Steven L. Goodbred, Jr.
Ph.D. College of William and Mary,
Virginia Institute of Marine Science, 1999
Sedimentology and Quaternary Environments
office: 5733 Science & Engineering Bldg.
phone: 615-343-6424
email: steven.goodbred@vanderbilt.edu
Steve Goodbred investigates the interaction of environmental systems along the boundary of land and ocean– particularly within rivers, deltas, and coastal wetlands. This portion of the continental margin is a critical gateway that links the 71% of Earth covered by ocean with the much smaller land surface that is home to 6 billion people. Moreover, half of this human population lives within 100 km of the coast, whereby added risk is assumed for regional environments, physical infrastructure, economy, and culture. Just in the past decade we have observed the recurring hazards that threaten the coastal environment and populations, including tsunamis, hurricanes, erosion and land loss – less obvious are the longer-term impacts of climate change, sea-level rise, and overpopulation. Weaved within this global situation remain many fundamental questions about past environmental change, about the recurrence and impact of coastal hazards, and the effect of human alterations to the landscape. These are some of the broader issues related the research in our lab and Vanderbilt's Earth and Environmental Sciences Department.
Steve’s ongoing research projects are being conducted in three primary arenas — (1) marshes, coasts, and estuaries of the U.S. Atlantic coast; (2) the massive Himalayan rivers and deltas of South Asia, and most recently, (3) the arid coastal plains of northern Peru.
Along our nation’s coasts, Steve and his lab interpret high-resolution sedimentary records to understand the history and behavior of shoreline environments over timescales of years to millennia. This research includes the response of salt marshes to sea-level change, anthropogenic activities, and climate over the last century, as well as longer-term studies on the development of coastal ecosystems during the Holocene transgression. Most recently we have been pursuing evidence for a possible major tsunami event along the New York metropolitan coast about 2300 years ago (see Fig. 1). This exciting research involves collaborators from Columbia University, some of whom are also investigating whether an extraterrestrial impact event occurred around the same time. In the coming few years, we hope to be able to confirm whether the New York region indeed experienced a series of devastating and related events just 2300 years ago.
In South Asia, Steve’s research focuses on the major deltas being formed by rivers draining the Himalayas. Driven by a strong but variable monsoon climate, this region presently sustains seven of the world’s ten largest rivers and four out of every ten humans on the planet – it is an amazing region! Research over the past several years has centered on the country of Bangladesh and its dominant feature, the Ganges-Brahmaputra river delta. Within this complex system, though, we are addressing a great variety of topics. One of the most environmentally and culturally significant is work on the widespread contamination of groundwater by arsenic, which is poisoning 10s of millions of people in the region. Our role in the study of this problem has been to understand how the bewildering heterogeneity of arsenic concentrations can be understood in the context of delta and floodplain evolution – for, in fact, the distribution of sediments within the shallow aquifer largely define both groundwater flow and sediment geochemistry. We are also investigating how the mighty Himalayan rivers have varied through the Quaternary glacial epochs, when climate variability has caused dramatic changes in the strength of these monsoon-fed rivers. We are not only landlubbers but do much of our work offshore in the marine zone. In just the past two years we have been fortunate that our research has captured the impacts of a major cyclone that struck the region in 2007, resulting in major offshore sediment failures documented with our subbottom sonar system (Fig. 2).
The newest research around the Goodbred lab is a project in coastal Peru being conducted with Prof. Tom Dillehay from Vanderbilt's Department of Anthropology. The project focuses on a pre-ceramic archaeological site that was active from 7000-3000 year ago. Goodbred and students are reconstructing the history of floodplain development near the site to understand how major cultural changes may be linked with environmental change during this period (Fig. 3).
 
One of the primary tools Steve’s group uses in these studies is radioisotope geochronology, which makes use of sediment-bound radionuclides to reconstruct patterns of accretion and sediment dynamics. This suite of nuclides – including 7Be, 234Th, 137Cs, and 210Pb – encompass timescales from months to decades and are delivered via atmospheric, terrestrial, and marine pathways, thereby allowing a broad range of questions to be addressed. The radionuclides are measured by gamma-decay spectrometry in Vanderbilt's Sediments Lab. In addition to radioisotope techniques, other methods used in our study of the sedimentary record include coring (Fig. 1) and sub-bottom profiling (Fig. 2), the latter using an Edgetech chirp sonar system and 3D Triton post-processing software. The Sediments Lab is also home to a Geotek high-resolution core logger with magnetic susceptibility, natural gamma attenuation, and high-resolution digital camera used for the continuous downcore measurement of physical sediment properties. Our work employs geochemical approaches as well, particularly using elemental and isotopic fingerprints to assess provenance in mixed sediments. These include Sr and Nd isotopes, major and trace elements, and U-Pb dating of zircons.
