A large-scale model of virus transport in aquifers is derived using spectral perturbation analysis. The effects of spatial variability in aquifer hydraulic conductivity and virus transport (attachment, detachment, and inactivation) parameters on large-scale virus transport are evaluated. A stochastic mean model of virus transport is developed by linking a simple system of local-scale free-virus transport and attached-virus conservation equations from the current literature with a random-field representation of aquifer and virus transport properties. The resultant mean equations for free and attached viruses are found to differ considerably from the local-scale equations on which they are based and include effects such as a free-virus effective velocity that is a function of aquifer heterogeneity as well as virus transport parameters. Stochastic mean free-virus breakthrough curves are compared with local model output in order to observe the effects of spatial variability on mean one-dimensional virus transport in three-dimensionally heterogeneous porous media. Significant findings from this theoretical analysis include the following: (1) Stochastic model breakthrough occurs earlier than local model breakthrough, and this effect is most pronounced for the least conductive aquifers studied. (2) A high degree of aquifer heterogeneity can lead to virus breakthrough actually preceding that of a conservative tracer. (3) As the mean hydraulic conductivity is increased, the mean model shows less sensitivity to the variance of the natural-logarithm hydraulic conductivity and mean virus diameter. (4) Incorporation of a heterogeneous colloid filtration term results in higher predicted concentrations than a simple first-order adsorption term for a given mean attachment rate. (5) Incorporation of aquifer heterogeneity leads to a greater range of virus diameters for which significant breakthrough occurs. (6) The mean model is more sensitive to the inactivation rate of viruses associated with solid surfaces than to the inactivation rate of viruses in solution.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/1999WR900059","usgsCitation":"Campbell Rehmann, L.L., Welty, C., and Harvey, R.W., 1999, Stochastic analysis of virus transport in aquifers: Water Resources Research, v. 35, no. 7, p. 1987-2006, https://doi.org/10.1029/1999WR900059.","productDescription":"20 p.","startPage":"1987","endPage":"2006","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":229457,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"35","issue":"7","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b9849e4b08c986b31bf5a","contributors":{"authors":[{"text":"Campbell Rehmann, Linda L.","contributorId":15073,"corporation":false,"usgs":false,"family":"Campbell Rehmann","given":"Linda","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":391765,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Welty, Claire","contributorId":39416,"corporation":false,"usgs":true,"family":"Welty","given":"Claire","email":"","affiliations":[],"preferred":false,"id":391766,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"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":391764,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70020969,"text":"70020969 - 1999 - Relation of streams, lakes, and wetlands to groundwater flow systems","interactions":[],"lastModifiedDate":"2024-03-05T01:34:21.33467","indexId":"70020969","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1923,"text":"Hydrogeology Journal","active":true,"publicationSubtype":{"id":10}},"title":"Relation of streams, lakes, and wetlands to groundwater flow systems","docAbstract":"Surface-water bodies are integral parts of groundwater flow systems. Groundwater interacts with surface water in nearly all landscapes, ranging from small streams, lakes, and wetlands in headwater areas to major river valleys and seacoasts. Although it generally is assumed that topographically high areas are groundwater recharge areas and topographically low areas are groundwater discharge areas, this is true primarily for regional flow systems. The superposition of local flow systems associated with surface-water bodies on this regional framework results in complex interactions between groundwater and surface water in all landscapes, regardless of regional topographic position. Hydrologic processes associated with the surface-water bodies themselves, such as seasonally high surface-water levels and evaporation and transpiration of groundwater from around the perimeter of surface-water bodies, are a major cause of the complex and seasonally dynamic groundwater flow fields associated with surface water. These processes have been documented at research sites in glacial, dune, coastal, mantled karst, and riverine terrains.
