Data on hydrometeorological conditions and E. coli concentration were simultaneously collected on 57 occasions during the summer of 2000 at 63rd Street Beach, Chicago, Illinois. The data were used to identify and calibrate a statistical regression model aimed at predicting when the bacterial concentration of the beach water was above or below the level considered safe for full body contact. A wide range of hydrological, meteorological, and water quality variables were evaluated as possible predictive variables. These included wind speed and direction, incoming solar radiation (insolation), various time frames of rainfall, air temperature, lake stage and wave height, and water temperature, specific conductance, dissolved oxygen, pH, and turbidity. The best-fit model combined real-time measurements of wind direction and speed (onshore component of resultant wind vector), rainfall, insolation, lake stage, water temperature and turbidity to predict the geometric mean E.coliconcentration in the swimming zone of the beach. The model, which contained both additive and multiplicative (interaction) terms, accounted for 71% of the observed variability in the log E. coliconcentrations. A comparison between model predictions of when the beach should be closed and when the actualbacterial concentrations were above or below the 235 cfu 100 ml-1 threshold value, indicated that the model accurately predicted openingsversus closures 88% of the time.
","language":"English","publisher":"Springer","doi":"10.1023/B:EMAS.0000038185.79137.b9","usgsCitation":"Olyphant, G.A., and Whitman, R.L., 2004, Elements of a predictive model for determining beach closures on a real time basis: the case of 63rd Street Beach Chicago: Environmental Monitoring and Assessment, v. 98, no. 1-3, p. 175-190, https://doi.org/10.1023/B:EMAS.0000038185.79137.b9.","productDescription":"16 p.","startPage":"175","endPage":"190","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"links":[{"id":128766,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"98","issue":"1-3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4a19e4b07f02db60605c","contributors":{"authors":[{"text":"Olyphant, Greg A.","contributorId":57007,"corporation":false,"usgs":true,"family":"Olyphant","given":"Greg","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":310310,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Whitman, Richard L. rwhitman@usgs.gov","contributorId":542,"corporation":false,"usgs":true,"family":"Whitman","given":"Richard","email":"rwhitman@usgs.gov","middleInitial":"L.","affiliations":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"preferred":true,"id":310309,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":1001035,"text":"1001035 - 2004 - Implications of hydrologic variability on the succession of plants in Great Lakes wetlands","interactions":[],"lastModifiedDate":"2016-05-12T15:55:34","indexId":"1001035","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":865,"text":"Aquatic Ecosystem Health & Management","active":true,"publicationSubtype":{"id":10}},"title":"Implications of hydrologic variability on the succession of plants in Great Lakes wetlands","docAbstract":"Primary succession of plant communities directed toward a climax is not a typical occurrence in wetlands because these ecological systems are inherently dependent on hydrology, and temporal hydrologic variability often causes reversals or setbacks in succession. Wetlands of the Great Lakes provide good examples for demonstrating the implications of hydrology in driving successional processes and for illustrating potential misinterpretations of apparent successional sequences. Most Great Lakes coastal wetlands follow cyclic patterns in which emergent communities are reduced in area or eliminated by high lake levels and then regenerated from the seed bank during low lake levels. Thus, succession never proceeds for long. Wetlands also develop in ridge and swale terrains in many large embayments of the Great Lakes. These formations contain sequences of wetlands of similar origin but different age that can be several thousand years old, with older wetlands always further from the lake. Analyses of plant communities across a sequence of wetlands at the south end of Lake Michigan showed an apparent successional pattern from submersed to floating to emergent plants as water depth decreased with wetland age. However, paleoecological analyses showed that the observed vegetation changes were driven largely by disturbances associated with increased human settlement in the area. Climate-induced hydrologic changes were also shown to have greater effects on plant-community change than autogenic processes. Other terms, such as zonation, maturation, fluctuations, continuum concept, functional guilds, centrifugal organization, pulse stability, and hump-back models provide additional means of describing organization and changes in vegetation; some of them overlap with succession in describing vegetation processes in Great Lakes wetlands, but each must be used in the proper context with regard to short- and long-term hydrologic variability.
","language":"English","publisher":"Taylor & Francis","doi":"10.1080/14634980490461579","usgsCitation":"Wilcox, D.A., 2004, Implications of hydrologic variability on the succession of plants in Great Lakes wetlands: Aquatic Ecosystem Health & Management, v. 7, no. 2, p. 223-231, https://doi.org/10.1080/14634980490461579.","productDescription":"9 p.","startPage":"223","endPage":"231","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"links":[{"id":478283,"rank":1,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"http://hdl.handle.net/20.500.12648/2296","text":"External Repository"},{"id":133742,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"7","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e49fde4b07f02db5f6017","contributors":{"authors":[{"text":"Wilcox, Douglas A.","contributorId":36880,"corporation":false,"usgs":true,"family":"Wilcox","given":"Douglas","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":310285,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":1000913,"text":"1000913 - 2004 - Great Lakes clams find refuge from zebra mussels in restored, lake-connected marsh (Ohio)","interactions":[],"lastModifiedDate":"2012-02-02T00:04:41","indexId":"1000913","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1462,"text":"Ecological Restoration","active":true,"publicationSubtype":{"id":10}},"title":"Great Lakes clams find refuge from zebra mussels in restored, lake-connected marsh (Ohio)","docAbstract":"Since the early 1990s, more than 95 percent of the freshwater clams once found in Lake Erie have died due to the exotic zebara mussel (Dreissena polymorpha). Zebra mussels attach themselves to native clams in large numbers, impeding the ability of the clams to eat and burrow. However, in 1996, we discovered a population of native clams in Metzger Marsh in western Lake Erie (about 50 miles [80 km] east of Toledo) that were thriving despite the longtime presence of zebra mussel in surrounding waters. At that time, Metzger Marsh was undergoing extensive restoration, including construction of a dike to replace the eroded barrier beach and of a water-control structure to maintain hydrologic connections with the lake (Wilcox and Whillans 1999). The restoration plan called for a drawdown of water levels to promote plant growth from the seedbank -- a process that would also destroy most of the clam population. State and federal resource managers recommended removing as many clams as possible to a site that was isolated from zebra mussels, and then returning them to the marsh after it was restored. We removed about 7,000 native clams in 1996 and moved them back to Metzger Marsh in 1999.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Ecological Restoration","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","usgsCitation":"Nichols, S.J., and Wilcox, D.A., 2004, Great Lakes clams find refuge from zebra mussels in restored, lake-connected marsh (Ohio): Ecological Restoration, v. 22, no. 1, p. 51-52.","productDescription":"p. 51-52","startPage":"51","endPage":"52","numberOfPages":"1","costCenters":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"links":[{"id":133112,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"22","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4abae4b07f02db671f4b","contributors":{"authors":[{"text":"Nichols, S. Jerrine","contributorId":25887,"corporation":false,"usgs":true,"family":"Nichols","given":"S.","email":"","middleInitial":"Jerrine","affiliations":[],"preferred":false,"id":309825,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wilcox, Douglas A.","contributorId":36880,"corporation":false,"usgs":true,"family":"Wilcox","given":"Douglas","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":309826,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":1000880,"text":"1000880 - 2004 - A Holocene history of dune-mediated landscape change along the southeastern shore of Lake Superior","interactions":[],"lastModifiedDate":"2013-01-22T15:45:29","indexId":"1000880","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1801,"text":"Geomorphology","active":true,"publicationSubtype":{"id":10}},"title":"A Holocene history of dune-mediated landscape change along the southeastern shore of Lake Superior","docAbstract":"Causal links that connect Holocene high stands of Lake Superior with dune