In the recent past, graduate students working with Steve have conducted a range of projects. Those who have tackled projects in the U.S. have mainly worked in coastal settings such as salt marshes and lagoon systems. Such projects involve frequent field work for sample and data collection. For M.S. students, such sedimentary research is appropriate for careers in environmental consulting, environmental law, science writing, and science teaching. At the Ph.D. level, students will become prepared for careers in college teaching, academic research, and government agencies (e.g., USGS, EPA). Graduate students interested in working on foreign projects will have the opportunity to travel overseas and spend many weeks or more in the field. However, trips are often a year or more apart, often making such projects suited to a Ph.D. curriculum. However, several hard-working M.S. students have done well in tackling foreign research projects. For a career, the questions being addressed in our Ganges-Brahmaputra research are new, exciting, and provide important contributions to the earth sciences. Students pursuing this type of project will be best prepared for an academic career, especially one with a focus on research. The experience in a foreign nation and the relevance to human issues can also open doors with international consulting firms and non-governmental agencies.
*Weinman, B.A., Goodbred, Jr., S.L., Zheng, Y., van Geen, A., Aziz, Z., Srivastava, P., 2008. Arsenic concentrations in shallow groundwater of Araihazar, Bangladesh: Geological control through floodplain evolution. Geological Society of America Bulletin, 120: 1567–1580.
Goodbred, Jr., S.L., 2008. Deltaic Sediments – Climate Records. In Gornitz, V., Fairbridge, R., Rampino, M. (eds.), Encyclopedia of Paleoclimatology and Ancient Environments. Kluwer Academic Press, 265-268.
van Geen, A., Y. Zheng, S. Goodbred Jr., A. Horneman, Z. Aziz, Z. Cheng, M. Stute, B. Mailloux, B. Weinman*, M.A. Hoque, A.A. Seddique, M.S. Hossain, S.H. Chowdhury, and K. M. Ahmed. 2008. Flushing History as a Hydrogeological Control on the Regional Distribution of Arsenic in Shallow Groundwater of the Bengal Basin. Environmental Science and Technology, 42: 2283–2288.
Giosan, L., and Goodbred, S.L., 2007. Deltaic Environments. In, Encyclopedia of Quaternary Science. Elsevier, p. 704-716.
Wright, E.E., Hine, A.C., Goodbred, Jr., S.L., Locker, S.D., 2005. The effect of climate and sea-level change on the development of a mixed siliclastic-carbonate, deltaic coastline: Suwannee River, Florida. Journal of Sedimentary Research, 75: 621-635.
Kuehl, S.A., Allison, M.A., Goodbred, S.L., Kudrass, H.-R., 2005. The Ganges-Brahmaputa Delta. In Giosan, L. and Bhattacharya, J., Deltas – Old and New, SEPM Special Publication 83: 413-434.
Goodbred, Jr., S.L., 2003. Response of the Ganges dispersal system to climate change: a source-to-sink view since the last interstade. Sedimentary Geology, 162: 83-104.
Goodbred, Jr., S.L., Kuehl, S.A., Steckler, M., and Sarker, M.H., 2003. Controls on facies distribution and stratigraphic preservation in the Ganges-Brahmaputra delta sequence. Sedimentary Geology, 155: 301-316.
Allison, M.A., Khan, S.R., Goodbred, Jr., S.L., and Kuehl, S.A., 2003. Stratigraphic evolution of the late Holocene Ganges-Brahmaputra lower delta plain. Sedimentary Geology, 155: 317-342.
Heroy, D.C., Kuehl, S.A., and Goodbred, Jr., S.L., 2003. Sand- and clay-size mineralogy of the Ganges and Brahmaputra rivers: Records of river switching and Late Quaternary climate change. Sedimentary Geology, 155: 343-359.
Goodbred, Jr., S.L., 2001. Ocean Margin Sediments. In Steele, J., Thorpe, S., and Turekian, K. (eds.), Encyclopedia of Ocean Sciences. Academic Press, p. 1965-1973
Goodbred, Jr., S.L., Kuehl, S.A., 2000. Enormous Ganges-Brahmaputra sediment load during strengthened early Holocene monsoon. Geology, 28: 1083-1086.
Goodbred, Jr., S.L., Kuehl, S.A., 2000. The significance of large sediment supply, active tectonism, and eustasy on margin sequence development: Late Quaternary stratigraphy and evolution of the Ganges-Brahmaputra delta. Sedimentary Geology, 133: 227-248.
Goodbred, Jr., S.L., and Kuehl, S.A., 1999. Holocene and modern sediment budgets for the Ganges-Brahmaputra river: Evidence for highstand dispersal to floodplain, shelf, and deep-sea depocenters. Geology, 27: 559-562.
Goodbred, Jr., S.L., and Kuehl, S.A., 1998. Floodplain processes in the Bengal Basin and the storage of Ganges-Brahmaputra river sediment: an accretion study using 137Cs and 210Pb geochronology. Sedimentary Geology, 121: 239-258.
Goodbred, Jr., S.L., Wright, E.E., and Hine, A.C., 1998. Sea-level change and storm-surge deposition in a Late Holocene Florida salt marsh. Journal of Sedimentary Research, 68: 240-252.
Goodbred, Jr., S.L., and Hine, A.C., 1995. Coastal storm deposition: Salt-marsh response to a severe extratropical storm, 1993, west-central Florida. Geology, 23: 679-682.
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