@article {2888,
	title = {Decreased sedimentation efficiency of petro- and non-petro-carbon caused by a dispersant for Macondo surrogate oil in a mesocosm simulating a coastal microbial community},
	journal = {Marine Chemistry},
	volume = {206},
	year = {2018},
	month = {Jan-10-2018},
	pages = {34 - 43},
	abstract = {Large amounts of mucous-rich oil-containing marine snow formed in surface waters adjacent to the Deepwater Horizon spill. This marine oil snow (MOS) was implicated in oil delivery to the seafloor. Whether the use of chemical dispersants increased or decreased MOS sedimentation remains controversial. We conducted mesocosm experiments testing the effects of oil and oil plus a dispersant on MOS formation and sedimentation, in coastal seawater. The four treatments used were a surrogate Macondo oil water accommodated fraction ({\textquotedblleft}WAF{\textquotedblright}), two concentrations of chemically-enhanced WAF ({\textquotedblleft}CEWAF{\textquotedblright} and diluted CEWAF, {\textquotedblleft}DCEWAF{\textquotedblright}) containing a dispersant and oil, and Controls (no additions). Based on radiocarbon and 13C NMR results, the presence of dispersants enhanced the amounts of petro-carbon being incorporated into the sinking oil-carrying aggregates (aka MOS). However, most of the chemically-dispersed oil preferentially partitioned into the colloidal and suspended particulate fractions rather than into the rapidly forming MOS. Thus the oil and non-petro-carbon sedimentation efficiency in treatments with a dispersant was much lower, compared to those in the Control and WAF treatments, during the four-day mesocosm experiment. Formation of MOS and its subsequent sinking sequestered the oil in two stages: first via terrestrial-derived detritus containing humic compounds, and subsequently via freshly produced material, such as exopolymeric substances produced by phytoplankton and bacteria.},
	issn = {03044203},
	doi = {10.1016/j.marchem.2018.09.002},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0304420318301415},
	author = {Xu, Chen and Zhang, Saijin and Beaver, Morgan and Wozniak, Andrew and Obeid, Wassim and Lin, Youmin and Wade, Terry L. and Schwehr, Kathleen A. and Lin, Peng and Sun, Luni and Hatcher, Patrick G. and Chin, Wei-Chun and Chiu, Meng-Hsuen and Knap, Anthony H. and Dean, Kendra and Quigg, Antonietta and Santschi, Peter H.}
}
@article {72,
	title = {An investigation of size-fractionated organic matter from Lake Superior and a tributary stream using radiocarbon, stable isotopes and NMR},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {127},
	year = {2014},
	pages = {264-284},
	abstract = {This study investigated the concentration and isotopic composition of different size fractions of organic matter (OM) in Lake Superior and in one of its many tributary streams and rivers (Amity Creek, Duluth, Minnesota, USA). Structural compositional drivers of the Δ14C of high molecular weight (HMW, >1 kDa) dissolved organic carbon (DOC) in the lake were also evaluated. Low molecular weight (LMW, 0.7 μm) was generally 13C-depleted (-29 {\textpm} 1.2{\textperthousand}) relative to {\textquotedblleft}bulk{\textquotedblright} (<0.7 μm) DOC (-26.4 {\textpm} 0.7{\textperthousand}), {\textquotedblleft}init{\textquotedblright} (<0.2 μm) DOC (-26.6 {\textpm} 0.8{\textperthousand}), HMW DOC (-26.9 {\textpm} 0.3{\textperthousand}) and LMW DOC (-26.5 {\textpm} 0.9{\textperthousand}), and had more variable 14C content (Δ14C of -94{\textperthousand} to 53{\textperthousand}; 735 years BP to modern) than the other size fractions. Init DOC (Δ14C of 17{\textendash}59{\textperthousand}), HMW DOC (Δ14C of 23{\textendash}64{\textperthousand}) and LMW DOC (Δ14C of 16{\textendash}62{\textperthousand}) all reflected contemporary (modern) radiocarbon signatures. Bulk DOC (Δ14C of -19{\textperthousand} to 57{\textperthousand}; 90 years BP to modern) had modern radiocarbon values in the offshore sites (Δ14C of 2{\textendash}57{\textperthousand}) with pre-aged samples (Δ14C of -8{\textperthousand} to -19{\textperthousand}) seen at the nearshore site. HMW DOM was relatively N-poor (C:N of 12{\textendash}19) compared to particulate organic matter (POM, C:N of 8{\textendash}10) revealing either a more diagenetically altered state or contrasting sources. 