building, stream damming and diversion and reservoir impoundment and infilling are inferred from a multidisciplinary investigation of a small watershed along the SE shore of Lake Superior. Radiocarbon ages of wood fragments from in-place stumps and soil O horizons, recovered from the bottom of 300-ha Grand Sable Lake, suggest that the near-shore inland lake was formed during multiple episodes of late Holocene dune damming of ancestral Sable Creek. Forest drownings at ~3000, 1530, and 300 cal. years BP are highly correlated with local soil burial events that occurred during high stands of Lake Superior. During these and earlier events, Sable Creek was diverted onto eastward-graded late Pleistocene meltwater terraces. Ground penetrating radar (GPR) reveals the early Holocene valley of Sable Creek (now filled) and its constituent sedimentary structures. Near-planar paleosols, identified with GPR, suggest two repeating modes of landscape evolution mediated by levels of Lake Superior. High lake stands drove stream damming, reservoir impoundment, and eolian infilling of impoundments. Falling Lake Superior levels brought decreased sand supply to dune dams and lowered stream base level. These latter factors promoted stream piracy, breaching of dune dams, and aerial exposure and forestation of infilled lakebeds. The bathymetry of Grand Sable Lake suggests that its shoreline configuration and depth varied in response to events of dune damming and subsequent dam breaching. The interrelated late Holocene events apparent in this study area suggest that variations in lake level have imposed complex hydrologic and geomorphic signatures on upper Great Lakes coasts.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Geomorphology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.geomorph.2004.01.005","usgsCitation":"Loope, W.L., Fisher, T.G., Jol, H.M., Anderton, J.B., and Blewett, W.L., 2004, A Holocene history of dune-mediated landscape change along the southeastern shore of Lake Superior: Geomorphology, v. 61, no. 3-4, p. 303-322, https://doi.org/10.1016/j.geomorph.2004.01.005.","productDescription":"p. 303-322","startPage":"303","endPage":"322","numberOfPages":"19","costCenters":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"links":[{"id":133541,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":266265,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.geomorph.2004.01.005"}],"volume":"61","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b30e4b07f02db6b4100","contributors":{"authors":[{"text":"Loope, Walter L. wloope@usgs.gov","contributorId":4616,"corporation":false,"usgs":true,"family":"Loope","given":"Walter","email":"wloope@usgs.gov","middleInitial":"L.","affiliations":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"preferred":true,"id":309719,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Fisher, Timothy G.","contributorId":45659,"corporation":false,"usgs":true,"family":"Fisher","given":"Timothy","email":"","middleInitial":"G.","affiliations":[],"preferred":false,"id":309722,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Jol, Harry M.","contributorId":11571,"corporation":false,"usgs":true,"family":"Jol","given":"Harry","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":309720,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Anderton, John B.","contributorId":23880,"corporation":false,"usgs":true,"family":"Anderton","given":"John","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":309721,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Blewett, William L.","contributorId":57031,"corporation":false,"usgs":true,"family":"Blewett","given":"William","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":309723,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":1000867,"text":"1000867 - 2004 - Rapid assessment indicator of wetland integrity as an unintended predictor of avian diversity","interactions":[],"lastModifiedDate":"2016-05-12T11:51:30","indexId":"1000867","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1919,"text":"Hydrobiologia","onlineIssn":"1573-5117","printIssn":"0018-8158","active":true,"publicationSubtype":{"id":10}},"title":"Rapid assessment indicator of wetland integrity as an unintended predictor of avian diversity","docAbstract":"Rapid assessment of aquatic ecosystems has been widely implemented, sometimes without thorough evaluation of the robustness of rapid assessment metrics as indicators of ecological integrity. Here, we evaluate whether the Ohio Rapid Assessment Method (ORAM) for Wetlands Version 5.0 is a useful indicator of ecological integrity beyond its intended purpose. ORAM was developed to categorize natural wetlands for regulatory purposes and to contribute to the development of indicators of biotic integrity. It was never intended for use as an index of the quality of habitat for wetland birds. Nonetheless, it is conceivable that ORAM scores could serve as adequate predictors of avian diversity. We evaluated whether avian species richness in wetlands could be reliably predicted from each of the following variables: (1) total ORAM score, (2) total score minus the score for one metric that did not apply to all wetlands, and (3) sum of scores for the four ORAM components (of 16 scored) with the highest potential point total. These four components corresponded to aquatic vegetation communities, microtopography, modifications to natural hydrologic regime, and sources of water. All three variables were significant predictors of both total species richness and mean species richness of birds of conservation concern. Variable (3) was a significant predictor of mean species richness of wetland-dependent birds. Variable (2) was a weak predictor of both total and mean species richness of all birds combined. These results extend the robustness of ORAM as an indicator of the ecological integrity of wetlands.
","language":"English","publisher":"Springer","doi":"10.1023/B:HYDR.0000027731.16535.53","usgsCitation":"Stapanian, M.A., Waite, T.A., Krzys, G., Mack, J.J., and Micacchion, M., 2004, Rapid assessment indicator of wetland integrity as an unintended predictor of avian diversity: Hydrobiologia, v. 520, no. 1-3, p. 119-126, https://doi.org/10.1023/B:HYDR.0000027731.16535.53.","productDescription":"8 p.","startPage":"119","endPage":"126","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"links":[{"id":133562,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"520","issue":"1-3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4a80e4b07f02db64945e","contributors":{"authors":[{"text":"Stapanian, Martin A. 0000-0001-8173-4273 mstapanian@usgs.gov","orcid":"https://orcid.org/0000-0001-8173-4273","contributorId":3425,"corporation":false,"usgs":true,"family":"Stapanian","given":"Martin","email":"mstapanian@usgs.gov","middleInitial":"A.","affiliations":[{"id":324,"text":"Great Lakes Science Center","active":true,"usgs":true}],"preferred":true,"id":309663,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Waite, Thomas A.","contributorId":98691,"corporation":false,"usgs":true,"family":"Waite","given":"Thomas","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":309667,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Krzys, Gregory","contributorId":87508,"corporation":false,"usgs":true,"family":"Krzys","given":"Gregory","email":"","affiliations":[],"preferred":false,"id":309666,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Mack, John J.","contributorId":55395,"corporation":false,"usgs":true,"family":"Mack","given":"John","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":309665,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Micacchion, Mick","contributorId":21511,"corporation":false,"usgs":true,"family":"Micacchion","given":"Mick","affiliations":[],"preferred":false,"id":309664,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70027385,"text":"70027385 - 2004 - Conservative and reactive solute transport in constructed wetlands","interactions":[],"lastModifiedDate":"2018-11-14T10:41:28","indexId":"70027385","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","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":"Conservative and reactive solute transport in constructed wetlands","docAbstract":"The transport of bromide, a conservative tracer, and rhodamine WT (RWT), a photodegrading tracer, was evaluated in three wastewater‐dependent wetlands near Phoenix, Arizona, using a solute transport model with transient storage. Coupled sodium bromide and RWT tracer tests were performed to establish conservative transport and reactive parameters in constructed wetlands with water losses ranging from (1) relatively impermeable (15%), (2) moderately leaky (45%), and (3) significantly leaky (76%). RWT first‐order photolysis rates and sorption coefficients were determined from independent field and laboratory experiments. Individual wetland hydraulic profiles influenced the extent of transient storage interaction in stagnant water areas and consequently RWT removal. Solute mixing and transient storage interaction occurred in the impermeable wetland, resulting in 21% RWT mass loss from main channel and storage zone photolysis (10%) and sorption (11%) reactions. Advection and dispersion governed solute transport in the leaky wetland, limiting RWT photolysis removal (1.2%) and favoring main channel sorption (3.6%). The moderately leaky wetland contained islands parallel to flow, producing channel flow and minimizing RWT losses (1.6%).
