Lakes and ponds play a disproportionate role in removing sediment, carbon, nitrogen, and phosphorus from their global cycles, thereby mitigating potential negative environmental effects such as global climate change and harmful algal blooms. However, how sequestration rates change over a pond’s lifetime, and how rates are affected by conservation tillage practices in their watershed remain poorly characterized. In this study we attempt to address these questions by quantifying sediment, carbon, nitrogen, and phosphorus burial rates along with ecosystem services in three ponds between 19-25 years of age (as of 2019), and whose watersheds experienced a dramatic shift to conservation tillage. We found that sediment burial rates decreased over time within these ponds, which is consistent with the reduced soil erosion rates associated with conservation tillage. However, patterns in carbon, nitrogen, and phosphorus burial rates were not as clear; slightly fewer than half of the elemental burial rates we quantified actually increased over time. We suggest that this may be due to increased importance of in-pond processes, such in situ photosynthesis and subsequent sedimentation of this matter, as the ponds age. Finally, using the social cost of carbon and nitrogen, the cost of removal of phosphorus, and the cost of damages from flooding and resulting sedimentation, we approximate that these three ponds have saved approximately 1.7 million US dollars over their lifetimes through burial of sediment, carbon, nitrogen, and phosphorus. This research is not only relevant to limnology (the study of inland aquatic ecosystems), but also to my intended career as a researching professor of analytical chemistry, with a focus on addressing environmental issues.
Author: Martina Rogers
Faculty Advisor: Michael Vanni, Biology
Graduate Student Advisor: Tanner Williamson, Biology
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