Christopher G. Smith, Ph.D.
As a coastal geologist, my research focuses on the transport, transformation, and deposition of particulate and dissolved constituents within the coastal realm and how system processes will respond to large-scale environmental forcings (e.g., climate change).
Coastal systems provide a dynamic interface between terrestrial and marine realms; anthropogenic activity and natural processes occurring within terrestrial ecosystems can have a significant impact to the coastal zone and adjacent marine system. Augmentation of coastal systems is inevitable from a human perspective as nearly half of the population of the United States reside within coastal counties. Understanding modern processes (sedimentologic, hydrologic, and geochemical) occurring along this terrestrial-marine continuum is critical in predicting the response associated with natural and anthropogenic perturbations.
My research interests generally fall into two categories: 1) fluid exchange (e.g., surface water – groundwater exchange, submarine and coastal groundwater discharge) and 2) fine-grained sediment dynamics, specifically in marsh and estuarine environments. Linking these two seemingly disparate research topics are naturally-occurring (e.g., U-Th series) and anthropogenically-introduced/spiked (e.g., 137Cs) radionuclides. Particle reactive radionuclides (e.g., 7Be, 234Th, 210Pb, 210Po, and 137Cs) provide excellent tracers to quantify sediment deposition and re-mobilization over time-scales of months to decades. Examining the final sedimentary product in the context of the temporal framework and associated transient changes also provide a breadth of knowledge to environmental conditions that persisted in recent past and the outcome that may be expected if similar conditions persist in the present or future. Alternatively, the more conservative behavior of radon and radium isotopes have proven these as excellent tracers to quantify groundwater discharge in both fresh and marine environments.
Over the last three decades, groundwater discharge to the coastal zone has received increasing recognition as a substantial material vector, influencing water quality and nutrient fluxes. Quantification of fresh and marine groundwater end-members and the processes that drive the exchange (e.g., seasonal recharge cycles, hurricanes and tropical cyclones) are critical to assess the overall importance of coastal groundwater and has been at the forefront of my research.
Professional Experience
2010-Present: Research Geologist, USGS, St. Petersburg Coastal and Marine Science Center
2008 - 2010: USGS Mendenhall Fellow, St. Petersburg Coastal and Marine Science Center
Education and Certifications
PhD - Oceanography & Coastal Science (Geological conc) (2008) from Louisiana State University (Geaux Tigers!)
MS - Geology (2004) from East Carolina University
BS - Geology (2001) from East Carolina University (NC)
Science and Products
Surface-water radon-222 distribution along the west-central Florida shelf
Nearshore morphology, benthic structure, hydrodynamics, and coastal groundwater discharge near Kahekili Beach Park, Maui, Hawaii
Radioisotopic data of sediment collected in Mobile and Bon Secour Bays, Alabama
An investigation of submarine groundwater—borne nutrient fluxes to the west Florida shelf and recurrent harmful algal blooms
Over 100 years of environmental change recorded by foraminifers and sediments in a large Gulf of Mexico estuary, Mobile Bay, AL, USA
Reactive-transport modeling of iron diagenesis and associated organic carbon remineralization in a Florida (USA) subterranean estuary
Natural radium and radon tracers to quantify water exchange and movement in reservoirs
Influence of sea level rise on iron diagenesis in an east Florida subterranean estuary
Recognizing former flood-tide deltas in the Holocene stratigraphic record from the Outer Banks, North Carolina, USA
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
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Surface-water radon-222 distribution along the west-central Florida shelf
In February 2009 and August 2009, the spatial distribution of radon-222 in surface water was mapped along the west-central Florida shelf as collaboration between the Response of Florida Shelf Ecosystems to Climate Change project and a U.S. Geological Survey Mendenhall Research Fellowship project. This report summarizes the surface distribution of radon-222 from two cruises and evaluates potentialAuthorsC.G. Smith, L. L. RobbinsNearshore morphology, benthic structure, hydrodynamics, and coastal groundwater discharge near Kahekili Beach Park, Maui, Hawaii
This report presents a brief summary of recent fieldwork conducted off Kahekili Beach Park, Maui, Hawaii, the site of the newly established U.S. Coral Reef Task Force priority study area at Kaanapali and the Hawaii Department of Land and Natural Resources, Division of Aquatic Resources, Kahekili Herbivore Fisheries Management Area (HFMA). The goals of this fieldwork are to provide new baseline infAuthorsPeter W. Swarzenski, Curt D. Storlazzi, M. Katherine Presto, Ann E. Gibbs, Christopher G. Smith, Natasha T. Dimova, Meghan L. Dailer, Joshua B. LoganRadioisotopic data of sediment collected in Mobile and Bon Secour Bays, Alabama
The focus of this study was to determine the extent of natural and (or) anthropogenic impacts on the sedimentary records of Mobile and Bon Secour Bays, Alabama during the last 150 years. These bays are unique in that anthropogenic activities are generally widespread and span both the eastern and western shorelines. However, there is a clear distinction in the types of human development and infrastAuthorsMarci E. Marot, Christopher G. SmithAn investigation of submarine groundwater—borne nutrient fluxes to the west Florida shelf and recurrent harmful algal blooms
