Geology topics

Gloria M. Ferrell

Publications and source records attributed to Gloria M. Ferrell.

3 recordsLinked to original sources

USGS2014

Water-quality characteristics indicative of wastewater in selected streams in the upper Neuse River Basin, Durham and Orange Counties, North Carolina, from 2004 to 2013

Data were collected during three time periods to assess the effects of wastewater treatment and disposal practices on the occurrence of selected contaminants indicative of wastewater in the upper Neuse River Basin, North Carolina. The first phase of data collection, December 2004 to June 2005, and the second phase, April to October 2008, addressed the effects of point and nonpoint sources of wastewater effluent on stream quality during baseflow conditions. Point-source effects were assessed by sampling a municipal wastewater treatment plant outfall and sites on the Eno River upstream and downstream from the outfall. Water-quality data suggest that the wastewater treatment plant effluent contributed to increases in concentrations of nitrogen and carbamazepine at the downstream site. Nonpoint source effects were assessed by sampling seven small streams that drained an undeveloped area and residential areas served by either centralized or onsite wastewater treatment systems. Samples were analyzed for inorganic constituents, including nutrients, ions, and metals; organic compounds considered indicative of wastewater contamination; antibiotics, optical brighteners, and fecal coliform bacteria. Hypothesized differences in water quality between the sites with primarily centralized and onsite wastewater treatment were not apparent, likely due to the relatively large heterogeneity of the sites within each category. During the third phase of data collection, May 2012 to January 2013, data were collected to address the suitability of optical brighteners as tracers of wastewater in small streams during streamflow recession. Samples were collected at five small streams following periods of rainfall and analyzed for optical brighteners, specific conductance nutrients, and selected hormones. Optical brighteners were absent in the undeveloped catchment but were present in the recession period after rainfall events in catchments with centralized though possibly leaky sewage treatment and areas with onsite treatment. Sand filter systems in areas with onsite treatment appear to change the effluent flow and retention characteristics such that optical brighteners were present both before and after rainfall events. Nitrate plus nitrite, as nitrogen concentrations in samples from this last study phase generally were larger than those collected during baseflow conditions in the previous phases of this study.

North Carolina↗

USGS2007

Effects of Canals and Roads on Hydrologic Conditions and Health of Atlantic White Cedar at Emily and Richardson Preyer Buckridge Coastal Reserve, North Carolina, 2003-2006

The effects of canals and roads on hydrologic conditions and on the health of Atlantic white cedar at the Emily and Richardson Preyer Buckridge Coastal Reserve in North Carolina were evaluated by using data collected from the 1980s to 2006. Water levels were monitored along two transects established perpendicular to roads and canals in areas of healthy and unhealthy Atlantic white cedar as part of a study conducted from February 2003 through March 2006. Because of the low hydraulic gradient at the Reserve, the rate and direction of water movement are sensitive to disturbance. Canals increased drainage and contributed to lower water levels in some parts of the Reserve, whereas roads, depending on orientation, impeded drainage. Canals also appeared to facilitate movement of brackish water from the Alligator River into the interior of the Reserve during storms and wind tides. Data indicate that an influx of brackish water occurred in mid-September 2005 several days after the passage of Hurricane Ophelia. Although precipitation amounts and wind speeds associated with Hurricane Ophelia were not large, substantial changes in specific conductance occurred at the canal site on the unhealthy Atlantic white cedar transect. No corresponding increase in specific conductance was observed at the canal site on the healthy Atlantic white cedar transect. The specific conductance of water samples from canals and piezometers was highly correlated with concentrations of chloride and sodium. Ion ratios of some of the water samples, particularly samples with high specific conductance, were similar to those of seawater. Thermal and chemical stratification of water in the canals occurred during summer and winter months, and turnover and mixing occurred in the spring and fall. Upwelling of ground water as a result of excavation for roads did not appear to have a significant effect on the water quality of samples from the canals or piezometers. The specific conductance of water samples from piezometers installed in the root zone of healthy stands of Atlantic white cedar generally was lower than in water samples from unhealthy stands. This pattern also was observed in samples from piezometers installed on the transects and in other areas of the Reserve. Roads appear to have isolated some areas of the Reserve from the high-conductivity water in nearby canals. The paths by which brackish water entered the Reserve cannot be determined from the data obtained during this investigation. It appears that water can enter the Reserve from various directions, depending on wind patterns and water levels in the Alligator River.

North Carolina↗

USGS2001

Effects of land use on water quality and transport of selected constituents in streams in Mecklenburg County, North Carolina, 1994–98

Transport rates for total solids, total nitrogen, total phosphorus, biochemical oxygen demand, chromium, copper, lead, nickel, and zinc during 1994–98 were computed for six stormwater-monitoring sites in Mecklenburg County, North Carolina. These six stormwater-monitoring sites were operated by the Mecklenburg County Department of Environmental Protection, in cooperation with the City of Charlotte, and are located near the mouths of major streams. Constituent transport at the six study sites generally was dominated by nonpoint sources, except for nitrogen and phosphorus at two sites located downstream from the outfalls of major municipal wastewater-treatment plants. To relate land use to constituent transport, regression equations to predict constituent yield were developed by using water-quality data from a previous study of nine stormwater-monitoring sites on small streams in Mecklenburg County. The drainage basins of these nine stormwater sites have relatively homogeneous land-use characteristics compared to the six study sites. Mean annual construction activity, based on building permit files, was estimated for all stormwater-monitoring sites and included as an explanatory variable in the regression equations. These regression equations were used to predict constituent yield for the six study sites. Predicted yields generally were in agreement with computed yields. In addition, yields were predicted by using regression equations derived from a national urban water-quality database. Yields predicted from the regional regression equations generally were about an order of magnitude lower than computed yields. Regression analysis indicated that construction activity was a major contributor to transport of the constituents evaluated in this study except for total nitrogen and biochemical oxygen demand. Transport of total nitrogen and biochemical oxygen demand was dominated by point-source contributions. The two study basins that had the largest amounts of construction activity also had the highest total solids yields (1,300 and 1,500 tons per square mile per year). The highest total phosphorus yields (3.2 and 1.7 tons per square mile per year) attributable to nonpoint sources also occurred in these basins. Concentrations of chromium, copper, lead, nickel, and zinc were positively correlated with total solids concentrations at most of the study sites (Pearson product-moment correlation >0.50). The site having the highest median concentrations of chromium, copper, and nickel also was the site having the highest computed yield for total solids.

North Carolina↗