- Environment, general 41
- Ecotoxicology 23
- Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution 20
- Atmospheric Protection/Air Quality Control/Air Pollution 19
- Environmental Chemistry 19
- Environmental Health 18
- Earth Sciences, general 8
- Engineering, general 5
- Soil Science & Conservation 5
- Chemistry/Food Science, general 4
- Ecology 4
- Environmental Physics 3
- Geography, general 3
- Physics, general 3
- Pollution, general 3
- Sustainable Development 3
- Agriculture 2
- Climate Change 2
- Environmental Science and Engineering 2
- Natural Hazards 2