@article {2972,
	title = {Comparing paleo-oxygenation proxies (benthic foraminiferal surface porosity, I/Ca, authigenic uranium) on modern sediments and the glacial Arabian Sea},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {331},
	year = {2022},
	month = {08/2022},
	pages = {69 - 85},
	abstract = {Oceanic oxygen reconstructions of the last glacial period are needed to understand the mechanisms of glacial deep ocean carbon storage and to validate climate model simulations. However, existing bottom-water oxygen (BWO) reconstructions are ambiguous due to limitations of each paleo-BWO proxy. Here we present data on three proxies for BWO: benthic foraminiferal surface porosity, benthic foraminiferal iodine/calcium (I/Ca), and authigenic uranium (aU), from globally distributed core-top samples, and we evaluate the potential advantages and limitations of these BWO proxies on global and regional scales. All three proxies are most sensitive to changes at relatively low BWO concentrations (<\~{}50 {\textmu}mol/kg). Data from globally-distributed core tops confirm that foraminiferal surface porosity is correlated with BWO between 0 and 100 {\textmu}mol/kg. Our analysis further confirms that benthic surface porosity is predominantly controlled directly by BWO rather than other potential functionalities of surface pores such as organic carbon uptake and respiratory CO2 release. Low benthic I/Ca can identify low BWO (<50 {\textmu}mol/kg), whereas higher benthic I/Ca values are not associated with specific BWO, possibly due to additional dependence of I/Ca on temperature, salinity, carbonate ion concentration, or water mass mixing at higher BWO. The relationship between aU and BWO is regionally dependent. In the Arabian Sea, variable aU enrichments occur only within the Oxygen Minimum Zone (OMZ), driven by high export production and organic matter fluxes to the sediment. Finally, we combine foraminiferal surface porosity, I/Ca and aU to generate the first quantitative glacial-Holocene BWO reconstructions using a sediment core taken from within the modern Arabian Sea OMZ. All three proxies consistently suggest BWO < 50 μmol/kg in the shallow Arabian Sea during the last \~{}30 kyr, with relatively higher BWO during the glacial period than the Holocene. A comparison with the benthic carbon isotope gradient proxy (Δδ13C) confirms that Δδ13C over-estimates BWO in low-oxygen settings possibly due to sediment diagenesis impacts. Our study provides new insights on the merits and limitations of these BWO proxies and confirms the importance of multi-proxy reconstructions for more reliable paleo-BWO estimates.

},
	keywords = {13 Climate Action},
	isbn = {0016-7037},
	doi = {10.1016/j.gca.2022.06.001},
	url = {https://www.sciencedirect.com/science/article/pii/S0016703722002666},
	author = {Lu, Wanyi and Wang, Yi and Oppo, Delia W. and Nielsen, Sune G. and Costa, Kassandra M.}
}
@article {3006,
	title = {Enhanced iceberg discharge in the western North Atlantic during all Heinrich events of the last glaciation},
	journal = {Earth and Planetary Science Letters},
	volume = {564},
	year = {2021},
	month = {06/2021},
	pages = {116910},
	abstract = {A series of catastrophic iceberg and meltwater discharges to the North Atlantic, termed Heinrich events, punctuated the last ice age. During Heinrich events, coarse terrigenous debris released from the drifting icebergs was preserved in deep-sea sediments, serving as an indicator of iceberg passage. Quantifying the vertical flux of ice-rafted debris (IRD) in open-ocean settings can resolve questions regarding the timing and spatial variation in ice sheet calving intensity. In this study, 230Thxs-based IRD flux throughout the last glacial period was measured in a deep-sea sediment core from the western North Atlantic, and complemented by data spanning 0-32 ka from a sediment core in the Labrador Sea. The cores were recovered from sites downstream from Hudson Strait, a likely conduit for icebergs calving from the Laurentide ice sheet (LIS). We compare our results with equivalent existing data from the eastern North Atlantic and show that the two cores in our study have higher IRD fluxes during all Heinrich events, notably including events H3 (\~{}31 ka) and H6 (\~{}60 ka). This study demonstrates that the LIS played a role in all Heinrich events, and raises the likelihood that a single mechanism can account for the genesis of these events.},
	keywords = {Heinrich event, IRD flux, thorium normalization, western north atlantic},
	isbn = {0012-821X},
	doi = {10.1016/j.epsl.2021.116910},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X21001692},
	author = {Zhou, Yuxin and McManus, Jerry F. and Jacobel, Allison W. and Costa, Kassandra M. and Wang, Shouyi and Alvarez Caraveo, Blanca}
}
