環境水の保管温度・期間が溶存態137Cs濃度の変動に及ぼす影響

Hideki Tsuji; 辻英樹; Seiichi Takechi; 武地誠一; Hirokazu Ozaki; 尾崎宏和; Tatsuhiro Nishikiori; 錦織達啓; Tomijiro Kubota; 久保田富次郎; Seiji Hayashi; 林誠二

doi:10.3769/radioisotopes.69.315

環境水の保管温度・期間が溶存態¹³⁷Cs濃度の変動に及ぼす影響Effect of Storage Temperature and Duration of Environmental Water on Dissolved ¹³⁷Cs Concentration

辻英樹¹，武地誠一¹，尾崎宏和¹，錦織達啓²，久保田富次郎³，林誠二¹Hideki Tsuji¹, Seiichi Takechi¹, Hirokazu Ozaki¹, Tatsuhiro Nishikiori², Tomijiro Kubota³, Seiji Hayashi¹

¹ 国立環境研究所福島支部National Institute for Environmental Studies

² 農業・食品産業技術総合研究機構東北農業研究センター農業放射線研究センターAgricultural Radiation Research Center, Tohoku Agricultural Research Center, National Agriculture and Food Research Organization

³ 農業・食品産業技術総合研究機構農村工学研究所National Agriculture and Food Research Organization, Institute for Rural Engineering

受付日：2020年2月7日Received: February 7, 2020

受理日：2020年7月9日Accepted: July 9, 2020

発行日：2020年10月15日Published: October 15, 2020

環境水を未ろ過状態で保管する間の溶存態¹³⁷Cs濃度の変動を明らかにするため，森林河川，都市河川，ため池水を25°C・5°C・−20°Cで定温保管し溶存態¹³⁷Cs濃度を測定した。採水直後に酸を添加し保管した場合，溶存態¹³⁷Cs濃度は現地濃度に比べ大きく上昇した。酸を添加しない場合の濃度は保管温度・日数と水の性状に応じて変動し，短期間冷蔵保管後，ろ過処理前に採水時の水温に戻す処理により現地濃度を再現できる可能性が示唆された。

We examined fluctuations of dissolved ¹³⁷Cs concentration in the constant temperature storage of unfiltered water samples from forest rivers, urban rivers and agricultural reservoirs. When the water was acidified immediately after sampling, the dissolved ¹³⁷Cs concentration during the 30-day storage period increased from the in situ concentration. The dissolved ¹³⁷Cs concentration without acid varied depending on the storage temperature, number of storage days, and the nature of the water. The findings suggest that it is possible to reproduce the in situ dissolved ¹³⁷Cs concentration by restoring the water temperature to that of the originally sampled water after a short period storage of refrigeration prior to filtration.

Key words: caesium-137; dissolved form; storage temperature; short period storage of refrigeration

RADIOISOTOPES

原著Article

環境水の保管温度・期間が溶存態¹³⁷Cs濃度の変動に及ぼす影響Effect of Storage Temperature and Duration of Environmental Water on Dissolved ¹³⁷Cs Concentration

環境水の保管温度・期間が溶存態137Cs濃度の変動に及ぼす影響Effect of Storage Temperature and Duration of Environmental Water on Dissolved 137Cs Concentration

環境水の保管温度・期間が溶存態¹³⁷Cs濃度の変動に及ぼす影響Effect of Storage Temperature and Duration of Environmental Water on Dissolved ¹³⁷Cs Concentration