Water-quality trends and basin activities and characteristics for the Albemarle-Pamlico estuarine system, North Carolina and Virginia

Abstract

25. Suspended-solids concentrations for selected waterquality zones, by year: A. Chowan River zone CH7, B. Perquimans River zone PQ1, and C. Pasquotank River zone PS1 .

Simulation of hydrodynamics and solute transport in the Pamlico River estuary, North Carolina

“…The difference between maximum observed and minimum observed salinity at each site ranged from 13.2 ppt to 20.4 ppt, which generally agrees with the results reported by Harned and Davenport (1990). High salinities were observed at site SI (13.2 ppt near the surface and 13.5 ppt near the bottom).…”

“…Elevated levels of mercury, cadmium, copper, and other trace metals occur in Pamlico River bed sediments (Riggs and others, 1989). Total ammonia plus organic nitrogen and total phosphorus concentrations in the Pamlico River generally increased between 1970 and 1988 (Harned and Davenport, 1990). In 1989, the Tar-Pamlico River Basin was designated as Nutrient Sensitive Waters by the State Environmental Management Commission, resulting in more strict limits on the discharge of nutrients into the waters of the basin.…”

Ecosystem responses to internal and watershed organic matter loading:consequences for hypoxia in the eutrophying Neuse River Estuary, North Carolina, USA

“…The following methods were employed: ammonium = 3 1-107-06-l-A; nitratehitrite = 31-107-04-1-C; phosphate = 31-115-01-3-A. Silicate analyses conducted throughout our sampling transect over the past 2 decades have indicated consistently high concentrations in the main stem of the estuary (40 to 150 VM SiOz; Si:DIN ratios ranging from 4:l to over 10:l) and no seasonal Si pattern in relation to diatom biomass [Harned & Davenport 1990; U.S. Geological Survey (USGS), Raleigh, NC]. Previous nutrient addition bioassays in which Si (as SiO,) was added over a range of concentrations (alone and in combination with N and P) indicated no Si stimulation of natural phytoplankton community productivity or biomass, while N stimulation was observed on a year-round basis (Paerl 1983, 1987, Paerl et al 1990a.…”

“…Watershed N-loading trends over the past 2 decades and experimental evidence (Paerl & Bowles 1987, Stanley 1988, Harned & Davenport 1990, Dodd et al 1993) suggest at least a 30% annual cutback on N inputs accompanied by a nutrient cap restricting maximum annual N inputs to current levels will be needed to achieve perceptible improvements in water quality, including long-term reductions in phytoplankton blooms and associated hypoxia/anoxia (North Carolina State Senate 1996). While such nutrient management strategies may yield improvements in water quality for mean hydrological years (e.g.…”

“…Like most temperate estuaries, primary production is controlled by rates of nitrogen (N) supply (Ryther & Dunstan 1971, D'Elia et al 1986, Graneli et al 1990, Paerl et al 1990a, b, Rudek et al 1991, Fisher et al 1992, which in the case of the Neuse River are dominated by non-point sources (-75% of annual N load) (Harned & Davenport 1990, Dodd et al 1993. The total N load has increased by at least 30% over the past 2 decades (Stanley 1988, Harned & Davenport 1990, Dodd et al 1993. Within this time frame, the Neuse River Estuary has experienced increased symptoms of water quality degradation.…”