Nitrogen sources and cycling in the San Francisco Bay estuary: A nitrate dual isotopic composition approach
Scott D. Wankel, C. Kendall, C.A. Francis, A. Paytan
2006, Limnology and Oceanography (51) 1654-1664
We used the dual isotopic composition of nitrate (δ15N and δ18O) within the estuarine system of San Francisco (SF) Bay, California, to explore the utility of this approach for tracing sources and cycling of nitrate (NO2−). Surface water samples from 49 sites within the estuary were sampled during July–August 2004....
Evaluating uncertainty in predicting spatially variable representative elementary scales in fractured aquifers, with application to Turkey Creek Basin, Colorado
Tristan P. Wellman, Eileen P. Poeter
2006, Water Resources Research (42)
Computational limitations and sparse field data often mandate use of continuum representation for modeling hydrologic processes in large‐scale fractured aquifers. Selecting appropriate element size is of primary importance because continuum approximation is not valid for all scales. The traditional approach is to select elements by identifying a single representative elementary...
Temporal variations of heavy metals in coral Porites lutea from Guangdong Province, China: Influences from industrial pollution, climate and economic factors
Z. Peng, J. Liu, C. Zhou, B. Nie, T. Chen
2006, Chinese Journal of Geochemistry (25) 132-138
The eight heavy metals Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb have been determined in samples of coral Porites lutea collected from Dafangji Island waters (21°21′N, 111°11′E), Dianbai County, Guangdong Province, China, by the ICP-MS method. The samples represent the growth of coral in the period of...
Use of radars to monitor stream discharge by noncontact methods
J. E. Costa, R. T. Cheng, F.P. Haeni, N. Melcher, K.R. Spicer, E. Hayes, W. Plant, K. Hayes, C. Teague, D. Barrick
2006, Water Resources Research (42)
Conventional measurements of river flows are costly, time‐consuming, and frequently dangerous. This report evaluates the use of a continuous wave microwave radar, a monostatic UHF Doppler radar, a pulsed Doppler microwave radar, and a ground‐penetrating radar to measure river flows continuously over long periods and without touching the water with...
Sediment distribution and transport across the continental shelf and slope under idealized wind forcing
S.A. Condie, C. R. Sherwood
2006, Progress in Oceanography (70) 255-270
Resuspension, transport, and deposition of sediments over the continental shelf and slope are complex processes and there is still a need to understand the underlying spatial and temporal dynamical scales. As a step towards this goal, a two-dimensional slice model (zero gradients in the alongshore direction) based on the primitive...
Pharmaceuticals and other organic chemicals in selected north-central and northwestern Arkansas streams
B. E. Haggard, J.M. Galloway, W. R. Green, M. T. Meyer
2006, Journal of Environmental Quality (35) 1078-1087
Recently, our attention has focused on the low level detection of many antibiotics, pharmaceuticals, and other organic chemicals in water resources. The limited studies available suggest that urban or rural streams receiving wastewater effluent are more susceptible to contamination. The purpose of this study was to evaluate the occurrence of...
Peak flow responses to landscape disturbances caused by the cataclysmic 1980 eruption of Mount St. Helens, Washington
Jon J. Major, Linda E. Mark
2006, Geological Society of America Bulletin (118) 938-958
Years of discharge measurements that precede and follow the cataclysmic 1980 eruption of Mount St. Helens, Washington, provide an exceptional opportunity to examine the responses of peak flows to abrupt, widespread, devastating landscape disturbance. Multiple basins surrounding Mount St. Helens (300–1300 km2 drainage areas) were variously disturbed by: (1) a debris...
Usoi dam wave overtopping and flood routing in the Bartang and Panj Rivers, Tajikistan
J. C. Risley, J. S. Walder, R.P. Denlinger
2006, Natural Hazards (38) 375-390
The Usoi dam was created in the winter of 1911 after an enormous seismogenic rock slide completely blocked the valley of the Bartang River in the Pamir Mountains of southeastern Tajikistan. At present the dam impounds 17 million cubic meters of water in Lake Sarez. Flood volume and discharge estimates...
Pleistocene corals of the Florida keys: Architects of imposing reefs - Why?
