@article {2542,
	title = {No iron fertilization in the equatorial Pacific Ocean during the last ice age},
	journal = {Nature},
	volume = {529},
	year = {2016},
	month = {Mar-01-2018},
	pages = {519 - 522},
	abstract = {The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron1. Greater atmospheric dust deposition2 could have fertilized the equatorial Pacific with iron during the last ice age{\textemdash}the Last Glacial Period (LGP){\textemdash}but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain3, 4, 5, 6. Here we present meridional transects of dust (derived from the 232Th proxy), phytoplankton productivity (using opal, 231Pa/230Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ15N) from six cores in the central equatorial Pacific for the Holocene (0{\textendash}10,000 years ago) and the LGP (17,000{\textendash}27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region7, 8. Thus, ice-age iron fertilization in the Subantarctic Zone would have ultimately worked to lower, not raise, equatorial Pacific productivity.},
	keywords = {Biogeochemistry, Palaeoceanography},
	issn = {0028-0836},
	doi = {10.1038/nature16453},
	url = {http://www.nature.com/doifinder/10.1038/nature16453},
	author = {Costa, K. M. and McManus, J. F. and Anderson, R. F. and Ren, H. and Sigman, D. M. and Winckler, G. and Fleisher, M. Q. and Marcantonio, F. and Ravelo, A. C.}
}
@article {2544,
	title = {Silicon isotopes indicate enhanced carbon export efficiency in the North Atlantic during deglaciation},
	journal = {Nature Communications},
	volume = {5},
	year = {2014},
	month = {Nov-01-2015},
	abstract = {Today{\textquoteright}s Sargasso Sea is nutrient starved, except for episodic upwelling events caused by wind-driven winter mixing and eddies. Enhanced diatom opal burial in Sargasso Sea sediments indicates that silicic acid, a limiting nutrient today, may have been more available in subsurface waters during Heinrich Stadials, millennial-scale climate perturbations of the last glacial and deglaciation. Here we use the geochemistry of opal-forming organisms from different water depths to demonstrate changes in silicic acid supply and utilization during the most recent Heinrich Stadial. We suggest that during the early phase (17.5{\textendash}18 ka), wind-driven upwelling replenished silicic acid to the subsurface, resulting in low Si utilization. By 17 ka, stratification reduced the surface silicic acid supply leading to increased Si utilization efficiency. This abrupt shift in Si cycling would have contributed to high regional carbon export efficiency during the recent Heinrich Stadial, despite being a period of increasing atmospheric CO2.},
	keywords = {Biogeochemistry, Cryospheric science, Ocean sciences},
	doi = {10.1038/ncomms4107},
	url = {http://www.nature.com/doifinder/10.1038/ncomms4107},
	author = {Hendry, Katharine R. and Robinson, Laura F. and McManus, Jerry F. and Hays, James D.}
}
@article {2508,
	title = {Export of submicron particulate organic matter to mesopelagic depth in an oligotrophic gyre},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {110},
	year = {2013},
	month = {Jun-07-2015},
	pages = {12565 - 12570},
	abstract = {Sixty percent of the world ocean by area is contained in oligotrophic gyres [Longhurst A (1995) Prog Oceanog 36:77-16], the biomass of which is dominated by picophytoplankton, including cyanobacteria and picoeukaryotic algae, as well as picoheterotrophs. Despite their recognized importance in carbon cycling in the surface ocean, the role of small cells and their detrital remains in the transfer of particulate organic matter (POM) to the deep ocean remains disputed. Because oligotrophic marine conditions are projected to expand under current climate trends, a better understanding of the role of small particles in the global carbon cycle is a timely goal. Here we use the lipid profiles, radiocarbon, and stable carbon isotopic signatures of lipids from the North Pacific Subtropical Gyre to show that in the surface ocean, lipids from submicron POM (here called extra-small POM) are distinct from larger classes of suspended POM. Remarkably, this distinct extra-small POM signature dominates the total lipids collected at mesopelagic depth, suggesting that the lipid component of mesopelagic POM primarily contains the exported remains of small particles. Transfer of submicron material to mesopelagic depths in this location is consistent with model results that claim the biological origin of exported carbon should be proportional to the distribution of cell types in the surface community, irrespective of cell size [Richardson TL, Jackson GA (2007) Science 315:838-840]. Our data suggest that the submicron component of exported POM is an important contributor to the global biological pump, especially in oligotrophic waters. 
