Here you have some useful links for your investigations on Environmental Issues.
¡Use them!
The Ecology of Overpopulation
http://www.paulchefurka.ca/Population%20and%20Food%20Production.html
Articles on Environmental Issues ()
http://www.humboldt.org.co/chmcolombia/servicios/jsp/noticias/noticias.jsp?desde=0&hasta=5&jsp=noticias.jsp
Ozone Layer Depletion
http://www.buzzle.com/articles/ozone-layer-depletion-effects-and-causes-of-ozone-depletion.html
Pollution and Waste
http://www.ec.gc.ca/education/default.asp?lang=En&n=6072A21C-1
Environmental Decay
http://www.pcresearch.org/climate-change.html
I will keep adding more to cover all of the topics you are working with!
Have fun!