Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2–2.0 μm e.s.d.), medium (0.02–0.2 μm e.s.d.), and fine (> 0.02 μm e.s.d.) clay subfractions from three Midwestern soils and characterized the organic material associated with these subfractions using 13C-CPMAS-NMR, DTG, SEM-EDX, incubations, and radiocarbon age. Most of the C in the coarse clay subfraction was present as discrete particles (0.2–5 μm as seen in SEM images) of black carbon (BC) and consisted of approximately 60% aromatic C, with the remainder being a mixture of aliphatic, anomeric and carboxylic C. We hypothesize that BC particles were originally charcoal formed during prairie fires. As the BC particles aged in soil their surfaces were oxidized to form carboxylic groups and anomeric and aliphatic C accumulated in the BC particles either by adsorption of dissolved biogenic compounds from the soil solution or by direct deposition of biogenic materials from microbes living within the BC particles. The biogenic soil organic matter was physically separated with the medium and fine clay subfractions and was dominated by aliphatic, anomeric, and carboxylic C. The results indicate that the biogenic humic materials in our soils have little aromatic C, which is inconsistent with the traditional heteropolymer model of humic substances.
Quantifying biogeochemical cycles of nitrogen (N) and the associated fluxes to surface waters remains challenging, given the need to deal with spatial and temporal variability and to characterize complex and heterogeneous landscapes. We focused our study on catchments S14 and S15 located in the Adirondack Mountains of New York, USA, which have similar topographic and hydrologic characteristics but contrasting stream nitrate ($\\hbox{NO}_{3}^{-}$) concentrations. We characterized the mechanisms by which $\\hbox{NO}_{3}^{-}$ reaches the streams during hydrological events in these catchments, aiming to reconcile our field data with our conceptual model of factors that regulate nutrient exports from forested catchments. Combined hydrometric, chemical and isotopic (δ$\\hbox{NO}_{3}^{-}$) data showed that the relative contributions of both soil and ground water sources were similar between the two catchments. Temporal patterns of stream chemistry were markedly different between S14 and S15, however, because the water sources in the two catchments have different solute concentrations. During late summer/fall, the largest source of $\\hbox{NO}_{3}^{-}$ in S14 was till groundwater, whereas shallow soil was the largest $\\hbox{NO}_{3}^{-}$ source in S15. $\\hbox{NO}_{3}^{-}$ concentrations in surface water decreased in S14, whereas they increased in S15 because an increasing proportion of stream flow was derived from shallow soil sources. During snowmelt, the largest sources of $\\hbox{NO}_{3}^{-}$were in the near‐surface soil in both catchments. Concentrations of $\\hbox{NO}_{3}^{-}$ increased as stream discharge increased and usually peaked before peak discharge, when shallow soil water sources made the largest contribution to stream discharge. The timing of peaks in stream $\\hbox{NO}_{3}^{-}$concentrations was affected by antecedent moisture conditions. By elucidating the factors that affect sources and transport of N, including differences in the soil nutrient cycling and hydrological characteristics of S14 and S15, this study contributes to the overall conceptualization of $\\hbox{NO}_{3}^{-}$ release from temperate forested catchments.
Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized as terrestrial, microbial, or intermediate humic substances or transphilic acids. All anion exchange experiments were conducted using a magnetic ion exchange (MIEX) resin. The charge density of the DOM isolates, determined by direct potentiometric titration, was fundamental to quantifying the stoichiometry of the anion exchange mechanism. The results clearly show that all DOM isolates were removed by anion exchange; however, differences among the DOM isolates did influence their removal by MIEX resin. In particular, MIEX resin had the greatest affinity for DOM with high charge density and the least affinity for DOM with low charge density and low aromaticity. This work illustrates that the chemical characteristics of DOM and solution conditions must be considered when evaluating anion exchange treatment for the removal of DOM.
Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated “intact” sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress.
Largemouth bass (Micropterus salmoides) and common carp (Cyprinus carpio) were collected from 13 sites located in the Mobile (MRB), Apalachicola–Flint–Chattahoochee (ARB), Savannah (SRB), and Pee Dee (PRB) River Basins to document spatial trends in accumulative chemical contaminants, health indicators, and reproductive biomarkers. Organochlorine residues, 2,3,7,8-tetrachlorodibenzo-p-dioxin-like activity (TCDD-EQ), and elemental contaminants were measured in composite samples of whole fish, grouped by species and gender, from each site. Mercury (Hg) and polychlorinated biphenyls (PCBs) were the primary contaminants of concern. Concentrations of Hg in bass samples from all basins exceeded toxicity thresholds for piscivorous mammals (> 0.1 μg/g ww), juvenile and adult fish (> 0.2 μg/g ww), and piscivorous birds (> 0.3 μg/g ww). Total PCB concentrations in samples from the MRB, ARB, and PRB were > 480 ng/g ww and may be a risk to piscivorous wildlife. Selenium concentrations also exceeded toxicity thresholds (> 0.75 μg/g ww) in MRB and ARB fish. Concentrations of other formerly used (total chlordanes, dieldrin, endrin, aldrin, mirex, and hexachlorobenzene) and currently used (pentachlorobenzene, pentachloroanisole, dacthal, endosulfan, γ-hexachlorocyclohexane, and methoxychlor) organochlorine residues were generally low or did not exceed toxicity thresholds for fish and piscivorous wildlife. TCDD-EQs exceeded wildlife dietary guidelines (> 5 pg/g ww) in MRB and PRB fish. Hepatic ethoxyresorufin O-deethylase (EROD) activity was generally greatest in MRB bass and carp. Altered fish health indicators and reproductive biomarker were noted in individual fish, but mean responses were similar among basins. The field necropsy and histopathological examination determined that MRB fish were generally in poorer health than those from the other basins, primarily due to parasitic infestations. Tumors were found in few fish (n = 5; 0.01%); ovarian tumors of smooth muscle origin were found in two ARB carp from the same site. Intersex gonads were identified in 47 male bass (42%) representing 12 sites and may indicate exposure to potential endocrine disrupting compounds. Comparatively high vitellogenin concentrations (> 0.35 mg/mL) in male fish from the MRB, SRB, and PRB indicate exposure to estrogenic or anti-androgenic chemicals.
Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of this soil carbon. It is unclear, however, how changes in environmental conditions influence decomposition in these systems, and if substrate controls of decomposition vary with hydrologic and thermal regime. We addressed these issues by investigating the effects of temperature, moisture, and organic matter chemical characteristics on decomposition of fibric soil horizons from three black spruce forest sites. The sites varied in drainage and permafrost, and included a “Well Drained” site where permafrost was absent, and “Moderately well Drained” and “Poorly Drained” sites where permafrost was present at about 0.5 m depth. Samples collected from each site were incubated at five different moisture contents (2, 25, 50, 75, and 100% saturation) and two different temperatures (10°C and 20°C) in a full factorial design for two months. Organic matter chemistry was analyzed using pyrolysis gas chromatography-mass spectrometry prior to incubation, and after incubation on soils held at 20°C, 50% saturation. Mean cumulative mineralization, normalized to initial carbon content, ranged from 0.2% to 4.7%, and was dependent on temperature, moisture, and site. The effect of temperature on mineralization was significantly influenced by moisture content, as mineralization was greatest at 20°C and 50–75% saturation. While the relative effects of temperature and moisture were similar for all soils, mineralization rates were significantly greater for samples from the “Well Drained” site compared to the other sites. Variations in the relative abundances of polysaccharide-derivatives and compounds of undetermined source (such as toluene, phenol, 4-methyl phenol, and several unidentifiable compounds) could account for approximately 44% of the variation in mineralization across all sites under ideal temperature and moisture conditions. Based on our results, changes in temperature and moisture likely have similar, additive effects on in situ soil organic matter (SOM) decomposition across a wide range of black spruce forest systems, while variations in SOM chemistry can lead to significant differences in decomposition rates within and among forest sites.
Mercury and organic carbon concentrations vary dynamically in streamwater at the Sleepers River Research Watershed in Vermont, USA. Total mercury (THg) concentrations ranged from 0.53 to 93.8 ng/L during a 3-year period of study. The highest mercury (Hg) concentrations occurred slightly before peak flows and were associated with the highest organic carbon (OC) concentrations. Dissolved Hg (DHg) was the dominant form in the upland catchments; particulate Hg (PHg) dominated in the lowland catchments. The concentration of hydrophobic acid (HPOA), the major component of dissolved organic carbon (DOC), explained 41–98% of the variability of DHg concentration while DOC flux explained 68–85% of the variability in DHg flux, indicating both quality and quantity of the DOC substantially influenced the transport and fate of DHg. Particulate organic carbon (POC) concentrations explained 50% of the PHg variability, indicating that POC is an important transport mechanism for PHg. Despite available sources of DHg and wetlands in the upland catchments, dissolved methylmercury (DmeHg) concentrations in streamwaters were below detection limit (0.04 ng/L). PHg and particulate methylmercury (PmeHg) had a strong positive correlation (r 2 = 0.84, p < 0.0001), suggesting a common source; likely in-stream or near-stream POC eroded or re-suspended during spring snowmelt and summer storms. Ratios of PmeHg to THg were low and fairly constant despite an apparent higher methylmercury (meHg) production potential in the summer. Methylmercury production in soils and stream sediments was below detection during snowmelt in April and highest in stream sediments (compared to forest and wetland soils) sampled in July. Using the watershed approach, the correlation of the percent of wetland cover to TmeHg concentrations in streamwater indicates that poorly drained wetland soils are a source of meHg and the relatively high concentrations found in stream surface sediments in July indicate these zones are a meHg sink.
Fires in terrestrial ecosystems produce large amounts of charcoal that persist in the environment and represent a substantial pool of sequestered carbon in soil. The objective of this research was to investigate the effect of charring on mid-infrared spectra of materials likely to be present in forest fires in order to determine the feasibility of determining charred organic matter in soils. Four materials (cellulose, lignin, pine bark, and pine wood) and char from these materials, created by charring for various durations (1 to 168 h) and at various temperatures (200 to 450 °C), were studied. Mid-infrared spectra and measures of acidity (total acids, carboxylic acids, lactones, and phenols as determined by titration) were determined for 56 different samples (not all samples were charred at all temperatures/durations). Results showed spectral changes that varied with the material, temperature, and duration of charring. Despite the wide range of spectral changes seen with the differing materials and length/temperature of charring, partial least squares calibrations for total acids, carboxylic acids, lactones, and phenols were successfully created (coefficient of determination and root mean squared deviation of 0.970 and 0.380; 0.933 and 0.227; 0.976 and 0.120; and 0.982 and 0.101 meq/g, respectively), indicating that there is a sufficient commonality in the changes to develop calibrations without the need for unique calibrations for each specific material or condition of char formation.
