SUMMARY: Reduction and oxidation reactions are the drivers behind many biological processes. Energy is both stored and transferred through these reactions. This article talks about the various redox reactions that can occur, both biotically and abiotically, and how that affects both biogeochemical cycles and contaminants. The first section talks about the cycling of carbon, nitrogen, phosphorus, and the effects that metals such as iron and manganese have on these cycles (either in how bacteria use these transition metals in their cells or how these metals can disrupt cycles). The second section talks about metals that are considered to be pollutants and how they are absorbed, run off, or precipitate. This has an effect on both microorganisms and reactive enzymes/metals. Uranium and other radioactive elements that leach into the ground are also discussed. Finally, the last section talks about the impacts that organic pollutants can have on biogeochemical cycles. The last paragraph talks about how climate change could impact all these reactions due to increasing thermal energy available in the environment as well as an increase in floods and precipitation (leading to more run off and interactions with water).
LESSON COMMENTS: A great article for both chemistry, biology, and environmental science. It’s not often that there is an article that can span three classes, requiring students to master foundational topics in order to understand the paper. Topics covered include: redox reactions, photophosphorylation, electron transport chain, aerobic, anaerobic respiration, solubility, and biogeochemical cycles.
Borch, T., Kretzschmar, R., Kappler, A., Cappellen, P. V., Ginder-Vogel, M., Voegelin, A., & Campbell, K. (2010). Biogeochemical Redox Processes and their Impact on Contaminant Dynamics. Environmental Science & Technology,44(1), 15-23. doi:10.1021/es9026248