Dissolved organic carbon in Alaskan boreal forest: Sources, chemical characteristics, and biodegradability
Kimberly P. Wickland, Jason C. Neff, George R. Aiken
2007, Ecosystems (10) 1323-1340
The fate of terrestrially-derived dissolved organic carbon (DOC) is important to carbon (C) cycling in both terrestrial and aquatic environments, and recent evidence suggests that climate warming is influencing DOC dynamics in northern ecosystems. To understand what determines the fate of terrestrial DOC, it is essential to quantify the chemical...
Input, flux, and persistence of six select pesticides in San Francisco Bay
Kathryn Kuivila, B.E. Jennings
2007, International Journal of Environmental Analytical Chemistry (87) 897-911
Temporal patterns of pesticide inputs to San Francisco Bay were identified and correlated with timing of application and transport mechanism. Fluxes were calculated from measured concentrations and estimated flow. Persistence of the pesticides under typical riverine or estuarine conditions were estimated from laboratory experiments. Simazine was detected most frequently and...
Oxygen and chlorine isotopic fractionation during perchlorate biodegradation: Laboratory results and implications for forensics and natural attenuation studies
Neil C. Sturchio, John Karl Bohlke, Abelardo D. Beloso Jr., S.H. Streger, Linnea J. Heraty, Paul B. Hatzinger
2007, Environmental Science & Technology (41) 2796-2802
Perchlorate is a widespread environmental contaminant having both anthropogenic and natural sources. Stable isotope ratios of O and Cl in a given sample of perchlorate may be used to distinguish its source(s). Isotopic ratios may also be useful for identifying the extent of biodegradation of perchlorate, which is critical for...
Diel cycling of zinc in a stream impacted by acid rock drainage: Initial results from a new in situ Zn analyzer
Thomas P. Chapin, David A. Nimick, Christopher H. Gammons, Richard B. Wanty
2007, Environmental Monitoring and Assessment (133) 161-167
Recent work has demonstrated that many trace metals undergo dramatic diel (24-h) cycles in near neutral pH streams with metal concentrations reproducibly changing up to 500% during the diel period (Nimick et al., 2003). To examine diel zinc cycles in streams affected by acid rock drainage, we have developed a...
Hydrologic significance of carbon monoxide concentrations in ground water
Francis H. Chapelle, Paul M. Bradley
2007, Ground Water (45) 272-280
Dissolved carbon monoxide (CO) is present in ground water produced from a variety of aquifer systems at concentrations ranging from 0.2 to 20 nanomoles per liter (0.0056 to 0.56 μg/L). In two shallow aquifers, one an unconsolidated coastal plain aquifer in Kings Bay, Georgia, and the other a fractured‐bedrock aquifer...
Discontinuities in stream nutrient uptake below lakes in mountain drainage networks
C.D. Arp, M. A. Baker
2007, Limnology and Oceanography (52) 1978-1990
In many watersheds, lakes and streams are hydrologically linked in spatial patterns that influence material transport and retention. We hypothesized that lakes affect stream nutrient cycling via modifications to stream hydrogeomorphology, source-waters, and biological communities. We tested this hypothesis in a lake district of the Sawtooth Mountains, Idaho. Uptake of...
Thioarsenates in geothermal waters of Yellowstone National Park: Determination, preservation, and geochemical importance
B. Planer-Friedrich, J. London, R. Blaine McCleskey, D. Kirk Nordstrom, D. Wallschlager
2007, Environmental Science & Technology (41) 5245-5251
Mono-, di-, tri-, and tetrathioarsenate, as well as methylated arsenic oxy- and thioanions, were determined besides arsenite and arsenate in geothermal waters of Yellowstone National Park using anion-exchange chromatography inductively coupled plasma mass spectrometry. Retention time match with synthetic standards, measured S:As ratios, and molecular electrospray mass spectra support the...
Efficiency of conventional drinking-water-treatment processes in removal of pharmaceuticals and other organic compounds
Paul E. Stackelberg, Jacob Gibs, Edward T. Furlong, Michael T. Meyer, Steven D. Zaugg, R.L. Lippincott
2007, Science of the Total Environment (377) 255-272
Samples of water and sediment from a conventional drinking-water-treatment (DWT) plant were analyzed for 113 organic compounds (OCs) that included pharmaceuticals, detergent degradates, flame retardants and plasticizers, polycyclic aromatic hydrocarbons (PAHs), fragrances and flavorants, pesticides and an insect repellent, and plant and animal steroids. 45 of these compounds were detected...