Although riparian areas in the arid southwestern United States are critical for maintaining species diversity, their extent and health have been declining since Euro‐American settlement. The purpose of this study was to develop a methodology to evaluate the potential for riparian vegetation restoration and groundwater recharge. A numerical groundwater flow model was coupled with a conceptual riparian vegetation model to predict hydrologic conditions favorable to maintaining riparian vegetation downstream of a reservoir. A Geographic Information System (GIS) was used for this one‐way coupling. Constant and seasonally varying releases from the dam were simulated using volumes anticipated to be permitted by a regional water supplier. Simulations indicated that seasonally variable releases would produce surface flow 5.4–8.5 km below the dam in a previously dry reach. Using depth to groundwater simulations from the numerical flow model with conceptual models of depths to water necessary for maintenance of riparian vegetation, the GIS analysis predicted a 5‐ to 6.5‐fold increase in the area capable of sustaining riparian vegetation.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/1999WR900233","usgsCitation":"Springer, A., Wright, J.M., Shafroth, P.B., Stromberg, J.C., and Patten, D.T., 1999, Coupling groundwater and riparian vegetation models to assess effects of reservoir releases: Water Resources Research, v. 35, no. 12, p. 3621-3630, https://doi.org/10.1029/1999WR900233.","productDescription":"10 p.","startPage":"3621","endPage":"3630","costCenters":[],"links":[{"id":479551,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/1999wr900233","text":"Publisher Index Page"},{"id":229258,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"35","issue":"12","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059fc8de4b0c8380cd4e2f2","contributors":{"authors":[{"text":"Springer, Abraham E.","contributorId":9558,"corporation":false,"usgs":true,"family":"Springer","given":"Abraham E.","affiliations":[],"preferred":false,"id":390731,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wright, Julie M.","contributorId":145733,"corporation":false,"usgs":false,"family":"Wright","given":"Julie","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":390729,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Shafroth, Patrick B. 0000-0002-6064-871X shafrothp@usgs.gov","orcid":"https://orcid.org/0000-0002-6064-871X","contributorId":2000,"corporation":false,"usgs":true,"family":"Shafroth","given":"Patrick","email":"shafrothp@usgs.gov","middleInitial":"B.","affiliations":[{"id":291,"text":"Fort Collins Science Center","active":true,"usgs":true}],"preferred":true,"id":390730,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Stromberg, Juliet C.","contributorId":52280,"corporation":false,"usgs":true,"family":"Stromberg","given":"Juliet","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":390732,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Patten, Duncan T.","contributorId":124573,"corporation":false,"usgs":false,"family":"Patten","given":"Duncan","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":390728,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70021605,"text":"70021605 - 1999 - Evaluation of stream water quality in Atlanta, Georgia, and the surrounding region (USA)","interactions":[],"lastModifiedDate":"2012-03-12T17:19:41","indexId":"70021605","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1934,"text":"IAHS-AISH Publication","active":true,"publicationSubtype":{"id":10}},"title":"Evaluation of stream water quality in Atlanta, Georgia, and the surrounding region (USA)","docAbstract":"A water-quality index (WQI) was developed from historical data (1986-1995) for streams in the Atlanta Region and augmented with 'new' and generally more comprehensive biweekly data on four small urban streams, representing an industrial area, a developed medium-density residential area and developing and developed low-density residential areas. Parameter WQIs were derived from percentile ranks of individual water-quality parameter values for each site by normalizing the constituent ranks for values from all sites in the area for a base period, i.e. 1990-1995. WQIs were developed primarily for nutrient-related parameters due to data availability. Site WQIs, which were computed by averaging the parameter WQIs, range from 0.2 (good quality) to 0.8 (poor quality), and increased downstream of known nutrient sources. Also, annual site WQI decreases from 1986 to 1995 at most long-term monitoring sites. Annual site WQI for individual parameters correlated with annual hydrological characteristics, particularly runoff, precipitation quantity, and water yield, reflecting the effect of dilution on parameter values. The WQIs of the four small urban streams were evaluated for the core-nutrient-related parameters, parameters for specific dissolved trace metal concentrations and sediment characteristics, and a species diversity index for the macro-invertebrate taxa. The site WQI for the core-nutrient-related parameters used in the retrospective analysis was, as expected, the worst for the industrial area and the best for the low-density residential areas. However, macro-invertebrate data indicate that although the species at the medium-density residential site were diverse, the taxa at the site were for species tolerant of degraded water quality. Furthermore, although a species-diversity index indicates no substantial difference between the two low-density residential areas, the number for macro-invertebrates for the developing area was much less than that for the developed area, consistent with observations of recent sediment problems probably associated with construction in the basin. However, sediment parameters were similar for the two sites suggesting that the routine biweekly measurements may not capture the short-term increases in sediment transport associated with rainstorms. The WQI technique is limited by the number and types of parameters included in it, the general conditions of those parameters for the range of conditions in area streams, and by the effects of external factors, such as hydrology, and therefore, should be used with caution.