Characteristic of dissolved radiocesium leaching from a forest litter observed from litterbag experiment

リターバック実験から得られた森林リターからの溶存態放射性セシウム溶出の特性

佐久間 一幸   ; 吉村 和也  

Sakuma, Kazuyuki; Yoshimura, Kazuya

福島県太田川上流域において、リターバックを用いて針葉樹および広葉樹からの溶存態Csの溶出特性を調査した。各樹種のリターを24個のリターバックにそれぞれ封入し、2017年6月に各林床に設置した。2017年8月および12月に、各林床から3つずつサンプルを採取し、速やかに実験室へ運び、バケツに移し、純水に浸漬した。その後溶出水を、浸漬後20分, 2時間, 24時間後に採取した。溶存態Cs濃度, 溶存有機物濃度, 主要イオンについて分析した。浸漬後24時間後における溶存態Cs溶出率については、針葉樹(夏季: 1.80.2%、冬季: 1.20.4%)に比べ、広葉樹(夏季: 8.32.6%、冬季: 6.80.9%)が高かった。

We investigated characteristic of dissolved Cs leaching from litters collected at a coniferous needle and a deciduous broadleaf forests using litterbags at upstream area of Ota River in Fukushima. Each leaf type of litters was collected into 24 litterbags, respectively, and installed each forest floor in June, 2017. Triplicate samples were collected at each forest floor and readily transported to laboratory in August and December, 2017. Samples were put in buckets and soaked in purified water immediately after back to laboratory. We took leaching water samples from the buckets at 20 min., 2 hours, 24 hours after soaking litter samples in the water. These samples were analysed about Cs activity, dissolved organic carbon concentration, and major ions concentration etc. The main results are that the deciduous broadleaf litter showed much higher leaching ratio of dissolved Cs (Summar:8.32.6%, Winter:6.80.9%) than that of the coniferous needle litter (Summar:1.80.2%, Winter:1.20.4%) after soaking during 24 hours.