Geology topics

E. T. Oaksford

Publications and source records attributed to E. T. Oaksford.

6 recordsLinked to original sources

USGS1997

A comparison of drainage basin nutrient inputs with instream nutrient loads for seven rivers in Georgia and Florida, 1986-90

Instream nutrient loads of the Altamaha, Suwannee, St. Johns, Satilla, Ogeechee, Withlacoochee, and Ochlockonee River Basins were computed and compared with nutrient inputs for each basin for the period 1986-90. Nutrient constituents that were considered included nitrate, ammonia, organic nitrogen, and total phosphorus. Sources of nutrients considered for this analysis included atmospheric deposition, fertilizer, animal waste, wastewater-treatment plant discharge, and septic discharge. The mean nitrogen input ranged from 2,400 kilograms per year per square kilometer (kg/yr)km2 in the Withlacoochee River Basin to 5,470 (kg/yr)km2 in the Altamaha River Basin. The Satilla and Ochlockonee River Basins also had large amounts of nitrogen input per unit area, totaling 5,430 and 4,920 (kg/yr)km2, respectively. Fertilizer or animal waste, as sources of nitrogen, predominated in all basins. Atmospheric deposition contributed less than one-fourth of the mean total nitrogen input to all basins and was consistently the third largest input in all but the Ogeechee River Basin, where it was the second largest. The mean total phosphorus input ranged from 331 (kg/yr)km2 in the Withlacoochee River Basin to 1,380 (kg/yr)km2 in both the Altamaha and Satilla River Basins. The Ochlockonee River Basin had a phosphorus input of 1,140 (kg/yr)km2. Per unit area, the Suwannee River discharged the highest instream mean total nitrogen and phosphorus loads and also discharged higher instream nitrate loads per unit area than the other six rivers. Phosphorus loads in stream discharge were highest in the Suwannee and Ochlockonee Rivers. The ratio of nutrient outputs to inputs for the seven studied rivers ranged from 4.2 to 14.9 percent, with the St. Johns (14.9 percent) and Suwannee (12.1 percent) Rivers having significantly higher percentages than those from the other basins. The output/input percentages for mean total phosphorus ranged from 1.0 to 7.0 percent, with the St. Johns (6.2 percent) and Suwannee (7.0 percent) Rivers exporting the highest percentage of phosphorus. Although instream nutrient loads constitute only one of the various pathways nutrients may take in leaving a river basin, only a relatively small part of nutrient input to the basin leaves the basin in stream discharge for the major coastal rivers examined in this study. The actual amount of nutrient transported in a river basin depends on the ways in which nutrients are physically handled, geographically distributed, and chemically assimilated within a river basin.

Florida, Georgia↗

USGS1997

Spring contributions to water quantity and nitrate loads in the Suwannee River during base flow in July 1995

The Suwannee River flows through an area of north-central Florida where ground water has elevated nitrate concentrations. A study was conducted to determine how springs and other ground-water inflow affect the quantity and quality of water in the Suwannee River. The study was done on a 33-mile (mi) reach of the lower Suwannee River from just downstream of Dowling Park, Fla., to Branford, Fla. Water samples for nitrate concentrations (dissolved nitrite plus nitrate as nitrogen) and discharge data were collected at 11 springs and 3 river sites during the 3-day period in July 1995 during base flow in the river. In the study reach, all inflow to the river is derived from ground water. Measured springs and other ground-water inflow, such as unmeasured springs and upward diffuse leakage through the riverbed, increased the river discharge 47 percent over the 33-mi reach. The 11 measured springs contributed 41 percent of the increased discharge and other ground-water inflow contributed the remaining 59 percent. River nitrate loads increased downstream from 2,300 to 6,000 kilograms per day (kg/d), an increase of 160 percent in the 33-mi study reach. Measured springs contributed 46 percent of this increase and other ground-water inflow contributed the remaining 54 percent. The study reach was divided at Luraville, Fla., into an 11-mi upper segment and a 22-mi lower segment to determine whether the ground-water inflows and nitrate concentrations were uniform throughout the entire study reach (fig. 1). The two segments were dissimilar. The amount of water added to the river by measured springs more than tripled from the upper to the lower segment. Even though the median nitrate concentration for the three springs in the upper segment (1.7 milligrams per liter (mg/L)) was similar to the median for the eight springs in the lower segment (1.8 mg/L), nitrate concentrations in the river almost doubled from 0.46 to 0.83 mg/L in the lower segment. Only 11 percent of the increase in nitrate load for the study reach occurred in the upper segment; the remaining 89 percent occurred in the lower segment. Measured springs were the major source of nitrate load in the upper reach and other ground-water inflow was the major source in the lower segment. Differences in nitrate loads between the upper and lower river segments are probably controlled by such factors as differences in the magnitude of the spring discharges, the size and location of spring basins, and the hydrologic characteristics of ground water in the study area.

