@article {holt_tropical_2023,
	title = {A Tropical Cocktail of Organic Matter Sources: Variability in Supraglacial and Glacier Outflow Dissolved Organic Matter Composition and Age Across the Ecuadorian Andes},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {128},
	number = {5},
	year = {2023},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JG007188},
	month = {05/2023},
	pages = {e2022JG007188},
	abstract = {The biogeochemistry of rapidly retreating Andean glaciers is poorly understood, and Ecuadorian glacier dissolved organic matter (DOM) composition is unknown. This study examined molecular composition and carbon isotopes of DOM from supraglacial and outflow streams (n = 5 and 14, respectively) across five ice capped volcanoes in Ecuador. Compositional metrics were paired with streamwater isotope analyses (δ18O) to assess if outflow DOM composition was associated with regional precipitation gradients and thus an atmospheric origin of glacier DOM. Ecuadorian glacier outflows exported ancient, biolabile dissolved organic carbon (DOC), and DOM contained a high relative abundance (RA) of aliphatic and peptide-like compounds (>=27\%RA). Outflows were consistently more depleted in Δ14C-DOC (i.e., older) compared to supraglacial streams (mean -195.2 and -61.3{\textperthousand} respectively), perhaps due to integration of spatially heterogenous and variably aged DOM pools across the supraglacial environment, or incorporation of aged subglacial OM as runoff was routed to the outflow. Across Ecuador, Δ14C-DOC enrichment was associated with decreased aromaticity of DOM, due to increased contributions of organic matter (OM) from microbial processes or atmospheric deposition of recently fixed and subsequently degraded OM (e.g., biomass burning byproducts). There was a regional gradient between glacier outflow DOM composition and streamwater δ18O, suggesting covariation between regional precipitation gradients and the DOM exported from glacier outflows. Ultimately, this highlights that atmospheric deposition may exert a control on glacier outflow DOM composition, suggesting regional air circulation patterns and precipitation sources in part determine the origins and quality of OM exported from glacier environments.},
	keywords = {cryosphere, dissolved organic carbon, Dissolved organic matter, Ecuador, FT-ICR MS, glaciers, δ13C-DOC, Δ14C-DOC},
	issn = {2169-8961},
	doi = {10.1029/2022JG007188},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JG007188},
	author = {Holt, Amy D. and Kellerman, Anne M. and Battin, Tom. I. and McKenna, Amy M. and Hood, Eran and Andino, Patricio and Crespo-P{\'e}rez, Ver{\'o}nica and Peter, Hannes and Sch{\"o}n, Martina and De Staercke, Vincent and Styllas, Michail and Tolosano, Matteo and Spencer, Robert G. M.}
}
@article {2460,
	title = {Seasonal variability of organic matter composition in an Alaskan glacier outflow: insights into glacier carbon sources},
	journal = {Environmental Research Letters},
	volume = {9},
	year = {2014},
	month = {Jan-05-2014},
	pages = {055005},
	abstract = {Glacier ecosystems are a significant source of bioavailable, yet ancient dissolved organic carbon
(DOC). Characterizing DOC in Mendenhall Glacier out flow (southeast Alaska) we document a
seasonal persistence to the radiocarbon-depleted signature of DOC, highlighting ancient DOC as
a ubiquitous feature of glacier out flow. We observed no systematic depletion in Δ14C-DOC with
increasing discharge during the melt season that would suggest mobilization of an aged subglacial carbon store. However, DOC concentration, δ13C-DOC,Δ14C-DOC and fluorescence signatures appear to have been in fluenced by runoff from vegetated hillslopes above the glacier during onset and senescence of melt. In the peak glacier melt period, the Δ 14 C-DOC of stream samples at the out flow (-181.7 to-355.3{\textperthousand}) was comparable to the Δ 14 C-DOC for snow samples from the accumulation zone (-207.2 to-390.9{\textperthousand}), suggesting that ancient DOC from the glacier surface is exported in glacier runoff. The pre-aged DOC in glacier snow and runoff is consistent with contributions from fossil fuel combustion sources similar to those documented previously in ice cores and thus provides evidence for anthropogenic perturbation of the carbon cycle. Overall, our results emphasize the need to further characterize DOC inputs to glacier ecosystems, particularly in light of predicted changes in glacier mass and runoff in the coming century.},
	keywords = {alaska, dissolved organic carbon, glacier, organic matter, radiocarbon},
	doi = {10.1088/1748-9326/9/5/055005},
	url = {http://iopscience.iop.org/article/10.1088/1748-9326/9/5/055005/meta},
	author = {Spencer, Robert G M and Vermilyea, Andrew and Fellman, Jason and Raymond, Peter and Stubbins, Aron and Scott, Durelle and Hood, Eran}
}