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"IAHS-AISH Publication","largerWorkSubtype":{"id":10,"text":"Journal Article"},"conferenceTitle":"Proceedings of the 1999 IUGG 99, the XXII General Assembly of the International Union of Geodesy and Geophysics","conferenceDate":"18 July 1999 through 30 July 1999","conferenceLocation":"Birmingham, UK","language":"English","publisher":"IAHS","publisherLocation":"Houston, TX, United States","issn":"01447815","usgsCitation":"Peters, N., and Kandell, S., 1999, Evaluation of stream water quality in Atlanta, Georgia, and the surrounding region (USA): IAHS-AISH Publication, no. 259, p. 279-290.","startPage":"279","endPage":"290","numberOfPages":"12","costCenters":[],"links":[{"id":229177,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"issue":"259","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a0cc8e4b0c8380cd52cc8","contributors":{"authors":[{"text":"Peters, N.E.","contributorId":33332,"corporation":false,"usgs":true,"family":"Peters","given":"N.E.","email":"","affiliations":[],"preferred":false,"id":390453,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kandell, S.J.","contributorId":73067,"corporation":false,"usgs":true,"family":"Kandell","given":"S.J.","affiliations":[],"preferred":false,"id":390454,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":7000061,"text":"7000061 - 1999 - Hydrologic units","interactions":[],"lastModifiedDate":"2012-02-02T00:15:07","indexId":"7000061","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":6,"text":"USGS Unnumbered Series"},"seriesTitle":{"id":363,"text":"General Interest Publication","active":false,"publicationSubtype":{"id":6}},"title":"Hydrologic units","language":"ENGLISH","doi":"10.3133/7000061","usgsCitation":"Water Resources Division, U.S. Geological Survey, 1999, Hydrologic units: General Interest Publication, 1 sheet ([1] leaf) : col. maps ; 28 cm., https://doi.org/10.3133/7000061.","productDescription":"1 sheet ([1] leaf) : col. maps ; 28 cm.","costCenters":[],"links":[{"id":198001,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":18614,"rank":100,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.usgs.gov/gip/hydrologic_units/","linkFileType":{"id":5,"text":"html"}}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4a18e4b07f02db605244","contributors":{"authors":[{"text":"Water Resources Division, U.S. Geological Survey","contributorId":128075,"corporation":true,"usgs":false,"organization":"Water Resources Division, U.S. Geological Survey","id":535090,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70021607,"text":"70021607 - 1999 - Distribution of microbial physiologic types in an aquifer contaminated by crude oil","interactions":[],"lastModifiedDate":"2018-12-14T07:23:46","indexId":"70021607","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2729,"text":"Microbial Ecology","active":true,"publicationSubtype":{"id":10}},"title":"Distribution of microbial physiologic types in an aquifer contaminated by crude oil","docAbstract":"We conducted a plume-scale study of the microbial ecology in the anaerobic portion of an aquifer contaminated by crude-oil compounds. The data provide insight into the patterns of ecological succession, microbial nutrient demands, and the relative importance of free-living versus attached microbial populations. The most probable number (MPN) method was used to characterize the spatial distribution of six physiologic types: aerobes, denitrifiers, iron-reducers, heterotrophic fermenters, sulfate-reducers, and methanogens. Both free-living and attached numbers were determined over a broad cross-section of the aquifer extending horizontally from the source of the plume at a nonaqueous oil body to 66 m downgradient, and vertically from above the water table to the base of the plume below the water table. Point samples from widely spaced locations were combined with three closely spaced vertical profiles to create a map of physiologic zones for a cross-section of the plume. Although some estimates suggest that less than 1% of the subsurface microbial population can be grown in laboratory cultures, the MPN results presented here provide a comprehensive qualitative picture of the microbial ecology at the plume scale. Areas in the plume that are evolving from iron-reducing to methanogenic conditions are clearly delineated and generally occupy 25-50% of the plume thickness. Lower microbial numbers below the water table compared to the unsaturated zone suggest that nutrient limitations may be important in limiting growth in the saturated zone. Finally, the data indicate that an average of 15% of the total population is suspended.","language":"English","publisher":"Springer","doi":"10.1007/s002489900149","issn":"00953628","usgsCitation":"Bekins, B., Godsy, E., and Warren, E., 1999, Distribution of microbial physiologic types in an aquifer contaminated by crude oil: Microbial Ecology, v. 37, no. 4, p. 263-275, https://doi.org/10.1007/s002489900149.","productDescription":"13 