B. H. Lidz
2006, Journal of Coastal Research (22) 750-759
Five asymmetrical, discontinuous, stratigraphically successive Pleistocene reef tracts rim the windward platform margin off the Florida Keys. Built of large head corals, the reefs are imposing in relief (???30 m high by 1 km wide), as measured from seismic profiles. Well dated to marine oxygen isotope substages 5c, 5b, and...
Genetic variation among subspecies of Least Tern (Sterna antillarum): Implications for conservation
Joanna B. Whittier, David M. Leslie Jr., Ronald A. Van Den Bussche
2006, Waterbirds (29) 176-184
DNA sequence variation from two nuclear introns and part of the mitochondrial cytochrome-b gene were used to Evaluate population structure among three subspecies of Least Term that nest in the United States (California [Sterna antillarum browni], Interior [S. a. athalassos], Eastern [S. a. antillarum]). Sequence variation was highest for nuclear...
Evidence for wing molt and breeding site fidelity in King Eiders
Laura M. Phillips, A.N. Powell
2006, Waterbirds (29) 148-153
Fidelity of King Eiders (Somateria spectabilis) to breeding and wing molt sites was examined using satellite telemetry data obtained opportunistically when battery life of transmitters provided locations in a second year. Consecutive breeding locations were obtained for eleven female and 23 male King Eiders. All females exhibited breeding site fidelity...
Seasonal dynamics of microbial community composition and function in oak canopy and open grassland soils
M. P. Waldrop, M.K. Firestone
2006, Microbial Ecology (52) 470-479
Soil microbial communities are closely associated with aboveground plant communities, with multiple potential drivers of this relationship. Plants can affect available soil carbon, temperature, and water content, which each have the potential to affect microbial community composition and function. These same variables change seasonally, and thus plant control on microbial...
Influence of water flow on Neosho madtom (Noturus placidus) reproductive behavior
J.L. Bryan, M. L. Wildhaber, Douglas B. Noltie
2006, American Midland Naturalist (156) 305-318
The Neosho madtom is a small, short-lived catfish species endemic to gravel bars of the Neosho River in Kansas, Oklahoma and Missouri, U.S.A. It spawns during summer in nesting cavities excavated in gravel. Although the species has survived dam construction within the Neosho River basin, its declining numbers resulted in...
Spatial patterns of fish communities along two estuarine gradients in southern Florida
D.P.J. Green, J.C. Trexler, J.J. Lorenz, C.C. McIvor, T. Philippi
2006, Hydrobiologia (569) 387-399
In tropical and subtropical estuaries, gradients of primary productivity and salinity are generally invoked to explain patterns in community structure and standing crops of fishes. We documented spatial and temporal patterns in fish community structure and standing crops along salinity and nutrient gradients in two subtropical drainages of Everglades National...
Nitrogen loads through baseflow, stormflow, and underflow to Rehoboth Bay, Delaware
J.A. Volk, K.B. Savidge, J.R. Scudlark, A.S. Andres, W.J. Ullman
2006, Journal of Environmental Quality (35) 1742-1755
A detailed study of water and nitrogen (N) discharge from a small, representative subwatershed of Rehoboth Bay, Delaware, was conducted to determine total N loads to the bay. The concentrations of ammonium (NH 4+), nitrate + nitrite (NO3- + NO2-), and dissolved and particulate organic N were determined in baseflow...
Stochastic uncertainty analysis for unconfined flow systems
Gaisheng Liu, Dongxiao Zhang, Zhiming Lu
2006, Water Resources Research (42)
A new stochastic approach proposed by Zhang and Lu (2004), called the Karhunen‐Loeve decomposition‐based moment equation (KLME), has been extended to solving nonlinear, unconfined flow problems in randomly heterogeneous aquifers. This approach is on the basis of an innovative combination of Karhunen‐Loeve decomposition, polynomial expansion, and perturbation methods. The random...