Groundwater noble gas, age, and temperature signatures in an Alpine watershed: Valuable tools in conceptual model development
Andrew H. Manning, Jonathan S. Caine
2007, Water Resources Research (43)
Bedrock groundwater in alpine watersheds is poorly understood, mainly because of a scarcity of wells in alpine settings. Groundwater noble gas, age, and temperature data were collected from springs and wells with depths of 3–342 m in Handcart Gulch, an alpine watershed in Colorado. Temperature profiles indicate active groundwater circulation...
Urbanization and nutrient retention in freshwater riparian wetlands
D.M. Hogan, M.R. Walbridge
2007, Ecological Applications (17) 1142-1155
Urbanization can degrade water quality and alter watershed hydrology, with profound effects on the structure and function of both riparian wetlands (RWs) and aquatic ecosystems downstream. We used freshwater RWs in Fairfax County, Virginia, USA, as a model system to examine: (1) the effects of increasing urbanization (indexed by the...
Potential effects of regional pumpage on groundwater age distribution
Brendan A. Zinn, Leonard F. Konikow
2007, Water Resources Research (43)
Groundwater ages estimated from environmental tracers can help calibrate groundwater flow models. Groundwater age represents a mixture of traveltimes, with the distribution of ages determined by the detailed structure of the flow field, which can be prone to significant transient variability. Effects of pumping on age distribution were assessed using...
A classification of U.S. estuaries based on physical and hydrologic attributes
V.D. Engle, J.C. Kurtz, L.M. Smith, C. Chancy, P. Bourgeois
2007, Environmental Monitoring and Assessment (129) 397-412
A classification of U.S. estuaries is presented based on estuarine characteristics that have been identified as important for quantifying stressor-response relationships in coastal systems. Estuaries within a class have similar physical and hydrologic characteristics and would be expected to demonstrate similar biological responses to stressor loads from the adjacent watersheds....
The collapse of pelagic fishes in the upper San Francisco estuary
T. Sommer, C. Armor, R. Baxter, R. Breuer, L. Brown, M. Chotkowski, S. Culberson, F. Feyrer, M. Gingras, B. Herbold, W. Kimmerer, A. Mueller-Solger, M. Nobriga, K. Souza
2007, Fisheries (32) 270-277
Although the pelagic fish community of the upper San Francisco Estuary historically has shown substantial variability, a recent collapse has captured the attention of resource managers, scientists, legislators, and the general public. The ecological and management consequences of the decline are most serious for delta smelt (Hypomesus transpacificus), a threatened...
Developing a flood monitoring system from remotely sensed data for the Limpopo basin
K.O. Asante, R.D. Macuacua, G. A. Artan, R.W. Lietzow, J. P. Verdin
2007, IEEE Transactions on Geoscience and Remote Sensing (45) 1709-1714
This paper describes the application of remotely sensed precipitation to the monitoring of floods in a region that regularly experiences extreme precipitation and flood events, often associated with cyclonic systems. Precipitation data, which are derived from spaceborne radar aboard the National Aeronautics and Space Administration's Tropical Rainfall Measuring Mission and...
Reconstructing sediment age profiles from historical bathymetry changes in San Pablo Bay, California
Shawn A. Higgins, Bruce E. Jaffe, Christopher C. Fuller
2007, Estuarine, Coastal and Shelf Science (73) 165-174
Sediment age profiles reconstructed from a sequence of historical bathymetry changes are used to investigate the subsurface distribution of historical sediments in a subembayment of the San Francisco Estuary. Profiles are created in a grid-based GIS modeling program that stratifies historical...
Groundwater flow with energy transport and water-ice phase change: Numerical simulations, benchmarks, and application to freezing in peat bogs
J.M. McKenzie, Clifford I. Voss, D. I. Siegel
2007, Advances in Water Resources (30) 966-983
In northern peatlands, subsurface ice formation is an important process that can control heat transport, groundwater flow, and biological activity. Temperature was measured over one and a half years in a vertical profile in the Red Lake Bog, Minnesota. To successfully simulate the transport of heat within the peat profile,...
The chemical response of particle-associated contaminants in aquatic sediments to urbanization in New England, U.S.A.