The vulnerability of a municipal well in the Northwest well field in southeastern Florida to potential contamination by Cryptosporidium parvum oocysts was assessed in a large‐scale, forced‐gradient (convergent) injection and recovery test. The field study involved a simultaneous pulse introduction of a nonreactive tracer (SF6, an inert gas) and oocyst‐sized (1.6, 2.9, and 4.9 μm diameter) carboxylated polystyrene microspheres into karst limestone of the Biscayne aquifer characterized by a complex triple (matrix, touching‐vug, and conduit) porosity. Fractional recoveries 97 m down gradient were inversely related to diameter and ranged from 2.9% for the 4.9 μm microspheres to 5.8% for 1.6 μm microspheres. Their centers of mass arrived at the pumping well approximately threefold earlier than that of the nonreactive tracer SF6 (gas), underscoring the need for use of colloid tracers and field‐scale tracer tests for these kinds of evaluations. In a modified triaxial cell using near in situ chemical conditions, 2.9 and 4.9 μm microspheres underestimated by fourfold to sixfold the attachment potential of the less electronegative 2.9–4.1 μm oocysts in the matrix porosity of limestone core samples. The field and laboratory results collectively suggested that it may take 200–300 m of transport to ensure even a 1‐log unit removal of oocysts, even though the limestone surfaces exhibited a substantive capability for their sorptive removal. The study further demonstrated the utility of microspheres as oocyst surrogates in field‐scale assessments of well vulnerability in limestone, provided that differences in attachment behaviors between oocysts and microspheres are taken into account.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2007WR006060","usgsCitation":"Harvey, R.W., Metge, D.W., Shapiro, A.M., Renken, R.A., Osborn, C.L., Ryan, J.N., Cunningham, K.J., and Landkamer, L.L., 2008, Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 3. Use of microspheres to estimate the transport potential of Cryptosporidium parvum oocysts: Water Resources Research, v. 44, no. 8, W08431; 12 p., https://doi.org/10.1029/2007WR006060.","productDescription":"W08431; 12 p.","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":476722,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/2007wr006060","text":"Publisher Index Page"},{"id":242057,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"44","issue":"8","noUsgsAuthors":false,"publicationDate":"2008-08-23","publicationStatus":"PW","scienceBaseUri":"505a7596e4b0c8380cd77c20","contributors":{"authors":[{"text":"Harvey, Ronald W. 0000-0002-2791-8503 rwharvey@usgs.gov","orcid":"https://orcid.org/0000-0002-2791-8503","contributorId":564,"corporation":false,"usgs":true,"family":"Harvey","given":"Ronald","email":"rwharvey@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441663,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Metge, David W. dwmetge@usgs.gov","contributorId":663,"corporation":false,"usgs":true,"family":"Metge","given":"David","email":"dwmetge@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441665,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Shapiro, Allen M. 0000-0002-6425-9607 ashapiro@usgs.gov","orcid":"https://orcid.org/0000-0002-6425-9607","contributorId":2164,"corporation":false,"usgs":true,"family":"Shapiro","given":"Allen","email":"ashapiro@usgs.gov","middleInitial":"M.","affiliations":[{"id":37277,"text":"WMA - Earth System Processes Division","active":true,"usgs":true},{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":true,"id":441667,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Renken, Robert A. rarenken@usgs.gov","contributorId":269,"corporation":false,"usgs":true,"family":"Renken","given":"Robert","email":"rarenken@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":441668,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Osborn, Christina L.","contributorId":118702,"corporation":false,"usgs":false,"family":"Osborn","given":"Christina","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":441662,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Ryan, Joseph N.","contributorId":54290,"corporation":false,"usgs":false,"family":"Ryan","given":"Joseph","email":"","middleInitial":"N.","affiliations":[{"id":604,"text":"University of Colorado- Boulder","active":false,"usgs":true}],"preferred":false,"id":441669,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Cunningham, Kevin J. 0000-0002-2179-8686 kcunning@usgs.gov","orcid":"https://orcid.org/0000-0002-2179-8686","contributorId":1689,"corporation":false,"usgs":true,"family":"Cunningham","given":"Kevin","email":"kcunning@usgs.gov","middleInitial":"J.","affiliations":[{"id":269,"text":"FLWSC-Ft. Lauderdale","active":true,"usgs":true}],"preferred":true,"id":441664,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Landkamer, Lee L.","contributorId":65679,"corporation":false,"usgs":true,"family":"Landkamer","given":"Lee","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":441666,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70033607,"text":"70033607 - 2008 - Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir","interactions":[],"lastModifiedDate":"2018-10-17T07:50:32","indexId":"70033607","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1169,"text":"Canadian Journal of Fisheries and Aquatic Sciences","active":true,"publicationSubtype":{"id":10}},"title":"Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir","docAbstract":"Physical and biogeochemical characteristics of the aquatic environment that affect growth dynamics of phytoplankton and the zooplankton communities that depend on them may also affect uptake of methylmercury (MeHg) into the pelagic food web of oligotrophic reservoirs. We evaluated changes in the quality and quantity of suspended particulate material, zooplankton taxonomy, and MeHg concentrations coincident with seasonal changes in water storage of a mining-impacted reservoir in northern California, USA. MeHg concentrations in bulk zooplankton increased from 4 ng·g–1 at low water to 77 ± 6.1 ng·g–1 at high water and were positively correlated with cladoceran biomass (r = 0.66) and negatively correlated with rotifer biomass (r = –0.65). Stable isotope analysis revealed overall higher MeHg concentrations in the pelagic-based food web relative to the benthic-based food web. Statistically similar patterns of trophic enrichment of MeHg (slopes) for the pelagic and benthic food webs and slightly higher MeHg concentrations in zooplankton than in benthic invertebrates suggest that the difference in MeHg bioaccumulation among trophic pathways is set at the base of the food webs. These results suggest an important role for plankton dynamics in driving the MeHg content of zooplankton and ultimately MeHg bioaccumulation in top predators in pelagic-based food webs.