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2003WR002130","usgsCitation":"Keefe, S.H., Barber, L.B., Runkel, R.L., Ryan, J.N., McKnight, D.M., and Wass, R.D., 2004, Conservative and reactive solute transport in constructed wetlands: Water Resources Research, v. 40, no. 1, W01201; 12 p., https://doi.org/10.1029/2003WR002130.","productDescription":"W01201; 12 p.","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":238007,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"40","issue":"1","noUsgsAuthors":false,"publicationDate":"2004-01-27","publicationStatus":"PW","scienceBaseUri":"5059f9f7e4b0c8380cd4d84b","contributors":{"authors":[{"text":"Keefe, Steffanie H. 0000-0002-3805-6101 shkeefe@usgs.gov","orcid":"https://orcid.org/0000-0002-3805-6101","contributorId":2843,"corporation":false,"usgs":true,"family":"Keefe","given":"Steffanie","email":"shkeefe@usgs.gov","middleInitial":"H.","affiliations":[{"id":37277,"text":"WMA - Earth System Processes Division","active":true,"usgs":true},{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":413436,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Barber, Larry B. 0000-0002-0561-0831 lbbarber@usgs.gov","orcid":"https://orcid.org/0000-0002-0561-0831","contributorId":921,"corporation":false,"usgs":true,"family":"Barber","given":"Larry","email":"lbbarber@usgs.gov","middleInitial":"B.","affiliations":[{"id":438,"text":"National Research Program - Western Branch","active":true,"usgs":true},{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":413439,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Runkel, Robert L. 0000-0003-3220-481X runkel@usgs.gov","orcid":"https://orcid.org/0000-0003-3220-481X","contributorId":685,"corporation":false,"usgs":true,"family":"Runkel","given":"Robert","email":"runkel@usgs.gov","middleInitial":"L.","affiliations":[{"id":191,"text":"Colorado Water Science Center","active":true,"usgs":true}],"preferred":true,"id":413440,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"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":413441,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"McKnight, Diane M.","contributorId":59773,"corporation":false,"usgs":false,"family":"McKnight","given":"Diane","email":"","middleInitial":"M.","affiliations":[{"id":16833,"text":"INSTAAR, University of Colorado","active":true,"usgs":false}],"preferred":false,"id":413438,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Wass, Roland D.","contributorId":72858,"corporation":false,"usgs":true,"family":"Wass","given":"Roland","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":413437,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70026139,"text":"70026139 - 2004 - Uranium adsorption on weathered schist - Intercomparison of modeling approaches","interactions":[],"lastModifiedDate":"2018-11-14T10:49:32","indexId":"70026139","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3226,"text":"Radiochimica Acta","active":true,"publicationSubtype":{"id":10}},"title":"Uranium adsorption on weathered schist - Intercomparison of modeling approaches","docAbstract":"Experimental data for uranium adsorption on a complex weathered rock were simulated by twelve modelling teams from eight countries using surface complexation (SC) models. This intercomparison was part of an international project to evaluate the present capabilities and limitations of SC models in representing sorption by geologic materials. The models were assessed in terms of their predictive ability, data requirements, number of optimised parameters, ability to simulate diverse chemical conditions and transferability to other substrates. A particular aim was to compare the generalised composite (GC) and component additivity (CA) approaches for modelling sorption by complex substrates. Both types of SC models showed a promising capability to simulate sorption data obtained across a range of chemical conditions. However, the models incorporated a wide variety of assumptions, particularly in terms of input parameters such as site densities and surface site types. Furthermore, the methods used to extrapolate the model simulations to different weathered rock samples collected at the same field site tended to be unsatisfactory. The outcome of this modelling exercise provides an overview of the present status of adsorption modelling in the context of radionuclide migration as practised in a number of countries worldwide.","language":"English","publisher":"De Gruyter","doi":"10.1524/ract.92.9.651.54992","issn":"00338230","usgsCitation":"Payne, T., Davis, J., Ochs, M., Olin, M., and Tweed, C., 2004, Uranium adsorption on weathered schist - Intercomparison of modeling approaches: Radiochimica Acta, v. 92, no. 9-11, p. 651-661, https://doi.org/10.1524/ract.92.9.651.54992.","productDescription":"11 p.","startPage":"651","endPage":"661","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":208663,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1524/ract.92.9.651.54992"},{"id":234555,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"92","issue":"9-11","noUsgsAuthors":false,"publicationDate":"2009-09-25","publicationStatus":"PW","scienceBaseUri":"505bbd82e4b08c986b329071","contributors":{"authors":[{"text":"Payne, T.E.","contributorId":31916,"corporation":false,"usgs":true,"family":"Payne","given":"T.E.","email":"","affiliations":[],"preferred":false,"id":408075,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Davis, J.A.","contributorId":71694,"corporation":false,"usgs":true,"family":"Davis","given":"J.A.","email":"","affiliations":[],"preferred":false,"id":408077,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Ochs, M.","contributorId":92025,"corporation":false,"usgs":true,"family":"Ochs","given":"M.","email":"","affiliations":[],"preferred":false,"id":408079,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Olin, M.","contributorId":58439,"corporation":false,"usgs":true,"family":"Olin","given":"M.","email":"","affiliations":[],"preferred":false,"id":408076,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Tweed, C.J.","contributorId":90087,"corporation":false,"usgs":true,"family":"Tweed","given":"C.J.","email":"","affiliations":[],"preferred":false,"id":408078,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70027247,"text":"70027247 - 2004 - Spatial and temporal changes in microbial community structure associated with recharge-influenced chemical gradients in a contaminated aquifer","interactions":[],"lastModifiedDate":"2018-11-14T10:43:22","indexId":"70027247","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1548,"text":"Environmental Microbiology","active":true,"publicationSubtype":{"id":10}},"title":"Spatial and temporal changes in microbial community structure associated with recharge-influenced chemical gradients in a contaminated aquifer","docAbstract":"In a contaminated water‐table aquifer, we related microbial community structure on aquifer sediments to gradients in 24 geochemical and contaminant variables at five depths, under three recharge conditions. Community amplified ribsosomal DNA restriction analysis (ARDRA) using universal 16S rDNA primers and denaturing gradient gel electrophoresis (DGGE) using bacterial 16S rDNA primers indicated: (i) communities in the anoxic, contaminated central zone were similar regardless of recharge; (ii) after recharge, communities at greatest depth were similar to those in uncontaminated zones; and (iii) after extended lack of recharge, communities at upper and lower aquifer margins differed from communities at the same depths on other dates. General aquifer geochemistry was as important as contaminant or terminal electron accepting process (TEAP) chemistry in discriminant analysis of community groups. The Shannon index of diversity (H) and the evenness index (E), based on DGGE operational taxonomic units (OTUs), were statistically different across community groups and aquifer depths. Archaea or sulphate‐reducing bacteria 16S rRNA abundance was not clearly correlated with TEAP chemistry indicative of methanogenesis or sulphate reduction. Eukarya rRNA abundance varied by depth and date from 0 to 13% of the microbial community. This contaminated aquifer is a dynamic ecosystem, with complex interactions between physical, chemical and biotic components, which should be considered in the interpretation of aquifer geochemistry and in the development of conceptual or predictive models for natural attenuation or remediation.
