Factors controlling the configuration of the fresh-saline water interface in the Dead Sea coastal aquifers: Synthesis of TDEM surveys and numerical groundwater modeling
Y. Yechieli, U. Kafri, M. Goldman, C.I. Voss
2001, Hydrogeology Journal (9) 367-377
TDEM (time domain electromagnetic) traverses in the Dead Sea (DS) coastal aquifer help to delineate the configuration of the interrelated fresh-water and brine bodies and the interface in between. A good linear correlation exists between the logarithm of TDEM resistivity and the chloride concentration of groundwater, mostly in the higher...
Radiocarbon dating of dissolved inorganic carbon in groundwater from confined parts of the Upper Floridan aquifer, Florida, USA
Niel Plummer, C.L. Sprinkle
2001, Hydrogeology Journal (9) 127-150
Geochemical reaction models were evaluated to improve radiocarbon dating of dissolved inorganic carbon (DIC) in groundwater from confined parts of the Upper Floridan aquifer in central and northeastern Florida, USA. The predominant geochemical reactions affecting the 14C activity of DIC include (1) dissolution of dolomite and anhydrite with calcite precipitation...
Formation and transport of the sulfonic acid metabolites of alachlor and metolachlor in soil
D.S. Aga, E.M. Thurman
2001, Environmental Science & Technology (35) 2455-2460
Alachlor and metolachlor are dechlorinated and transformed into their corresponding ethane sulfonic acid (ESA) metabolites in soil. In a field-disappearance study, it was shown that alachlor ESA was formed at a faster rate and at concentrations 2−4 times higher than metolachlor ESA, conforming with the observed longer...
Topographic controls on the chemistry of subsurface stormflow
D.L. Welsch, C.N. Kroll, Jeffery J. McDonnell, Douglas A. Burns
2001, Hydrological Processes (15) 1925-1938
Models are needed that describe how topography and other watershed characteristics affect the chemical composition of runoff waters, yet little spatially distributed data exist to develop such models. A topographically driven flushing mechanism for nitrate (NO3-) and dissolved organic carbon has been described in recent literature; however, this mechanism has...
Results from the Big Spring basin water quality monitoring and demonstration projects, Iowa, USA
R.D. Rowden, H. Liu, R.D. Libra
2001, Hydrogeology Journal (9) 487-497
Agricultural practices, hydrology, and water quality of the 267-km2 Big Spring groundwater drainage basin in Clayton County, Iowa, have been monitored since 1981. Land use is agricultural; nitrate-nitrogen (-N) and herbicides are the resulting contaminants in groundwater and surface water. Ordovician Galena Group carbonate rocks comprise the main aquifer in...
Regression models for estimating herbicide concentrations in U.S. streams from watershed characteristics
S.J. Larson, R. J. Gilliom
2001, Journal of the American Water Resources Association (37) 1349-1367
Regression models were developed for estimating stream concentrations of the herbicides alachlor, atrazine, cyanazine, metolachlor, and trifluralin from use-intensity data and watershed characteristics. Concentrations were determined from samples collected from 45 streams throughout the United States during 1993 to 1995 as part of the U.S. Geological Survey's National Water-Quality Assessment...
Hydrology of the coastal sabkhas of Abu Dhabi, United Arab Emirates
Ward E. Sanford, Warren W. Wood
2001, Hydrogeology Journal (9) 358-366
Water fluxes were estimated and a water budget developed for the land surface and a surficial 10-m-deep section of the coastal sabkhas that extend from the city of Abu Dhabi, United Arab Emirates, west to the border with Saudi Arabia. The fluxes were estimated on the basis of water levels...
Major herbicides in ground water: Results from the National Water-Quality Assessment
J.E. Barbash, G.P. Thelin, D.W. Kolpin, R. J. Gilliom
2001, Journal of Environmental Quality (30) 831-845
To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2227 sites (wells and springs) sampled in 20 major hydrologic...
