Interactions across spatial scales among forest dieback, fire, and erosion in northern New Mexico landscapes
Craig D. Allen
2007, Ecosystems (10) 797-808
Ecosystem patterns and disturbance processes at one spatial scale often interact with processes at another scale, and the result of such cross-scale interactions can be nonlinear dynamics with thresholds. Examples of cross-scale pattern-process relationships and interactions among forest dieback, fire, and erosion are illustrated from northern New Mexico (USA) landscapes,...
Development of a mercury speciation, fate, and biotic uptake (BIOTRANSPEC) model: Application to Lahontan Reservoir (Nevada, USA)
N. Gandhi, S.P. Bhavsar, M.L. Diamond, James S. Kuwabara, Mark C. Marvin-DePasquale, David P. Krabbenhoft
2007, Environmental Toxicology and Chemistry (26) 2260-2273
A mathematically linked mercury transport, speciation, kinetic, and simple biotic uptake (BIOTRANSPEC) model has been developed. An extension of the metal transport and speciation (TRANSPEC) model, BIOTRANSPEC estimates the fate and biotic uptake of inorganic (Hg(II)), elemental (Hg(0)) and organic (MeHg) forms of mercury and their species in the dissolved,...
Ammonia-oxidizing bacterial community composition in estuarine and oceanic environments assessed using a functional gene microarray
B.B. Ward, D. Eveillard, Julie D. Kirshtein, J.D. Nelson, Mary A. Voytek, G. A. Jackson
2007, Environmental Microbiology (9) 2522-2538
The relationship between environmental factors and functional gene diversity of ammonia-oxidizing bacteria (AOB) was investigated across a transect from the freshwater portions of the Chesapeake Bay and Choptank River out into the Sargasso Sea. Oligonucleotide probes (70-bp) designed to represent the diversity of ammonia monooxygenase (amoA) genes from Chesapeake Bay...
Ordination of breeding birds in relation to environmental gradients in three southeastern United States floodplain forests
J.S. Wakeley, M.P. Guilfoyle, T. J. Antrobus, R.A. Fischer, W.C. Barrow Jr., P.B. Hamel
2007, Wetlands Ecology and Management (15) 417-439
We used an ordination approach to identify factors important to the organization of breeding bird communities in three floodplains: Cache River, Arkansas (AR), Iatt Creek, Louisiana (LA), and the Coosawhatchie River, South Carolina (SC), USA. We used 5-min point counts to sample birds in each study area each spring from...
Effects of imposed salinity gradients on dissimilatory arsenate reduction, sulfate reduction, and other microbial processes in sediments from two California soda lakes
T.R. Kulp, S. Han, C.W. Saltikov, B.D. Lanoil, K. Zargar, Ron Oremland
2007, Applied and Environmental Microbiology (73) 5130-5137
Salinity effects on microbial community structure and on potential rates of arsenate reduction, arsenite oxidation, sulfate reduction, denitrification, and methanogenesis were examined in sediment slurries from two California soda lakes. We conducted experiments with Mono Lake and Searles Lake sediments over a wide range of salt concentrations...
Dams, floodplain land use, and riparian forest conservation in the semiarid Upper Colorado River Basin, USA
D.C. Andersen, D.J. Cooper, K. Northcott
2007, Environmental Management (40) 453-475
Land and water resource development can independently eliminate riparian plant communities, including Fremont cottonwood forest (CF), a major contributor to ecosystem structure and functioning in semiarid portions of the American Southwest. We tested whether floodplain development was linked to river regulation in the Upper Colorado River Basin (UCRB) by relating...
Modeling the movement of a pH perturbation and its impact on adsorbed zinc and phosphate in a wastewater‐contaminated aquifer
Douglas B. Kent, J.A. Wilkie, J.A. Davis
2007, Water Resources Research (43)
[1] Chemical conditions were perturbed in an aquifer with an ambient pH of 5.9 and wastewater-derived adsorbed zinc (Zn) and phosphate (P) contamination by injecting a pulse of amended groundwater. The injected groundwater had low concentrations of dissolved Zn and P, a pH value of...
Influence of groundwater pumping on streamflow restoration following upstream dam removal
James E. Constantz, Hedeff I. Essaid
2007, Hydrological Processes (21) 2823-2834
We compared streamflow in basins under the combined impacts of an upland dam and groundwater pumping withdrawals, by examining streamflow in the presence and absence of each impact. As a qualitative analysis, inter-watershed streamflow comparisons were performed for several rivers flowing into the east side...
