Date Approved

2022

Degree Type

Open Access Senior Honors Thesis

Department or School

Biology

First Advisor

Kristin Judd

Second Advisor

Aaron Liepman

Third Advisor

Anne Casper

Abstract

Dams and reservoirs are a significant source of Methane (CH4), a potent greenhouse gas, due to sediment and organic matter trapping, decomposition, and subsequent anoxia. Most measurements to assess methane production from dams are on large tropical impoundments and reservoirs, with few studies on methane emissions from small, midlatitude impoundments. These small impoundments make up most dams around the world and are underrepresented in the literature. Here, we evaluated methane from low-head dams on a midlatitude river in southeast Michigan. We measured emissions from impoundment and free-flowing sections using static floating chambers and dissolved methane along a longitudinal transect that included free-flowing and impoundment sites. Our findings suggest that emissions were around 23 – 72 times greater in the impoundment compared to the free-flowing river. Further, we found that aquatic vegetation is likely the most important pathway for methane release, with emissions around 8 – 27 times greater compared to other areas of the impoundment. These results suggest that small dams may be a significant source of methane, with summer emission rates around 374 mg C-CH4 m-2 d-1.

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