- Ecotoxicology 8
- Environmental Chemistry 7
- Environmental Health 7
- Atmospheric Protection/Air Quality Control/Air Pollution 5
- Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution 5
- Environment, general 4
- Monitoring/Environmental Analysis 3
- Pollution, general 3
- Soil Science & Conservation 3
- Ecology 1
- Environmental Management 1