Across
- 3. air in cities that is polluted by toxic gases
- 5. water in soil
- 6. an area at the river mouth where the main river divides into many small rivers
- 7. an underground water-bearing layer
Down
- 1. water on the surface of the Earth
- 2. The entire area that drains into the principal river system
- 4. the top pf the groundwater