A5013445180- Soil and Water Nutrient Dynamics
- Water Quality and Resources Studies
- Groundwater and Isotope Geochemistry
- Aquatic Ecosystems and Phytoplankton Dynamics
- Heavy metals in environment
- Mine drainage and remediation techniques
- Water Quality and Pollution Assessment
- Marine and coastal ecosystems
- Fish Ecology and Management Studies
- Water Quality Monitoring and Analysis
- Analytical chemistry methods development
- Mercury impact and mitigation studies
- Biocrusts and Microbial Ecology
- Image Processing and 3D Reconstruction
- Hydrocarbon exploration and reservoir analysis
- Freshwater macroinvertebrate diversity and ecology
- Coastal wetland ecosystem dynamics
- Electrochemical sensors and biosensors
- Chromium effects and bioremediation
- Analytical Chemistry and Sensors
- Environmental Toxicology and Ecotoxicology
- Aquatic Invertebrate Ecology and Behavior
- Electrochemical Analysis and Applications
- Geochemistry and Elemental Analysis
- Pesticide and Herbicide Environmental Studies
United States Geological Survey
1996-2022
United States Department of the Interior
1987
Environmental and Water Resources Engineering
1985
Algal blooms around the world are increasing in frequency and severity, often with possibility of adverse effects on human ecosystem health. The health economic impacts associated harmful algal blooms, or HABs, provide compelling rationale for developing new methods monitoring these events via remote sensing. Although concentrations chlorophyll-a key pigments like phycocyanin routinely estimated from satellite images used to infer cyanobacterial cell counts, current unable information...
The fate of antibiotics that bind to riverine sediment is notwell understood. A solution used in geochemical extraction schemes determine loosely bound species sediments, 1 M MgCl2 (pH 8), was chosen bound, and potentially bioavailable, tetracycline (TCs), including oxytetracycline (5-OH tetracycline) (OTC) samples from two rivers on the eastern shore Chesapeake Bay. Bottom sediments were collected at sites upstream from, at, downstream municipal sewage-treatment plants (STPs) situated...
Cyanobacterial blooms are a nuisance and potential hazard in freshwater systems worldwide. Remote sensing has been used to detect cyanobacterial blooms, but few studies have distinguished among genera of cyanobacteria. Because some more likely be toxic than others, this is useful distinction. Hyperspectral imaging reflectance microscopy was examine cyanobacteria from Upper Klamath Lake, Oregon, at high spatial spectral resolution determine if two species found commonly the lake,...
The Chesapeake Bay is the Nation's largest estuary and historically supported one of most productive fisheries in world. In addition to supporting aquatic communities wildlife, bay's watershed serves economic recreational needs 15 million people. fertile soils support significant agricultural production. Unfortunately, commercial, economic, value bay its has been degraded by poor water quality, loss habitat, overharvesting living resources. Since early 1980's, Program, which a partnership...
Executive Summary Five sampling trips were coordinated in April, May and August 2006, July 2007 to sample the water column benthos of Upper Klamath Lake, OR (Fig. 1; Table 1), before, during after annual cyanophyte bloom Aphanizomenon flos-aquae (AFA). A pore-water profiler was designed fabricated obtain first high-resolution (centimeter-scale) estimates vertical concentration gradients for diffusive-flux determinations. Estimates based on molecular diffusion may underestimate benthic flux...
Potentially harmful cyanobacterial blooms are an emerging environmental concern in freshwater bodies worldwide. Cyanobacterial generally caused by high nutrient inputs and warm, still waters have been appearing with increasing frequency water used for drinking supply recreation, a problem which will likely worsen warming climate. composed of genera known biological pigments can be distinguished analyzed via hyperspectral image collection technology such as remote sensing satellites,...
We reviewed a mass balance model developed in 2001 that guided establishment of the phosphorus total maximum daily load (TMDL) for Upper Klamath and Agency Lakes, Oregon. The purpose review was to evaluate strengths weaknesses determine whether improvements could be made using information derived from studies since first developed. new data have contributed understanding processes lakes, particularly internal loading sediment, include measurements diffusive fluxes bottom sediments,...
μThis study of phosphorus (P) cycling in eutrophic Upper Klamath Lake (UKL), Oregon, was conducted by the U.S. Geological Survey cooperation with Bureau Reclamation. Lakebed sediments from upper 30 centimeters (cm) cores collected 26 sites were characterized. Cores sampled at 0.5, 1.5, 2.5, 3.5, 4.5, 10, 15, 20, 25, and cm. Prior to freezing, water content sediment pH determined. After being freeze-dried, all samples separated into greater than 63-micron (μm) particle-size (coarse) less...
The chemical composition of bottom sediments and their associated pore waters from the tidal Potomac River Estuary was studied May 1978 through June 1980. Pore were routinely analyzed for pH, Eh, alkalinity, concentrations sulfide, sulfate, phosphate, carbon, ammonium, silica, iron, manganese, chloride, sodium, potassium, calcium, magnesium. Porosity, weight loss on ignition, nitrogen, phosphorus contents determined solid sediments. range salinity encountered in estuary frequently...
Abstract A rapid procedure has been developed for the analysis of orthophosphate, sulfate and chloride in riverine sediment interstitial water samples which have dissolved iron concentrations ranging from 0.5–2 mmol L−1. Interferences caused by precipitation hydroxides resulting air oxidation ferrous anoxic alkaline working pH range (9.0 – 10.5) Dionex1 ion chromatographic system were eliminated complexing with cyanide. Orthophosphate concentration values are compared reactive phosphate data...
Periphyton samples from Water Conservation Areas, Big Cypress National Preserve, and Everglades Park in south Florida were analyzed for concentrations of total mercury, methylmercury, nitrogen, phosphorus, organic carbon, inorganic carbon. Concentrations mercury periphyton decrease slightly along a gradient north‐to‐south. Both methylmercury are positively correlated with nitrogen phosphorus periphyton. In horizontal sections mats, tend to be largest at the tops bottoms mats. Methylmercury...
Abstract Using the coupled methods presented in this paper, methylmercury can be accurately and rapidly extracted from biological samples by modified supercritical fluid carbon dioxide quantitated using liquid chromatography with reductive electrochemical detection. Supercritical methanol effectively extracts underivatized certified reference materials Dorm-1 (dogfish muscle) Dolt-2 liver). Calcium chloride water, a ratio of 5:2 (by weight), provide acid environment required for extracting...
The purpose of this study was to characterize the cyanophyte Aphanizomenon flos-aquae (AFA) from Upper Klamath Lake, Oregon, (UKL) and, based on description, explore uses for AFA, which would have commercial value. AFA collected UKL in 2010 eight sites during a period approximately 2 weeks were similar composition spatially and temporally. 31P nuclear magnetic resonance analysis samples indicated that contained broad range phosphorus-containing compounds. largest variation organic phosphorus...