@article {2545,
	title = {Persistent export of 231Pa from the deep central Arctic Ocean over the past 35,000 years},
	journal = {Nature},
	volume = {497},
	year = {2013},
	month = {May-05-2015},
	pages = {603 - 606},
	abstract = {The Arctic Ocean has an important role in Earth{\textquoteright}s climate, both through surface processes1 such as sea-ice formation and transport, and through the production and export of waters at depth that contribute to the global thermohaline circulation2, 3. Deciphering the deep Arctic Ocean{\textquoteright}s palaeo-oceanographic history is a crucial part of understanding its role in climatic change. Here we show that sedimentary ratios of the radionuclides thorium-230 (230Th) and protactinium-231 (231Pa), which are produced in sea water and removed by particle scavenging on timescales of decades to centuries, respectively4, record consistent evidence for the export of 231Pa from the deep Arctic and may indicate continuous deep-water exchange between the Arctic and Atlantic oceans throughout the past 35,000 years. Seven well-dated box-core records provide a comprehensive overview of 231Pa and 230Th burial in Arctic sediments during glacial, deglacial and interglacial conditions. Sedimentary 231Pa/230Th ratios decrease nearly linearly with increasing water depth above the core sites, indicating efficient particle scavenging in the upper water column and greater influence of removal by lateral transport at depth. Although the measured 230Th burial is in balance with its production in Arctic sea water, integrated depth profiles for all time intervals reveal a deficit in 231Pa burial that can be balanced only by lateral export in the water column. Because no enhanced sink for 231Pa has yet been found in the Arctic, our records suggest that deep-water exchange through the Fram strait may export 231Pa. Such export may have continued for the past 35,000 years, suggesting a century-scale replacement time for deep waters in the Arctic Ocean since the most recent glaciation and a persistent contribution of Arctic waters to the global ocean circulation.},
	keywords = {Marine chemistry, Palaeoceanography, Palaeoclimate},
	issn = {0028-0836},
	doi = {10.1038/nature12145},
	url = {http://www.nature.com/doifinder/10.1038/nature12145},
	author = {Hoffmann, Sharon S. and McManus, Jerry F. and Curry, William B. and Brown-Leger, L. Susan}
}
@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.}
}