p.","startPage":"263","endPage":"275","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":229214,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":206249,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s002489900149"}],"volume":"37","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a02e2e4b0c8380cd50245","contributors":{"authors":[{"text":"Bekins, B.A.","contributorId":98309,"corporation":false,"usgs":true,"family":"Bekins","given":"B.A.","email":"","affiliations":[],"preferred":false,"id":390459,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Godsy, E.M.","contributorId":56685,"corporation":false,"usgs":true,"family":"Godsy","given":"E.M.","email":"","affiliations":[],"preferred":false,"id":390458,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Warren, E.","contributorId":15360,"corporation":false,"usgs":true,"family":"Warren","given":"E.","email":"","affiliations":[],"preferred":false,"id":390457,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70021703,"text":"70021703 - 1999 - Component flow processes at four streams in the Catskill Mountains, New York, analysed using episodic concentration/discharge relationship","interactions":[],"lastModifiedDate":"2012-03-12T17:19:41","indexId":"70021703","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","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":"Component flow processes at four streams in the Catskill Mountains, New York, analysed using episodic concentration/discharge relationship","docAbstract":"Plots of solute concentration against discharge have been used to relate stream hydrochemical variations to processes of flow generation, using data collected at four streams in the Catskill Mountains, New York, during the Episodic Response Project of the US Environmental Protection Agency. Results suggest that a two-component system of shallow and deep saturated subsurface flow, in which the two components respond simultaneously during hydrologic events, may be applicable to the study basins. Using a large natural sea-salt sodium input as a tracer for precipitation, it is argued that an additional distinction can be made between pre-event and event water travelling along the shallow subsurface flow path. Pre-event water is thought to be displaced by infiltrating event water, which becomes dominant on the falling limb of the hydrograph. Where, as appears to be the case for sulfate, a solute equilibrates rapidly within the soil, the pre-event-event water distinction is unimportant. However, for some solutes there are clear and consistent compositional differences between water from the two sources, evident as a hysteresis loop in concentration-discharge plots. Nitrate and acidity, in particular, appear to be elevated in event water following percolation through the organic horizon. Consequently, the most acidic, high nitrate conditions during an episode generally occur after peak discharge. A simple conceptual model of episode runoff generation is presented on the basis of these results.Plots of solute concentration against discharge have been used to relate stream hydrochemical variations to processes of flow generation, using data collected at four streams in the Catskill Mountains, New York, during the Episodic Response Project of the US Environmental Protection Agency. Results suggest that a two-component system of shallow and deep saturated subsurface flow, in which the two components respond simultaneously during hydrologic events, may be applicable to the study basins. Using a large natural sea-salt sodium input as a tracer for precipitation, it is argued that an additional distinction can be made between pre-event and event water travelling along the shallow subsurface flow path. Pre-event water is thought to be displaced by infiltrating event water, which becomes dominant on the falling limb of the hydrograph. Where, as appears to be the case for sulfate, a solute equilibrates rapidly within the soil, the pre-event - event water distinction is unimportant. However, for some solutes there are clear and consistent compositional differences between water from the two sources, evident as a hysteresis loop in concentration-discharge plots. Nitrate and acidity, in particular, appear to be elevated in event water following percolation through the organic horizon. Consequently, the most acidic, high nitrate conditions during an episode generally occur after peak discharge. A simple conceptual model of episode runoff generation is presented on the basis of these results.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrological Processes","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"John Wiley & Sons Ltd","doi":"10.1002/(SICI)1099-1085(199903)13:4<563::AID-HYP711>3.0.CO;2-N","issn":"08856087","usgsCitation":"Evans, C., Davies, T., and Murdoch, P., 1999, Component flow processes at four streams in the Catskill Mountains, New York, analysed using episodic concentration/discharge relationship: Hydrological Processes, v. 13, no. 4, p. 563-575, https://doi.org/10.1002/(SICI)1099-1085(199903)13:4<563::AID-HYP711>3.0.CO;2-N.","startPage":"563","endPage":"575","numberOfPages":"13","costCenters":[],"links":[{"id":206330,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/(SICI)1099-1085(199903)13:4<563::AID-HYP711>3.0.CO;2-N"},{"id":229439,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"13","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f913e4b0c8380cd4d409","contributors":{"authors":[{"text":"Evans, C.","contributorId":33449,"corporation":false,"usgs":true,"family":"Evans","given":"C.","email":"","affiliations":[],"preferred":false,"id":390791,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Davies, T.D.","contributorId":86513,"corporation":false,"usgs":true,"family":"Davies","given":"T.D.","email":"","affiliations":[],"preferred":false,"id":390793,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Murdoch, Peter