Category: Research Sponsored by GWRI

Principal Investigator: Todd Rasmussen (University of Georgia)

Sponsor: GWRI
Start Date: 1999-03-01; Completion Date: 2000-02-29;
Keywords: Geomorphological and Geochemical processes, Climate and Hydrologic processes, Non Point Pollution, Sediments

Problem and Research Objectives:

Sediment in streams and lakes within the Southeast adversely affects aquatic habitats and presents a substantial health hazard by reducing the clarity of water, thus reducing biologic productivity. Coarse suspended solids also bury benthic habitats, thus diminishing overall species abundance and diversity. The ecological consequences of sediments in streams have been particularly detrimental to Georgia’s native aquatic species. Additional consequences result from sediment transport. Nonpoint pollutant inputs to streams such as nutrients, metals, herbicides, insecticides, and fecal coliform are highly correlated with sediment inputs. The long term human and environmental health consequences from these non point sources are clearly a matter of local, regional, and national concern. Incomplete data limit the understanding of modern and historical sediment transport rates and inventories of Georgia Piedmont streams. A better understanding of historical and modern inputs provides the opportunity for identifying alternative management strategies for nonpoint pollution control that reduce or eliminate future environmental and health risks. The project investigated a multi-pronged approach for estimating the magnitude and distribution of suspended and bedload sediments.

Principal Investigator: Terry W. Sturm (Georgia Tech)

Sponsor: GWRI
Start Date: 1999-03-01; Completion Date: 2000-02-29;
Keywords: Climate and Hydrologic processes, Geomorphological and Geochemical processes, Sediments, Models

Problem and Research Objectives:

Continued development in urban watersheds without adequate controls on sediment production from construction activities contributes sediment load to urban streams that may affect its sediment regime. Subsequent deposition of the sediment chokes the benthic aquatic habitat, and affects storage in the channel and floodplain and thus the flooding potential of the stream. In addition, urbanization creates a greater volume of runoff and higher peak flows with a different timing than exists prior to urbanization. These higher flows may contribute to bank erosion in some stream reaches and deposition further downstream. The result is again a change in geometry and sediment regime of the natural stream with consequent adverse affects on aquatic habitat and stream water quality. Furthermore, the deposited finer-grained sediments from urbanized areas may carry with them attached contaminants that are subject of resuspension during subsequent flood conditions. While much work has been done on urban hydrology to predict changes in runoff characteristics due to urbanization, much less attention has been paid to the closely related sediment effects and the changes that they cause in flooding potential and water quality of the recieving stream over the entire watershed. The research project provides a case study of an urban stream to distinguish sediment contributions from watershed development and bank erosion, resultant changes in floodpain and channel storage, and the final effect on flood routing and thus flooding potential as well as movement of sediment-bound contaminants through the watershed system. In addition, a methodology has been developed that can be applied to other urban streams to predict the effects of urban development not just on the hydrology of the watershed, but on its sedimentology as well. As a result of the study, recommendations will be made on the relative efficacy of specific control measures such as best-management practices on contruction sites to limit sediment yield, artificially-created wetlands for aditional floodplain and sediment storage, streambank stabilization, vegetative buffer zones along the stream, and strict constols on development of the floodplain. This methodology allows decision makers to make more informed watershed-wide decisions rather than piecemeal approval and disapproval of particular development projects.

Principal Investigator: David Wenner (University of Georgia)

Sponsor: GWRI
Start Date: 1999-03-01; Completion Date: 2000-02-29;
Keywords: Groundwater Flow and Transport, Geomorphological and Geochemical processes, Groundwater, Nitrate Contamination

Problem and Research Objectives:

