Dual isotope analyses indicate efficient processing of atmospheric nitrate by forested watersheds in the northeastern U.S.
Barnes, Rebecca T.
Raymond, Peter A.
Casciotti, Karen L.
MetadataShow full item record
Nitrogen from atmospheric deposition serves as the dominant source of new nitrogen to forested ecosystems in the northeastern U.S.. By combining isotopic data obtained using the denitrifier method, with chemistry and hydrology measurements we determined the relative importance of sources and control mechanisms on nitrate (NO3-) export from five forested watersheds in the Connecticut River watershed. Microbially produced NO3- was the dominant source (82-100%) of NO3- to the sampled streams as indicated by the δ15N and δ18O of NO3-. Seasonal variations in the δ18O-NO3- in streamwater are controlled by shifting hydrology and temperature affects on biotic processing, resulting in a relative increase in unprocessed NO3- export during winter months. Mass balance estimates find that the unprocessed atmospherically derived NO3- stream flux represents less than 3% of the atmospherically delivered wet NO3- flux to the region. This suggests that despite chronically elevated nitrogen deposition these forests are not nitrogen saturated and are retaining, removing, and reprocessing the vast majority of NO3- delivered to them throughout the year. These results confirm previous work within Northeastern U.S. forests and extend observations to watersheds not dominated by a snow-melt driven hydrology. In contrast to previous work, unprocessed atmospherically derived NO3- export is associated with the period of high recharge and low biotic activity as opposed to spring snowmelt and other large runoff events.
Author Posting. © Springer, 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Biogeochemistry 90 (2008): 15-27, doi:10.1007/s10533-008-9227-2.
Suggested CitationPreprint: Barnes, Rebecca T., Raymond, Peter A., Casciotti, Karen L., "Dual isotope analyses indicate efficient processing of atmospheric nitrate by forested watersheds in the northeastern U.S.", 2008-07-15, https://doi.org/10.1007/s10533-008-9227-2, https://hdl.handle.net/1912/2904
Showing items related by title, author, creator and subject.
Variability in the carbon isotopic composition of foliage carbon pools (soluble carbohydrates, waxes) and respiration fluxes in southeastern U.S. pine forests Mortazavi, Behzad; Conte, Maureen H.; Chanton, Jeffrey P.; Weber, John C.; Martin, Timothy A.; Cropper, Wendell P. (American Geophysical Union, 2012-04-19)We measured the δ13C of assimilated carbon (foliage organic matter (δCOM), soluble carbohydrates (δCSC), and waxes (δCW)) and respiratory carbon (foliage (δCFR), soil (δCSR) and ecosystem 13CO2 (δCER)) for two years at ...
The role of biological production in pleistocene atmospheric carbon dioxide variations and the nitrogen isotope dynamics of the southern ocean Sigman, Daniel M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-09)This dissertation contributes to the search for a cause of glacial/interglacial variations in atmospheric carbon dioxide. The hypotheses addressed involve changes in low and high-latitude biological export production. A ...
Andreu-Hayles, Laia; Ummenhofer, Caroline C.; Barriendos, Mariano; Schleser, Gerhard H.; Helle, Gerhard; Leuenberger, Markus; Gutierrez, Emilia; Cook, Edward R. (2016-11)Tree rings are natural archives that annually record distinct types of past climate variability depending on the parameters measured. Here, we use ring-width and stable isotopes in cellulose of trees from the northwestern ...