S.","contributorId":73547,"corporation":false,"usgs":true,"family":"Murdoch","given":"Peter S.","affiliations":[],"preferred":false,"id":390792,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70021223,"text":"70021223 - 1999 - Seasonal variability in hydrologic-system response to intense rain events, Matanuska Glacier, Alaska, U.S.A.","interactions":[],"lastModifiedDate":"2013-03-12T20:26:58","indexId":"70021223","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":794,"text":"Annals of Glaciology","active":true,"publicationSubtype":{"id":10}},"title":"Seasonal variability in hydrologic-system response to intense rain events, Matanuska Glacier, Alaska, U.S.A.","docAbstract":"Two rain events at Matanuska Glacier illustrate how subglacial drainage system development and snowpack conditions affect hydrologic response at the terminus. On 21 and 22 September 1995, over 56 mm of rain fell in the basin during a period usually characterized by much drier conditions. This event caused an 8-fold increase in discharge and a 47-fold increase in suspended-sediment concentration. Peak suspended-sediment concentration exceeded 20 kg m-3, suggesting rapid evacuation of stored sediment. While water discharge returned to its pre-storm level nine days after the rain ceased, suspended-sediment concentrations took about 20 days to return to pre-storm levels. These observations suggest that the storm influx late in the melt season probably forced subglacial water into a more distributed system. In addition, subglacially transported sediments were supplemented to an unknown degree by the influx of storm-eroded sediments off hillslopes and from tributary drainage basins. A storm on 6 and 7 June 1997, dropped 28 mm of rain on the basin demonstrating the effects of meltwater retention in the snowpack and englacial and subglacial storage early in the melt season. Streamflow before the storm event was increasing gradually owing to warming temperatures; however, discharge during the storm and the following week increased only slightly. Suspended-sediment concentrations increased only a small amount, suggesting the drainage system was not yet well developed, and much of the runoff occurred across the relatively clean surface of the glacier or through englacial channels.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Annals of Glaciology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"Ingenta Connect","doi":"10.3189/172756499781821715","issn":"02603055","usgsCitation":"Denner, J., Lawson, D.E., Larson, G., Evenson, E., Alley, R.B., Strasser, J., and Kopczynski, S., 1999, Seasonal variability in hydrologic-system response to intense rain events, Matanuska Glacier, Alaska, U.S.A.: Annals of Glaciology, v. 28, no. 1, p. 267-271, https://doi.org/10.3189/172756499781821715.","startPage":"267","endPage":"271","numberOfPages":"5","costCenters":[],"links":[{"id":479566,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.3189/172756499781821715","text":"Publisher Index Page"},{"id":230098,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":269200,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.3189/172756499781821715"}],"volume":"28","issue":"1","noUsgsAuthors":false,"publicationDate":"2017-09-14","publicationStatus":"PW","scienceBaseUri":"505b88e3e4b08c986b316c07","contributors":{"authors":[{"text":"Denner, J.C.","contributorId":75562,"corporation":false,"usgs":true,"family":"Denner","given":"J.C.","email":"","affiliations":[],"preferred":false,"id":389124,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Lawson, D. E.","contributorId":9343,"corporation":false,"usgs":true,"family":"Lawson","given":"D.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":389121,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Larson, G.J.","contributorId":89680,"corporation":false,"usgs":true,"family":"Larson","given":"G.J.","email":"","affiliations":[],"preferred":false,"id":389126,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Evenson, E.B.","contributorId":79628,"corporation":false,"usgs":true,"family":"Evenson","given":"E.B.","email":"","affiliations":[],"preferred":false,"id":389125,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Alley, R. B.","contributorId":49533,"corporation":false,"usgs":false,"family":"Alley","given":"R.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":389123,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Strasser, J.C.","contributorId":21717,"corporation":false,"usgs":true,"family":"Strasser","given":"J.C.","email":"","affiliations":[],"preferred":false,"id":389122,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Kopczynski, S.","contributorId":90066,"corporation":false,"usgs":true,"family":"Kopczynski","given":"S.","affiliations":[],"preferred":false,"id":389127,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70021218,"text":"70021218 - 1999 - Robowell: An automated process for monitoring ground water quality using established sampling protocols","interactions":[],"lastModifiedDate":"2018-12-19T08:14:31","indexId":"70021218","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1864,"text":"Ground Water Monitoring and Remediation","active":true,"publicationSubtype":{"id":10}},"title":"Robowell: An automated process for monitoring ground water quality using established sampling protocols","docAbstract":"Robowell is an automated process for monitoring selected ground water quality properties and constituents by pumping a well or multilevel sampler. Robowell was developed and tested to provide a cost-effective