How do methylmercury levels increase from new hydroelectric developments?
- If a hydroelectric development creates a new or enlarged reservoir through flooding, the production of methylmercury may increase
- This occurs as flooded vegetation in the new reservoir decomposes, stimulating the conversion of existing inorganic mercury into methylmercury by bacteria. (Figure 1)
- Methylmercury can then start to build up in the food chain.
- The percentage of new flooding compared to the total reservoir area is an important factor in determining the extent to which methylmercury concentrations may increase.
- Wetland areas are known to be a greater source of methylmercury thanupland areas.