Physically based estimation of soil water retention from textural data: General framework, new models, and streamlined existing models
John R. Nimmo, William N. Herkelrath, Luna Laguna
2007, Vadose Zone Journal (6) 766-773
Numerous models are in widespread use for the estimation of soil water retention from more easily measured textural data. Improved models are needed for better prediction and wider applicability. We developed a basic framework from which new and existing models can be derived to facilitate improvements. Starting from the assumption...
Determining metal assimilation efficiency in aquatic invertebrates using enriched stable metal isotope tracers
Marie Noele Croteau, Samuel N. Luoma, B. Pellet
2007, Aquatic Toxicology (83) 116-125
We employ a novel approach that combines pulse-chase feeding and multi-labelled stable isotopes to determine gut passage time (GPT), gut retention time (GRT), food ingestion rate (IR) and assimilation efficiency (AE) of three trace elements for a freshwater gastropod. Lettuce isotopically enriched in 53Cr, 65Cu and 106Cd was fed for 2 h to Lymnaea stagnalis....
A simulation-based approach for estimating premining water quality: Red Mountain Creek, Colorado
Robert L. Runkel, Briant A Kimball, Katherine Walton-Day, Philip L. Verplanck
2007, Applied Geochemistry (22) 1899-1918
Regulatory agencies are often charged with the task of setting site-specific numeric water quality standards for impaired streams. This task is particularly difficult for streams draining highly mineralized watersheds with past mining activity. Baseline water quality data obtained prior to mining are often non-existent and application of generic water quality...
Nitrification in the euphotic zone as evidenced by nitrate dual isotopic composition: Observations from Monterey Bay, California
Scott D. Wankel, Carol Kendall, J.T. Pennington, Francisco P. Chavez, Adina Paytan
2007, Global Biogeochemical Cycles (21)
Coupled measurements of nitrate (NO3−), nitrogen (N), and oxygen (O) isotopic composition (δ15NNO3 and δ18ONO3) were made in surface waters of Monterey Bay to investigate multiple N cycling processes occurring within surface waters. Profiles collected throughout the year at three sites exhibit a wide range of values, suggesting simultaneous...
Recent climate trends and implications for water resources in the Catskill Mountain region, New York, USA
Douglas A. Burns, Julian Klaus, Michael R. McHale
2007, Journal of Hydrology (336) 155-170
Climate scientists have concluded that the earth’s surface air temperature warmed by 0.6 °C during the 20th century, and that warming induced by increasing concentrations of greenhouse gases is likely to continue in the 21st century, accompanied by changes in the hydrologic cycle. Climate change has important implications in the Catskill...
Isotopic characterization of three groundwater recharge sources and inferences for selected aquifers in the upper Klamath Basin of Oregon and California, USA
P.C. Palmer, M. W. Gannett, S.R. Hinkle
2007, Journal of Hydrology (336) 17-29
Stable isotope (??D and ??18O) signatures of three principal groundwater recharge areas in the 21,000-km2 upper Klamath Basin are used to infer recharge sources for aquifers in the interior parts of the basin. Two of the principal recharge areas, the Cascade Range on the western and southern margin of the...
Evidence for terrigenic SF6 in groundwater from basaltic aquifers, Jeju Island, Korea: Implications for groundwater dating
Dong-Chan Koh, Niel Plummer, Eurybiades Busenberg, Yongje Kim
2007, Journal of Hydrology (339) 93-104
Measurements of the concentrations of dichlorodifluoromethane (CFC-12), tritium (3H), and sulfur hexafluoride (SF6) in groundwater from basaltic aquifers in Jeju Island, Korea, demonstrate a terrigenic source of SF6. Using a lumped-parameter dispersion model, groundwater was identified as young water (<15 years), old water with negligible CFC-12 and 3H, and binary mixtures...
Nitrate dynamics within the Pajaro River, a nutrient-rich, losing stream
C.R. Ruehl, A.T. Fisher, Huertos M. Los, Scott D. Wankel, C.G. Wheat, Carol Kendall, C.E. Hatch, C. Shennan
2007, Journal of the North American Benthological Society (26) 191-206
The major ion chemistry of water from an 11.42-km reach of the Pajaro River, a losing stream in central coastal California, shows a consistent pattern of higher concentrations during the 2nd (dry) half of the water year. Most solutes are conserved during flow along the reach, but [NO3−] decreases by...