monitoring system that meets protocols expected for manual sampling. The process uses commercially available electronics, instrumentation, and hardware, so it can be configured to monitor ground water quality using the equipment, purge protocol, and monitoring well design most appropriate for the monitoring site and the contaminants of interest. A Robowell prototype was installed on a sewage treatment plant infiltration bed that overlies a well-studied unconfined sand and gravel aquifer at the Massachusetts Military Reservation, Cape Cod, Massachusetts, during a time when two distinct plumes of constituents were released. The prototype was operated from May 10 to November 13, 1996, and quality-assurance/quality-control measurements demonstrated that the data obtained by the automated method was equivalent to data obtained by manual sampling methods using the same sampling protocols. Water level, specific conductance, pH, water temperature, dissolved oxygen, and dissolved ammonium were monitored by the prototype as the wells were purged according to U.S Geological Survey (USGS) ground water sampling protocols. Remote access to the data record, via phone modem communications, indicated the arrival of each plume over a few days and the subsequent geochemical reactions over the following weeks. Real-time availability of the monitoring record provided the information needed to initiate manual sampling efforts in response to changes in measured ground water quality, which proved the method and characterized the screened portion of the plume in detail through time. The methods and the case study described are presented to document the process for future use.","language":"English","publisher":"Wiley","doi":"10.1111/j.1745-6592.1999.tb00243.x","issn":"10693629","usgsCitation":"Granato, G., and Smith, K., 1999, Robowell: An automated process for monitoring ground water quality using established sampling protocols: Ground Water Monitoring and Remediation, v. 19, no. 4, p. 81-89, https://doi.org/10.1111/j.1745-6592.1999.tb00243.x.","productDescription":"9 p.","startPage":"81","endPage":"89","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":230020,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"19","issue":"4","noUsgsAuthors":false,"publicationDate":"2007-02-22","publicationStatus":"PW","scienceBaseUri":"505aaddbe4b0c8380cd86faa","contributors":{"authors":[{"text":"Granato, G.E.","contributorId":61457,"corporation":false,"usgs":true,"family":"Granato","given":"G.E.","affiliations":[],"preferred":false,"id":389106,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Smith, K.P.","contributorId":54231,"corporation":false,"usgs":true,"family":"Smith","given":"K.P.","email":"","affiliations":[],"preferred":false,"id":389105,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70021217,"text":"70021217 - 1999 - Selenium isotope ratios as indicators of selenium sources and oxyanion reduction","interactions":[],"lastModifiedDate":"2018-12-21T06:37:55","indexId":"70021217","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1759,"text":"Geochimica et Cosmochimica Acta","active":true,"publicationSubtype":{"id":10}},"title":"Selenium isotope ratios as indicators of selenium sources and oxyanion reduction","docAbstract":"Selenium stable isotope ratio measurements should serve as indicators of sources and biogeochemical transformations of Se. We report measurements of Se isotope fractionation during selenate reduction, selenite sorption, oxidation of reduced Se in soils, and Se volatilization by algae and soil samples. These results, combined with previous work with Se isotopes, indicate that reduction of soluble oxyanions is the dominant cause of Se isotope fractionation. Accordingly, Se isotope ratios should be useful as indicators of oxyanion reduction, which can transform mobile species to forms that are less mobile and less bioavailable. Additional investigations of Se isotope fractionation are needed to confirm this preliminary assessment.
We have developed a new method for measurement of natural Se isotope ratio variation which requires less than 500 ng Se per analysis and yields ±0.2‰ precision on 80Se/76Se. A double isotope spike technique corrects for isotopic fractionation during sample preparation and mass spectrometry. The small minimum sample size is important, as Se concentrations are often below 1 ppm in solids and 1 μg/L in fluids. The Se purification process is rapid and compatible with various sample matrices, including acidic rock or sediment digests.
","language":"English","publisher":"Elsevier","doi":"10.1016/S0016-7037(99)00279-3","issn":"00167037","usgsCitation":"Johnson, T., Herbel, M., Bullen, T., and Zawislanski, P., 1999, Selenium isotope ratios as indicators of selenium sources and oxyanion reduction: Geochimica et Cosmochimica Acta, v. 63, no. 18, p. 2775-2783, https://doi.org/10.1016/S0016-7037(99)00279-3.","productDescription":"9 