A.T. Chalmers, P. C. Van Metre, E. Callender
2007, Journal of Contaminant Hydrology (91) 4-25
Relations between urbanization and particle-associated contaminants in New England were evaluated using a combination of samples from sediment cores, streambed sediments, and suspended stream sediments. Concentrations of PAHs, PCBs, DDT, and seven trace metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) were correlated strongly with urbanization, with the strongest relations...
Ground water stratification and delivery of nitrate to an incised stream under varying flow conditions
John Karl Bohlke, M. E. O’Connell, K.L. Prestegaard
2007, Journal of Environmental Quality (36) 664-680
Ground water processes affecting seasonal variations of surface water nitrate concentrations were investigated in an incised first-order stream in an agricultural watershed with a riparian forest in the coastal plain of Maryland. Aquifer characteristics including sediment stratigraphy, geochemistry, and hydraulic properties were examined in combination with chemical and isotopic analyses...
Quasi-horizontal circulation cells in 3D seawater intrusion
E. Abarca, J. Carrera, X. Sanchez-Vila, Clifford I. Voss
2007, Journal of Hydrology (339) 118-129
The seawater intrusion process is characterized by the difference in freshwater and seawater density that causes freshwater to float on seawater. Many confined aquifers have a large horizontal extension with respect to thickness. In these cases, while buoyancy acts in the vertical direction, flow is confined between the upper and...
Evidence of CFC degradation in groundwater under pyrite-oxidizing conditions
L.A. Sebol, W.D. Robertson, Eurybiades Busenberg, Niel Plummer, M.C. Ryan, S.L. Schiff
2007, Journal of Hydrology (347) 1-12
A detailed local-scale monitoring network was used to assess CFC distribution in an unconfined sand aquifer in southwestern Ontario where the zone of 1–5-year-old groundwater was known with certainty because of prior use of a bromide tracer. Groundwater ⩽5 years old was confined to an aerobic zone at ⩽5 m depth and had CFC concentrations...
Eogenetic karst hydrology: Insights from the 2004 hurricanes, peninsular Florida
L.J. Florea, H. Leonard Vacher
2007, Ground Water (45) 439-446
Eogenetic karst lies geographically and temporally close to the depositional environment of limestone in warm marine water at low latitude, in areas marked by midafternoon thunderstorms during a summer rainy season. Spring hydrographs from such an environment in north-central Florida are characterized by smooth, months-long, seasonal maxima. The passage of...
Altered stream-flow regimes and invasive plant species: The Tamarix case
J.C. Stromberg, S.J. Lite, R. Marler, C. Paradzick, P.B. Shafroth, D. Shorrock, J. M. White, M.S. White
2007, Global Ecology and Biogeography (16) 381-393
Aim: To test the hypothesis that anthropogenic alteration of stream-flow regimes is a key driver of compositional shifts from native to introduced riparian plant species. Location: The arid south-western United States; 24 river reaches in the Gila and Lower Colorado drainage basins of Arizona. Methods: We compared the abundance of...
Estimation of evapotranspiration by reed canarygrass using field observations and model simulations
K. E. Schilling, James R. Kiniry
2007, Journal of Hydrology (337) 356-363
Reed canarygrass (Phalaris arundinacea) commonly invades meadow wetlands, effectively dominating water use and outcompeting native plants. Objectives of this study were to (i) estimate daily, seasonal and annual water use by reed canarygrass using shallow water table fluctuations; and (ii) calibrate the ALMANAC (Agricultural Land Management Alternative with Numerical Assessment...
Using biodynamic models to reconcile differences between laboratory toxicity tests and field biomonitoring with aquatic insects
D.B. Buchwalter, Daniel J. Cain, W.H. Clements, S. N. Luoma
2007, Environmental Science & Technology (41) 4821-4828
Aquatic insects often dominate lotic ecosystems, yet these organisms are under-represented in trace metal toxicity databases. Furthermore, toxicity data for aquatic insects do not appear to reflect their actual sensitivities to metals in nature, because the concentrations required to elicit toxicity...
Paleoenvironmental assessment of recent environmental changes in Florida Bay, USA: a biomarker based study
Y. Xu, C. W. Holmes, R. Jaffe
2007, Estuarine, Coastal and Shelf Science (73) 201-210
The extractable lipid compositions in four Florida Bay cores were determined in order to understand environmental changes over the last 160 years. The most significant environmental change was recorded by oscillations in the amplitude and frequency of biomarkers during the 20th century. Two seagrass molecular proxies (Paq and the C25/C27n-alkan-2-one...
