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Grantee Research Project Results

The Role of Human-made Impoundments and Watershed Land Use on Carbon Cycling and Sequestration at Local and Regional Scales

EPA Grant Number: FP916938
Title: The Role of Human-made Impoundments and Watershed Land Use on Carbon Cycling and Sequestration at Local and Regional Scales
Investigators: Knoll, Lesley Beth
Institution: Miami University
EPA Project Officer: Just, Theodore J.
Project Period: September 1, 2008 through September 1, 2011
RFA: STAR Graduate Fellowships (2008)
Research Category: Academic Fellowships

Description:

Objective:

To date, most carbon sequestration studies have focused on carbon cycling in soils, forests, and the ocean, while freshwater systems (e.g. lakes, rivers, wetlands, human-made impoundments) have until recently been ignored. The Midwest US landscape is dominated by impoundments, many of which are located in degraded areas such as those characterized by intensive agricultural activities. Impoundments in agricultural landscapes often receive larger quantities of sediments and nutrients than those in forested landscapes, and are generally more productive. Thus, the degree of terrestrial organic carbon subsidy likely depends on watershed land use, and it is not surprising that some have suggested that landscape features (including watershed land use) may play a role in determining if a water body is a carbon source or sink. Despite the potential importance of impoundments, no studies have examined the fate of carbon in impoundments and how the fate may vary as a function of watershed land use. The overall objective of the proposed research is to test the hypothesis that human-made impoundments are a significant sink for carbon and that the magnitude of the sink is influenced by watershed land use.

Approach:

This research will be conducted using two field studies in Ohio. The first study will determine the percentage of incoming carbon that gets buried in impoundment sediments versus emitted as CO2 by utilizing two impoundments that differ in watershed land use and trophic state (productivity). I will quantify the percentage of incoming particulate carbon that gets buried in impoundment sediments, and also assess carbon cycling in impoundments by determining the relative importance of carbon loss through burial in sediments, atmospheric flux, and export from the outflow. For the second study, I will determine if the magnitude of carbon burial in impoundments can be predicted from watershed land use. To accomplish this, I will identify 30 impoundments that differ in land use and then quantify carbon burial in the sediments.

Expected Results:

Results from my research will provide a framework for understanding the importance of impoundments in sequestering carbon and the influence of watershed land use. Although impoundments are potentially significant sinks of terrestrially-derived carbon, very little is known about the magnitude of these sinks. Because impoundments reside in watersheds that vary greatly in land use, information on how carbon inputs and sequestration vary with land use is essential for us to quantify the regional and global roles of impoundments in the C cycle. My proposed research will answer the following basic, yet crucial questions: 1) Are impoundments carbon sinks?; 2) How does watershed land use mediate the input and fate of C in impoundments?; and 3) Can the amount of carbon sequestered in an impoundment be predicted by watershed land use?

Supplemental Keywords:

carbon, sequestration, impoundments, land use, carbon cycling,

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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