The bacterial denitrification method for isotopic analysis of nitrate using N2O generated from Pseudomonas aureofaciens may overestimate δ15N values by as much as 1–2‰ for samples containing atmospheric nitrate because of mass-independent 17O variations in such samples. By analyzing such samples for δ15N and δ18O using the denitrifier Pseudomonas chlororaphis, one obtains nearly correct δ15N values because oxygen in N2O generated by P. chlororaphis is primarily derived from H2O. The difference between the apparent δ15N value determined with P. aureofaciens and that determined with P. chlororaphis, assuming mass-dependent oxygen isotopic fractionation, reflects the amount of mass-independent 17O in a nitrate sample. By interspersing nitrate isotopic reference materials having substantially different δ18O values with samples, one can normalize oxygen isotope ratios and determine the fractions of oxygen in N2O derived from the nitrate and from water with each denitrifier. This information can be used to improve δ15N values of nitrates having excess 17O. The same analyses also yield estimates of the magnitude of 17O excess in the nitrate (expressed as Δ17O) that may be useful in some environmental studies. The 1-σ uncertainties of δ15N, δ18O and Δ17O measurements are ±0.2, ±0.3 and ±5‰, respectively.
","language":"English","publisher":"Elsevier","doi":"10.1002/rcm.1318","usgsCitation":"Coplen, T.B., Bohlke, J., and Casciotti, K.L., 2004, Using dual-bacterial denitrification to improve δ15N determinations of nitrates containing mass-independent 17O: Rapid Communications in Mass Spectrometry, v. 18, no. 3, p. 245-250, https://doi.org/10.1002/rcm.1318.","productDescription":"6 p.","startPage":"245","endPage":"250","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":238122,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"18","issue":"3","noUsgsAuthors":false,"publicationDate":"2004-01-06","publicationStatus":"PW","scienceBaseUri":"505bc048e4b08c986b32a031","contributors":{"authors":[{"text":"Coplen, Tyler B. 0000-0003-4884-6008 tbcoplen@usgs.gov","orcid":"https://orcid.org/0000-0003-4884-6008","contributorId":508,"corporation":false,"usgs":true,"family":"Coplen","given":"Tyler","email":"tbcoplen@usgs.gov","middleInitial":"B.","affiliations":[{"id":37464,"text":"WMA - Laboratory & Analytical Services Division","active":true,"usgs":true},{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true},{"id":27111,"text":"National Water Quality Program","active":true,"usgs":true},{"id":37277,"text":"WMA - Earth System Processes Division","active":true,"usgs":true}],"preferred":true,"id":413644,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Bohlke, J.K. 0000-0001-5693-6455 jkbohlke@usgs.gov","orcid":"https://orcid.org/0000-0001-5693-6455","contributorId":191103,"corporation":false,"usgs":true,"family":"Bohlke","given":"J.K.","email":"jkbohlke@usgs.gov","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},{"id":36183,"text":"Hydro-Ecological Interactions Branch","active":true,"usgs":true}],"preferred":true,"id":413646,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Casciotti, Karen L. 0000-0002-5286-7795","orcid":"https://orcid.org/0000-0002-5286-7795","contributorId":213205,"corporation":false,"usgs":false,"family":"Casciotti","given":"Karen","email":"","middleInitial":"L.","affiliations":[{"id":38718,"text":"Stanford University, Stanford, CA","active":true,"usgs":false}],"preferred":false,"id":413645,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70027439,"text":"70027439 - 2004 - Relative effect of temperature and pH on diel cycling of dissolved trace elements in Prickly Pear Creek, Montana","interactions":[],"lastModifiedDate":"2018-11-14T07:51:03","indexId":"70027439","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3728,"text":"Water, Air, & Soil Pollution","onlineIssn":"1573-2932","printIssn":"0049-6979","active":true,"publicationSubtype":{"id":10}},"title":"Relative effect of temperature and pH on diel cycling of dissolved trace elements in Prickly Pear Creek, Montana","docAbstract":"Diel (24 hr) cycles in dissolved metal and As concentrations have been documented in many northern Rocky Mountain streams in the U.S.A. The cause(s) of the cycles are unknown, although temperature- and pH-dependent sorption reactions have been cited as likely causes. A light/dark experiment was conducted to isolate temperature and pH as variables affecting diel metal cycles in Prickly Pear Creek, Montana. Light and dark chambers containing sediment and a strand of macrophyte were placed in the stream to simulate instream temperature oscillations. Photosynthesis-induced pH changes were allowed to proceed in the light chambers while photosynthesis was prevented in the dark chambers. Water samples were collected periodically for 22 hr in late July 2001 from all chambers and the stream. In the stream, dissolved Zn concentrations increased by 300% from late afternoon to early morning, while dissolved As concentrations exhibited the opposite pattern, increasing 33% between early morning and late afternoon. Zn and As concentrations in the light chambers showed similar, though less pronounced, diel variations. Conversely, Zn and As concentrations in the dark chambers had no obvious diel variation, indicating that light, or light-induced reactions, caused the variation. Temperature oscillations were nearly identical between light and dark chambers, strongly suggesting that temperature was not controlling the diel variations. As expected, pH was negatively correlated (P < 0.01) with dissolved Zn concentrations and positively correlated with dissolved As concentrations in both the light and dark chambers. From these experiments, photosynthesis-induced pH changes were determined to be the major cause of the diel dissolved Zn and As cycles in Prickly Pear Creek. Further research is necessary in other streams to verify that this finding is consistent among streams having large differences in trace-element concentrations and mineralogy of channel substrate.