Florida↗

USGS1996

Environmental setting and factors that affect water quality in the Georgia-Florida Coastal Plain study unit

The Georgia-Florida Coastal Plain study unit covers an area of nearly 62,000 square miles in the southeastern United States, mostly in the Coastal Plain physiographic province. Land resource provinces have been designated based on generalized soil classifications. Land resource provinces in the study area include: the Coastal Flatwoods, the Southern Coastal Plain, the Central Florida Ridge, the Sand Hills, and the Southern Piedmont. The study area includes all or parts of seven hydrologic subregions: the Ogeechee-Savannah, the Altamaha- St.Marys, the Suwannee, the Ochlockonee, the St. Johns, the Peace-Tampa Bay, and the Southern Florida. The primary source of water for public supply in the study area is ground water from the Upper Floridan aquifer. In 1990, more than 90 percent of the 2,888 million gallons per day of ground water used came from this aquifer. The population of the study area was 9.3 million in 1990. The cities of Jacksonville, Orlando, St. Petersburg, Tallahassee, and Tampa, Florida, and parts of Atlanta and Savannah, Georgia, are located in the study area. Forest and agricultural areas are the most common land uses in the study area, accounting for 48 percent and 25 percent of the study area, respectively. Climatic conditions range from temperate in Atlanta, Georgia, where mean annual temperature is about 61.3 degrees Fahrenheit, to subtropical in Tampa, Florida, where mean annual temperature is about 72.4 degrees Fahrenheit. Long-term average precipitation (1961-90) ranges from 43.9 inches per year in Tampa, Florida, and 44.6 in Macon, Georgia, to 65.7 inches per year in Tallahassee, Florida. Floods in the study area result from frontal systems, hurricanes, tropical storms, or severe thunderstorms. Droughts are not common in the study area,especially in the Florida part of the study area due to extensive maritime exposure. The primary physical and cultural characteristics in the study area include physiography, soils and land resource provinces, geologic setting, ground-water systems, surface- water systems, climate, floods, droughts, population, land use, and water use. Factors affecting water quality in the study area are land use (primarily urban and agricultural land uses), water use in coastal areas, hydrogeology, ground-water/surface-water interaction, geology, and climate. Surface-water quality problems in urban areas have occurred in the Ogeechee, Canoochee, Ocmulgee, St. Marys, Alapaha, Withlacoochee (north), Santa Fe, Ochlockonee, St. Johns, and Oklawaha Rivers and include nitrogen and phosphorus loading, low dissolved oxygen, elevated bacteria, sediment, and turbidity, and increased concentrations of metals. In agricultural areas, surface-water quality problems include elevated nitrogen and phosphorus concentrations, erosion, and sedimentation and have occurred in the Ocmulgee, St. Marys, Santa Fe, Ochlockonee, St. Johns, Oklawaha, Withlacoochee (South), Hillsborough, and Alafia Rivers. Ground water-quality problems such as saltwater intrusion have occurred mostly in coastal areas and were caused by excessive withdrawals.

