What is Environmental Chemistry

I just need a quick sum-up of Environmental chemistry for my science homework. Can anyone help me here?

Think of the causes, effects and control of the following forms of environmental polution:
Air pollution, water pollution, land pollution. Remember to add solid waste disopsal, waste water treatment and management. Add things like acid rain in cosequences of air pollution. Remember some current environmental issues like global warming, the green house effects. Dessertification and the melting of polar ice.etec