","language":"English","publisher":"Springer","doi":"10.1023/B:WATE.0000019934.64939.f0","usgsCitation":"Jones, C.A., Nimick, D., and McCleskey, R.B., 2004, Relative effect of temperature and pH on diel cycling of dissolved trace elements in Prickly Pear Creek, Montana: Water, Air, & Soil Pollution, v. 153, no. 1-4, p. 95-113, https://doi.org/10.1023/B:WATE.0000019934.64939.f0.","productDescription":"19 p.","startPage":"95","endPage":"113","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":238190,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Montana","otherGeospatial":"Prickly Pear Creek","volume":"153","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505aa67de4b0c8380cd84ea7","contributors":{"authors":[{"text":"Jones, Clain A.","contributorId":69917,"corporation":false,"usgs":false,"family":"Jones","given":"Clain","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":413679,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Nimick, D. A.","contributorId":70399,"corporation":false,"usgs":true,"family":"Nimick","given":"D. A.","affiliations":[],"preferred":false,"id":413680,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"McCleskey, R. Blaine 0000-0002-2521-8052 rbmccles@usgs.gov","orcid":"https://orcid.org/0000-0002-2521-8052","contributorId":147399,"corporation":false,"usgs":true,"family":"McCleskey","given":"R.","email":"rbmccles@usgs.gov","middleInitial":"Blaine","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true},{"id":438,"text":"National Research Program - Western Branch","active":true,"usgs":true},{"id":503,"text":"Office of Water Quality","active":true,"usgs":true}],"preferred":true,"id":413678,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70027477,"text":"70027477 - 2004 - Soil science and geology: Connects, disconnects and new opportunities in geoscience education","interactions":[],"lastModifiedDate":"2018-11-14T08:45:12","indexId":"70027477","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2324,"text":"Journal of Geoscience Education","active":true,"publicationSubtype":{"id":10}},"title":"Soil science and geology: Connects, disconnects and new opportunities in geoscience education","docAbstract":"Despite historical linkages, the fields of geology and soil science have developed along largely divergent paths in the United States during much of the mid- to late- twentieth century. The shift in recent decades within both disciplines to greater emphasis on environmental quality issues and a systems approach has created new opportunities for collaboration and cross-training. Because of the importance of the soil as a dynamic interface between the hydrosphere, biosphere, atmosphere, and lithosphere, introductory and advanced soil science classes are now being taught in a number of earth and environmental science departments. The National Research Council's recent report, Basic Research Opportunities in Earth Science, highlights the soil zone as part of the land surface-to-groundwater \"critical zone\" requiring additional investigation. To better prepare geology undergraduates to deal with complex environmental problems, their training should include a fundamental understanding of the nature and properties of soils. Those undergraduate geology students with an interest in this area should be encouraged to view soil science as a viable earth science specialty area for graduate study. Summer internships such as those offered by the National Science Foundation-funded Integrative Graduate Education, Research, and Training (IGERT) programs offer geology undergraduates the opportunity to explore research and career opportunities in soil science.","language":"English","publisher":"Taylor & Francis","doi":"10.5408/1089-9995-52.2.191","issn":"10899995","usgsCitation":"Landa, E.R., 2004, Soil science and geology: Connects, disconnects and new opportunities in geoscience education: Journal of Geoscience Education, v. 52, no. 2, p. 191-196, https://doi.org/10.5408/1089-9995-52.2.191.","productDescription":"6 p.","startPage":"191","endPage":"196","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":238264,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"52","issue":"2","noUsgsAuthors":false,"publicationDate":"2018-01-31","publicationStatus":"PW","scienceBaseUri":"505b9219e4b08c986b319cd3","contributors":{"authors":[{"text":"Landa, E. R.","contributorId":100002,"corporation":false,"usgs":true,"family":"Landa","given":"E.","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":413826,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70027490,"text":"70027490 - 2004 - High latitude meteoric δ18O compositions: Paleosol siderite in the Middle Cretaceous Nanushuk Formation, North Slope, Alaska","interactions":[],"lastModifiedDate":"2015-05-06T12:53:29","indexId":"70027490","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1786,"text":"Geological Society of America Bulletin","active":true,"publicationSubtype":{"id":10}},"title":"High latitude meteoric δ18O compositions: Paleosol siderite in the Middle Cretaceous Nanushuk Formation, North Slope, Alaska","docAbstract":"Siderite-bearing pedogenic horizons of the Nanushuk Formation of the North Slope, Alaska, provide a critical high paleolatitude oxygen isotopic proxy record of paleoprecipitation, supplying important empirical data needed for paleoclimatic reconstructions and models of \"greenhouse-world\" precipitation rates. Siderite ??18O values were determined from four paleosol horizons in the National Petroleum Reserve Alaska (NPR-A) Grandstand # 1 Core, and the values range between -17.6??? and -14.3??? Peedee belemnite (PDB) with standard deviations generally less than 0.6??? within individual horizons. The ??13C values are much more variable, ranging from -4.6??? to +10.8??? PDB. A covariant ??18O versus ??13C trend in one horizon probably resulted from mixing between modified marine and meteoric phreatic fluids during siderite precipitation. Groundwater values calculated from siderite oxygen isotopic values and paleobotanical temperature estimates range from -23.0??? to -19.5??? standard mean ocean water (SMOW). Minor element analyses show that the siderites are impure, having enrichments in Ca, Mg, Mn, and Sr. Minor element substitutions and Mg/Fe and Mg/ (Ca + Mg) ratios also suggest the influence of marine fluids upon siderite precipitation. The pedogenic horizons are characterized by gleyed colors, rare root traces, abundant siderite, abundant organic matter, rare clay and silty clay coatings and infillings, some preservation of primary sedimentary stratification, and a lack of ferruginous oxides and mottles. The pedogenic features suggest that these were poorly drained, reducing, hydromorphic soils that developed in coal-bearing delta plain facies and are similar to modern Inceptisols. Model-derived estimates of precipitation rates for the Late Albian of the North Slope, Alaska (485-626 mm/yr), are consistent with precipitation rates necessary to maintain modern peat-forming environments. This information reinforces the mutual consistency between empirical paleotemperature estimates and isotope mass balance models of the hydrologic cycle and can be used in future global circulation modeling (GCM) experiments of \"greenhouse-world\" climates to constrain high latitude precipitation rates in simulations of ancient worlds with decreased equator-to-pole temperature gradients. ?? 2004 Geological Society of America.","language":"English","publisher":"Geological Society of America","doi":"10.1130/B25289.1","issn":"00167606","usgsCitation":"Ufnar, D.F., Ludvigson, G.A., Gonzalez, L.A., Brenner, R.L., and Witzke, B.J., 2004, High latitude meteoric δ18O compositions: Paleosol siderite in the Middle Cretaceous Nanushuk Formation, North Slope, Alaska: Geological Society of America Bulletin, v. 116, no. 3-4, p. 463-473, https://doi.org/10.1130/B25289.1.","productDescription":"11 p.","startPage":"463","endPage":"473","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[],"links":[{"id":238449,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":211219,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1130/B25289.1"}],"volume":"116","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a30bee4b0c8380cd5d8e2","contributors":{"authors":[{"text":"Ufnar, David F.","contributorId":64371,"corporation":false,"usgs":true,"family":"Ufnar","given":"David","email":"","middleInitial":"F.","affiliations":[],"preferred":false,"id":413868,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ludvigson, Greg A.","contributorId":80803,"corporation":false,"usgs":true,"family":"Ludvigson","given":"Greg","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":413869,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gonzalez, Luis