Understanding the Nitrogen Cycle and Using Design Thinking to Reduce the "Dead Zone"

My mentor, Negin Ashoori, PhD, from the Luthy Group in the Civil and Environmental Engineering department at Stanford University, researches the removal of pollutants from stormwater passed through different media, such as wood-chips, sand, and biochar, identifying the various types of bacteria that carry out microbial remediation to improve the management of stormwater runoff. From this research, the Luthy Group helps to develop stormwater treatment regimes that can include buffer zones around drains and plant habitats for the phytoremediation of the toxins in stormwater runoff near recharge ponds. The biogeochemistry of nitrogen, which is taught in high school in the nitrogen cycle, is almost entirely dependent on the reduction-oxidation (redox) reactions primarily mediated by microorganisms. Understanding the nitrogen cycle is a challenging concept for most high school students. Yet, because of the nitrogen cycle’s relevance to air, water and soil quality, it is often considered one of most important nutrient cycles. Nitrogen is essential for the synthesis of nucleic acids and proteins— two important macromolecule polymers of life. The world’s population has more than doubled in the last 50 years and the Green Revolution of growing more food for the additional 3.5 billion people to be fed has lead to delivering more nitrogen and phosphorous compounds via fertilizers to agricultural fields. This move from nitrogen-limited agriculture and landscaping to nitrogen excess has had profound effects on our environment, especially water quality. Eutrophication, for instance, is caused when nitrogen and other nutrient compounds of the fertilizers are washed from the field when it rains after they have been applied. The nutrients  are transported from the field to nearby waterways and leads to several negative impacts on the affected ecosystem, and is often a direct result of nitrogen loading from agriculture and landscaping. This ETP is a series of student activities utilizing NGSS Crosscutting Concepts and Science and Engineering Practices to help students engage in a deeper understanding of the nitrogen cycle, its relevance to sustaining life, as well as the threat unlimited nitrogen loading poses to aquatic, terrestrial, and atmospheric ecosystems.  Innovating methods to reduce fertilizer runoff often use many of the same means to promote, contain, and control microbial action that the Luthy group employs to deal with stormwater runoff. Engaging students in evidence, data, argument, models, systems, as well as having them come at the nitrogen cycle from the perspectives of structure and function, scale and proportion, cause and effect, energy and matter promises to help them gain a deeper understanding of the nitrogen cycle and a greater realization of the challenges and means available for feeding an ever expanding human population without the complete destruction of the natural environment.