2014 Geodynamics Program
Anthropocene: From Land to the Ocean
Student ProjectsPre-generals students are required to carry out a research project related to this year’s theme - preferably something outside their current field of research. They will be required to write this work up in an 8-10 page report, due at our last class meeting. In addition, they will give a 12-15 minute oral presentation at the end of the course, reporting the results of their findings.
Some project ideas have been solicited from seminar quest speakers, WHOI staff and falculty and posted below. You can also come up with your own project idea. Please notify this year's science organizers of your project topic.
- "Impact of warming, ocean acidification and hypoxia on benthic foraminifera"
A number of marine environmental parameters are changing as a result of increased atmospheric carbon dioxide concentrations since the onset of the Industrial Revolution. The three most prominent changes are global warming, Ocean Acidification and the expansion of oxygen-limited zones (hypoxia). A larger study is assessing the compounded impacts of these three environmental changes on benthic foraminifera via a state-of-the-art experimental setup at the Bernhard laboratory at the Woods Hole Oceanographic Institution. Benthic foraminifera are cosmopolitan unicellular eukaryotes (Protists) and form a vital link in the benthic food web. Results of this study will help predict future foraminiferal responses to ongoing climate change. However, knowledge of potential changes that have already occurred since the Industrial Revolution is of equal importance to our understanding of foraminiferal ecology and its response to climate change. A number of sediment cores were collected from an area called the Mud Patch (80-m water depth), which is on the southern continental shelf of New England. The available Geodynamics project will sample a selected archival multicore to analyze for lead isotopes (210Pb) to establish an age model for the Mud Patch. This age model will subsequently be used to determine the depth of the onset of the Industrial Revolution (~ 1850 CE). The surface sample of the selected core (0-1 cm) and one pre-1850 C.E. sample will be analyzed for the total foraminiferal assemblage. Results will be directly compared to one another and already available assemblages (from other cores) to evaluate the impact of climate change on benthic foraminifera at this Mud Patch site since the Industrial Revolution. The student will be responsible for discrete sampling of the sediment core for age determinations, arranging analyses (in Donnelly lab), foraminiferal analyses, and the interpretation of data from the different techniques (including comparisons of the new data to our existing data).
Supervision: Joan Bernhard (G&G)
- The project would involve investigating how soil biogeochemical processes develop in recently created wetlands. Coastal wetlands are important components of the global carbon cycle and provide a variety of ecosystem services including nutrient removal and protection from shoreline erosion. These systems are being lost globally at a rapid rate and, in an effort to reverse that trend, new wetlands are being created. In South Florida local groups have created wetlands by restoring tidal hydrology and planting marsh grasses. The grasses are quickly out competed by mangroves that recruit to the new wetlands. Changes in hydrology and plant successional communities can have large effects on soil biogeochemistry. This project builds upon a recent study (Osland et al 2012) by analyzing the organic matter composition and quality of soil cores collected from wetlands created over ~20y. These data, in combination with porewater and surface water chemistry, will provide an integrated assessment of how soil biogeochemical processes develop in newly created salt marsh - mangrove wetlands.
Supervision: Amanda Spivak (MC&G)
- "Linkages between human activities and climate change effects on carbon cycling: molecular and isotopic reconstruction in the Mississippi River basin"
Description: The project will investigate processes acting on organic carbon stored behind recently-build damns on a major river system to constrain the role of sediment entrapment behind dams in the global carbon cycle. Changes in carbon delivery and storage through the short timescale (10's of years) of sediment accumulation in a reservoir of the Mississippi River system (Lake Whittington) will be characterized using a combination of detailed sediment chronology, compound class analyses, and detailed radiocarbon analyses. The chronology of the core used in this project has been established using 137Cs and 210Pb, showing that it provides a very high-resolution record of the past 70 years of sedimentation.
Supervision: Valier Galy (MC&G)
- Earthquakes are now being routinely induced across the entire U.S. as a result of various energy industry activities. One of the clearest examples of human induced seismicity is the Salton Sea Geothermal field in California which is of particular concern because of its proximity to the San Andreas fault. Recent studies have claimed that the probability of a damaging M8 earthquake in southern California is significantly increased by the geothermal plants based on statistical models but the physical mechanism connecting the geothermal wells with the plate boundary fault is complicated. The project would involve using seismology to detect changes in fault properties as a result of geothermal pumping.
Supervision: Jeff McGuire
- "Coupled Human-Coastal Behavior"
Models of coupled human-barrier evolution were presented in class. This project would involve the student performing novel (yet potentially simple) experiments using the presented coupled coastal/morphodynamic models with either different human decision-making scenarios or exploring model behavior across a range of environmental conditions and future scenarios. Although it would be advantageous to have some modeling background, we have several fairly straightforward Matlab model that might provide a gateway into other modeling scenarios.
Supervision: Andrew Ashton (G&G), Porter Hoagland (MPC), and Andy Solow (MPC)
- Mercury is a trace metal whose cycling has been significantly perturbed as a result of human activity. Indeed, and according to Senn and Peucker-Ehrenbrink, it is the most perturbed of the recognized toxic elements. This perturbation has raised concerns worldwide about enhanced human and ecological exposure to mercury. Interestingly, however, the anthropocene perturbation is currently at about the same level as has occurred in the past during glacial maxima.
Supervisuion: Carl Lamborg
- "Onset and variability of the Indian Monsoon"
The Asian monsoon affects over 2 billion people, yet its onset and evolution phases at various timescales remain contested after decades of intensive research. One reason for this is the conflicting records, which either come from marginal regions of the monsoon domain or are overprinted by the tectonics of Himalaya and Tibet. This project will take advantage of newly available sediment cores extending into Eocene that are located close to monsoon core zone on the Indian Peninsula to assess the utility of foraminifera isotopic composition to provide new proxy reconstructions of the Indian Monsoon.
