State Water Resources Research Institute Program

Project ID: 2008VT34B
Title: Tracing sources of eroded sediment with atmospherically produced 10-Be
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2009
Congressional District: First
Focus Categories: Sediments, Geomorphological Processes
Keywords: sediments, fluvial geomorphology, erosion
Principal Investigators: Dewoolkar, Mandar M. ; Bierman, Paul
Federal Funds: $ 23,738
Non-Federal Matching Funds: $ 68,440
Abstract: A growing concern over the past few decades in the Lake Champlain region is the eutrophication of Lake Champlain which may trigger increasing amounts of algae and potentially toxic cyanobacteria while disturbing the ecosystem balance of the Lake. High phosphorus levels in the Lake are held responsible for this occurrence. With over 7,000 miles of streams and rivers feeding the Lake, significant amounts of nutrient-bearing sediments are discharged each year. High phosphorus levels allow the algae to flourish because it is often the limiting nutrient for growth. Similar concerns exist in other regions. In order to mitigate the problem, one needs to get to the roots of it; yet, the source of nutrient-enriched sediment entering Lake Champlain is poorly constrained. Understanding where sediment and its particle-associated nutrients come from is critical for informed and effective land and water management.

We propose a proof-of-concept study, in essence a test case, to determine whether the rare isotope, Beryllium-10 (10-Be), can be used to fingerprint the source of fine-grain, particle reactive sediment transported by the Winooski River and deposited in Lake Champlain. In order to test the efficacy of 10-Be for tracing the source of sediment entering the Lake Champlain Basin, we propose to collect and process a number of samples of sediment from a suite of geomorphic/human impact settings as well as from spring snow-melt flows during which the bulk of sediment transport occurs. We will focus on the Winooski Basin as it is large, well-characterized, and amenable to event-based sampling. The proposed distribution of samples is designed to allow us to estimate both the mean and spatial/temporal variability of 10-Be concentration in fine grain sediment.

The primary benefit of the proposed research will be the first-ever application of atmospherically produced 10-Be as a tracer of sediment sourcing and movement in the glaciated Northeast. It is anticipated that once tested, the proposed approach can be extended to include additional watersheds leading to basin-scale generalized conclusions, getting at the broader root-level questions - from where is nutrient-enriched sediment coming. This will eventually allow managers to identify where and when nutrient-loaded sediment is delivered to the channel; thus, there exists the possible benefit of directly targeting for remediation areas contributing the most substantial nutrient load, a cost effective strategy. Graduate student research training is another substantial benefit of the project we propose; particularly valuable will be the cross-disciplinary training of an engineering MS student in cutting-edge geochemical laboratory and analysis methods.

Progress/Completion Report, PDF

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