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SFS Annual Meeting

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LOW BIOREACTIVITY OF DISSOLVED ORGANIC CARBON FROM STREAM FLOCCULENT ORGANIC MATTER

Dissolved organic carbon (DOC) controls energy transfer, biogeochemical cycling, and water quality in surface and subsurface waters. Flocculent organic matter (floc) that accumulates in stream environments is a potentially important source of organic carbon to aquatic ecosystems. The role of floc in stream biogeochemistry is presently unknown, but its ubiquitous presence in streams indicates it may be important. To test the relative bioreactivity of floc, we ran a series of laboratory batch reactor and field-based push-pull experiments. The batch reactor experiments isolated potential locations of floc decomposition (e.g. stream water, sediment) as compared to a control medium of ultrapure water. Also, nutrient (N and P) additions were made in parallel batch reactor experiments to test the effect of nutrient priming on floc reactivity. The push-pull experiments were conducted in a lowland Michigan stream to assess the degradation of floc leachate injected into sediments. Overall, the floc DOC showed little degradation over time across all experiments, revealing its low relative bioreactivity qualities under multiple controlled and field conditions. This suggests that floc accumulation and ubiquity in shallow aquatic environments may be a function of its low bioreactivity.

Rachel Geiger (Primary Presenter/Author), Western Washington University, omstijsn@gmail.com;


Jay Zarnetske (Co-Presenter/Co-Author), Department of Earth and Environmental Sciences, Michigan State University, USA, jpz@msu.edu;


Joseph Lee-Cullin (Co-Presenter/Co-Author), Department of Earth and Environmental Sciences, Michigan State University, USA, cullinjo@msu.edu;


Tyler Hampton (Co-Presenter/Co-Author), Department of Earth and Environmental Sciences, Michigan State University, USA, thampton@msu.edu;