","language":"English","publisher":"Canadian Science Publishing","doi":"10.1139/F08-140","issn":"07066","usgsCitation":"Stewart, A., Saiki, M.K., Kuwabara, J., Alpers, C.N., Marvin-DiPasquale, M., and Krabbenhoft, D., 2008, Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir: Canadian Journal of Fisheries and Aquatic Sciences, v. 65, no. 11, p. 2351-2366, https://doi.org/10.1139/F08-140.","productDescription":"16 p.","startPage":"2351","endPage":"2366","costCenters":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true},{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":242022,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214310,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1139/F08-140"}],"volume":"65","issue":"11","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3b65e4b0c8380cd624cd","contributors":{"authors":[{"text":"Stewart, A.R.","contributorId":20470,"corporation":false,"usgs":true,"family":"Stewart","given":"A.R.","email":"","affiliations":[],"preferred":false,"id":441646,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Saiki, M. K.","contributorId":28917,"corporation":false,"usgs":true,"family":"Saiki","given":"M.","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":441648,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kuwabara, J.S.","contributorId":57905,"corporation":false,"usgs":true,"family":"Kuwabara","given":"J.S.","email":"","affiliations":[],"preferred":false,"id":441649,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Alpers, Charles N. 0000-0001-6945-7365 cnalpers@usgs.gov","orcid":"https://orcid.org/0000-0001-6945-7365","contributorId":411,"corporation":false,"usgs":true,"family":"Alpers","given":"Charles","email":"cnalpers@usgs.gov","middleInitial":"N.","affiliations":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"preferred":true,"id":441651,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Marvin-DiPasquale, M.","contributorId":28367,"corporation":false,"usgs":true,"family":"Marvin-DiPasquale","given":"M.","affiliations":[],"preferred":false,"id":441647,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Krabbenhoft, D. P. 0000-0003-1964-5020","orcid":"https://orcid.org/0000-0003-1964-5020","contributorId":90765,"corporation":false,"usgs":true,"family":"Krabbenhoft","given":"D. P.","affiliations":[],"preferred":false,"id":441650,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70033600,"text":"70033600 - 2008 - Effects of ionic strength, temperature, and pH on degradation of selected antibiotics","interactions":[],"lastModifiedDate":"2018-10-22T07:35:02","indexId":"70033600","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2262,"text":"Journal of Environmental Quality","active":true,"publicationSubtype":{"id":10}},"title":"Effects of ionic strength, temperature, and pH on degradation of selected antibiotics","docAbstract":"Aqueous degradation rates, which include hydrolysis and epimerization, for chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TET), lincomycin (LNC), sulfachlorpyridazine (SCP), sulfadimethoxine (SDM), sulfathiazole (STZ), trimethoprim (TRM), and tylosin A (TYL) were studied as a function of ionic strength (0.0015, 0.050, or 0.084 mg/L as Na2HPO4), temperature (7, 22, and 35°C), and pH (2, 5, 7, 9, and 11). Multiple linear regression revealed that ionic strength did not significantly affect (α = 0.05) degradation rates for all compounds, but temperature and pH affected rates for CTC, OTC, and TET significantly (α = 0.05). Degradation also was observed for TYL at pH 2 and 11. No significant degradation was observed for LNC, SCP, SDM, STZ, TRM, and TYL (pH 5, 7, and 9) under study conditions. Pseudo first-order rate constants, half-lives, and Arrhenius coefficients were calculated where appropriate. In general, hydrolysis rates for CTC, OTC, and TET increased as pH and temperature increased following Arrhenius relationships. Known degradation products were used to confirm that degradation had occurred, but these products were not quantified. Half-lives ranged from less than 6 h up to 9.7 wk for the tetracyclines and for TYL (pH 2 and 11), but no degradation of LIN, the sulfonamides, or TRM was observed during the study period. These results indicate that tetracyclines and TYL at pH 2 and 11 are prone to pH-mediated transformation and hydrolysis in some cases, but not the sulfonamides, LIN nor TRM are inclined to degrade under study conditions. This indicates that with the exception of CTC, OTC, and TET, pH-mediated reactions such as hydrolysis and epimerization are not likely removal mechanisms in surface water, anaerobic swine lagoons, wastewater, and ground water.
","language":"English","publisher":"ACSESS","doi":"10.2134/jeq2007.0230","issn":"00472425","usgsCitation":"Loftin, K., Adams, C., Meyer, M.T., and Surampalli, R., 2008, Effects of ionic strength, temperature, and pH on degradation of selected antibiotics: Journal of Environmental Quality, v. 37, no. 2, p. 378-386, https://doi.org/10.2134/jeq2007.0230.","productDescription":"9 p.","startPage":"378","endPage":"386","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":241924,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214225,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2134/jeq2007.0230"}],"volume":"37","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a072ce4b0c8380cd515c3","contributors":{"authors":[{"text":"Loftin, K.A.","contributorId":25775,"corporation":false,"usgs":true,"family":"Loftin","given":"K.A.","email":"","affiliations":[],"preferred":false,"id":441617,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Adams, C.D.","contributorId":35135,"corporation":false,"usgs":true,"family":"Adams","given":"C.D.","email":"","affiliations":[],"preferred":false,"id":441618,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Meyer, M. T.","contributorId":92279,"corporation":false,"usgs":true,"family":"Meyer","given":"M.","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":441620,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Surampalli, R.","contributorId":52001,"corporation":false,"usgs":true,"family":"Surampalli","given":"R.","email":"","affiliations":[],"preferred":false,"id":441619,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70033596,"text":"70033596 - 2008 - Permeability of continental crust influenced by internal and external forcing","interactions":[],"lastModifiedDate":"2019-03-28T16:50:15","indexId":"70033596","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1765,"text":"Geofluids","active":true,"publicationSubtype":{"id":10}},"title":"Permeability of continental crust influenced by internal and external forcing","docAbstract":"The permeability of continental crust is so highly variable that it is often considered to defy systematic characterization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability–depth relations) on a very large scale? Here we argue that large‐scale crustal permeability adjusts to accommodate rates of internal and external forcing. In the deeper crust, internal forcing – fluxes induced by metamorphism, magmatism, and mantle degassing – is dominant, whereas in the shallow crust, external forcing – the vigor of the hydrologic cycle – is a primary control. Crustal petrologists have long recognized the likelihood of a causal relation between fluid flux and permeability in the deep, ductile crust, where fluid pressures are typically near‐lithostatic. It is less obvious that such a relation should pertain in the relatively cool, brittle upper crust, where near‐hydrostatic fluid pressures are the norm. We use first‐order calculations and numerical modeling to explore the hypothesis that upper‐crustal permeability is influenced by the magnitude of external fluid sources, much as lower‐crustal permeability is influenced by the magnitude of internal fluid sources. We compare model‐generated permeability structures with various observations of crustal permeability.