Florida, Georgia↗

USGS1995

Sampling design and procedures for fixed surface-water sites in the Georgia-Florida coastal plain study unit, 1993

The implementation of design guidelines for the National Water-Quality Assessment (NAWQA) Program has resulted in the development of new sampling procedures and the modification of existing procedures commonly used in the Water Resources Division of the U.S. Geological Survey. The Georgia-Florida Coastal Plain (GAFL) study unit began the intensive data collection phase of the program in October 1992. This report documents the implementation of the NAWQA guidelines by describing the sampling design and procedures for collecting surface-water samples in the GAFL study unit in 1993. This documentation is provided for agencies that use water-quality data and for future study units that will be entering the intensive phase of data collection. The sampling design is intended to account for large- and small-scale spatial variations, and temporal variations in water quality for the study area. Nine fixed sites were selected in drainage basins of different sizes and different land-use characteristics located in different land-resource provinces. Each of the nine fixed sites was sampled regularly for a combination of six constituent groups composed of physical and chemical constituents: field measurements, major ions and metals, nutrients, organic carbon, pesticides, and suspended sediments. Some sites were also sampled during high-flow conditions and storm events. Discussion of the sampling procedure is divided into three phases: sample collection, sample splitting, and sample processing. A cone splitter was used to split water samples for the analysis of the sampling constituent groups except organic carbon from approximately nine liters of stream water collected at four fixed sites that were sampled intensively. An example of the sample splitting schemes designed to provide the sample volumes required for each sample constituent group is described in detail. Information about onsite sample processing has been organized into a flowchart that describes a pathway for each of the constituent groups.

Florida, Georgia↗

USGS1989

Relation between land use and ground-water quality in the upper glacial aquifer in Nassau and Suffolk Counties, Long Island, New York

The chemical quality of groundwater in the upper glacial (water-table) aquifer beneath the 10 types of land-use areas of Nassau and Suffolk Counties, NY was examined to evaluate the effect of human activities on groundwater. The highest median chloride and total dissolved-solids concentrations were found in wells in high-density residential areas (more than five dwellings/acre), and the highest median nitrate, sulfate, and calcium concentrations were found in wells in agricultural and high density residential areas. Relatively low median concentrations of inorganic chemical constituents were found in wells in undeveloped and low-density residential areas (1 or fewer/acre): volatile organic compounds were rarely detected in these same areas. The highest concentrations and most frequent detection of volatile organic compounds were in industrial and commercial areas. The most commonly detected volatile organic compounds were 1,1,1-trichloroethane (24% of wells), tetrachloroethylene (20%), trichloroethylene (18%), chloroform (9%), and 1,2-dichloroethylene (5%). The spatial distributions of trichloroethylene, chloroform and other volatile organic compounds in the upper glacial aquifer are directly correlated with population density in the two-county area. (USGS)

Water-Resources Investigations Report↗

USGS1987

Hydrologic effects of artificial-recharge experiments with reclaimed water at East Meadow, Long Island, New York

Artificial recharge experiments were conducted at East Meadow, Long Island, New York, from October 1982 through January 1984 to evaluate the degree of groundwater mounding and the chemical effects of artificially replenishing the groundwater system with tertiary-treated wastewater. More than 800 million gallons of treated effluent was returned to the upper glacial aquifer through recharge basins and injection wells in the 15-month period. Reclaimed water was provided by the Cedar Creek advanced wastewater treatment facility in Wantagh, 6 miles away. The chlorinated effluent was pumped to the recharge facility, where it was fed to basins by gravity flow and to injection wells by pumps. Observations during the recharge tests indicate that the two most significant factors in limiting the rate of infiltration through the basin floor were the recharge test duration and quality of reclaimed water. Head buildup in the aquifer beneath the basins ranged from 4.3 to 6.7 ft, depending on the quantity and duration of water application. Head buildup near the injection wells within the aquifer ranged from 0.3 to 1.2 ft. Recharge basins provided a more effective means of moving large quantities of reclaimed water into the aquifer than injection wells. Results of 3-day and 176-day ponding tests in two basins indicate that reclaimed water is relatively unchanged chemically by percolation through the unsaturated zone because: (1) the sand and gravel of the upper glacial aquifer is unreactive, (2) the water moves to the water table rapidly, and (3) the water is highly treated before recharge. The quality of water in the aquifer zones affected by recharge improved, on the whole. Groundwater concentrations of nitrate nitrogen and several low molecular weight hydrocarbons, decreased to well within drinking water standards as a direct result of recharge. Sodium and chloride concentrations increased above background levels as a result of recharge but remained well within drinking water standards and the New York State effluent standards established for this groundwater recharge study. (Lantz-PTT)

Water-Resources Investigations Report↗