A.","contributorId":20922,"corporation":false,"usgs":true,"family":"Gonzalez","given":"Luis","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":413867,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Brenner, Richard L.","contributorId":94457,"corporation":false,"usgs":false,"family":"Brenner","given":"Richard","email":"","middleInitial":"L.","affiliations":[{"id":13387,"text":"Alaska Department of Fish and Game - Commercial Fisheries, P.O. Box 669, Cordova, AK 99574","active":true,"usgs":false}],"preferred":false,"id":413870,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Witzke, Brian J.","contributorId":40347,"corporation":false,"usgs":true,"family":"Witzke","given":"Brian","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":413866,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70027504,"text":"70027504 - 2004 - Hydrological effects of soil water repellency: On spatial and temporal uncertainties","interactions":[],"lastModifiedDate":"2012-03-12T17:20:48","indexId":"70027504","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","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":"Hydrological effects of soil water repellency: On spatial and temporal uncertainties","docAbstract":"[No abstract available]","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrological Processes","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1002/hyp.5518","issn":"08856087","usgsCitation":"Doerr, S., and Moody, J.A., 2004, Hydrological effects of soil water repellency: On spatial and temporal uncertainties: Hydrological Processes, v. 18, no. 4, p. 829-832, https://doi.org/10.1002/hyp.5518.","startPage":"829","endPage":"832","numberOfPages":"4","costCenters":[],"links":[{"id":210953,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.5518"},{"id":238054,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"18","issue":"4","noUsgsAuthors":false,"publicationDate":"2004-02-20","publicationStatus":"PW","scienceBaseUri":"505a36abe4b0c8380cd608d9","contributors":{"authors":[{"text":"Doerr, S.H.","contributorId":32725,"corporation":false,"usgs":true,"family":"Doerr","given":"S.H.","email":"","affiliations":[],"preferred":false,"id":413925,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Moody, J. A.","contributorId":32930,"corporation":false,"usgs":true,"family":"Moody","given":"J.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":413926,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70027512,"text":"70027512 - 2004 - Importance of the Vadose Zone in analyses of unconfined aquifer tests","interactions":[],"lastModifiedDate":"2018-11-14T07:34:19","indexId":"70027512","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1861,"text":"Ground Water","active":true,"publicationSubtype":{"id":10}},"title":"Importance of the Vadose Zone in analyses of unconfined aquifer tests","docAbstract":"Analytical models commonly used to interpret unconfined aquifer tests have been based on upper-boundary (water table) conditions that do not adequately address effects of time-varying drainage from the vadose zone. As a result, measured and simulated drawdown data may not agree and hydraulic parameters may be inaccurately estimated. A 72-hour aquifer test conducted in Cape Cod, Massachusetts, in a slightly heterogeneous, coarse-grained, glacial outwash deposit was found to be a good candidate for testing models with different upper-boundary conditions. In general, under the commonly invoked assumption of instantaneous drainage, measured and simulated draw-downs were found to agree with one another only at late time and early time. In the intermediate-time range, because of delayed drainage, measured drawdowns always exceeded simulated values, most noticeably in piezometers located near the water table. To reduce these discrepancies, an analytical model was developed that can fully account for time-varying drainage given that the aquifer is not strongly heterogeneous. The approach is flexible as the model, which makes use of empirical relations, does not constrain drainage to follow any particular functional relation. By this approach, measured and simulated drawdowns agree over the complete time range, and the estimated parameters are consistent with prior studies and with what is known about the aquifer geometry, stratigraphy, and composition. By properly accounting for vadose zone drainage, it was found that realistic estimates of all hydraulic parameters, including specific yield, could be obtained with or without the use of late-time data.","language":"English","publisher":"Wiley","doi":"10.1111/j.1745-6584.2004.tb02669.x","issn":"0017467X","usgsCitation":"Moench, A., 2004, Importance of the Vadose Zone in analyses of unconfined aquifer tests: Ground Water, v. 42, no. 2, p. 223-233, https://doi.org/10.1111/j.1745-6584.2004.tb02669.x.","productDescription":"11 p.","startPage":"223","endPage":"233","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":238193,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":211040,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1111/j.1745-6584.2004.tb02669.x"}],"volume":"42","issue":"2","noUsgsAuthors":false,"publicationDate":"2005-12-13","publicationStatus":"PW","scienceBaseUri":"505a3946e4b0c8380cd61880","contributors":{"authors":[{"text":"Moench, A.F.","contributorId":91495,"corporation":false,"usgs":true,"family":"Moench","given":"A.F.","email":"","affiliations":[],"preferred":false,"id":413958,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70027533,"text":"70027533 - 2004 - Strontium isotope geochemistry of groundwater in the central part of the Dakota (Great Plains) aquifer, USA","interactions":[],"lastModifiedDate":"2012-03-12T17:20:48","indexId":"70027533","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":835,"text":"Applied Geochemistry","active":true,"publicationSubtype":{"id":10}},"title":"Strontium isotope geochemistry of groundwater in the central part of the Dakota (Great Plains) aquifer, USA","docAbstract":"The Dakota aquifer of the central and eastern Great Plains of the United States is an important source of water for municipal supplies, irrigation and industrial use. Although the regional flow system can be characterized generally as east to northeasterly from the Rocky Mountains towards the Missouri River, locally the flow systems are hydrologically complex. This study uses Sr isotopic data from groundwater and leached aquifer samples to document the complex subsystems within the Dakota aquifer in Nebraska and Kansas. The interaction of groundwater with the geologic material through which it flows has created spatial patterns in the isotopic measurements that are related to: long-term water-rock interaction, during which varying degrees of isotopic equilibrium between water and rock has been achieved; and the alteration of NaCl fluids by water-rock interaction. Specifically, Sr isotopic data distinguish brines from Kansas and western Nebraska from those in eastern Nebraska: the former are interpreted to reflect interaction with Permian rocks, whereas the latter record interaction with Pennsylvanian rocks. The Sr isotopic composition of groundwater from other parts of Nebraska and Kansas are a function of the dynamic interaction between groundwater and unlithified sediments (e.g., glacial till and loess), followed by interaction with oxidized and unoxidized sediments within the Dakota Formation. This study illustrates the power of combining Sr chemistry with more conventional geochemical data to obtain a more complete understanding of groundwater flow systems within regional aquifer systems where extensive monitoring networks do not exist. ?? 2003 Elsevier Ltd. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Applied Geochemistry","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/S0883-2927(03)00132-X","issn":"08832927","usgsCitation":"Gosselin, D., Harvey, F., Frost, C., Stotler, R., and Macfarlane, P.A., 2004, Strontium isotope geochemistry of groundwater in the central part of the Dakota (Great Plains) aquifer, USA: Applied Geochemistry, v. 19, no. 3, p. 359-377, https://doi.org/10.1016/S0883-2927(03)00132-X.","startPage":"359","endPage":"377","numberOfPages":"19","costCenters":[],"links":[{"id":210902,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0883-2927(03)00132-X"},{"id":237982,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"19","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b9babe4b08c986b31d014","contributors":{"authors":[{"text":"Gosselin, D.C.","contributorId":93237,"corporation":false,"usgs":true,"family":"Gosselin","given":"D.C.","email":"","affiliations":[],"preferred":false,"id":414053,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Harvey, F.E.","contributorId":46161,"corporation":false,"usgs":true,"family":"Harvey","given":"F.E.","email":"","affiliations":[],"preferred":false,"id":414050,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Frost, C.","contributorId":65278,"corporation":false,"usgs":true,"family":"Frost","given":"C.","email":"","affiliations":[],"preferred":false,"id":414051,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Stotler, R.","contributorId":73404,"corporation":false,"usgs":true,"family":"Stotler","given":"R.","affiliations":[],"preferred":false,"id":414052,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Macfarlane, P. A.","contributorId":14597,"corporation":false,"usgs":true,"family":"Macfarlane","given":"P.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":414049,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70027246,"text":"70027246 - 2004 - SWICA-2 M3: Second conference on salt water intrusion in coastal aquifers: Monitoring, modeling, and management","interactions":[],"lastModifiedDate":"2017-03-27T10:38:55","indexId":"70027246","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3825,"text":"Groundwater","active":true,"publicationSubtype":{"id":10}},"title":"SWICA-2 M3: Second conference on salt water intrusion in coastal aquifers: Monitoring, modeling, and management","docAbstract":"No abstract available