Supervision: Liviu Giosan (G&G)
- "Developing proxies to assess the climate constraints on the Indus Civilization"
The Harappans, the most expansive Bronze Age civilization has thrived in arid and semi-arid environments along the Indus River and its tributaries. It is yet unclear if land degradation or climate or a combination of both was responsible for their rapid collapse. One reason for this uncertainty is the poor knowledge of the hydrological budget for their heartland. The project will explore the potential of foraminifera assemblages to provide new proxy reconstructions for seasonal hydrological components in the region.
Supervision: Liviu Giosan (G&G)
- “Human Influences on River Sediment Discharge“
Anthropogenic effects have long been known to influence sediment discharge from river catchments. Fine-grained, suspended sediment has little interaction with the bed and, once in the river, moves downstream rapidly, on scale with the river's velocity itself. At the reach scale, the coarser, bedload fraction, however, can primarily influence sediment that arrives at the coast through adjustments of the river profile itself, and such influences must migrate downstream. For this project, the student will develop a standard 1-dimensional river profile model with application and calibration to the Ebro River, Spain. The model will be used to estimate potential time lags from the moment coarse sediment enters the river to the time the sediment will be felt at the river delta. These effects can further be compared to the potential magnitude of water discharge-related effects on sediment delivery (to demonstrate how river damming could have both instantaneous and delayed effects on discharge).
Parker, 1D SEDIMENT TRANSPORT MORPHODYNAMICS with applications to RIVERS AND TURBIDITY CURRENTS. http://hydrolab.illinois.edu/people/parkerg//morphodynamics_e-book.htm
Supervision: Andrew Ashton (G&G), and Liviu Giosan (G&G)
- "Is Zipf’s Law Just Random?"
In class, Zipf’s Law for city size distribution was presented, yet the origin of this scaling remains unknown. It is possible that this relationship could similarly arise from analysis of interconnectivity arising from a random population surface. In this project, the student will create a cellular numerical model of random population distribution over space and analyze the rank order of interconnected cell populations, comparing the results to Zipf’s Law.
Supervision: Andrew Ashton (G&G)
Ecosystem responses to oxygen minimum zone variability in the Arabian Sea during the last Glacial-Interglacial cycle: A paleogenomics approach.
The northern Arabian Sea is characterized by strong seasonal variability of monsoonal upwelling and high algal primary productivity, that favor an exceptionally widespread formation of mid–water oxygen depletion, or so-called Oxygen Minimum Zone (OMZ). Sediment records from the region have been extensively studied since the 90’s to reconstruct causes, timing, and duration of OMZ extent since the last glacial-interglacial cycle. However, it remains entirely unknown how long-term changes in OMZ variability has impacted past ecosystems and food webs in the Arabian Sea. The project aims to use ultra-high-throughput sequencing of sedimentary ancient DNA signatures (i.e., the paleome) to reconstruct past plankton populations and to use advanced bioinformatics and statistical tools to identify species that were most strongly impacted by long-term fluctuations in OMZ strength during key climate intervals since the last 80,000 years. The DNA will be extracted from an undisturbed and radiocarbon-dated sediment record that was recently obtained from a classical coring location in the center of the OMZ on the continental slope northwest of the Indus Canyon. The high-resolution ancient DNA records will greatly help to refine past environmental and climate interpretations in the monsoon-impacted northeastern Arabian Sea area. Moreover, available monitoring data suggest that OMZs are expanding in the world’s oceans in the context of global warming. As these changes intensify, marine ecosystems are expected to experience disturbances in the structure and dynamics of food webs and in the production of greenhouse gasses, with resulting feedbacks on the climate system. This study will provide first insights into how ecosystems will respond to long-term periods of OMZ conditions and how these ecosystems adapt after the return of a well-mixed and oxygenated water column.
The student will be responsible for extraction and purification of fossil DNA. Initial experiments have shown that the DNA is very well preserved in the available core. The student will use the recovered DNA for the preparation of libraries for MiSeq Illumina amplicon sequencing of phyto- or zooplankton-derived barcoding genes (i.e., a targeted approach), as well as for the preparation of libraries for metagenome HiSeq Illumina sequencing. Fossil metagenomes have never been studied before, but are likely to reveal a detailed window into the overall changes in the taxonomy and functioning of past ecosystems from algal viruses to potentially megafauna. Data analysis will also be part of the learning curve.
Supervision: Marco Coolen (MC&G)
- A project that uses long-lived isotopes (e.g, Pb, Sr, Nd) to model mixing of mantle reservoirs. Things are poised to have a student run some software developed to use statistical techniques to identify 'best fitting' mixing models, and do things like determine the minimum number of independent reservoirs required to fit the global dataset (already compiled). This is not an anthropogenic themed but if there is a geochemist taking the class who would enjoy working on a topic closer to their field, then this might work well.
Supervision: Rob Sohn (G&G)
- We have been constructing some numerical studies of mantle convection with a floating "continent" on the top with general implications for the Wilson cycle. The continent moves back and forth across the top driven by the convection cell/continent interaction. Our program is in matlab and quite simple to learn and use, and possibly can be converted to fortran by a student if desired. There are some interesting extensions that would be excellent geodynamics projects such as the behavior of two continents or systematic studies of the behavior of one continent as a function of either continent size, Rayleigh number or both.
Supervision: Jack Whitehead (PO) and Mark Behn (G&G)