Shadows Underground: Hamamatsu's Story of Contamination and Regeneration.

Shadows Underground: Hamamatsu's Story of Contamination and Regeneration.

1. 2006: Past cases of groundwater contamination
In Hamamatsu City, 10 cases of groundwater contamination were confirmed as of FY2006. The causes include volatile organic compounds (chemical substances that easily evaporate in the air, e.g., cleaning agents and solvents). Examples include trichloroethylene used as a cleaning agent or solvent) and heavy metals (lead, cadmium, and other metals harmful to the environment and human health). Improper disposal and underground seepage of wastewater are major contributors.

2. 2023: Underground water monitoring survey
Twenty-six items were measured at 12 sites in the city, all of which achieved environmental standards. However, trichloroethylene (a solvent used in industrial applications, with long-term exposure posing a health risk) and tetrachloroethylene (a volatile organic compound used as a cleaning agent) were detected at some monitoring sites in excess of the standards.

3. July 2024: Detection of Nitrate-Nitrogen and Nitrite-Nitrogen
In the July 2024 survey, nitrate nitrogen and nitrite nitrogen exceeded the standard value (10 mg/L) at 6 of the 31 sites. Nitrate nitrogen is a component of fertilizers and can contaminate groundwater through excessive use or infiltration. These are particularly problematic in areas with high agricultural activity.

4. PFAS Contamination: Around Air Self-Defense Force Hamamatsu Air Base
In the vicinity of the Air Self-Defense Force Hamamatsu Air Base, PFAS (organic fluorine compounds, also known as "PFAS") have been found in the air. It has water and heat repellency and is used in industrial products and fire extinguishing agents) has been detected in excess of provisional guideline values. This substance is difficult to decompose in the environment and is also referred to as a "permanent chemical substance. Investigations and responses are underway in contaminated areas.

5. measures taken by Hamamatsu City and hope for the future
Hamamatsu City has implemented the following measures in response to groundwater contamination caused by illegal dumping:
- Identification of the source of contamination and cleanup work
- Increased monitoring of waste disposal companies
- Fines for illegal dumpers
- Introduction of groundwater monitoring system

These efforts have received widespread attention as a response to the nationwide groundwater contamination problem and have served as an opportunity to reaffirm the importance of legal regulations and monitoring systems.

Sources:.
- Hamamatsu City Groundwater Environmental Monitoring
- Hamamatsu City Survey of Nitrate-Nitrogen and Nitrite-Nitrogen
- Shizuoka Shimbun News PFAS issue
- Recent arrests and other cases in Hamamatsu City
- Groundwater salinization survey results