Laboratory and field evaluations of the LISST-100 instrument for suspended particle size determinations
J. W. Gartner, R. T. Cheng, P.-F. Wang, K. Richter
2001, Marine Geology (175) 199-219
Advances in technology have resulted in a new instrument that is designed for in-situ determination of particle size spectra. Such an instrument that can measure undisturbed particle size distributions is much needed for sediment transport studies. The LISST-100 (Laser In-Situ Scattering and Transmissometry)...
Pollen assemblages as paleoenvironmental proxies in the Florida Everglades
Debra A. Willard, L. M. Weimer, W.L. Riegel
2001, Review of Palaeobotany and Palynology (113) 213-235
Analysis of 170 pollen assemblages from surface samples in eight vegetation types in the Florida Everglades indicates that these wetland sub-environments are distinguishable from the pollen record and that they are useful proxies for hydrologic and edaphic parameters. Vegetation types sampled include sawgrass marshes, cattail marshes, sloughs with floating aquatics,...
Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria
L.G. Miller, Robert M. Kalin, S.E. McCauley, John T.G. Hamilton, D.B. Harper, D.B. Millet, R.S. Oremland, Allen H. Goldstein
2001, Proceedings of the National Academy of Sciences of the United States of America (98) 5833-5837
The largest biological fractionations of stable carbon isotopes observed in nature occur during production of methane by methanogenic archaea. These fractionations result in substantial (as much as ≈70‰) shifts in δ13C relative to the initial substrate. We now report that a stable carbon isotopic fractionation of...
Determination of the sources of nitrate contamination in karst springs using isotopic and chemical indicators
S.V. Panno, Keith C. Hackley, H.-H. Hwang, W.R. Kelly
2001, Chemical Geology (179) 113-128
The sources of nitrate (NO-3) in groundwater of the shallow karst aquifer in southwestern Illinois' sinkhole plain were investigated using chemical and isotopic techniques. The groundwater in this aquifer is an important source of potable water for about half of the residents of the sinkhole plain area. Previous work has...
pH dependence of iron photoreduction in a rocky mountain stream affected by acid mine drainage
Diane M. McKnight, B. A. Kimball, R.L. Runkel
2001, Hydrological Processes (15) 1979-1992
The redox speciation of dissolved iron and the transport of iron in acidic, metal‐enriched streams is controlled by precipitation and dissolution of iron hydroxides, by photoreduction of dissolved ferric iron and hydrous iron oxides, and by oxidation of the resulting dissolved ferrous iron. We examined the...
Timescales for nitrate contamination of spring waters, northern Florida, USA
B. G. Katz, J.K. Böhlke, H.D. Hornsby
2001, Chemical Geology (179) 167-186
Residence times of groundwater, discharging from springs in the middle Suwannee River Basin, were estimated using chlorofluorocarbons (CFCs), tritium (3H), and tritium/helium-3 (3H/3He) age-dating methods to assess the chronology of nitrate contamination of spring waters in northern Florida. During base-flow conditions for the Suwannee River in 1997–1999, 17 water samples...
Sulfate-reducing bacteria release barium and radium from naturally occurring radioactive material in oil-field barite
Elizabeth J.P. Phillips, E. R. Landa, T. Kraemer, R. Zielinski
2001, Geomicrobiology Journal (18) 167-182
Scale and sludge deposits formed during oil production can contain elevated levels of Ra, often coprecipitated with barium sulfate (barite). The potential for sulfate-reducing bacteria to release 226 Ra and Ba (a Ra analog) from oil-field barite was evaluated. The concentration of dissolved Ba increased when samples containing pipe scale,...
Effect of canopy removal on snowpack quantity and quality, fraser experimental forest, Colorado
R. Stottlemyer, C.A. Troendle
2001, Journal of Hydrology (245) 165-176
Snowpack peak water equivalent (PWE), ion concentration, content, and spatial distribution of ion load data from spring 1987-1996 in a 1 ha clearcut and adjacent forested plots vegetated by mature Picea engelmannii and Abies lasiocarpa in the Fraser experimental forest (FEF), Colorado are presented. Our objectives were: (1) to see...
Applying the scientific method to small catchment studies: Areview of the Panola Mountain experience
R. P. Hooper
2001, Hydrological Processes (15) 2039-2050
A hallmark of the scientific method is its iterative application to a problem to increase and refine the understanding of the underlying processes controlling it. A successful iterative application of the scientific method to catchment science (including the fields of hillslope hydrology and biogeochemistry) has been hindered by two factors....