","language":"English","publisher":"Wiley","doi":"10.1111/j.1468-8123.2008.00211.x","issn":"14688115","usgsCitation":"Rojstaczer, S., Ingebritsen, S.E., and Hayba, D., 2008, Permeability of continental crust influenced by internal and external forcing: Geofluids, v. 8, no. 2, p. 128-139, https://doi.org/10.1111/j.1468-8123.2008.00211.x.","productDescription":"12 p.","startPage":"128","endPage":"139","costCenters":[{"id":245,"text":"Eastern Mineral and Environmental Resources Science Center","active":true,"usgs":true},{"id":615,"text":"Volcano Hazards Program","active":true,"usgs":true}],"links":[{"id":214165,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1111/j.1468-8123.2008.00211.x"},{"id":241859,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"8","issue":"2","noUsgsAuthors":false,"publicationDate":"2008-05-20","publicationStatus":"PW","scienceBaseUri":"505a76ade4b0c8380cd78259","contributors":{"authors":[{"text":"Rojstaczer, S.A.","contributorId":54620,"corporation":false,"usgs":true,"family":"Rojstaczer","given":"S.A.","email":"","affiliations":[],"preferred":false,"id":441599,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ingebritsen, S. E.","contributorId":8078,"corporation":false,"usgs":true,"family":"Ingebritsen","given":"S.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":441598,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hayba, D.O. 0000-0003-4092-1894","orcid":"https://orcid.org/0000-0003-4092-1894","contributorId":57850,"corporation":false,"usgs":true,"family":"Hayba","given":"D.O.","affiliations":[],"preferred":false,"id":441600,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033575,"text":"70033575 - 2008 - Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow","interactions":[],"lastModifiedDate":"2018-10-22T08:41:54","indexId":"70033575","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3722,"text":"Water Resources Research","onlineIssn":"1944-7973","printIssn":"0043-1397","active":true,"publicationSubtype":{"id":10}},"title":"Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow","docAbstract":"The Biscayne aquifer is a highly transmissive karst limestone that serves as the sole source of drinking water to over two million residents in south Florida. The aquifer is characterized by eogenetic karst, where the most transmissive void space can be an interconnected, touching‐vug, biogenically influenced porosity of biogenic origin. Public supply wells in the aquifer are in close proximity to lakes established by surface mining. The mining of the limestone has occurred to the same depths as the production wells, which has raised concerns about pathogen and chemical transport from these surface water bodies. Hydraulic and forced gradient tracer tests were conducted to augment geologic and geophysical studies and to develop a hydrogeologic conceptual model of groundwater flow and chemical transport in the Biscayne aquifer. Geologic and geophysical data indicate multiple, areally extensive subhorizontal preferential flow zones of vuggy limestone separated by rock with a matrix pore system. The hydraulic response from an aquifer test suggests that the Biscayne aquifer behaves as a dual‐porosity medium; however, the results of the tracer test showed rapid transport similar to other types of karst. The tracer test and concurrent temperature logging revealed that only one of the touching‐vug flow zones dominates transport near the production wells. On the basis of the rising limb of the breakthrough curve, the dispersivity is estimated to be less than 3% of the tracer travel distance, which suggests that the fastest flow paths in the formation are likely to yield limited dilution of chemical constituents.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2007WR006058","usgsCitation":"Renken, R.A., Cunningham, K.J., Shapiro, A.M., Harvey, R.W., Zygnerski, M.R., Metge, D.W., and Wacker, M.A., 2008, Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow: Water Resources Research, v. 44, no. 8, W08429; 16 p., https://doi.org/10.1029/2007WR006058.","productDescription":"W08429; 16 p.","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":476744,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/2007wr006058","text":"Publisher Index Page"},{"id":242021,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"44","issue":"8","noUsgsAuthors":false,"publicationDate":"2008-08-23","publicationStatus":"PW","scienceBaseUri":"505a7595e4b0c8380cd77c14","contributors":{"authors":[{"text":"Renken, Robert A. rarenken@usgs.gov","contributorId":269,"corporation":false,"usgs":true,"family":"Renken","given":"Robert","email":"rarenken@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":441504,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Cunningham, Kevin J. 0000-0002-2179-8686 kcunning@usgs.gov","orcid":"https://orcid.org/0000-0002-2179-8686","contributorId":1689,"corporation":false,"usgs":true,"family":"Cunningham","given":"Kevin","email":"kcunning@usgs.gov","middleInitial":"J.","affiliations":[{"id":269,"text":"FLWSC-Ft. Lauderdale","active":true,"usgs":true}],"preferred":true,"id":441499,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Shapiro, Allen M. 0000-0002-6425-9607 ashapiro@usgs.gov","orcid":"https://orcid.org/0000-0002-6425-9607","contributorId":2164,"corporation":false,"usgs":true,"family":"Shapiro","given":"Allen","email":"ashapiro@usgs.gov","middleInitial":"M.","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true},{"id":37277,"text":"WMA - Earth System Processes Division","active":true,"usgs":true}],"preferred":true,"id":441502,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Harvey, Ronald W. 0000-0002-2791-8503 rwharvey@usgs.gov","orcid":"https://orcid.org/0000-0002-2791-8503","contributorId":564,"corporation":false,"usgs":true,"family":"Harvey","given":"Ronald","email":"rwharvey@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441498,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Zygnerski, Michael R.","contributorId":25469,"corporation":false,"usgs":true,"family":"Zygnerski","given":"Michael","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":441500,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Metge, David W. dwmetge@usgs.gov","contributorId":663,"corporation":false,"usgs":true,"family":"Metge","given":"David","email":"dwmetge@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441501,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Wacker, Michael A. mwacker@usgs.gov","contributorId":2162,"corporation":false,"usgs":true,"family":"Wacker","given":"Michael","email":"mwacker@usgs.gov","middleInitial":"A.","affiliations":[{"id":269,"text":"FLWSC-Ft. Lauderdale","active":true,"usgs":true}],"preferred":true,"id":441503,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70033573,"text":"70033573 - 2008 - Passive microwave (SSM/I) satellite predictions of valley glacier hydrology, Matanuska Glacier, Alaska","interactions":[],"lastModifiedDate":"2012-03-12T17:21:29","indexId":"70033573","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1807,"text":"Geophysical Research Letters","active":true,"publicationSubtype":{"id":10}},"title":"Passive microwave (SSM/I) satellite predictions of valley glacier hydrology, Matanuska Glacier, Alaska","docAbstract":"We advance an approach to use satellite passive microwave observations to track valley glacier snowmelt and predict timing of spring snowmelt-induced floods at the terminus. Using 37 V GHz brightness temperatures (Tb) from the Special Sensor Microwave hnager (SSM/I), we monitor snowmelt onset when both Tb and the difference between the ascending and descending overpasses exceed fixed thresholds established for Matanuska Glacier. Melt is confirmed by ground-measured air temperature and snow-wetness, while glacier hydrologic responses are monitored by a stream gauge, suspended-sediment sensors and terminus ice velocity measurements. Accumulation area snowmelt timing is correlated (R2 = 0.61) to timing of the annual snowmelt flood peak and can be predicted within ??5 days. Copyright 2008 by the American Geophysical Union.