 mercury in foodwebs in the introductory unit we introduced students to mercury they learned that it is toxic and they should also have at least a rough idea of the kinds of quantities that we might expect to find in human hair and in fish they should also have a general familiarity with the way that mercury in its different forms moves through the environment more specifically they should think about how it moves through their study site and organisms students using the activities in this unit will diagram the mercury cycle  as it pertains to their research site and can develop a general understanding of toxicology and can play the food chain game   mercury in watersheds background  