Document Type

Article

Journal/Book Title/Conference

Environmental Science & Technology

Volume

45

Publisher

American Chemical Society

Publication Date

2011

First Page

8804

Last Page

8810

Abstract

Although sediment is a natural constituent of rivers, excess loading to rivers and streams is a leading cause of impairment and biodiversity loss. Remedial actions require identification of the sources and mechanisms of sediment supply. This task is complicated by the scale and complexity of large watersheds as well as changes in climate and land use that alter the drivers of sediment supply. Previous studies in Lake Pepin, a natural lake on the Mississippi River, indicate that sediment supply to the lake has increased 10-fold over the past 150 years.Herein we combine geochemical fingerprinting and a suite of geomorphic change detection techniques with a sediment mass balance for a tributary watershed to demonstrate that, although the sediment loading remains very large, the dominant source of sediment has shifted from agricultural soil erosion to accelerated erosion of stream banks and bluffs, driven by increased river discharge. Such hydrologic amplification of natural erosion processes calls for a new approach to watershed sediment modeling that explicitly accounts for channel and floodplain dynamics that amplify or dampen landscape processes. Further, this finding illustrates a new challenge in remediating nonpoint sediment pollution and indicates that management efforts must expand from soil erosion to factors contributing to increased water runoff.

Comments

This is a manuscript. The published version may be found here: http://pubs.acs.org/doi/abs/10.1021/es2019109?mi=s7seqh&af=R&pageSize=20&publication=40025991&searchText=chloride Copyright is held by the publisher, and the publisher may require a subscription to access the published version.

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