Rosenheim Group Projects
Age Distributions of Organic Material Transported by Rivers
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. Personnel within the group 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 events. Members of the group use one of two in-house 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
- Highlight in Nature Geosciences
Paleo-Ice Shelf Retreat Chronology
Along with colleagues Amelia Shevenell and Eugene Domack (University of South Florida), members of the Rosenheim group have obtained sediment cores from the Antarctica peninsula. We will be using ramped pyrolysis radiocarbon 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.
Recent publication: Rosenheim et al., 2013, Radiocarbon
Isotope Forensics of Gulf of Mexico Deepwater Horizon Oil Spill
The Rosenheim 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. A proof of concept paper has been published in Environmental Research Letters with a Masters student as the lead author. In June, 2012, members of the group 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 accepted article (Deep Sea Research II) and another two in the pipeline. The 2013 cruise sampled along the plume-influenced 1100 m isobath.
Recent publications: Pendergraft et al., 2013, ERL
Recent Climate Change of the Antarctic Peninsula (Larsen Ice Shelf System)
The Rosenheim group 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 atmospheric warming of the region.
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.
Carbon and Sediment Cycling on the Island of Lana’i, Hawai’i
The island of Lana’i, Hawai’i, has undergone profound changes since the arrival of Polynesians as well as the arrival of colonial settlers. Included in these changes is the formation of a prograding sediment deposit on the NE coast of the island that has buried sections of coral reef, changed drainage channels as they meet the ocean, and buried human structures. Group personnel are part of a larger group (Tulane Earth Surface Processes Group and LUMCON Wetlands and Subsidence Laboratory) that is studying the relationships between slope, sediment, and reef as it pertains to land use history.