Radiocesium in Japan Sea associated with sinking particles from Fukushima Dai-ichi Nuclear Power Plant accident
Radiocesium in Japan Sea associated with sinking particles from Fukushima Dai-ichi Nuclear Power Plant accident
复制标题
DOI：
10.1016/j.jenvrad.2020.106348
复制
发表时间：
2020-10-01
影响因子：
2.3
通讯作者：
Minakawa, Masayuki
中科院分区：
文献类型：
--
作者：
Kaeriyama, Hideki;Fujimoto, Ken;Minakawa, Masayuki
本研究研究了2010年9月至2012年7月期间日本海东北部与沉降颗粒相关的放射性铯浓度的时间变化。我们分析了2011年3月福岛第一核电站（FDNPP）事故后这一时期的沉积物捕获器样本。在2011年5月至7月期间收集的1100米深度（4.2-11 mBq g-dry(-1)）的样品中检测到铯-134，但在1100米或更深（3100和3500米）的其他时期未检测到铯-134。这些结果证实了fdnpp衍生的放射性铯在2011年4月下旬在日本海东北部的地表水上沉积，并在北太平洋沉积约40天后随着沉降颗粒迅速下沉至至少1100 m的深度。如果排除fdnpp衍生的Cs-137，下沉颗粒的Cs-137活性浓度没有季节变化，颗粒的Cs-137活性浓度随着深度的增加而增加。从沉降颗粒Cs-137的浓度、总质量通量和有机质含量的季节变化来看，造岩颗粒对沉降颗粒伴生的放射性元素很重要。这些数据还有力地表明，2010-2011年和2011-2012年部署期间粒子下沉特征的差异。由于底栖锋的存在，在2010-2011年部署期间，浅水（1100 m）和深水（3500 m）是分开的，但在2011-2012年冬季，该锋消失，地表水颗粒似乎下沉到3100 m的深度。在1100 m处，粒子沉降速度为33 ~ 62 m day(-1)，平均沉降速度为43 m day（-1）。这些值与FDNPP事故后在北太平洋浅于1000米的深度，或切尔诺贝利事故后在地中海、北海和黑海的估计值相当。
This study examined the temporal variations in radiocesium concentration associated with sinking particles in the northeastern Japan Sea between September 2010 and July 2012. We analyzed sediment trap samples from this period after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011. Cesium-134 was detected in samples collected between May and July 2011 at a depth of 1100 m (4.2-11 mBq g-dry(-1)) but not in other periods at 1100 m or deeper (3100 and 3500 m). These results confirmed the deposition of FDNPP-derived radiocesium on the surface water in the late April 2011, which rapidly sank with sinking particles to a depth of at least 1100 m, in the northeastern Japan Sea, about 40 days after the deposition in the North Pacific. If FDNPPderived Cs-137 was excluded, no seasonal changes were detected in the Cs-137 activity concentration of the sinking particles, and the Cs-137 activity concentration of the particles increased with increasing depth. Judging from the concentration of Cs-137 of sinking particle and seasonal variation of total mass flux and organic matter content, the lithogenic particle seems to be important for radiocesium associated with sinking particles. These data also strongly suggest a difference in sinking features of particles between 2010-2011 and 2011-2012 deployments. Due to the existence of benthic front, shallow water (1100 m) and deep water (3500 m) are separated during 2010-2011 deployment, but in the winter of 2011-2012, this front disappeared and the particles in surface water seem to have sunk to the depth of 3100 m. The sinking velocity of the particles at 1100 m was estimated to be 33-62 m day(-1), with a mean sinking velocity of 43 m day(-1). These values were comparable to those estimated at depths shallower than 1000 m in the North Pacific after the FDNPP accident, or in the Mediterranean, North, and Black Seas after the Chernobyl accident.