The increase in tritium concentration caused by Fukushima discharge over a years.
Macroscopic and tiny simulations of Fukushima nuclear accident contaminated water discharge.
On August26, 2021, the Japanese Cabinet passed a bill to discharge cured Fukushima nuclear mishap infected water into the Pacific Ocean to ease the problem of nuclear wastewater storage. Large quantities of radionuclides can affect marine biological chains when inhaled by marine life and negatively affect marine fisheries and human health. The worldwide effects of Fukushima discharge, which will last 30-40 years, stay unidentified. Hence, recognizing the diffusion procedure of radioactive water in oceans is critical.
(d) Variations in the pollutant concentration in the waters near the 3 seaside cities. (e) Comparison of the pollutant concentration curves by macro and micro approaches. According to the trend of the three curves, the pollutant concentration in each region increases quickly at the beginning prior to stabilization. San Diego is the last city among the three to be impacted, the steady-state concentration of pollutants in its surrounding waters is even greater than that near Miyazaki.
The differences in contaminant concentrations near Miyazaki, Shanghai, and San Diego result from the strong ocean existing near Japan.
To solve this problem, a group from Tsinghua University, China, developed analysis models from both tiny and macroscopic perspectives, to replicate the diffusing procedure of the nuclear aspects. The former one concentrates on the general circulation of contaminants, while the latter focuses on the behavior of private toxins.
Macro simulation results (Figure b) exposed that in the early phases of pollutant discharge, the polluted location increases rapidly, reaching 30 ° of latitude × 40 ° of longitude within 120 days. Due to ocean currents, the contaminant diffusion speed is significantly greater in the latitude instructions than that in the longitude instructions.
In 1200 days, the pollutants will cover practically the entire North Pacific area, reaching as far as the coast of North America to the east, and the Australia to the south. The toxins will then spread rapidly to the South Pacific Ocean, under the influence of the equatorial existing along the Panama Canal. The Indian Ocean will likewise be affected, due to the waters infilling from north of Australia, in 2400 days. On day 3600, the contaminants will cover nearly the whole Pacific Ocean.
Especially, although the infected water is discharged near the Japanese island, the contamination center (represented by yellow and red in Fig. b and c) will with time move eastward along the 35 ° N latitude line.
(d) Variations in the pollutant concentration in the waters near the 3 coastal cities. (e) Comparison of the pollutant concentration curves by macro and micro methods.
The team outlined the pollutant concentrations in surrounding waters of Miyazaki, Shanghai, and San Diego, all near 30 ° N, as shown in Figure d. Miyazaki gets polluted initially, followed by Shanghai and San Diego, in order of their distances from Fukushima. According to the pattern of the three curves, the pollutant concentration in each region increases rapidly at the start prior to stabilization. Although San Diego is the last city among the 3 to be impacted, the steady-state concentration of pollutants in its adjacent waters is even greater than that near Miyazaki.
The differences in pollutant concentrations near Miyazaki, Shanghai, and San Diego result from the strong ocean existing near Japan. A lot of contaminants do not migrate towards north and south along the land edges but spread eastward with the North Pacific west wind drift.
Referral: “Discharge of dealt with Fukushima nuclear mishap infected water: tiny and macroscopic simulations” by Yi Liu, Xue-Qing Guo, Sun-Wei Li, Jian-Min Zhang and Zhen-Zhong Hu 2021, 26 November 2021, National Science Review.DOI: 10.1093/ nsr/nwab209.