SILT U Projects

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Isotope Forensics of Gulf of Mexico Deepwater Horizon Oil Spill

N. Atlantic Radiocarbon Records and Heat Transport

Records of age-corrected radiocarbon (14C) from corals and

sclerosponges (collected and shared by researchers at the

Stable Isotope Laboratory of the University of Miami) will

be used to constrain heat transport by the Subtropical Cells

(STC’s) of the tropical N. Atlantic Ocean.  Locations of the

records in the Bahamas (subsurface return flow) and the

island of Principe (equatorial upwelling zone) will be

compared to records from the Cape Verde Islands (frontal zone between upwelling and subducting water masses) to constrain positioning of the upwelling and subduction zones that comprise the STC’s.  These data will be used to attempt to constrain oceanographic influence on Caribbean proxies that show a larger-than-global-average temperature increase for the 20th century. 

See ERSSTv3b animations!

The SILT U group has continuously sampled oil deposited along the coast of Grand Isle, Louisiana, and in Barataria Bay, Louisiana, since June, 2010.  Isotopic measurements have tracked the weathering and mixing of this oil.  Isotope measurements on individual compounds will allow us to “fingerprint” it.  In June, 2012, SILT U sampled bottom sediments as part of the Consortium for Advanced Research of Hydrocarbon Transport in the Environment (CARTHE).  This was the first of three cruises; the second is now planned for June 24-29, 2013.    The 2012 cruise has led to one submitted article (Marine Geology) and another two in the pipeline.  The 2013 cruise will aim to sample along the plume-influenced 1100 m isobath. 

Recent Climate Change of the Antarctic Peninsula (Larsen Ice Shelf System)
SILT U has teamed with Noel Gourmelen and Andrew Shepherd at the Leeds Center for Polar Science to investigate ice cores taken from the Larsen Ice Shelf.  These cores span ~30 years, during which significant change has taken place on the ice shelf and during which only limited local or regional meteorological time series are available.  The team has measured hydrogen and oxygen isotope ratios of the water melted from the ice cores.  Work on the ice cores was performed by members of both teams at the British Antarctic Survey.  The work suggests marine driven thinning of the ice, and limited warming.

Rivers large and small transport not only water, but sediment and affiliated carbon.  Transport of the latter plays an important role in the part of the carbon cycle that is most affected by anthropogenic release of CO2.  SILT U personnel are involved in analyzing sediment from the Mississippi River to determine the spectrum

of ages (determined by measuring 14C content)

present in particulate organic carbon sediment

during different flow regimes of the river. 

These flow regimes include the 2008 and 2011

high water event.  SILT U houses a novel

programmed temperature pyrolysis/

combustion system (PTP/CS) that allows ramped pyrolysis radiocarbon dating. 

Mississippi/Atchafalaya River System - Rosenheim et al., 2013, Global Biogeochemical Cycles

Narayani River, Ganges River System - Rosenheim and Galy, 2012, Geophysical Research Letters

    -Highlight in Nature Geosciences

Age Distributions of Organic Material Transported by Rivers

Paleo-Ice Shelf Retreat Chronology
SILT U has teamed with Amelia Shevenell (University of South Florida) and Eugene Domack (Hamilton College) to obtain sediment cores from Antarctica.  SILT U researchers will be using their ramped pyrolysis radiocarbon technique to better constrain the age of autochthonous particulate organic matter contained in the sediments immediately above glacial diamicton sediment in Antarctic Peninsula paleo-ice streams.  These ages will represent the best approximation to date of the maximum age of pelagic drape deposits.  The results of this work will have implications on the timing of meltwater pulses and correlation with Antarctic ice core climate records.  

see Rosenheim et al., 2013, Radiocarbon, more information

20th century proxy trends (circles = sessile, triangle = planktic) on gridded 20th century trends in ERSSTv3b. FL Keys corals calibrated to ERSSTv3b.