","language":"English","publisher":"Wiley","doi":"10.1111/j.1745-6584.2004.tb02678.x","issn":"0017467X","usgsCitation":"Marin, L., and Voss, C., 2004, SWICA-2 M3: Second conference on salt water intrusion in coastal aquifers: Monitoring, modeling, and management: Groundwater, v. 42, no. 3, p. 318-322, https://doi.org/10.1111/j.1745-6584.2004.tb02678.x.","productDescription":"5 p.","startPage":"318","endPage":"322","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":235304,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":209103,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1111/j.1745-6584.2004.tb02678.x"}],"volume":"42","issue":"3","noUsgsAuthors":false,"publicationDate":"2005-12-13","publicationStatus":"PW","scienceBaseUri":"505aafb0e4b0c8380cd8771f","contributors":{"authors":[{"text":"Marin, L.E.","contributorId":76471,"corporation":false,"usgs":true,"family":"Marin","given":"L.E.","email":"","affiliations":[],"preferred":false,"id":412897,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Voss, C.I.","contributorId":79515,"corporation":false,"usgs":true,"family":"Voss","given":"C.I.","email":"","affiliations":[],"preferred":false,"id":412898,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70027243,"text":"70027243 - 2004 - Nitrate and herbicide loading in two groundwater basins of Illinois' sinkhole plain","interactions":[],"lastModifiedDate":"2012-03-12T17:20:32","indexId":"70027243","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2342,"text":"Journal of Hydrology","active":true,"publicationSubtype":{"id":10}},"title":"Nitrate and herbicide loading in two groundwater basins of Illinois' sinkhole plain","docAbstract":"This investigation was designed to estimate the mass loading of nitrate (NO3-) and herbicides in spring water discharging from groundwater basins in an agriculturally dominated, mantled karst terrain. The loading was normalized to land use and NO3- and herbicide losses were compared to estimated losses in other agricultural areas of the Midwestern USA. Our study area consisted of two large karst springs that drain two adjoining groundwater basins (total area of 37.7 km2) in southwestern Illinois' sinkhole plain, USA. The springs and stream that they form were monitored for almost 2 years. Nitrate-nitrogen (NO3-N) concentrations at three monitoring sites were almost always above the background concentration (1.9 mg/l). NO3-N concentrations at the two springs ranged from 1.08 to 6.08 with a median concentration of 3.61 mg/l. Atrazine and alachlor concentrations ranged from <0.01 to 34 ??g/l and <0.01 to 0.98 ??g/l, respectively, with median concentrations of 0.48 and 0.12 ??g/l, respectively. Approximately 100,000 kg/yr of NO3-N, 39 kg/yr of atrazine, and 2.8 kg/yr of alachlor were discharged from the two springs. Slightly more than half of the discharged NO3- came from background sources and most of the remainder probably came from fertilizer. This represents a 21-31% loss of fertilizer N from the groundwater basins. The pesticide losses were 3.8-5.8% of the applied atrazine, and 0.05-0.08% of the applied alachlor. The loss of atrazine adsorbed to the suspended solid fraction was about 2 kg/yr, only about 5% of the total mass of atrazine discharged from the springs. ?? 2004 Elsevier B.V. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Hydrology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.jhydrol.2003.12.017","issn":"00221694","usgsCitation":"Panno, S., and Kelly, W., 2004, Nitrate and herbicide loading in two groundwater basins of Illinois' sinkhole plain: Journal of Hydrology, v. 290, no. 3-4, p. 229-242, https://doi.org/10.1016/j.jhydrol.2003.12.017.","startPage":"229","endPage":"242","numberOfPages":"14","costCenters":[],"links":[{"id":209078,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.jhydrol.2003.12.017"},{"id":235270,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"290","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a6667e4b0c8380cd72dac","contributors":{"authors":[{"text":"Panno, S.V.","contributorId":102990,"corporation":false,"usgs":true,"family":"Panno","given":"S.V.","email":"","affiliations":[],"preferred":false,"id":412892,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kelly, W.R.","contributorId":74120,"corporation":false,"usgs":true,"family":"Kelly","given":"W.R.","email":"","affiliations":[],"preferred":false,"id":412891,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70027242,"text":"70027242 - 2004 - Use of chemical and isotopic tracers to assess nitrate contamination and ground-water age, Woodville Karst Plain, USA","interactions":[],"lastModifiedDate":"2012-03-12T17:20:32","indexId":"70027242","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2342,"text":"Journal of Hydrology","active":true,"publicationSubtype":{"id":10}},"title":"Use of chemical and isotopic tracers to assess nitrate contamination and ground-water age, Woodville Karst Plain, USA","docAbstract":"Concerns regarding ground-water contamination in the Woodville Karst Plain have arisen due to a steady increase in nitrate-N concentrations (0.25-0.90 mg/l) during the past 30 years in Wakulla Springs, a large regional discharge point for water (9.6 m3/s) from the Upper Floridan aquifer (UFA). Multiple isotopic and chemical tracers were used with geochemical and lumped-parameter models (exponential mixing (EM), dispersion, and combined exponential piston flow) to assess: (1) the sources and extent of nitrate contamination of ground water and springs, and (2) mean transit times (ages) of ground water. Delta 15N-NO3 values (1.7-13.8???) indicated that nitrate in ground water originated from localized sources of inorganic fertilizer and human/animal wastes. Nitrate in spring waters (??15N-NO3=5.3-8.9???) originated from both inorganic and organic N sources. Nitrate-N concentrations (<0.02-16 mg/l) were highly variable both spatially and vertically in the oxic UFA, based on water samples from 46 wells and four springs collected from 1997 to 2000. During high-flow conditions, spring waters had decreased nitrate and increased DOC concentrations that resulted from mixtures of 20-95% surface water. Although higher nitrate-N concentrations (>1.0 mg/l) were associated with shallow wells (open intervals less than 15 m below land surface), elevated nitrate concentrations in deeper wells are consistent with mixtures of water from shallow and deep zones in the UFA as indicated from geochemical mixing models and the distribution of mean transit times (5-90 years) estimated using lumped-parameter flow models. Ground water with mean transit times of 10 years or less tended to have higher dissolved organic carbon concentrations, lower dissolved solids, and lower calcite saturation indices than older waters, indicating mixing with nearby surface water that directly recharges the aquifer through sinkholes. Significantly higher values of pH, magnesium, dolomite saturation index, and phosphate in springs and deep water (>45 m) relative to a shallow zone (<45 m) were associated with longer ground-water transit times (50-90 years). Chemical differences with depth in the aquifer result from deep regional flow of water recharged through low permeability sediments (clays and clayey sands of the Hawthorn Formation) that overlie the UFA upgradient from the karst plain.