The presence of nitrate in groundwater in the Floridan Aquifer near Albany Georgia has prompted an investigation using nitrogen isotopic data to identify the source contamination. It is thought that the contamination originates from a farm and that nitrates were transported by groundwater flow to an adjacent residential community. This community’s water supply comes from homeowner wells, some of which exceed the MCL for nitrate in drinking water. A variety of materials capable of producing this contamination, such as cattle manure, biosolids (sewage sludge), and synthetic inorganic fertilizers are present or have been used on this farm. Biosolids were utilized as fertilizers over a twelve year period from 1984 to 1996 and a cattle feed lot was in operation from 1980-1984. Synthetic inorganic fertilizers were used prior to 1984. A hydrogeologic study conducted by the Georgia Geological Survey indicated that the most probable source of groundwater contamination is a disused cattle feed lot on the suspect property. To further assist in identifying the source of contamination, d15N values were measured for dissolved nitrate from nine wells both on the farm and within the residential community. The data from the contamination plume ranged from +5.5‰ to +2.3‰. This range is consistent with the idea that the major source of contamination stems from synthetic inorganic fertilizers. This conclusion is predicated on numerous studies indicating that different nitrate sources produce different ranges of d 15N values for dissolved nitrates. Typically, nitrates derived from inorganic fertilizers range from -5‰ to + 3.5‰, soil organic material from + 3.5‰ to +7.5‰, and manure and septic system effluent from +10‰ to +20‰. There are no known study of the d15N values of nitrates derived from biosolids. To reinforce this conclusion, d15N values were measured for grasses at sites where only cattle manure and biosolids were present. Analysis of plants serve as proxies for dissolved nitrate in soils because there is little or no isotope fractionation between plants and the dissolved nitrate that they uptake. The aim of this investigation was to directly assess the d15N values of dissolved nitrates in soils derived from decomposition of cattle manure and sewage sludge. A second investigation was initiated in order to constrain the age of nitrate contamination by measuring the tritium concentration of groundwaters within the area.

Principal Investigator: Aris Georgakakos (GWRI/Georgia Tech)      About…

Sponsor: GWRI
Start Date: 1998-07-01; Completion Date: 1999-12-31;
Keywords: Climate and Hydrologic Processes, Hydrology, Management and Planning
Problem and Research Objectives:

Climate variability and change pose both challenges and opportunities for the US. To be better prepared, the United States has developed a national assessment process to identify and analyze the potential consequences of climate variability and change.

Principal Investigator: Aris Georgakakos (GWRI/Georgia Tech)

Sponsor: GWRI
Start Date: 1998-12-01; Completion Date: 1999-07-31;
Keywords: Hydrology, Management and Planning, Drought

Problem and Research Objectives:

This project intends at developing a state-of-the-art river basin planning and management system that can (a) assess the potential of the ACF basin to meet various water uses, and (b) quantify the trade-offs associated with various water allocation scenarios and policies. The purpose of this system is to assist the ongoing tri-state (Alabama, Florida, and Georgia) water allocation negotiation. The project is co-sponsored by citizen groups in Georgia.

Principal Investigator: Aris Georgakakos (GWRI/Georgia Tech)

Sponsor: GWRI
Start Date: 1997-08-01; Completion Date: 1999-06-30;
Keywords: Climate and Hydrologic processes, Hydrology, Management and Planning
Problem and Research Objectives:

This project aims at demonstrating the value of climate and hydrologic forecasts on the operation of multi-purpose reservoirs in the US.

Short Course

Instructor: Huaming Yao (GWRI/Georgia Tech)
Instructor: Aris Georgakakos (GWRI/Georgia Tech)

Sponsor: GWRI

Principal Investigator: J. Owens Smith (University of Georgia)

Sponsor: GWRI
Start Date: 1996-06-01; Completion Date: 1996-06-01;
Keywords: interstate water law, interstate compacts, common law water rights

Description:

In a predictable and inevitable demonstration of frustration with increasing tensions over interstate water allocation circumstances, Alabama brought suit in federal court against Georgia. This action precipitated formation of cooperative study efforts among the states of Georgia, Alabama, and Florida and the U.S. Army Corps of Engineers to provide the factual basis for an intersate mechanism through which the shares waters could be equitably allocated.

The impetus for cooperation was derived from the realization that the alternate methods of allocation-equitable apportiuonment, Congressional apportionment, and allocation via the dormant commerce clause – were all less acceptable to the states.

Georgia entered the negotiations with a long history of water allocation litigation as well as recent legislative efforts to alter historical tenants of state surface and groundwater law.