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Geophysical Research Letters","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1029/2008GL034615","issn":"00948","usgsCitation":"Kopczynski, S., Ramage, J., Lawson, D., Goetz, S., Evenson, E., Denner, J., and Larson, G., 2008, Passive microwave (SSM/I) satellite predictions of valley glacier hydrology, Matanuska Glacier, Alaska: Geophysical Research Letters, v. 35, no. 16, https://doi.org/10.1029/2008GL034615.","costCenters":[],"links":[{"id":214280,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1029/2008GL034615"},{"id":241985,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"35","issue":"16","noUsgsAuthors":false,"publicationDate":"2008-08-29","publicationStatus":"PW","scienceBaseUri":"505a757ce4b0c8380cd77b93","contributors":{"authors":[{"text":"Kopczynski, S.E.","contributorId":81318,"corporation":false,"usgs":true,"family":"Kopczynski","given":"S.E.","email":"","affiliations":[],"preferred":false,"id":441491,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ramage, J.","contributorId":73833,"corporation":false,"usgs":true,"family":"Ramage","given":"J.","affiliations":[],"preferred":false,"id":441490,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Lawson, D.","contributorId":98129,"corporation":false,"usgs":true,"family":"Lawson","given":"D.","affiliations":[],"preferred":false,"id":441492,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Goetz, S.","contributorId":101097,"corporation":false,"usgs":true,"family":"Goetz","given":"S.","email":"","affiliations":[],"preferred":false,"id":441493,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Evenson, E.","contributorId":53180,"corporation":false,"usgs":true,"family":"Evenson","given":"E.","email":"","affiliations":[],"preferred":false,"id":441489,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Denner, J.","contributorId":31215,"corporation":false,"usgs":true,"family":"Denner","given":"J.","email":"","affiliations":[],"preferred":false,"id":441487,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Larson, G.","contributorId":41585,"corporation":false,"usgs":true,"family":"Larson","given":"G.","email":"","affiliations":[],"preferred":false,"id":441488,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70033553,"text":"70033553 - 2008 - Evaporite-karst problems and studies in the USA","interactions":[],"lastModifiedDate":"2012-03-12T17:21:32","indexId":"70033553","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Evaporite-karst problems and studies in the USA","docAbstract":"Evaporites, including rock salt (halite) and gypsum (or anhydrite), are the most soluble among common rocks; they dissolve readily to form the same types of karst features that commonly are found in limestones and dolomites. Evaporites are present in 32 of the 48 contiguous states in USA, and they underlie about 40% of the land area. Typical evaporite-karst features observed in outcrops include sinkholes, caves, disappearing streams, and springs, whereas other evidence of active evaporite karst includes surface-collapse structures and saline springs or saline plumes that result from salt dissolution. Many evaporites also contain evidence of paleokarst, such as dissolution breccias, breccia pipes, slumped beds, and collapse structures. All these natural karst phenomena can be sources of engineering or environmental problems. Dangerous sinkholes and caves can form rapidly in evaporite rocks, or pre-existing karst features can be reactivated and open up (collapse) under certain hydrologic conditions or when the land is put to new uses. Many karst features also propagate upward through overlying surficial deposits. Human activities also have caused development of evaporite karst, primarily in salt deposits. Boreholes (petroleum tests or solution-mining operations) or underground mines may enable unsaturated water to flow through or against salt deposits, either intentionally or accidentally, thus allowing development of small to large dissolution cavities. If the dissolution cavity is large enough and shallow enough, successive roof failures can cause land subsidence and/or catastrophic collapse. Evaporite karst, natural and human-induced, is far more prevalent than is commonly believed. ?? 2007 Springer-Verlag.","largerWorkTitle":"Environmental Geology","language":"English","doi":"10.1007/s00254-007-0716-8","issn":"09430105","usgsCitation":"Johnson, K., 2008, Evaporite-karst problems and studies in the USA, in Environmental Geology, v. 53, no. 5, p. 937-943, https://doi.org/10.1007/s00254-007-0716-8.","startPage":"937","endPage":"943","numberOfPages":"7","costCenters":[],"links":[{"id":214487,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s00254-007-0716-8"},{"id":242218,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"53","issue":"5","noUsgsAuthors":false,"publicationDate":"2007-04-13","publicationStatus":"PW","scienceBaseUri":"505a0d16e4b0c8380cd52dfb","contributors":{"authors":[{"text":"Johnson, K.S.","contributorId":24385,"corporation":false,"usgs":true,"family":"Johnson","given":"K.S.","email":"","affiliations":[],"preferred":false,"id":441411,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70033513,"text":"70033513 - 2008 - Susceptibility to enhanced chemical migration from depression-focused preferential flow, High Plains aquifer","interactions":[],"lastModifiedDate":"2018-10-17T10:45:36","indexId":"70033513","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3674,"text":"Vadose Zone Journal","active":true,"publicationSubtype":{"id":10}},"title":"Susceptibility to enhanced chemical migration from depression-focused preferential flow, High Plains aquifer","docAbstract":"Aquifer susceptibility to contamination is controlled in part by the inherent hydrogeologic properties of the vadose zone, which includes preferential-flow pathways. The purpose of this study was to investigate the importance of seasonal ponding near leaky irrigation wells as a mechanism for depression-focused preferential flow and enhanced chemical migration through the vadose zone of the High Plains aquifer. Such a mechanism may help explain the widespread presence of agrichemicals in recently recharged groundwater despite estimates of advective chemical transit times through the vadose zone from diffuse recharge that exceed the historical period of agriculture. Using a combination of field observations, vadose zone flow and transport simulations, and probabilistic neural network modeling, we demonstrated that vadose zone transit times near irrigation wells range from 7 to 50 yr, which are one to two orders of magnitude faster than previous estimates based on diffuse recharge. These findings support the concept of fast and slow transport zones and help to explain the previous discordant findings of long vadose zone transit times and the presence of agrichemicals at the water table. Using predictions of aquifer susceptibility from probabilistic neural network models, we delineated approximately 20% of the areal extent of the aquifer to have conditions that may promote advective chemical transit times to the water table of <50 yr if seasonal ponding and depression-focused flow exist. This aquifer-susceptibility map may help managers prioritize areas for groundwater monitoring or implementation of best management practices.