Estimating background and threshold nitrate concentrations using probability graphs
S.V. Panno, W.R. Kelly, A.T. Martinsek, Keith C. Hackley
2006, Ground Water (44) 697-709
Because of the ubiquitous nature of anthropogenic nitrate (NO 3-) in many parts of the world, determining background concentrations of NO3- in shallow ground water from natural sources is probably impossible in most environments. Present-day background must now include diffuse sources of NO3- such as disruption of soils and oxidation...
Groundwater-transported dissolved organic nitrogen exports from coastal watersheds
K.D. Kroeger, Marci L. Cole, I. Valiela
2006, Limnology and Oceanography (51) 2248-2261
We analyzed groundwater-transported nitrogen (N) exports from 41 watershed segments that comprised 10 Cape Cod, Massachusetts watersheds to test the hypotheses that chemical form of N exports is related to land use and to length of flow paths through watersheds. In the absence of human habitation, these glacial outwash-plain watersheds...
Secondary gas emissions during coal desorption, Marathon Grassim Oskolkoff-1 Well, Cook Inlet Basin, Alaska: Implications for resource assessment
C.E. Barker, T. Dallegge
2006, Bulletin of Canadian Petroleum Geology (54) 273-291
Cuttings samples of sub-bituminous humic coals from the Oligocene to Pliocene Tyonek Formation, Cook Inlet Basin, Alaska show secondary gas emissions whose geochemistry is consistent with renewed microbial methanogenesis during canister desorption. The renewed methanogenesis was noted after initial desorption measurements had ceased and a canister had an air and...
Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana
M.C. Woodin, T.C. Michot
2006, Conference Paper, Hydrobiologia
Redheads, Aythya americana, concentrate in large numbers annually in traditional wintering areas along the western and northern rim of the Gulf of Mexico. Two of these areas are the Laguna Madre of Texas and Chandeleur Sound of Louisiana. We collected data on 54,340 activities from 103 redhead flocks in Texas...
The feasibility of well-logging measurements of arsenic levels using neutron-activation analysis
C.P. Oden, J.S. Schweitzer, G.M. McDowell
2006, Applied Radiation and Isotopes (64) 1074-1081
Arsenic is an extremely toxic metal, which poses a significant problem in many mining environments. Arsenic contamination is also a major problem in ground and surface waters. A feasibility study was conducted to determine if neutron-activation analysis is a practical method of measuring in situ arsenic levels. The response of...
Deep-water antipatharians: Proxies of environmental change
B. Williams, Michael J. Risk, Steve W. Ross, K. J. Sulak
2006, Geology (34) 773-776
Deep-water (307-697 m) antipatharian (black coral) specimens were collected from the southeastern continental slope of the United States and the north-central Gulf of Mexico. The sclerochronology of the specimens indicates that skeletal growth takes place by formation of concentric coeval layers. We used 210Pb to estimate radial growth rate of...
The role of biological uptake in iron and manganese cycling in Lake Baikal
L.Z. Granina, E. Callender
2006, Conference Paper, Hydrobiologia
The role of biological uptake in the internal cycling of Fe and Mn in Lake Baikal was quantified. Biological uptake, sedimentation consisting of the biogenic and lithogenic fluxes, and remineralization have been evaluated. The results of calculations show that about 5-10% of Fe and Mn accumulated in the lake are...
Comparative evaluation of short-term leach tests for heavy metal release from mineral processing waste
S. R. Al-Abed, P. L. Hageman, G. Jegadeesan, N. Madhavan, D. Allen
2006, Science of the Total Environment (364) 14-23
Evaluation of metal leaching using a single leach test such as the Toxicity Characteristic Leaching Procedure (TCLP) is often questionable. The pH, redox potential (Eh), particle size and contact time are critical variables in controlling metal stability, not accounted for in the TCLP. This paper compares the leaching behavior of...
Quantifying surface water–groundwater interactions using time series analysis of streambed thermal records: Method development
Christine E Hatch, Andrew T. Fisher, Justin S. Revenaugh, Jim Constantz, Chris Ruehl
2006, Water Resources Research (42)
We present a method for determining streambed seepage rates using time series thermal data. The new method is based on quantifying changes in phase and amplitude of temperature variations between pairs of subsurface sensors. For a reasonable range of streambed thermal properties and sensor spacings the time series method should...
