Marine Environment Monitoring Survey regarding the Great East Japan Earthquake - Results collected from 2011 to 2020 -

(September 28, 2021, Tokyo) The Ministry of the Environment, Japan (MOEJ), has been annually conducting Marine Environment Monitoring Surveys in response to the Great East Japan Earthquake since fiscal year 2011. The purpose of this survey is to understand the current status and evolution of marine pollution caused by chemical substances and waste discharged as a result of the earthquake and the radioactive substances released from the Fukushima Daiichi Nuclear Power Plant. MOEJ has compiled the results of the monitoring surveys conducted from FY 2011 to FY 2020, based on the consideration by the Committee for Marine Environment Monitoring Study regarding the Great East Japan Earthquake.

Survey results (FY 2011-FY 2020) revealed the following:

• General effects on the marine environment

The collected data shows no potential impacts to the environmental quality standards for the conservation of the living environment and for human health. Concentrations of polychlorinated biphenyls (PCBs) and dioxins have been continuously lower than the environmental quality standard or interim standards for sediment removal by more than one or more orders of magnitude since the start of the survey in FY 2011. In addition, the detected concentrations have generally remained stable or shown a decreasing trend over the years.

• Effects of fires

The concentration of dioxins has been continuously lower than the environmental quality standard by more than one or more orders of magnitude since the start of the survey in FY 2011. In addition, the detected concentrations have generally remained stable or shown a decreasing trend over the years.

• Effects of oil spills

  The concentrations of oil (hydrocarbons) in seawater were within the range of concentrations detected in existing surveys in Japan's major bay areas*¹, and generally remained stable or decreased over the years. As for polycyclic aromatic hydrocarbons (PAHs) in sediments, high concentrations were detected in some areas of the sea, which were caused by oil spills, but the concentrations in such areas tended to decrease over the years.

• Effects of building collapse and water runoff

  As for PCBs, concentrations have remained lower than the interim standards for sediment removal. In addition, the detected concentrations were generally stable. As for brominated flame retardants (PDBE, HBCD), the detected concentrations were higher in some areas compared to the average value of the national survey*², but in most areas the concentrations were similar or lower than the average value of the national survey*². Overall, measured concentrations generally remained stable or decreased over the years. In recent years, most of the sea areas were at the same level or lower than the average value from the national survey*². As for organofluorine compounds (PFOS, PFOA), some areas showed higher concentrations than the average value from the national survey*², but the concentrations were within the range of those detected in the national survey*². The concentrations were generally stable over the years.

• Effects of the nuclear power plant accident

  In the immediate aftermath of the disaster, higher concentrations of radioactive materials were detected due to the accident, but concentrations have been steadily decreasing over the years.

Outline of survey:

• Surveys:

  Seafloor sediment survey, seawater survey, and seafloor litter survey.

(Seawater survey was terminated in FY2016 and seafloor litter survey in FY2013.)

• Survey area:

  1km, 10km, and 20km off the coast of Aomori, Iwate, Miyagi, and Fukushima Prefectures.

  (The survey in Aomori Prefecture was terminated in FY 2014.)

• Surveyed substances:

  Environmental standard items, general items for bottom sediment, polychlorinated biphenyls, dioxins, hydrocarbons, polycyclic aromatic hydrocarbons, brominated flame retardants, organofluorine compounds, and radioactive materials (Cs-134, Cs-137, Sr-90).

The measurement of radioactive materials in this survey was conducted in accordance with the "Comprehensive Monitoring Plan" formulated by the Monitoring Coordination Council of the government.

*¹ Results of the Japan Coast Guard "Marine Pollution Survey" (2008 - 2018)

*² Results of MOEJ "Chemicals in the Environment" (FY2011 - FY2019)

Attachment (Japanese):

Marine Environment Monitoring Survey regarding the Great East Japan Earthquake

<FY 2011 - FY 2020>

https://www.env.go.jp/press/files/jp/116831.pdf

For Japanese