","language":"English","publisher":"Soil Science Society of America","doi":"10.2136/vzj2007.0145","usgsCitation":"Gurdak, J., Walvoord, M.A., and McMahon, P.B., 2008, Susceptibility to enhanced chemical migration from depression-focused preferential flow, High Plains aquifer: Vadose Zone Journal, v. 7, no. 4, p. 1172-1184, https://doi.org/10.2136/vzj2007.0145.","productDescription":"13 p.","startPage":"1172","endPage":"1184","costCenters":[{"id":191,"text":"Colorado Water Science Center","active":true,"usgs":true},{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":476776,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.2136/vzj2007.0145","text":"Publisher Index Page"},{"id":242183,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Canada, United States","otherGeospatial":"High Plains","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -110.6,35.33 ], [ -110.6,49.69 ], [ -99.54,49.69 ], [ -99.54,35.33 ], [ -110.6,35.33 ] ] ] } } ] }","volume":"7","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505ba2f9e4b08c986b31fac3","contributors":{"authors":[{"text":"Gurdak, Jason J.","contributorId":65125,"corporation":false,"usgs":true,"family":"Gurdak","given":"Jason J.","affiliations":[],"preferred":false,"id":441216,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Walvoord, Michelle Ann 0000-0003-4269-8366 walvoord@usgs.gov","orcid":"https://orcid.org/0000-0003-4269-8366","contributorId":147211,"corporation":false,"usgs":true,"family":"Walvoord","given":"Michelle","email":"walvoord@usgs.gov","middleInitial":"Ann","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441217,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"McMahon, Peter B. 0000-0001-7452-2379 pmcmahon@usgs.gov","orcid":"https://orcid.org/0000-0001-7452-2379","contributorId":724,"corporation":false,"usgs":true,"family":"McMahon","given":"Peter","email":"pmcmahon@usgs.gov","middleInitial":"B.","affiliations":[{"id":191,"text":"Colorado Water Science Center","active":true,"usgs":true}],"preferred":true,"id":441215,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033507,"text":"70033507 - 2008 - Understanding the relationship between audiomagnetotelluric data and models, and borehole data in a hydrological environment","interactions":[],"lastModifiedDate":"2012-03-12T17:21:32","indexId":"70033507","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Understanding the relationship between audiomagnetotelluric data and models, and borehole data in a hydrological environment","docAbstract":"Audiomagnetotelluric (AMT) data and resulting models are analyzed with respect to geophysical and geological borehole logs in order to clarify the relationship between the two methodologies of investigation of a hydrological environment. Several profiles of AMT data collected in basins in southwestern United States are being used for groundwater exploration and hydrogeological framework studies. In a systematic manner, the AMT data and models are compared to borehole data by computing the equivalent one-dimensional AMT model and comparing with the two-dimensional (2-D) inverse AMT model. The spatial length is used to determine if the well is near enough to the AMT profile to quantify the relationship between the two datasets, and determine the required resolution of the AMT data and models. The significance of the quality of the borehole data when compared to the AMT data is also examined.","largerWorkTitle":"SEG Technical Program Expanded Abstracts","language":"English","doi":"10.1190/1.3063902","issn":"10523","usgsCitation":"McPhee, D., and Pellerin, L., 2008, Understanding the relationship between audiomagnetotelluric data and models, and borehole data in a hydrological environment, in SEG Technical Program Expanded Abstracts, v. 27, no. 1, p. 2684-2688, https://doi.org/10.1190/1.3063902.","startPage":"2684","endPage":"2688","numberOfPages":"5","costCenters":[],"links":[{"id":214391,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1190/1.3063902"},{"id":242114,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"27","issue":"1","noUsgsAuthors":false,"publicationDate":"2008-12-15","publicationStatus":"PW","scienceBaseUri":"505bbc5fe4b08c986b328bbc","contributors":{"authors":[{"text":"McPhee, D.K.","contributorId":96775,"corporation":false,"usgs":true,"family":"McPhee","given":"D.K.","email":"","affiliations":[],"preferred":false,"id":441197,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Pellerin, L.","contributorId":94073,"corporation":false,"usgs":true,"family":"Pellerin","given":"L.","email":"","affiliations":[],"preferred":false,"id":441196,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70033493,"text":"70033493 - 2008 - Transport and fate of nitrate at the ground-water/surface-water interface","interactions":[],"lastModifiedDate":"2018-10-22T07:59:39","indexId":"70033493","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2262,"text":"Journal of Environmental Quality","active":true,"publicationSubtype":{"id":10}},"title":"Transport and fate of nitrate at the ground-water/surface-water interface","docAbstract":"Although numerous studies of hyporheic exchange and denitrification have been conducted in pristine, high-gradient streams, few studies of this type have been conducted in nutrient-rich, low-gradient streams. This is a particularly important subject given the interest in nitrogen (N) inputs to the Gulf of Mexico and other eutrophic aquatic systems. A combination of hydrologic, mineralogical, chemical, dissolved gas, and isotopic data were used to determine the processes controlling transport and fate of NO3 − in streambeds at five sites across the USA. Water samples were collected from streambeds at depths ranging from 0.3 to 3 m at three to five points across the stream and in two to five separate transects. Residence times of water ranging from 0.28 to 34.7 d m−1 in the streambeds of N-rich watersheds played an important role in allowing denitrification to decrease NO3 − concentrations. Where potential electron donors were limited and residence times were short, denitrification was limited. Consequently, in spite of reducing conditions at some sites, NO3 − was transported into the stream. At two of the five study sites, NO3 − in surface water infiltrated the streambeds and concentrations decreased, supporting current models that NO3 − would be retained in N-rich streams. At the other three study sites, hydrogeologic controls limited or prevented infiltration of surface water into the streambed, and ground-water discharge contributed to NO3 − loads. Our results also show that in these low hydrologic-gradient systems, storm and other high-flow events can be important factors for increasing surface-water movement into streambeds.
