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 sediment dispersal, strata formation, and system development along continental margins — particularly within rivers, deltas, and wetlands. These subaerial portions of the margin serve as critical gateways between land and ocean, serving to filter, mitigate, or otherwise alter the tremendous flux of material reaching our coasts. As well, over 50% of the world's population lives along the coastline and thus may be threatened by sea-level rise, storm events, shoreline erosion, wetland loss, and climate change. Continued losses of life, infrastructure and habitat have exposed the need to better understand the causes and consequences of these processes. In terms of geological processes, sediments that accumulate along continental margins also preserve a detailed record of past environmental conditions; this record is an important window through which we can study Earth’s responses to climate change, land-use patterns, and tectonics.
Steve’s research takes place in two primary arenas — marshes and estuaries of the U.S. and rivers and deltas of South Asia. 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. 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 addressed. The radionuclides are measured by both gamma and alpha-decay spectroscopy in Vanderbilt’s state-of-the-art Radioisotope Lab. Other methods commonly used in Steve’s coastal research are sediment coring and sub-bottom profiling, the latter using our Edgetech 216s chirp sonar system. In Asia, Steve’s research focuses on large deltas formed by rivers originating in the Himalayas. Driven by a strong but variable monsoon system, this region sustains seven of the world’s ten largest rivers and about 40% of the humans on our planet. It is an amazing region. Research over the past decade has centered on the country of Bangladesh and its dominant feature, the Ganges-Brahmaputra river delta. Several of ongoing projects include: the control of floodplain development on groundwater arsenic contamination, in collaboration with Columbia University (van Geen, Zheng); source-to-sink responses to Quaternary climate change, in collaboration with University of Colorado (Overeem, Syvitski); geochemical tracing of source-area erosion under different climate regimes, in collaboration with Stony Brook University (Hanson); and sediment dispersal and seabed dynamics on the inner shelf, in collaboration with Texas A&M (Mullenbach). In addition to previously mentioned radioisotope and sonar techniques, these projects involve other methods such as Sr and Nd isotopes measured via thermal ionization mass spectrometry (TIMS), major and trace elements determined by inductively-coupled plasma mass spectrometry (ICPMS), optically stimulated luminescence dating of sediments (OSL), and high-resolution core logging using magnetic susceptibility, natural gamma emissions, and electrical conductivity. Aside from these more quantitative approaches, Steve also stresses strong observational skills that can provide unique and insightful perspectives that complement an increasingly analytical world.
Graduate students working with Steve have conducted a broad range of projects in the past several years. Those who have focused on environmental issues have mainly worked in salt marshes and estuaries, although new opportunities at Vanderbilt will include lake (reservoir), river, and freshwater wetland settings. Such projects involve frequent on-site field work. Research on these systems would be suitable for both M.S. and Ph.D. level research and would prepare one for careers in environmental consulting, law, and government, or academics and research at the Ph.D. level. Graduate students that might pursue work in the Asian delta systems are typically more geared toward Ph.D. research. Such students 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, making such projects better to suited to a Ph.D. curriculum. Nevertheless, the questions being answered for the Ganges-Brahamputra and other delta systems are new, exciting, and have provided several key 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 global human issues can also open doors for jobs with international consulting firms and non-governmental agencies.
van Geen, A., Z. Aziz, A. Horneman, B. Weinman, R.K. Dhar, Y. Zheng, S. Goodbred, R. Versteeg, A.A. Seddique, M.A. Hoque and K.M. Ahmed, 2006. Preliminary evidence of a link between surface soil properties and the arsenic content of shallow groundwater in Bangladesh. Journal of Geochemical Exploration, in press.
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 siliciclastic-carbonate, deltaic coastline: Suwannee River, Florida. Journal of Sedimentary Research, 75:621-635.
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.
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.
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.
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., 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, March 1993, west-central Florida. Geology, 23:679-682.
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