Principal Investigator: Diana L. Bittner (Georgia Institute of Technology)
Principal Investigator: Greta Olsen (Georgia Institute of Technology)
Principal Investigator: Kenneth D. Hughes (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1995-04-01; Completion Date: 1996-04-01;
Keywords: fluorescence, rapid toxicity assays, enzyme activity, selectivity

Description:

The use of microorganisms and small aquatic organisms as monitors of water and sediment quality is increasing and therefore the development of improved methodology and new technologies that facilitate the handling of these organisms is a high priority. Methodological changes that have occurred in the last several years have included a concerted effort to monitor changes in organism health at the molecular level. This is in stark contrast to assays that simply measure a single data point such as the LC50. The ultimate goal in these molecular level assays is to rapidly ascertain the very first sign of stress in an organism exposed to a water or sediment based toxicant. One of the first indicators of stress in many organisms is a perturbation in enzyme activity associated with metabolism or detoxification. Perturbations in enzyme activity may be monitored with high sensitivity by utilizing fluorescence techniques.
Design of rapid toxicity assays for accessing water and sediment quality demands simple experimental protocols that do not involve complicated fluorogenic substrate delivery mechanisms, time consuming steps for the separation and isolation of the resulting fluorophore, and expensive fluorescence intensity measurement instrumentation. Improvements in any one of these areas ultimately translate into more sensitive and reliable ecological data. Recently, fluorogenic substrates incorporating micron-diameter polymeric particles have been synthesized and investigated as a novel means of quantitating enzyme activity in the digestive tract of microorganisms. This project involved obtaining initial experimental evidence that this new technology (enzyme probes) can reduce, and in some cases eliminate, the limitations of using soluble enzyme substrates for toxicity measurements in whole organisms. Brachionus calyciflorous (rotifer) and Nannochloris (green algae) were used in these studies. It was clearly demonstrated that the enzyme probes based upon micron-diameter particles could be ingested by the rotifers, facilitating simultaneous measurement of ingestion rate and enzyme activity. These enzyme probes, however, were not accessible to the Nannochloris cells. These results provide evidence that enzyme probes based upon microndiameter particles will be useful in the targeting of rotifers and similar organisms in the presence of single cell organisms in aquaculture and field samples.

Principal Investigator: A. Amirtharajah (Georgia Institute of Technology)
Principal Investigator: Rasheed Ahmad (Georgia Institute of Technology)

Sponsor: GWRI
Start Date: 1994-04-01; Completion Date: 1996-03-01;
Keywords: Water Treatment, Biofilms, Microbial Detachment, Hydrophobicity, Hydrophobic Interaction, Biological Filtration, Backwashing, Bed Expansions, Air Scour

Description:

There is a strong interest in biological processes for drinking water treatment stemming from recent regulations on pathogenic protozoa and disinfection by-products. By operation of filters in the biological mode, it is possible to obtain a water with low assimilable organic carbon (AGC) and hence prevent significant growth of biofilms in the distribution systems. Since granular activated carbon (GAC) biological filters accumulate both biological and non-biological particles on the filter bed, the differences in the detachment of these groups of particles during backwashing will be an important aspect of operation of these filters. The objectives of present study include determination of effluent quality of biological filters, comparison of biological particle detachment with non-biological particles during filter backwashing, determination of the impact of different fluidized bed expansions on bacterial detachment, impact of water wash by fluidization, air scqur and chlorinated backwash on filtration performance and analysis of these experimental results in terms of a microscopic force model. The filtration and backwashing experiments were completed in a packed glass column with GAC/sand media and an indigenous bacterial population. The operation of a biological filter was simulated by using filter influent water from the nearby Water Treatment Plant with the addition of a carbon source. In biological filters, the effluent microbial counts were considerably higher than that of influent. To develop a valid microscopic force model for microbial detachment, the hydrophobic force must be included in the total force calculations. Hydrophobic colloids produce a deeper primary minimum as compared to hydrophilic colloids. Consequently, hydrophobic bacteria are far more strongly attached to the GAC surface as compared to hydrophilic clay particles. During backwash of a biological filter, the maximum turbidity occurs close to zero time in contrast to the maximum microbial detachment which occurs later. A sixty percent bed expansion produced maximum bacterial removal. Water washed filters even at optimum porosity build up excessive headloss over successive filter runs. The biological filters backwashed with a combination of air plus subfluidization water flow at collapse-pulsing followed by water wash with 20% bed expansion produced not only lower headloss but also little headloss build up over successive runs.