lithuania, correspondingly 1,1–1,2 and 1,2–1,6 times. Migration of 90Sr and 137Cs from the soil to plants varies and depends on soil properties and types of plants. The coefficients of 137Cs and 90Sr movement from the soil to plants were 0,24–0,53 and 0,37–0,87, respectively. In most cases long term fertilization had no influence on 90Sr and 137Cs accumulation and migration in the soil.