4. In areas with high concentrations of tourist activities and attractive natural attractions, waste ___ is a serious problem. ( dispose)
5. Unlike pesticides, ___ are not directly toxic but their presence in freshwater changes the nutrient system. (fertilize)
6. ____ caused by deforestation can also lead to increased flooding.( erode)
4. In areas with high concentrations of tourist activities and attractive natural attractions, waste _disposal__ is a serious problem. ( dispose)
5. Unlike pesticides, _fertilizers__ are not directly toxic but their presence in freshwater changes the nutrient system. (fertilize)
6. __Erosion__ caused by deforestation can also lead to increased flooding.( erode)