p.","startPage":"2775","endPage":"2783","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":229983,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":206488,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/S0016-7037(99)00279-3"}],"volume":"63","issue":"18","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b8cf9e4b08c986b3181f1","contributors":{"authors":[{"text":"Johnson, T.M.","contributorId":22332,"corporation":false,"usgs":true,"family":"Johnson","given":"T.M.","affiliations":[],"preferred":false,"id":389101,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Herbel, M.J.","contributorId":57232,"corporation":false,"usgs":true,"family":"Herbel","given":"M.J.","email":"","affiliations":[],"preferred":false,"id":389102,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Bullen, T.D.","contributorId":79911,"corporation":false,"usgs":true,"family":"Bullen","given":"T.D.","email":"","affiliations":[],"preferred":false,"id":389103,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Zawislanski, P.T.","contributorId":86134,"corporation":false,"usgs":true,"family":"Zawislanski","given":"P.T.","email":"","affiliations":[],"preferred":false,"id":389104,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70021199,"text":"70021199 - 1999 - Agrichemicals in ground water of the midwestern USA: Relations to soil characteristics","interactions":[],"lastModifiedDate":"2018-12-19T10:15:03","indexId":"70021199","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","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":"Agrichemicals in ground water of the midwestern USA: Relations to soil characteristics","docAbstract":"A comprehensive set of soil characteristics were examined to determine the effect of soil on the transport of agrichemicals to ground water. This paper examines the relation of local soil characteristics to concentrations and occurrence of nitrate, atrazine (2-chloro-4 ethylamino-6-isopropylamino-s-trazine), and atrazine residue [atrazine + deethylatrazine (2-amino-4-chloro-6-isopropylamino-s-triazine) + deisopropylatrazine (2-amino-4-chloro-6-ethylamino-s-triazine)] from 99 wells completed in unconsolidated aquifers across the midwestern USA. The occurrence and concentrations of nitrate and atrazine in ground water were directly related to soil characteristics that determine the rate of water movement. The substantial differences in the relations found among soil characteristics and nitrate and atrazine in ground water suggest that different processes affect the transformation, adsorption, and transport of these contaminants. A multivariate analysis determined that the soil characteristics examined explained the amount of variability in concentrations for nitrate (19.0%), atrazine (33.4%), and atrazine residue (28.6%). These results document that, although soils do affect the transport of agrichemicals to ground water, other factors such as hydrology, land use, and climate must also be considered to understand the occurrence of agrichemicals in ground water.
","language":"English","publisher":"ACSESS","doi":"10.2134/jeq1999.00472425002800060030x","issn":"00472425","usgsCitation":"Burkart, M.R., Kolpin, D., Jaquis, R., and Cole, K., 1999, Agrichemicals in ground water of the midwestern USA: Relations to soil characteristics: Journal of Environmental Quality, v. 28, no. 6, p. 1908-1915, https://doi.org/10.2134/jeq1999.00472425002800060030x.","productDescription":"8 p.","startPage":"1908","endPage":"1915","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":351,"text":"Iowa Water Science Center","active":true,"usgs":true},{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":229702,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","volume":"28","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e90ee4b0c8380cd48082","contributors":{"authors":[{"text":"Burkart, M. R.","contributorId":42190,"corporation":false,"usgs":true,"family":"Burkart","given":"M.","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":389038,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kolpin, D.W.","contributorId":87565,"corporation":false,"usgs":true,"family":"Kolpin","given":"D.W.","email":"","affiliations":[],"preferred":false,"id":389040,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Jaquis, R.J.","contributorId":26835,"corporation":false,"usgs":true,"family":"Jaquis","given":"R.J.","email":"","affiliations":[],"preferred":false,"id":389037,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Cole, K.J.","contributorId":65245,"corporation":false,"usgs":true,"family":"Cole","given":"K.J.","email":"","affiliations":[],"preferred":false,"id":389039,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70020971,"text":"70020971 - 1999 - Slip-rate increase at Parkfield in 1993 detected by high-precision EDM and borehole tensor strainmeters","interactions":[],"lastModifiedDate":"2012-03-12T17:19:48","indexId":"70020971","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","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":"Slip-rate increase at Parkfield in 1993 detected by high-precision EDM and borehole tensor strainmeters","docAbstract":"On two of the instrument networks at Parkfield, California, the two-color Electronic Distance Meter (EDM) network and Borehole Tensor Strainmeter (BTSM) network, we have detected a rate change starting in 1993 that has persisted at least 5 years. These and other instruments capable of measuring crustal deformation were installed at Parkfield in anticipation of a moderate, M6, earthquake on the San Andreas fault. Many of these instruments have been in operation since the mid 1980s and have established an excellent baseline to judge changes in rate of deformation and the coherence of such changes between instruments. The onset of the observed rate change corresponds in time to two other changes at Parkfield. From late 1992 through late 1994, the Parkfield region had an increase in number of M4 to M5 earthquakes relative to the preceding 6 years. The deformation-rate change also coincides with the end of a 7-year