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Hydrology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.jhydrol.2003.11.001","issn":"00221694","usgsCitation":"Katz, B., Chelette, A., and Pratt, T., 2004, Use of chemical and isotopic tracers to assess nitrate contamination and ground-water age, Woodville Karst Plain, USA: Journal of Hydrology, v. 289, no. 1-4, p. 36-61, https://doi.org/10.1016/j.jhydrol.2003.11.001.","startPage":"36","endPage":"61","numberOfPages":"26","costCenters":[],"links":[{"id":209077,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.jhydrol.2003.11.001"},{"id":235269,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"289","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bbed2e4b08c986b3297d4","contributors":{"authors":[{"text":"Katz, B. G.","contributorId":82702,"corporation":false,"usgs":true,"family":"Katz","given":"B. G.","affiliations":[],"preferred":false,"id":412888,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Chelette, A.R.","contributorId":107476,"corporation":false,"usgs":true,"family":"Chelette","given":"A.R.","email":"","affiliations":[],"preferred":false,"id":412890,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Pratt, T.R.","contributorId":89323,"corporation":false,"usgs":true,"family":"Pratt","given":"T.R.","email":"","affiliations":[],"preferred":false,"id":412889,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70027236,"text":"70027236 - 2004 - Inorganic N and P dynamics of Antarctic glacial meltwater streams as controlled by hyporheic exchange and benthic autotrophic communities","interactions":[],"lastModifiedDate":"2018-11-14T08:29:03","indexId":"70027236","displayToPublicDate":"2004-01-01T00:00:00","publicationYear":"2004","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2564,"text":"Journal of the North American Benthological Society","onlineIssn":"1937-237X","printIssn":"0887-3593","active":true,"publicationSubtype":{"id":10}},"title":"Inorganic N and P dynamics of Antarctic glacial meltwater streams as controlled by hyporheic exchange and benthic autotrophic communities","docAbstract":"The McMurdo Dry Valleys of South Victoria Land, Antarctica, contain numerous glacial meltwater streams that drain into lakes on the valley floors. Many of the streams have abundant perennial mats of filamentous cyanobacteria. The algal mats grow during streamflow in the austral summer and are in a dormant freeze-dried state during the rest of the year. NO3 and soluble reactive P (SRP) concentrations were lower in streams with abundant algal mats than in streams with sparse algal mats. NO3 and SRP concentrations were higher in the hyporheic zone of a stream with abundant algal mats than in the stream itself. An experimental injection of LiCl, NaNO3, and K3PO4 was conducted in Green Creek, which has abundant algal mats. Substantial hyporheic exchange occurred. The NO3 and PO4 concentrations at 50 m below the injection were 55 μM and 18 μM, respectively, during the experiment. NO3and PO4 concentrations were below the detection limit of 1 to 2 μM at a site 497 m below the injection during the Cl tracer arrival, indicating a high capacity for nutrient uptake by algal communities. NO2 and NH4 were present at sites 226 and 327 m below the injection, indicating that, in addition to denitrification and algal uptake, dissimilatory NO3 reduction to NO2 and NH4 may be a NO3 sink during transport. Transport modelling with nutrient uptake represented as a 1st-order process yielded reach-scale parameters of 4.3 × 10−5 to 3.9 × 10−4/s and 1.4 × 10−4 to 3.8 × 10−4/s for uptake of NO3 and PO4, respectively. The best match with the observed data was a model in which PO4 uptake occurred only in the main channel and NO3 uptake occurred in the main channel and in the hyporheic zone. Hyporheic NO3 uptake was 7 to 16% of the total uptake for the different stream reaches. These results demonstrate that nutrient flux to the lakes is controlled by hyporheic exchange and nutrient uptake by algal mats in dry valley streams. Streams without algal mats contribute more nutrients to the lakes than streams with algal mats.
The proportion of chloroacetanilide herbicide degradates, specifically the ethane sulfonic (ESA) and oxanilic (OA) acids, averaged 70% of the total herbicide concentration in samples from the Upper Mississippi River. In samples from the Missouri River and the Ohio River, the proportion of chloroacetanilide degradates in the total herbicide concentration was much less, 24% and 41%, respectively. The amount of tile drainage throughout the Mississippi River Basin appeared to be related to the occurrence and distribution of chloroacetanilide degradates in water samples. Pesticide concentrations in streams of the Mississippi River Basin have been well characterized. However, recent research demonstrates that in order to more fully understand the fate and transport of pesticides, the major pesticide degradates need to be included in the analysis. From March 1999 through May 2001, water samples from four major junctures of the Mississippi River Basin were collected and analyzed for a suite of herbicides and their degradate compounds. Each sampling site was selected to represent a major part of the Mississippi River: upper and lower Mississippi, Missouri and Ohio Rivers. Each basin has unique landscape variables, geology, hydrology, precipitation, and land use, which is reflected in the pesticide content at the most downstream sample site near the mouth of the Mississippi River. Atrazine was the most frequently detected herbicide (detected in 97% of the samples), followed by metolachlor (60%), and acetochlor (31%). The most frequently detected degradates were metolachlor ESA (69%), followed by deethylatrazine (62%), metolachlor OA (37%), and alachlor ESA (37%). Metolachlor ESA was detected more frequently than its parent compound (69 vs. 60%), as was alachlor ESA (37 vs. 9%). After an improvement was made in the analytical method, metolachlor ESA was detected in every sample, metolachlor OA in 89% of the samples, alachlor ESA in 84%, acetochlor ESA in 71%, and acetochlor OA in 66%.
Analyses of samples of untreated ground water from 413 community-, non-community- (such as restaurants), and domestic-supply wells throughout the US were used to determine the frequency of detection of halogenated volatile organic compounds (VOCs) in drinking-water sources. The VOC data were compiled from archived chromatograms of samples analyzed originally for chlorofluorocarbons (CFCs) by purge-and-trap gas chromatography with an electron-capture detector (GC-ECD). Concentrations of the VOCs could not be ascertained because standards were not routinely analyzed for VOCs other than trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113). Nevertheless, the peak areas associated with the elution times of other VOCs on the chromatograms can be classified qualitatively to assess concentrations at a detection limit on the order of parts per quadrillion. Three or more VOCs were detected in 100% (percent) of the chromatograms, and 77.2% of the samples contained 10 or more VOCs. The maximum number of VOCs detected in any sample was 24. Modeled ground-water residence times, determined from concentrations of CFC-12, were used to assess historical trends in the cumulative occurrence of all VOCs detected in this analysis, as well as the occurrence of individual VOCs, such as CFC-11, carbon tetrachloride (CCl4), chloroform and tetrachloroethene (PCE). The detection frequency for all of the VOCs detected has remained relatively constant from approximately 1940 to 2000; however, the magnitude of the peak areas on the chromatograms for the VOCs in the water samples has increased from 1940 to 2000. For CFC-11, CCl4, chloroform and PCE, small peaks decrease from 1940 to 2000, and large peaks increase from 1940 to 2000. The increase in peak areas on the chromatograms from analyses of more recently recharged water is consistent with reported increases in atmospheric concentrations of the VOCs. Approximately 44% and 6.7% of the CCl4 and PCE detections, respectively, in pre-1940 water, and 68% and 62% of the CCl4 and PCE detections, respectively, in water recharged in 2000 exceed solubility equilibrium with average atmospheric concentrations. These exceedences can be attributed to local atmospheric enrichment or direct contaminant input to ground-water flow systems. The detection of VOCs at concentrations indicative of atmospheric sources in 100% of the samples indicates that untreated drinking water from ground-water sources in the US recharged within the past 60 years has been affected by anthropogenic activity. Additional inputs from a variety of sources such as spills, underground injections and leaking landfills or storage tanks increasingly are providing additional sources of contamination to ground water used as drinking-water sources.