- Atmospheric Protection/Air Quality Control/Air Pollution 7
- Hydrogeology 6
- Freshwater & Marine Ecology 4
- Climate Change 3
- Climate Change/Climate Change Impacts 3
- Environment, general 3
- Soil Science & Conservation 3
- Ecology 2
- Geology 2
- Paleontology 2
- Physical Geography 2
- Science, Humanities and Social Sciences, multidisciplinary 2
- Science, multidisciplinary 2
- Sedimentology 2
- Water Quality/Water Pollution 2
- Atmospheric Sciences 1
- Biochemistry, general 1
- Environmental Science and Engineering 1
- Geochemistry 1
- Zoology 1