Osburn Christopher L.

No Thumbnail Available
Last Name
Osburn
First Name
Christopher L.
ORCID

Filters

2011 - 2020 2
2
2
Reset filters

Settings

Search Results

Now showing 1 - 2 of 2
  • Article
    Representing the function and sensitivity of coastal interfaces in earth system models
    (Nature Research, 2020-05-18) Ward, Nicholas D. ; Megonigal, J. Patrick ; Bond-Lamberty, Benjamin ; Bailey, Vanessa L. ; Butman, David ; Canuel, Elizabeth A. ; Diefenderfer, Heida ; Ganju, Neil K. ; Goni, Miguel ; Graham, Emily B. ; Hopkinson, Charles S. ; Khangaonkar, Tarang ; Langley, J. Adam ; McDowell, Nate G. ; Myers-Pigg, Allison N. ; Neumann, Rebecca B. ; Osburn, Christopher L. ; Price, René M. ; Rowland, Joel ; Sengupta, Aditi ; Simard, Marc ; Thornton, Peter E. ; Tzortziou, Maria ; Vargas, Rodrigo ; Weisenhorn, Pamela B. ; Windham-Myers, Lisamarie
    Between the land and ocean, diverse coastal ecosystems transform, store, and transport material. Across these interfaces, the dynamic exchange of energy and matter is driven by hydrological and hydrodynamic processes such as river and groundwater discharge, tides, waves, and storms. These dynamics regulate ecosystem functions and Earth’s climate, yet global models lack representation of coastal processes and related feedbacks, impeding their predictions of coastal and global responses to change. Here, we assess existing coastal monitoring networks and regional models, existing challenges in these efforts, and recommend a path towards development of global models that more robustly reflect the coastal interface.
  • Article
    Multiple tracers demonstrate distinct sources of dissolved organic matter to lakes of the Mackenzie Delta, western Canadian Arctic
    (Association for the Sciences of Limnology and Oceanography, 2011-07) Tank, Suzanne E. ; Lesack, Lance F. W. ; Gareis, Jolie A. L. ; Osburn, Christopher L. ; Hesslein, Ray H.
    Lakes of the Mackenzie Delta occur across a gradient that contains three clear end members: those that remain connected to river-water channels throughout the summer; those that receive only brief inputs of river water during an annual spring flood but contain dense macrophyte stands; and those that experience significant permafrost thaw along their margins. We measured dissolved organic carbon (DOC) concentration, dissolved organic matter (DOM) absorption and fluorescence, and stable isotopes of DOM, DOM precursor materials, and bacteria to elucidate the importance of river water, macrophytes, and thermokarst as DOM sources to Mackenzie Delta lakes. Despite standing stocks of macrophyte C that are sevenfold to 12-fold greater than those of total DOC, stable isotopes indicated that autochthonous sources contributed less than 15% to overall DOM in macrophyte-rich lakes. Instead, fluorescence and absorption indicated that the moderate summertime increase in DOC concentration in macrophyte-rich lakes was the result of infrequent flushing, while bacterial δ13C indicated rapid bacterial removal of autochthonous DOC from the water column. In thermokarst lakes, summertime increases in DOC concentration were substantial, and stable isotopes indicated that much of this increase came from C released as a result of thermokarst-related processes. Our results indicate that these distinct sources of DOM to neighboring arctic Delta lakes may drive between-lake differences in C cycling and energy flow. Rapidly assimilated macrophyte DOM should be an important contributor to microbial food webs in our study lakes. In contrast, the accumulation of thermokarst-origin DOM allows for a significant role in physico-chemistry but indicates a lesser contribution of this DOM to higher trophic levels.