Find what rots and what does not. Put measured discs of leaves or other known materials in bags of different mesh size in soil and record the changes over time. This will establish the role of different-sized organisms in the decomposition of materials Data on the bioaccumulation of DDT, DDE and other organo-chlorines at different trophic levels in food chains (like those featuring fish, herons, ospreys or sparrowhawks) are in most standard texts. Use them to reinforce the information in the article about the long-term effects and difficult dilemmas associated with the use of synthetic chemicals in the environment.
Lead is just one of the heavy metals that affect animals and plants.
Research the effects of others, such as mercury (at Minimata and Nigata in 1950s Japan), copper and zinc (in drainage water and spoil heaps of mines) and cadmium (linked to smelters) as part of a pollution topic.
Investigate the efficiency of different pest-control measures on populations of common pests like greenfly. Try soap solution, Bordeaux mixture and salt solution as well as chemical sprays. Study the labels on pesticide sprays available from garden centres and compare them with the chemicals named in the article.