- Environment, general 48
- Ecology 42
- Science, Humanities and Social Sciences, multidisciplinary 36
- Science, multidisciplinary 28
- Plant Sciences 25
- Environmental Management 24
- Environmental Chemistry 23
- Atmospheric Protection/Air Quality Control/Air Pollution 18
- Atmospheric Sciences 18
- Plant Physiology 18
- Environmental Health 16
- Freshwater & Marine Ecology 16
- Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution 16
- Characterization and Evaluation of Materials 15
- Ecotoxicology 14
- Environmental Engineering/Biotechnology 14
- Biotechnology 13
- Engineering, general 12
- Industrial Chemistry/Chemical Engineering 12
- Materials Science, general 12