Grantee Research Project Results
Final Report: A Multidisciplinary Approach to Quantify and Model the Transport and Deposition of Organic Pollutants in Coastal Environments: Science and Engineering Environmental Research (SEER) Project #1
EPA Grant Number: R829424E02Title: A Multidisciplinary Approach to Quantify and Model the Transport and Deposition of Organic Pollutants in Coastal Environments: Science and Engineering Environmental Research (SEER) Project #1
Investigators: Goni, Miguel , Ferry, John L. , Voulgaris, George
Institution: University of South Carolina at Columbia
EPA Project Officer: Chung, Serena
Project Period: October 1, 2001 through September 30, 2003
Project Amount: $198,993
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2000) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
Objective:
The specific scientific objective of this research project was to examine the dynamics between flow, sediment resuspension, and bound particle substances in the estuarine environment. We proposed to measure the fluxes of water, suspended sediments, and dissolved, colloid-bound, and particle-bound substances in Winyah Bay, South Carolina. With these data, we planned to estimate the residence time of polycyclic aromatic hydrocarbons (PAHs) in this estuary and estimate the impact of photochemical degradation of PAHs on the total estuarine loading. Finally, we determined the sources of PAHs and their carrying phases in Winyah Bay and integrated our measurements in the new three-dimensional U.S. Environmental Protection Agency (EPA) model, the Environmental Fluid Dynamics Code.
Summary/Accomplishments (Outputs/Outcomes):
The findings from the Science and Engineering Environmental Research (SEER) Project #1 include new understanding of the physical controls in the circulation and sediment transport within Winyah Bay. Semidiurnal tide (M2) is the predominant constituent throughout the estuary. The amplitudes of diurnal (K1) and quarterdiurnal (M4) constituents are 10-20 percent of that of M2, which cause diurnal inequality and tidal asymmetry, respectively. The phase differences between M2 (semidiurnal) and M4 (quarterdiurnal) components denote ebb-dominating conditions up stream from the northern junction. In the middle estuary, the surface layer is governed by ebb-dominant tidal regime, whereas flood dominance is observed in the bottom layer. The results of the bay mouth show ebb dominance within the channel and flood dominance over the bank. This tidal asymmetry reinforces residual currents in the middle and lower estuary. Residual currents in the upper and middle part of Winyah Bay Estuary are directed landward near the bed and seaward near the surface in accordance with the traditional gravitational estuarine circulation. The residual circulation differs from one channel to another in the middle part of the estuary that consists of the main deep (8.2 m) channel to the east and a shallower (5 m) western channel. The seaward residual flow near the surface is stronger in the western channel than in the main channel. Near the bed, the residual flow is directed landward, and it is stronger in the main channel than in the western channel. Overall, the deeper, dredged main channel acts as a conduit for landward delivery of salt water, whereas the surface riverine water flows out through the shallow western channel. Near the bay mouth, the residual currents in the channel are seaward for the whole water column, whereas the residual flow on the channel bank is landward.
In terms of the contaminant transport and behavior within the estuary, particle-associated total PAH concentrations from the water column in the Winyah Bay stations ranged from 0.05 to 2 µg/L of water (0.05 to 2 ppb). The generally low levels of PAHs measured in the water column may be in a large part due to the low total suspended sediment concentrations that characterized the extremely low discharge periods of our study (October 2001 and May 2002). The PAH analyses showed a direct positive relationship between particle-bound PAH concentrations and current magnitude and directions, with the highest concentrations (> 1 µg/L) occurring when the flood tidal current exceeded 40 cm/second. In contrast, slack water and ebb conditions were typically characterized by low particle-bound PAH concentrations, with concentrations less than 0.5 mg/L typically measured during periods when the ebb tidal current exceeded 40 cm/second. The higher particle-bound PAH concentrations during maximum flood were consistent with the trends observed in total suspended sediments (TSS) and particulate organic carbon (POC) concentrations. TSS and POC showed a strong positive relationship with current magnitude and direction, with the highest concentrations measured during peak flood. Overall, net landward fluxes of TSS, POC, and particulate nitrogen were measured over two tidal cycles, indicating a significant input of organic material from the lower reaches of the bay towards the estuarine turbidity maximum in Winyah Bay during low discharge.
The trends in PAH concentrations, however, are not entirely caused by the presence of higher total suspended sediment concentrations in the water column during the flood tide. In fact, during maximum flood, the particles isolated from the water column display higher carbon-normalized PAH concentrations than those particles collected during the ebbing tide. What these findings suggest is that during the flood tide, the particle pool mobilized by the current is not only greater than during the ebb tide but also contains higher pollutant content. We hypothesize that this is in part a result of the fact that there was a net transport of organic matter-enriched particles from the lower reaches of the estuary to its upper part during the period when we made our measurements. The carbon-rich particles are probably finer in size and greater in surface area and contain higher loadings of pollutants. Overall, our results suggest that during the low discharge conditions that characterized the October 2001 and May 2002 field campaigns, there was a net landward transport of pollutants along the estuary.
Conclusions:
Overall, considering inter- and intratidal variation in hydrographic and hydrodynamic conditions, net flux of water and sediment was examined in the upper and middle parts of the estuary. General landward flux of water and sediment for the study area implies import of sediment in suspension as well as particle-related contaminant materials (PAHs) and POC during low river discharge conditions.
Journal Articles on this Report : 5 Displayed | Download in RIS Format
Other project views: | All 19 publications | 6 publications in selected types | All 5 journal articles |
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Goni MA, Cathey MW, Kim YH, Voulgaris G. Fluxes and sources of suspended organic matter in an estuarine turbidity maximum region during low discharge conditions. Estuarine Coastal and Shelf Science 2005;63(4):683-700. |
R829424E02 (Final) |
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Kim YH, Voulgaris G. Effect of channel bifurcation on residual estuarine circulation: Winyah Bay, South Carolina. Estuarine Coastal and Shelf Science 2005;65(4):671-686. |
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Styles R, Glenn SM. Modeling bottom roughness in the presence of wave-generated ripples. Journal of Geophysical Research-Oceans 2002;107(C8):24-1--24-15. |
R829424E02 (2003) R829424E02 (Final) |
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Styles R, Glenn SM. A theoretical investigation of bed-form shapes. Ocean Dynamics 2003;53(3):278-287. |
R829424E02 (2003) R829424E02 (Final) |
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Styles R, Glenn SM. Long-term sediment mobilization at a sandy inner shelf site, LEO-15. Journal of Geophysical Research-Oceans 2005;110(C4):04S90, doi:10.1029/2003JC002175. |
R829424E02 (2003) R829424E02 (Final) |
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Supplemental Keywords:
sediment transport, contaminant transport, estuarine circulation, organic matter, organic contaminants, environmental chemistry, monitoring, analytical surveys, measurement methods, general circulation models, discharge, southeast, Atlantic coast, Winyah Bay, South Carolina,, RFA, Scientific Discipline, Waste, Water, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Contaminated Sediments, Environmental Chemistry, State, Fate & Transport, chemical mixtures, Ecology and Ecosystems, aquatic life, biogeochemical partitioning, aquatic ecosystem, fate and transport, organic pollutants, contaminant transport, erosion, predictive understanding, resuspension, sediment transport, transport contaminants, bioavailability, contaminated sediment, PAH, modeling, aquatic ecosystems, South Carolina (SC), ecology assessment models, aquatic biota, ecological researchRelevant Websites:
http://www.scepscoridea.org/index.html Exit
http://www.geol.sc.edu/gvoulgar/cpsdlab.html Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.