},
	keywords = {Biogeochemistry, biomarkers, carbon isotopes, Oceanography},
	issn = {0027-8424},
	doi = {10.1073/pnas.1217514110},
	url = {http://www.pnas.org/cgi/doi/10.1073/pnas.1217514110https://syndication.highwire.org/content/doi/10.1073/pnas.1217514110},
	author = {Close, H. G. and Shah, S. R. and Ingalls, A. E. and Diefendorf, A. F. and Brodie, E. L. and Hansman, R. L. and Freeman, K. H. and Aluwihare, L. I. and Pearson, A.}
}
@article {2546,
	title = {Transient stratification as the cause of the North Pacific productivity spike during deglaciation},
	journal = {Nature Geoscience},
	volume = {6},
	year = {2013},
	month = {Feb-07-2014},
	pages = {622 - 626},
	abstract = {During the B{\o}lling{\textendash}Aller{\o}d warm period of the last deglaciation, about 14 kyr ago, there was a strong and pervasive spike in primary productivity in the North Pacific Ocean1. It has been suggested that this productivity event was caused by an influx of the micronutrient iron from surrounding continental shelves as they were flooded by sea-level rise2. Here we test this hypothesis by comparing numerous proxies of productivity with iron flux and provenance measured from a core from the subarctic Pacific Ocean. We find no evidence for an abrupt deglacial pulse of iron from any source at the time of peak productivity. Instead, we argue that the deglacial productivity peak was caused by two stepwise events. First, deep convection during early deglaciation increased nutrient supply to the surface but also increased the depth of the mixed layer, which pushed surface production deeper in the water column and induced light limitation. A subsequent input of meltwater from northern American ice sheets then stratified the water column, which relieved light limitation while leaving the surface waters enriched in nutrients. We conclude that iron plays, at most, a secondary role in controlling productivity during the glacial and deglacial periods in the subarctic Pacific Ocean.},
	keywords = {Biogeochemistry, Marine biology, Marine chemistry, Palaeoceanography},
	issn = {1752-0894},
	doi = {10.1038/ngeo1873},
	url = {http://www.nature.com/doifinder/10.1038/ngeo1873},
	author = {Lam, Phoebe J. and Robinson, Laura F. and Blusztajn, Jerzy and Li, Camille and Cook, Mea S. and McManus, Jerry F. and Keigwin, Lloyd D.}
}
@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.}
}
@article {2488,
	title = {Geologic methane seeps along boundaries of Arctic permafrost thaw and melting glaciers},
	journal = {Nature Geoscience},
	volume = {5},
	year = {2012},
	month = {Aug-05-2013},
	pages = {419 - 426},
	abstract = {Methane, a potent greenhouse gas, accumulates in subsurface hydrocarbon reservoirs, such as coal beds and natural gas deposits. In the Arctic, permafrost and glaciers form a {\textquoteleft}cryosphere cap{\textquoteright} that traps gas leaking from these reservoirs, restricting flow to the atmosphere. With a carbon store of over 1,200 Pg, the Arctic geologic methane reservoir is large when compared with the global atmospheric methane pool of around 5 Pg. As such, the Earth{\textquoteright}s climate is sensitive to the escape of even a small fraction of this methane. Here, we document the release of 14C-depleted methane to the atmosphere from abundant gas seeps concentrated along boundaries of permafrost thaw and receding glaciers in Alaska and Greenland, using aerial and ground surface survey data and in situ measurements of methane isotopes and flux. We mapped over 150,000 seeps, which we identified as bubble-induced open holes in lake ice. These seeps were characterized by anomalously high methane fluxes, and in Alaska by ancient radiocarbon ages and stable isotope values that matched those of coal bed and thermogenic methane accumulations. Younger seeps in Greenland were associated with zones of ice-sheet retreat since the Little Ice Age. Our findings imply that in a warming climate, disintegration of permafrost, glaciers and parts of the polar ice sheets could facilitate the transient expulsion of 14C-depleted methane trapped by the cryosphere cap.},
	keywords = {Biogeochemistry, Cryospheric science},
	issn = {1752-0894},
