Friday's sessions--Section III: Earth and atmospheric sciences

Georgia Journal of Science, 2002

104 Herty Hall

Gian S. Ghuman, Presiding

1:15 VARIATION IN THE CHEMICAL COMPOSITION OF COASTAL WATERS, Gian S. Ghuman, Kailash Chandra, Kenneth S. Sajwan and S. Paramasvian, Savannah State University, Savannah, GA 31404. Two water samples from Savannah and Thunderbolt Cities domestic water supplies and eight surface water samples from Lake Meyer, Savannah River and its distributaries terminating in the Atlantic Coast were analyzed for the chemical composition. Metal concentrations were determined by the ICP-OES method and the dissolved salts were measured by gravimetric analysis. Results were compared with the composition of these waters observed 26 years ago. All samples showed the same pH as in the past. An appreciable increase occurred in the salinity of the ocean and tidal waters, however, the fresh surface and domestic water samples showed a slight decrease in the dissolved salts and metal concentrations. The high water mark of the ocean tide extended backwards into the river, indicating a rise in the ocean level. In this presentation variation in the chemical composition of domestic waters and coastal fresh waters, and possibly attributing factors for change will be discussed.

1:30 USING HISTORICAL MAPS TO QUANTIFY SHORELINE CHANGE, Anna J. Austin*, Emily A. Polonus, Susan K. Langley and Clark R. Alexander, Department of Geology and Geography, Georgia Southern University, Statesboro, GA 30460. Human development may accelerate erosional and depositional processes on barrier islands. Our goal was to quantify long-term (decades to centuries) and recent short-term (year to decade) rates of shoreline change for Georgia barrier islands in order to identify and quantify erosion and accretion sites, and spatial and temporal trends in shoreline change. Historical, non-photographic shoreline data from topographic survey sheets (T-sheets) were georeferenced and digitized for use in the shoreline change analysis. We developed protocols for onscreen registration and digitization of 60 T-sheets of the study region. The database produced from the T-sheets includes a series of maps showing the positions of historical shorelines (e.g. mid 1800s, late 1800s, and early 1900s). Preliminary erosion estimates for three of the developed barrier islands (St. Simon's, Jekyll and Tybee Islands) indicate that the degree of development may influence the magnitude of erosional and depositional processes.

1:45 LIVING WITH KARST: A PRELIMINARY STUDY OF THE KARSTIC FEATURES OF BERRY COLLEGE, Chris Faulkner* and Deborah Freile, Berry College, Mt. Berry, GA 30149. Berry College is located in the Valley and Ridge province of Northwest Georgia. Folded and faulted Paleozoic sedimentary strata underlie this area. The main campus of Berry rests on top of Cambrian shales with some interbedded limestone beds and the Mississippian Floyd Shale. The Floyd Shale has a basal limestone unit that only outcrops in a few areas. Some of these areas have been actively quarried for years. This calcium-rich limestone is the one that contains the bulk of the karst features visible at Berry College. Old as well as active dolines or sinkholes dot the Berry campus. These sinkholes typically form along joint sets. To date over 27 sinkholes have been measured. They range in size from 50.6 meters to 0.75 m on the long axis and 36.4 m to 0.5 m on the short axis with a mean of 12.1 meters and 8.3 m respectively. Most of the sinkholes are observed to form along the same roughly N-S trend. To date, Berry College has spent millions of dollars on repair work for building foundations. As the need to construct more buildings arises, it would be beneficial for the college to have an accurate geologic map delineating the zones of major limestone outcrops as observed through sinkhole mapping and joint set patterns within the limestone units. These data will hopefully be used to create a hazards map to use in future planning for buildings and other structures.

Bill Wall, Presiding

2:00 THE INFLUENCE OF WATER, CLAY, TEMPERATURE AND CARBONATE MINERALS ON SOIL ELECTRICAL CONDUCTIVITY READINGS TAKEN WITH AN EM-38 IN CENTRAL IOWA, Eric C. Brevik and Thomas E. Fenton, Valdosta State University, Valdosta, GA 31698-0055 and Iowa State University, Ames, IA 50011. There has been considerable interest in using soil electrical conductivity (EC) as a soil survey tool in the Midwest. EC is determined by a combination of soluble salts, clay content and mineralogy, soil water content, and soil temperature. We measured EC, water content, and temperature along a Mollisol catena in Boone County, Iowa approximately once every two weeks from May-September 200. Water content was determined gravimetrically to a depth of 0.9 m, temperature with a type T thermocouple to a depth of 0.6 m, and EC with a Geonics(R) EM-38. Clay and carbonate content were determined to a depth of 0.9 m. Data was analyzed using multiple regressions. Soil water content has the greatest influence on EC, followed by clay content, carbonate content, and temperature. The regression coefficient for soil water content is an order of magnitude greater than the other coefficients, and the carbonate coefficient is negative.