","language":"English","publisher":"ACSESS","doi":"10.2134/jeq2006.0550","issn":"00472425","usgsCitation":"Puckett, L., Zamora, C., Essaid, H., Wilson, J., Johnson, H., Brayton, M., and Vogel, J.R., 2008, Transport and fate of nitrate at the ground-water/surface-water interface: Journal of Environmental Quality, v. 37, no. 3, p. 1034-1050, https://doi.org/10.2134/jeq2006.0550.","productDescription":"17 p.","startPage":"1034","endPage":"1050","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":241919,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214220,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2134/jeq2006.0550"}],"volume":"37","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bb741e4b08c986b327154","contributors":{"authors":[{"text":"Puckett, L.J.","contributorId":27503,"corporation":false,"usgs":true,"family":"Puckett","given":"L.J.","email":"","affiliations":[],"preferred":false,"id":441127,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Zamora, C.","contributorId":47180,"corporation":false,"usgs":true,"family":"Zamora","given":"C.","email":"","affiliations":[],"preferred":false,"id":441128,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Essaid, H.","contributorId":47181,"corporation":false,"usgs":true,"family":"Essaid","given":"H.","email":"","affiliations":[],"preferred":false,"id":441129,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Wilson, J.T.","contributorId":97489,"corporation":false,"usgs":true,"family":"Wilson","given":"J.T.","affiliations":[],"preferred":false,"id":441131,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Johnson, H.M. 0000-0002-7571-4994","orcid":"https://orcid.org/0000-0002-7571-4994","contributorId":75339,"corporation":false,"usgs":true,"family":"Johnson","given":"H.M.","affiliations":[],"preferred":false,"id":441130,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Brayton, M.J.","contributorId":26730,"corporation":false,"usgs":true,"family":"Brayton","given":"M.J.","affiliations":[],"preferred":false,"id":441126,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Vogel, J. R.","contributorId":21639,"corporation":false,"usgs":true,"family":"Vogel","given":"J.","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":441125,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70033463,"text":"70033463 - 2008 - Peat porewater chloride concentration profiles in the Everglades during wet/dry cycles from January 1996 to June 1998: Field measurements and theoretical analysis","interactions":[],"lastModifiedDate":"2018-10-22T08:15:01","indexId":"70033463","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"Peat porewater chloride concentration profiles in the Everglades during wet/dry cycles from January 1996 to June 1998: Field measurements and theoretical analysis","docAbstract":"Water quality is a key aspect of the Everglades Restoration Project, the largest water reclamation and ecosystem management project proposed in the United States. Movement of nutrients and contaminants to and from Everglades peat porewater could have important consequences for Everglades water quality and ecosystem restoration activities. In a study of Everglades porewater, we observed complex, seasonally variable peat porewater chloride concentration profiles at several locations. Analyses and interpretation of these changing peat porewater chloride concentration profiles identifies processes controlling conservative solute movement at the peat–surface water interface, that is, solutes whose transport is minimally affected by chemical and biological reactions. We examine, with an advection–diffusion model, how alternating wet and dry climatic conditions in the Florida Everglades mediate movement of chloride between peat porewater and marsh surface water. Changing surface water–chloride concentrations alter gradients at the interface between peat and overlying water and hence alter chloride flux across that interface. Surface water chloride concentrations at two frequently monitored sites vary with marsh water depth, and a transfer function was developed to describe daily marsh surface water chloride concentration as a function of marsh water depth. Model results demonstrate that porewater chloride concentrations are driven by changing surface water chloride concentrations, and a sensitivity analysis suggests that inclusion of advective transport in the model improves the agreement between the calculated and the observed chloride concentration profiles.
","language":"English","publisher":"Wiley","doi":"10.1002/hyp.6739","issn":"08856087","usgsCitation":"Reddy, M., Reddy, M., Kipp, K., Burman, A., Schuster, P., and Rawlik, P., 2008, Peat porewater chloride concentration profiles in the Everglades during wet/dry cycles from January 1996 to June 1998: Field measurements and theoretical analysis: Hydrological Processes, v. 22, no. 11, p. 1713-1724, https://doi.org/10.1002/hyp.6739.","productDescription":"12 p.","startPage":"1713","endPage":"1724","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":241978,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214273,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.6739"}],"volume":"22","issue":"11","noUsgsAuthors":false,"publicationDate":"2007-07-24","publicationStatus":"PW","scienceBaseUri":"505a761fe4b0c8380cd77f2d","contributors":{"authors":[{"text":"Reddy, M.M.","contributorId":24363,"corporation":false,"usgs":true,"family":"Reddy","given":"M.M.","email":"","affiliations":[],"preferred":false,"id":440972,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Reddy, M.B.","contributorId":91300,"corporation":false,"usgs":true,"family":"Reddy","given":"M.B.","email":"","affiliations":[],"preferred":false,"id":440975,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kipp, K.L.","contributorId":96715,"corporation":false,"usgs":true,"family":"Kipp","given":"K.L.","affiliations":[],"preferred":false,"id":440976,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Burman, A.","contributorId":72214,"corporation":false,"usgs":true,"family":"Burman","given":"A.","email":"","affiliations":[],"preferred":false,"id":440974,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Schuster, Peter","contributorId":61607,"corporation":false,"usgs":true,"family":"Schuster","given":"Peter","email":"","affiliations":[],"preferred":false,"id":440973,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Rawlik, P.S. Jr.","contributorId":19329,"corporation":false,"usgs":true,"family":"Rawlik","given":"P.S.","suffix":"Jr.","affiliations":[],"preferred":false,"id":440971,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ]}