13C NMR data showed that biochemical composition of HMW DOC in Lake Superior was dominated by carbohydrates (53{\textendash}65\%) with only trace aromatic components (2{\textendash}4\%). Structurally complex components such as heteropolysaccharides (HPS), amide/peptides and amino sugars (AMS) constitute 75{\textendash}84\% of HMW DOC whereas carboxylic-rich alicyclic molecules (CRAM) made up 16{\textendash}25\% of HMW DOC in the lake. Combined HPS and AMS, O-alkyl carbohydrate carbon, and total carbohydrate carbon contents were significantly positively correlated to the Δ14C of HMW DOC suggesting they contribute a contemporary 14C-enriched component to the HMW DOC in the lake. In contrast, CRAM and aliphatic carbons were significantly inversely correlated with Δ14C of HMW DOC implying that these represent 14C-depleted (older) components of HMW DOC in the lake. At Amity Creek, storm events led to larger loads of bulk DOC and POC, which were both 14C-enriched (modern). However, in baseflow conditions 14C-depleted bulk DOC and POC were exported. LMW DOC from the creek was considerably 14C-depleted compared to concurrent HMW DOC.},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2013.11.037},
	url = {http://www.sciencedirect.com/science/article/pii/S0016703713006765},
	author = {Zigah, Prosper K. and Minor, Elizabeth C. and Abdulla, Hussain A. N. and Werne, Josef P. and Hatcher, Patrick G.}
}
@article {2663,
	title = {An investigation of size-fractionated organic matter from Lake Superior and a tributary stream using radiocarbon, stable isotopes and NMR},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {127},
	year = {2014},
	month = {Jan-02-2014},
	pages = {264 - 284},
	issn = {00167037},
	doi = {10.1016/j.gca.2013.11.037},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0016703713006765https://api.elsevier.com/content/article/PII:S0016703713006765?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0016703713006765?httpAccept=text/plain},
	author = {Zigah, Prosper K. and Minor, Elizabeth C. and Abdulla, Hussain A.N. and Werne, Josef P. and Hatcher, Patrick G.}
}
@article {2458,
	title = {Anthropogenic aerosols as a source of ancient dissolved organic matter in glaciers},
	journal = {Nature Geoscience},
	volume = {5},
	year = {2012},
	month = {Jul-02-2013},
	pages = {198 - 201},
	abstract = {Glacier-derived dissolved organic matter represents a quantitatively significant source of ancient, yet highly bioavailable carbon to downstream ecosystems1. This finding runs counter to logical perceptions of age{\textendash}reactivity relationships, in which the least reactive material withstands degradation the longest and is therefore the oldest2. The remnants of ancient peatlands and forests overrun by glaciers have been invoked as the source of this organic matter1, 3, 4. Here, we examine the radiocarbon age and chemical composition of dissolved organic matter in snow, glacier surface water, ice and glacier outflow samples from Alaska to determine the origin of the organic matter. Low levels of compounds derived from vascular plants indicate that the organic matter does not originate from forests or peatlands. Instead, we show that the organic matter on the surface of the glaciers is radiocarbon depleted, consistent with an anthropogenic aerosol source. Fluorescence spectrophotometry measurements reveal the presence of protein-like compounds of microbial or aerosol origin. In addition, ultrahigh-resolution mass spectrometry measurements document the presence of combustion products found in anthropogenic aerosols. Based on the presence of these compounds, we suggest that aerosols derived from fossil fuel burning are a source of pre-aged organic matter to glacier surfaces. Furthermore, we show that the molecular signature of the organic matter is conserved in snow, glacier water and outflow, suggesting that the anthropogenic carbon is exported relatively unchanged in glacier outflows.},
	keywords = {Atmospheric chemistry, Biogeochemistry, Cryospheric science},
	issn = {1752-0894},
	doi = {10.1038/ngeo1403},
	url = {http://www.nature.com/doifinder/10.1038/ngeo1403},
	author = {Stubbins, Aron and Hood, Eran and Raymond, Peter A. and Aiken, George R. and Sleighter, Rachel L. and Hernes, Peter J. and Butman, David and Hatcher, Patrick G. and Striegl, Robert G. and Schuster, Paul and Abdulla, Hussain A. N. and Vermilyea, Andrew W. and Scott, Durelle T. and Spencer, Robert G. M.}
}
