The CAS Xiguang hyperspectral remote sensing satellite is conducting real-time monitoring of the pollution situation and subsequent trends in the area where nuclear wastewater was discharged from the Fukushima nuclear site in Japan.

The dangers of discharging nuclear-contaminated water into the sea

▲A simulation of the spread rate and impact of nuclear-contaminated water by German marine science research. The image shows that radioactive materials will continue to spread over time, eventually reaching oceans worldwide.

The widespread dissemination of radioactive materials has caused radioactive contamination.

First, Japan's Pacific coastal waters will be affected, particularly the waters around Fukushima Prefecture. The contaminated waters will then pollute the East China Sea. A German marine research institution points out that the Fukushima coast has some of the world's strongest ocean currents. Within 57 days of the release, the radioactive material will have spread to most of the Pacific Ocean; three years later, the United States and Canada will be affected by nuclear contamination; and ten years later, it will have spread to oceans worldwide.

Long-term impact on biodiversity

Even after treatment, nuclear-contaminated water still contains high concentrations of radioactive tritium, which cannot be eliminated. Once released into the ocean, tritium will also produce low-intensity beta rays, potentially causing long-term impacts on biodiversity, including fish, plankton, benthic organisms, and birds.

Impact on the marine environment and public health of neighboring countries

An assessment report by the International Atomic Energy Agency (IAEA) expert group clearly states that if tritium-containing wastewater from the Fukushima nuclear power plant is discharged into the ocean, it will impact the marine environment and public health of neighboring countries. Furthermore, the existing treated wastewater still contains other radioactive nuclides and requires further purification.

The negative effects are long-lasting and may cause genetic damage.

Greenpeace nuclear experts have pointed out that the carbon-14 contained in the contaminated water from the Japanese nuclear disaster poses a danger for thousands of years and could cause genetic damage.

CAS Xiguang Remote Sensing Satellite: Assisting in Marine Environmental Monitoring

Today, remote sensing satellite technology is becoming an effective means for my country to monitor the marine environment. With its high precision, multi-band, and integrated image and spectrum capabilities, remote sensing satellite technology has significant advantages in the accuracy, sensitivity, and timeliness of marine water quality monitoring. It can greatly improve the accuracy of water quality parameter estimation and is an ideal tool for global, macroscopic marine environmental monitoring.

Recently, the "Xiamen Science and Technology No. 1" XIGUANG-003 satellite has been continuously observing the sea area near Fukushima, Japan, and transmitting clear image data in real time.Since late May, the "Xiamen Science and Technology No. 1" XIGUANG-003 satellite has conducted eight monitoring missions, acquiring a total of 24 images of the area surrounding Fukushima. The following images show the area around Fukushima taken on different dates:

▲Image of the sea off Fukushima on June 26

▲Image of the sea off Fukushima on July 17

▲Image of the sea off Fukushima on July 30

▲Image of the sea off Fukushima on August 3

In remote sensing image data, short-term nuclear contamination water discharge may cause some specific changes, especially in terms of water quality, water transparency, and water color.By interpreting and analyzing images, parameters such as ocean color and water transparency can be effectively obtained, providing data support for relevant departments such as marine environmental monitoring, and playing a significant role in marine ecological environment protection, planning, and sustainable development.

In terms of water color,Nuclear contaminants can alter the absorption and scattering properties of water bodies, causing changes in water color. These changes can be observed using the water color index in remote sensing images.

▲Water color index inversion map before drainage on August 22

▲Water color index inversion diagram after drainage on August 25

The water color index reflects the color and turbidity of a water body. An increase in the water color index means an increase in the concentration of suspended solids in the water body, which may be caused by silt, pollutants, etc. A decrease in the water color index indicates an increase in phytoplankton in the water body, which is related to an increase in nutrients in the water.As can be seen from the comparison charts above, after the drainage on August 25, the water color index near the drainage outlet changed significantly, showing a decreasing trend.

▲Water transparency inversion image before drainage on August 22

▲Water transparency inversion image after drainage on August 25

Regarding water transparency,Nuclear contamination may lead to an increase in the concentration of suspended solids, sediments, and particulate matter, making water bodies turbid and affecting their transparency. This change in turbidity can be monitored using the reflectance characteristics of remote sensing data.

Transparency data can be used to further analyze the health status and pollution levels of water bodies, facilitating appropriate measures by relevant departments. Water transparency inversion maps show a trend of lower transparency closer to the shore and higher transparency further away from the shore.As can be seen from the comparison charts above, after the drainage occurred on August 25, the transparency near the drainage outlet changed significantly, showing a decreasing trend.

With the development of science and technology, hyperspectral remote sensing has become a cutting-edge field in marine remote sensing. Using remote sensing inversion technology, water quality information such as suspended matter, organic particles, chlorophyll concentration, suspended sediment content, inorganic salts and chemical oxygen demand in the ocean can be extracted. It can also detect certain pollutants and surface water temperature, and obtain the spatiotemporal distribution of regional water quality in a large area in a fast and real-time manner, reflecting the main sources of pollutants.

Meanwhile, water quality remote sensing monitoring can also predict the flow trend of pollutants, meet the requirements of spatiotemporal monitoring of water quality in large-scale water areas, make up for the shortcomings of traditional water quality monitoring methods, seek more accurate inversion models for water quality remote sensing inversion of water bodies with different characteristics in different regions, and thus obtain accurate and frequent seawater quality observations, providing valuable information for understanding marine ecosystems and improving human activities.

Faced with critical nuclear safety issues, the Japanese government ignored strong doubts and opposition from the international community and unilaterally and forcibly initiated the discharge of contaminated water from the Fukushima nuclear accident into the sea, infringing upon the health, development, and environmental rights of people in all countries and violating its own moral responsibilities and obligations under international law.

As a domestic commercial aerospace company in my country,Xi'an Institute of Optics and Precision Mechanics CAS Aerospace Science and Technology Group Co.,LTD will resolutely respond to the national call, utilize remote sensing satellite monitoring methods to continuously track the pollution situation and subsequent trends, assess the potential impact of Fukushima nuclear contaminated water discharge into the sea on our marine radiation environment, and earnestly safeguard our national interests and people's health.