Correcting acoustic Doppler current profiler discharge measurement bias from moving-bed conditions without global positioning during the 2004 Glen Canyon Dam controlled flood on the Colorado River
J. W. Gartner, N. K. Ganju
2007, Limnology and Oceanography: Methods (5) 156-162
Discharge measurements were made by acoustic Doppler current profiler at two locations on the Colorado River during the 2004 controlled flood from Glen Canyon Dam, Arizona. Measurement hardware and software have constantly improved from the 1980s such that discharge measurements by acoustic profiling instruments are now routinely made over a...
Flux and age of dissolved organic carbon exported to the Arctic Ocean: A carbon isotopic study of the five largest arctic rivers
P.A. Raymond, J.W. McClelland, R.M. Holmes, A.V. Zhulidov, K. Mull, B. J. Peterson, Robert G. Striegl, G. R. Aiken, T.Y. Gurtovaya
2007, Global Biogeochemical Cycles (21)
The export and Δ14C-age of dissolved organic carbon (DOC) was determined for the Yenisey, Lena, Ob', Mackenzie, and Yukon rivers for 2004–2005. Concentrations of DOC elevate significantly with increasing discharge in these rivers, causing approximately 60% of the annual export to occur during a 2-month period following spring ice breakup....
Phosphorus budgets in Everglades wetland ecosystems: The effects of hydrology and nutrient enrichment
G.B. Noe, D.L. Childers
2007, Wetlands Ecology and Management (15) 189-205
The Florida Everglades is a naturally oligotrophic hydroscape that has experienced large changes in ecosystem structure and function as the result of increased anthropogenic phosphorus (P) loading and hydrologic changes. We present whole-ecosystem models of P cycling for Everglades wetlands with differing hydrology and P enrichment with the goal of...
Bedrock aquifers and population growth in the Denver Basin, Colorado, USA
J.E. Moore, R.G. Raynolds, M. Dechesne
2007, Episodes (30) 115-118
The Denver Basin bedrock aquifer system consists of Tertiary and Cretaceous age sedimentary rocks known as the Dawson, Denver, Arapahoe and Laramie-Fox Hills aquifers. The number of bedrock wells has increased from 12,000 in 1985 to over 33,700 in 2001 and the withdrawal of groundwater has caused water level declines...
Formation of mixed Al-Fe colloidal sorbent and dissolved-colloidal partitioning of Cu and Zn in the Cement Creek - Animas River Confluence, Silverton, Colorado
Laurence E. Schemel, Briant A. Kimball, Robert L. Runkel, Marisa H. Cox
2007, Applied Geochemistry (22) 1467-1484
Transport and chemical transformations of dissolved and colloidal Al, Fe, Cu and Zn were studied by detailed sampling in the mixing zone downstream from the confluence of Cement Creek (pH 4.1) with the Animas River (pH 7.6). Complete mixing resulted in...
Role of chemotaxis in the transport of bacteria through saturated porous media
R.M. Ford, Ronald W. Harvey
2007, Advances in Water Resources (30) 1608-1617
Populations of chemotactic bacteria are able to sense and respond to chemical gradients in their surroundings and direct their migration toward increasing concentrations of chemicals that they perceive to be beneficial to their survival. It has been suggested that this phenomenon may facilitate bioremediation processes by bringing bacteria into closer...
The science and practice of environmental flows and the role of hydrogeologists
M. Sophocleous
2007, Ground Water (45) 393-401
Conflicts between ecosystems and human needs for fresh water are increasing. The purpose of this paper is to raise awareness in the hydrogeologic community of environmental flows (EFs) and to address the major challenges involved in their protection. Ground water is a key component of EFs, and therefore hydrogeologists are...
Origin of halite brine in the Onondaga Trough near Syracuse, New York State, USA: Modeling geochemistry and variable-density flow
Richard M. Yager, William M. Kappel, Niel Plummer
2007, Hydrogeology Journal (15) 1321-1339
Halite brine (saturation ranging from 45 to 80%) lies within glacial sediments that fill the Onondaga Trough, a bedrock valley deepened by Pleistocene glaciation near Syracuse, New York State, USA. The most concentrated brine occupies the northern end of the trough, about 10 km downgradient of the northern limit 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...
