Importance of desorption process from Abukuma River's suspended particles in increasing dissolved Cs in coastal water during river-flood caused by typhoons.

Desorption of radiocesium (Cs) from riverine particles into seawater strongly influences Cs concentrations in coastal seawater. This process is important for quantifying the input of radionuclides to marine environments. Here we quantify the particulate Cs flux from the Abukuma River, Japan, during typhoon Hagibis and following typhoons in 2019 and estimate the resulting increased dissolved Cs levels in coastal seawater.

The contribution of Cs export flux from the Tone River Japan to the marine environment.

The contribution of Cs transport to the marine environment via the Tone River, Japan was investigated. This river has the largest discharge among rivers on the North Pacific side of eastern Japan. The sampling site was located upstream near the river mouth and dissolved and particulate Cs in the river water was measured during 2014-2015, three years after the Tokyo Electric Power Corporation Fukushima Daiichi Nuclear Power Plant (FDNPP) accident.

Appearances of Fukushima Daiichi Nuclear Power Plant-Derived Cs in Coastal Waters around Japan: Results from Marine Monitoring off Nuclear Power Plants and Facilities, 1983-2016.

Monitoring of Cs in seawater in coastal areas around Japan between 1983 and 2016 yielded new insights into the sources and transport of Fukushima Daiichi Nuclear Power Plant (FDNPP)-derived Cs, particularly along the west coast of Japan. Before the FDNPP accident (1983-2010), the activity concentrations of Cs, mainly from fallout, were decreasing exponentially. Effective Cs half-lives in surface seawater ranged from 15.

The Contribution of Sources to the Sustained Elevated Inventory of (137)Cs in Offshore Waters East of Japan after the Fukushima Dai-ichi Nuclear Power Station Accident.

We have evaluated the contribution of sources of (137)Cs to the inventory of radiocesium in waters (surface area: 6160 km(2), water volume: 753 km(3)) off Fukushima Prefecture and neighboring prefectures from May 2011 to February 2015. A time-series of the inventory of (137)Cs in the offshore waters revealed a clearly decreasing trend from May 2011 (283.4 TBq) to February 2015 (1.

Plutonium isotopes concentration in seawater and bottom sediment off the Pacific coast of Aomori sea area during 1991-2005.

A radioactivity survey was launched in 1991 to determine the background levels of ²³⁹+²⁴⁰Pu in the marine environment off a commercial spent nuclear fuel reprocessing plant before full operation of the facility. Particular attention was focused on the ²⁴⁰Pu/²³⁹Pu atom ratio in seawater and bottom sediment to identify the origins of Pu isotopes. The concentration of ²³⁹+²⁴⁰Pu was almost uniform in surface water, decreasing slowly over time.