- Environment, general 40
- Environmental Management 26
- Sustainable Development 26
- Environmental Engineering/Biotechnology 22
- Monitoring/Environmental Analysis 22
- Analytical Chemistry 20
- Pollution, general 19
- Environmental Policy 15
- Natural Resource and Energy Economics 9
- Ecology 7
- Environmental Economics 7
- Urban Ecology 7
- Applied Ecology 6
- Atoms and Molecules in Strong Fields, Laser Matter Interaction 6
- Electrical Engineering 6
- Industrial Chemistry/Chemical Engineering 6
- Plasma Physics 6
- Ecotoxicology 5
- Geoengineering, Foundations, Hydraulics 5
- Governance and Government 5