Title

Nitrogen Deposition to Lakes in National Parks of the Western Great Lakes Region: Isotopic Signatures, Watershed Retention, and Algal Shifts

Authors

William O. Hobbs
Brenda Moraska Lafrancois
Robert Stottlemyer
David Toczydlowski
Daniel R. Engstrom
Mark B. Edlund
James E. Almendinger
Kristin E. Strock, Dickinson College
David VanderMeulen
Joan E. Elias
Jasmine E. Saros

Document Type

Article

Publication Date

3-19-2016

Department

Environmental Science

Language

English

Publication Title

Global Biogeochemical Cycles

Abstract

Atmospheric deposition is a primary source of reactive nitrogen (Nr) to undisturbed watersheds of the Great Lakes region of the U.S., raising concerns over whether enhanced delivery over recent decades has affected lake ecosystems. The National Atmospheric Deposition Program (NADP) has been measuring Nr deposition in this region for over 35 years. Here we explore the relationships among NADP-measured Nr deposition, nitrogen stable isotopes (δ¹⁵N) in lake sediments, and the response of algal communities in 28 lakes situated in national parks of the western Great Lakes region of the U.S. We find that 36% of the lakes preserve a sediment δ¹⁵N record that is statistically correlated with some form of Nr deposition (total dissolved inorganic N, nitrate, or ammonium). Furthermore, measured long-term (since 1982) nitrogen biogeochemistry and inferred critical nitrogen loads suggest that watershed nitrogen retention and climate strongly affect whether sediment δ¹⁵N is related to Nr deposition in lake sediment records. Measurements of algal change over the last ~ 150 years suggest that Nr deposition, in-lake nutrient cycling, and watershed inputs are important factors affecting diatom community composition, in addition to direct climatic effects on lake physical limnology. The findings suggest that bulk sediment δ¹⁵N does reflect Nr deposition in some instances. In addition, this study highlights the interactive effects of Nr deposition and climate variability.

Comments

This published version is made available on Dickinson Scholar with the permission of the publisher. For more information on the published version, visit AGU. Publication's Website.

©2016. American Geophysical Union. All Rights Reserved.

DOI

10.1002/2015GB005228

Recommended Citation

Hobbs, William O., Brenda Moraska Lafrancois, Robert Stottlemyer, David Toczydlowski, Daniel R. Engstrom, Mark B. Edlund, James E. Almedinger, Kristin E. Strock, David VanderMeulen, Joan E. Elias, and Jasmine E. Saros. "Nitrogen Deposition to Lakes in National Parks of the Western Great Lakes Region: Isotopic Signatures, Watershed Retention, and Algal Shifts." Global Biogeochemical Cycles 30, no. 3 (2016): 514-533. doi: 10.1002/2015GB005228