	doi = {10.1038/ngeo1480},
	url = {http://www.nature.com/doifinder/10.1038/ngeo1480},
	author = {Walter Anthony, Katey M. and Anthony, Peter and Grosse, Guido and Chanton, Jeffrey}
}
@article {1008,
	title = {Chemostratigraphy of Paleoproterozoic carbonate successions of the Wyoming Craton: tectonic forcing of biogeochemical change?},
	journal = {Precambrian Research},
	volume = {120},
	year = {2002},
	note = {id: 1586},
	pages = {279-325},
	abstract = {The Archean Wyoming Craton is flanked on the south and east by belts of Paleoproterozoic supracrustal successions whose correlation is complicated by lack of geochronologic constraints and continuous outcrop. However, carbonate units in these successions may be correlated by integrating carbon isotope stratigraphy with lithostratigraphy. The \~{}10 km thick Paleoproterozoic Snowy Pass Supergroup in the Medicine Bow Mountains was deposited on the present-day southern flank of the Wyoming Craton; it contains three discrete levels of glacial diamictite correlative with those in the Huronian Supergroup, on the southern margin of the Superior Craton. The Nash Fork Formation of the upper Snowy Pass Supergroup is significantly younger than the uppermost diamictite and was deposited after the end of the Paleoproterozoic glacial epoch. Carbonates at the base of the Nash Fork Formation record remarkable 13C-enrichment, up to +28{\textperthousand} (V-PDB), whereas those from overlying members of the lower Nash Fork Formation have δ13C values between +6 and +8{\textperthousand}. Carbonates from the upper Nash Fork Formation above the carbonaceous shale have carbon isotope values ranging between 0 and +2.5{\textperthousand}. The transition from high carbon isotope values to those near 0{\textperthousand} in the Nash Fork Formation is similar to that at the end of the ca. 2.2{\textendash}2.1 Ga carbon isotope excursion in Fennoscandia. This chemostratigraphic trend and deposition of BIFs, Mn-rich lithologies, carbonaceous shales and phosphorites at the end of the global ca. 2.2{\textendash}2.1 Ga carbon isotope excursion are likely related to ocean overturn associated with the final breakup of the Kenorland supercontinent. Correlative carbonates from the Slaughterhouse Formation in the Sierra Madre, WY, and from the Whalen Group in the Rawhide Creek area in the Hartville Uplift, WY, have highly positive carbon isotope values. In contrast, carbonates from other exposures of the Whalen Group in the Hartville Uplift and all carbonate units in the Black Hills, SD, have carbon isotope values close to 0{\textperthousand}. Combined with existing geochronologic and stratigraphic constraints, these data suggest that the Slaughterhouse Formation and the succession exposed in the Rawhide Creek area of the Hartville Uplift are correlative with the lower and middle Nash Fork Formation and were deposited during the ca. 2.2{\textendash}2.1 Ga carbon isotope excursion. The Estes and Roberts Draw formations in the Black Hills and carbonates from other exposures in the Hartville Uplift postdate the ca. 2.2{\textendash}2.1 Ga positive carbon isotope excursion and are most likely correlative with the upper Nash Fork Formation. The passive margin, on which the carbonates with highly positive carbon isotope values were deposited, extended around the southern flank of the Wyoming Craton through the Sierra Madre, Medicine Bow Mountains and Hartville Uplift. The presence of carbonates with carbon isotope values close to 0{\textperthousand} in the upper Nash Fork Formation and the Whalen Group indicates that the passive margin persisted on the southern flank of the Wyoming Craton after the carbon isotope excursion. Rifting in the Black Hills, likely related to the final breakup of the Kenorland, succeeded the carbon isotope excursion, since the Estes and Roberts Draw formations, deposited during rifting and ocean opening on the eastern flank of the Wyoming Craton, postdate the carbon isotope excursion.},
	keywords = {Biogeochemistry, Chemostratigraphy, Kenorland, Paleoproterozoic, Wyoming},
	doi = {10.1016/S0301-9268(02)00164-X},
	author = {Bekker, A. and Karhu, J. A. and Eriksson, A. and Kaufman, A. J.}
}