A cross‐shelf, water‐column mass balance of radon‐222 (222Rn) provided estimates of submarine groundwater discharge (SGD), which were then used to quantify benthic nutrient fluxes. Surface water and groundwater were collected along a shore‐normal transect that extended from Tampa Bay, Florida, across the Pinellas County peninsula, to the 10‐m isobath in the Gulf of Mexico. Samples were analyzed foAuthorsChristopher G. Smith, Peter W. SwarzenskiOver 100 years of environmental change recorded by foraminifers and sediments in a large Gulf of Mexico estuary, Mobile Bay, AL, USA
The marine microfauna of Mobile Bay has been profoundly influenced by the development and expansion of the primary shipping channel over the last ˜100 years. Foraminifers and sediments from seven box cores with excess lead-210 chronology document that channel dredging and spoil disposal have altered circulation, reduced estuarine mixing, changed sedimentation patterns, and caused a faunal turnoverAuthorsLisa E. Osterman, Christopher G. SmithReactive-transport modeling of iron diagenesis and associated organic carbon remineralization in a Florida (USA) subterranean estuary
Iron oxides are important terminal electron acceptors for organic carbon (OC) remineralization in subterranean estuaries, particularly where oxygen and nitrate concentrations are low. In Indian River Lagoon, Florida, USA, terrestrial Fe-oxides dissolve at the seaward edge of the seepage face and flow upward into overlying marine sediments where they precipitate as Fe-sulfides. The dissolved Fe conAuthorsMoutusi Roy, Jonathan B. Martin, Christopher G. Smith, Jaye E. CableNatural radium and radon tracers to quantify water exchange and movement in reservoirs
Radon and radium isotopes are routinely used to quantify exchange rates between different hydrologic reservoirs. Since their recognition as oceanic tracers in the 1960s, both radon and radium have been used to examine processes such as air-sea exchange, deep oceanic mixing, benthic inputs, and many others. Recently, the application of radon-222 and the radium-quartet (223,224,226,228Ra) as coastalAuthorsChristopher G. SmithInfluence of sea level rise on iron diagenesis in an east Florida subterranean estuary
Subterranean estuary occupies the transition zone between hypoxic fresh groundwater and oxic seawater, and between terrestrial and marine sediment deposits. Consequently, we hypothesize, in a subterranean estuary, biogeochemical reactions of Fe respond to submarine groundwater discharge (SGD) and sea level rise. Porewater and sediment samples were collected across a 30-m wide freshwater dischargeAuthorsM. Roy, J.B. Martin, J. Cherrier, J.E. Cable, C.G. SmithRecognizing former flood-tide deltas in the Holocene stratigraphic record from the Outer Banks, North Carolina, USA
Foraminiferal and sedimentologic data were collected by vibracoring a small, relict, short-lived, migrating inlet (New Inlet) and its flood-tide delta on the Outer Banks, North Carolina. These data, placed in the context of geospatial data derived from ground penetrating radar, were developed into a stratigraphic model for this sedimentary environment. The model was applied to vibracores collectedAuthorsC.G. Smith, S.J. Culver, D. J. Mallinson, S.R. Riggs, D.R. CorbettNon-USGS Publications**
Cable, J.E., Smith, C.G., Blanford, W.J. 2009. Dispersivity and distribution coefficients in marine sediments using Tritium and Radium-226. Radioprotection, 44:185-190.Smith, C.G., Cable, J.E., Martin, J.B., and Roy, M. 2008. Evaluating the source and seasonality of submarine groundwater discharge using a Radon-222 pore water transport model, Earth and Planetary Science Letters 273:312-322.Culver, S.J., Grand Pre, C., Mallinson, D., Riggs, S., Corbett, D.R., Foley, J., Hale, M., Ricardo, J., Rosenberger, J., Smith, C.G., Smith, C.W., Snyder, S., Twamley, D., Farrell, K., Horton, B. 2007. Late Holocene barrier island collapse: Outer Banks, North Carolina, U.S.A. The Sedimentary Record 5:4-8.Smith, C.G., Cable, J.E., Martin, J.B. 2008. Episodic high intensity mixing events in a subterranean estuary: Effects of tropical cyclones, Limnology and Oceanography 53:666-674.Smith, C.G., Culver, S.J., Riggs, S.R., Ames, D., Corbett, D.R., Mallinson, D.J. 2008. Geospatial analysis of barrier island width of two segments of the Outer Banks, North Carolina, USA: anthropogenic curtailment of natural self-sustaining processes. Journal of Coastal Research 24:70-83.Martin, J.B., Cable, J., Smith, C.G., Roy, M. and Cherrier, J. 2007. Magnitudes of submarine groundwater discharge from marine and terrestrial sources: Indian River Lagoon, Florida. Water Resources Research 43: doi:10.1029/2006WR005266.Smith, C.G., Cable, J.E., Martin, J.B., Cherrier, J., and Roy, M. 2006. Mixing in the subterranean estuary: a comparison of Radon-222 pore water models. p. 355-368, In V. P. Singh and Y. J. Xu [eds.], Annual American Institute of Hydrology Meeting & International Conference: Challenges in Coastal Hydrology and Water Quality. Water Resources Publications, LLC, 534 pp.Martin, J.B., Cable, J.E., Jaeger, J., Hartl, K.M., and Smith, C.G. 2006. Thermal and chemical evidence for rapid water exchange across the sediment-water interface by bioirrigation in the Indian River Lagoon, Florida. Limnology and Oceanography 51:1332-1341.Culver, S.J., Ames, D.V., Corbett, D.R., Malllinson, D., Riggs, S.R., Smith, C.G., and Vance, D. 2005. Foraminiferal and sedimentary record of late Holocene barrier island evolution, Pea Island, North Carolina. Journal of Coastal Research 21:406-416.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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