Mercury (Hg)
Heavy Metal · measured in mg/L
A heavy metal released by industrial and mining activity and atmospheric deposition, which can accumulate in water bodies and the food chain.
Common sources
Industrial discharge, legacy mining operations, and atmospheric deposition from coal combustion settling into lakes and streams.
Health risks
Inorganic mercury exposure is linked to kidney damage and neurological symptoms. Methylmercury — the organic form that bioaccumulates in fish — is especially harmful to fetal brain development; the EPA and FDA jointly issue fish consumption advisories for pregnant women for this reason.
Sources & further reading
- EPA — Mercury Study Report to Congress
- WHO — Mercury and Health Fact Sheet
How ClearDive rates severity
Readings are bucketed for map color-coding using thresholds referenced from EPA regulatory limits where available. This is a simplified public-awareness scale, not a substitute for certified lab analysis.
How to test for it
Field test kits are limited and mostly qualitative; certified lab analysis (cold vapor atomic absorption spectroscopy) is recommended for a reliable reading.