A look inside 'black box' hydrograph separation models: A study at the hydrohill catchment
C. Kendall, Jeffery J. McDonnell, W. Gu
2001, Hydrological Processes (15) 1877-1902
Runoff sources and dominant flowpaths are still poorly understood in most catchments; consequently, most hydrograph separations are essentially 'black box' models where only external information is used. The well-instrumented 490 m2 Hydrohill artificial grassland catchment located near Nanjing (China) was used to examine internal catchment processes. Since groundwater levels never...
Influence of reactive sulfide (AVS) and supplementary food on Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata
J.-S. Lee, B.-G. Lee, H. Yoo, C.-H. Koh, S. N. Luoma
2001, Marine Ecology Progress Series (216) 129-140
A laboratory bioassay determined the relative contribution of various pathways of Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata exposed to moderately contaminated sediments. Juvenile worms were exposed for 25 d to experimental sediments containing 5 different reactive sulfide (acid volatile sulfides, AVS) concentrations (1 to 30...
Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons
T.M. Yanosky, B. P. Hansen, M.R. Schening
2001, Journal of Contaminant Hydrology (50) 159-173
Oaks (Quercus velutina Lam.) growing over a shallow aquifer contaminated by chlorinated hydrocarbons were studied to determine if it was possible to estimate the approximate year that contamination began. The annual rings of some trees downgradient from the contaminant release site contained elevated concentrations of chloride possibly derived from dechlorination...
Evaluation of flash-flood discharge forecasts in complex terrain using precipitation
D. Yates, T.T. Warner, E.A. Brandes, G.H. Leavesley, Jielun Sun, C.K. Mueller
2001, Journal of Hydrologic Engineering (6) 265-274
Operational prediction of flash floods produced by thunderstorm (convective) precipitation in mountainous areas requires accurate estimates or predictions of the precipitation distribution in space and time. The details of the spatial distribution are especially critical in complex terrain because the watersheds are generally small in size, and small position errors...
Possible environmental factors underlying amphibian decline in eastern Puerto Rico: Analysis of U.S. government data archives
R.F. Stallard
2001, Conservation Biology (15) 943-953
The past three decades have seen major declines in populations of several species of amphibians at high elevations in eastern Puerto Rico, a region unique in the humid tropics because of the degree of environmental monitoring that has taken place through the efforts of U.S. government agencies. I examined changes...
Long-term changes in consentrations and flux fo nitrogen in the Mississippi River Basin, USA
D. A. Goolsby, W.A. Battaglin
2001, Hydrological Processes (15) 1209-1226
Current and historical data show that nitrogen concentrations and flux in the Mississippi River Basin have increased significantly during the past 100 years. Most of the increase observed in the lower Mississippi River has occurred since the early 1970s and is due almost entirely to an increase in nitrate. The...
Quantifying contributions to storm runoff through end-member mixing analysis and hydrologic measurements at the Panola Mountain research watershed (Georgia, USA)
Douglas A. Burns, Jeffery J. McDonnell, R. P. Hooper, N.E. Peters, J.E. Freer, C. Kendall, K. Beven
2001, Hydrological Processes (15) 1903-1924
The geographic sources and hydrologic flow paths of stormflow in small catchments are not well understood because of limitations in sampling methods and insufficient resolution of potential end members. To address these limitations, an extensive hydrologic dataset was collected at a 10 ha catchment at Panola Mountain research watershed near...
Carbon and nitrogen isotopic compositions of particulate organic matter in four large river systems across the United States
C. Kendall, S. R. Silva, V.J. Kelly
2001, Hydrological Processes (15) 1301-1346
Riverine particulate organic matter (POM) samples were collected bi‐weekly to monthly from 40 sites in the Mississippi, Colorado, Rio Grande, and Columbia River Basins (USA) in 1996–97 and analysed for carbon and nitrogen stable isotopic compositions. These isotopic compositions and C : N ratios were used to identify four endmember...
