- Environment, general 16
- Atmospheric Protection/Air Quality Control/Air Pollution 6
- Ecotoxicology 6
- Environmental Chemistry 6
- Environmental Health 6
- Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution 6
- Environmental Engineering/Biotechnology 3
- Waste Management/Waste Technology 3
- Engineering, general 2
- Industrial Pollution Prevention 2
- Renewable and Green Energy 2
- Environmental Science and Engineering 1
- Nanotechnology and Microengineering 1