Christopher G Smith
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.
Science and Products
Hurricane Sandy Response- Linking the Delmarva Peninsula's Geologic Framework to Coastal Vulnerability
The Delmarva Peninsula is a 220-kilometer-long headland, spit, and barrier island complex that was significantly affected by Hurricane Sandy. In order to better constrain controls on coastal vulnerability and evolution, the region’s sediment sources, transport pathways and sediment sinks must be identified. This project defines the geologic framework of the Delmarva coastal system through...
This project assesses the physical controls of sediment and material exchange between wetlands and estuarine environments along the northern Gulf of Mexico (Grand Bay Alabama/Mississippi and Vermilion Bay, Louisiana) and the Atlantic coast (Chincoteague Bay, Virginia/Maryland).
Assessing the impact of open-ocean and back-barrier shoreline change on Dauphin Island, Alabama, at multiple time scales over the last 75 years
Dauphin Island and Little Dauphin Island, collectively, make up a geomorphically complex barrier island system located along Alabama’s southern coast, separating Mississippi Sound from the Gulf of Mexico and Mobile Bay. The barrier island system provides numerous economical (tourism, fisheries) and natural (habitat for migratory birds, natural...Smith, Christopher G.; Long, Joseph W.; Henderson, Rachel E.; Nelson, Paul R.
The effects of tropical cyclone-generated deposition on the sustainability of the Pearl River marsh, Louisiana: The importance of the geologic framework
Shoreline retreat is a tremendously important issue along the coast of the northern Gulf of Mexico, especially in Louisiana. Although this marine transgression results from a variety of causes, the crucial factor is the difference between marsh surface elevation and rising sea levels. In most cases, the primary cause of a marsh's inability to keep...McCloskey, Terrence A.; Smith, Christopher G.; Liu, Kam-Biu; Nelson, Paul R.
Barrier-island and estuarine-wetland physical-change assessment after Hurricane Sandy
IntroductionThe Nation’s eastern coast is fringed by beaches, dunes, barrier islands, wetlands, and bluffs. These natural coastal barriers provide critical benefits and services, and can mitigate the impact of storms, erosion, and sea-level rise on our coastal communities. Waves and storm surge resulting from Hurricane Sandy, which made landfall...Plant, Nathaniel G.; Smith, Kathryn E.L.; Passeri, Davina L.; Smith, Christopher G.; Bernier, Julie C.
The sedimentological characteristics and geochronology of the marshes of Dauphin Island, Alabama
In August 2015, scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center collected 11 push cores from the marshes of Dauphin Island and Little Dauphin Island, Alabama. Sample site environments included high marshes, low salt marshes, and salt flats, and varied in distance from the shoreline. The sampling efforts...Ellis, Alisha M.; Smith, Christopher G.; Marot, Marci E.
How could a freshwater swamp produce a chemical signature characteristic of a saltmarsh?
Reduction–oxidation (redox) reaction conditions, which are of great importance for the soil chemistry of coastal marshes, can be temporally dynamic. We present a transect of cores from northwest Florida wherein radical postdepositional changes in the redox regime has created atypical geochemical profiles at the bottom of the sedimentary column....McCloskey, Terrence A.; Smith, Christopher G.; Liu, Kam-biu; Marot, Marci E.; Haller, Christian
Single-beam bathymetry data collected in 2015 from Grand Bay, Alabama-Mississippi
As part of the Sea-level and Storm Impacts on Estuarine Environments and Shorelines (SSIEES) project, scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center conducted a single-beam bathymetry survey within the estuarine, open-bay, and tidal creek environments of Grand Bay, Alabama-Mississippi, from May...DeWitt, Nancy T.; Stalk, Chelsea A.; Smith, Christopher G.; Locker, Stanley D.; Fredericks, Jake J.; McCloskey, Terrence A.; Wheaton, Cathryn J.
A seasonal and spatial comparison of metals, and stable carbon and nitrogen isotopes, in Chincoteague Bay and the marsh deposits of Assateague Island and the adjacent vicinity, Maryland and Virginia
After Hurricane Sandy, scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center conducted a seasonal collection of estuarine, marsh, and sandy overwash surface sediments from Chincoteague Bay, Tom’s Cove, and the surrounding Assateague Island and Delmarva Peninsula in March–April and October 2014. Surplus...Ellis, Alisha M.; Smith, Christopher G.
Distribution of foraminifera in Chincoteague Bay and the marshes of Assateague Island and the adjacent vicinity, Maryland and Virginia
Scientists from the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center conducted a seasonal collection of estuarine, marsh, and sandy washover surface sediments from Chincoteague Bay, Tom’s Cove, and the surrounding Assateague Island and Delmarva Peninsula in March–April and October 2014, after Hurricane Sandy....Ellis, Alisha M.; Shaw, Jaimie; Osterman, Lisa E.; Smith, Christopher G.
The magnitude and origin of groundwater discharge to eastern U.S. and Gulf of Mexico coastal waters
Fresh groundwater discharge to coastal environments contributes to the physical and chemical conditions of coastal waters, but the role of coastal groundwater at regional to continental scales remains poorly defined due to diverse hydrologic conditions and the difficulty of tracking coastal groundwater flow paths through heterogeneous subsurface...Befus, Kevin; Kroeger, Kevin D.; Smith, Christopher G.; Swarzenski, Peter W.
Archive of sediment physical properties and grain-size data for sediment samples collected offshore of Assateague Island, Maryland and Virginia:
This data release serves as an archive of sediment physical properties and grain-size data for surficial samples collected offshore of Assateague Island, Maryland and Virginia, for comparison with surficial estuarine and subaerial sedimentological samples collected and assessed following Hurricane Sandy (Ellis and others, 2015; Smith and others,...Ellis, Alisha M.; Wheaton, Cathryn J.; Smith, Christopher G.
Hydrological data concerning submarine groundwater discharge along the western margin of Indian River Lagoon, east-central Florida - December 2016 and January 2017
Indian River Lagoon, one of the most biologically diverse estuarine systems in the continental United States, is a shallow brackish lagoon stretching along approximately 200 kilometers (km) of the Atlantic coast of central Florida. Lagoon width varies from ~0.5 – 9.0 km, with substantial human infrastructure lining both shores. Scientists from the...McCloskey, Terrence A.; Smith, Christopher G.; Zaremba, Nicholas; McBride, Elsie; Everhart, Cheyenne
Seasonal sedimentary data collected from Old Tampa Bay, Florida, 2015–2016
The toxic dinoflagellate Pyrodinium bahamense (P. bahamense) produces recurring, persistent summer algal blooms in Old Tampa Bay, Florida, which degrade water quality and are potentially harmful to humans if contaminated shellfish is consumed. As part of its life cycle, P. bahamense produces dormant cysts, which settle to the...Marot, Marci E.; Wheaton, Cathryn J.; Smith, Christopher G.