period of sub-normal rainfall. Both the spatial coherence of the rate change and hydrological modeling suggest a tectonic explanation for the rate change. From these observations, we infer that the rate of slip increased over the period 1993-1998.On two of the instrument networks at Parkfield, California, the two-color Electronic Distance Meter (EDM) network and Borehole Tensor Strainmeter (BTSM) network, we have detected a rate change starting in 1993 that has persisted at least 5 years. These and other instruments capable of measuring crustal deformation were installed at Parkfield in anticipation of a moderate, M6, earthquake on the San Andreas fault. Many of these instruments have been in operation since the mid 1980s and have established an excellent baseline to judge changes in rate of deformation and the coherence of such changes between instruments. The onset of the observed rate change corresponds in time to two other changes at Parkfield. From late 1992 through late 1994, the Parkfield region had an increase in number of M4 to M5 earthquakes relative to the preceding 6 years. The deformation-rate change also coincides with the end of a 7-year period of sub-normal rainfall. Both the spatial coherence of the rate change and hydrological modeling suggest a tectonic explanation for the rate change. From these observations, we infer that the rate of slip increased over the period 1993-1998.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Geophysical Research Letters","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"American Geophysical Union","publisherLocation":"Washington, DC, United States","issn":"00948276","usgsCitation":"Langbein, J., Gwyther, R.L., Hart, R., and Gladwin, M.T., 1999, Slip-rate increase at Parkfield in 1993 detected by high-precision EDM and borehole tensor strainmeters: Geophysical Research Letters, v. 26, no. 16, p. 2529-2532.","startPage":"2529","endPage":"2532","numberOfPages":"4","costCenters":[],"links":[{"id":229845,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"26","issue":"16","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b9158e4b08c986b31985c","contributors":{"authors":[{"text":"Langbein, J.","contributorId":16990,"corporation":false,"usgs":true,"family":"Langbein","given":"J.","affiliations":[],"preferred":false,"id":388155,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gwyther, R. L.","contributorId":67683,"corporation":false,"usgs":false,"family":"Gwyther","given":"R.","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":388158,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hart, R.H.G.","contributorId":42743,"corporation":false,"usgs":true,"family":"Hart","given":"R.H.G.","email":"","affiliations":[],"preferred":false,"id":388157,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Gladwin, M. T.","contributorId":30373,"corporation":false,"usgs":true,"family":"Gladwin","given":"M.","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":388156,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70021932,"text":"70021932 - 1999 - A record of hydrocarbon input to San Francisco Bay as traced by biomarker profiles in surface sediment and sediment cores","interactions":[],"lastModifiedDate":"2020-01-04T14:46:58","indexId":"70021932","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2662,"text":"Marine Chemistry","active":true,"publicationSubtype":{"id":10}},"title":"A record of hydrocarbon input to San Francisco Bay as traced by biomarker profiles in surface sediment and sediment cores","docAbstract":"San Francisco Bay is one of the world's largest urbanized estuarine systems. Its water and sediment receive organic input from a wide variety of sources; much of this organic material is anthropogenically derived. To document the spatial and historical record of the organic contaminant input, surficial sediment from 17 sites throughout San Francisco Bay and sediment cores from two locations Richardson Bay and San Pablo Bay were analyzed for biomarker constituents. Biomarkers, that is, 'molecular fossils', primarily hopanes, steranes, and n-alkanes, provide information on anthropogenic contamination, especially that related to petrogenic sources, as well as on recent input of biogenic material. The biomarker parameters from the surficial sediment and the upper horizons of the cores show a dominance of anthropogenic input, whereas the biomarker profiles at the lower horizons of the cores indicate primarily biogenic input. In the Richardson Bay core the gradual upcore transition from lower maturity background organics to a dominance of anthropogenic contamination occurred about 70-100 years ago and corresponds to the industrial development of the San Francisco Bay area. In San Pablo Bay, the transition was very abrupt, reflecting the complex depositional history of the area. This sharp transition, perhaps indicating a depositional hiatus or erosional period, dated at pre-1952, is clearly visible. Below, the hiatus the biomarker parameters are immature; above, they are mature and show an anthropogenic overlay. Higher concentrations of terrigenous n-alkanes in the upper horizons in this core are indicative of an increase in terrigenous organic matter input in San Pablo Bay, possibly a result of water diversion projects and changes in the fresh water flow into the Bay from the Delta. Alternatively, it could reflect a dilution of organic material in the lower core sections with hydraulic mining debris.
","language":"English","publisher":"Elsevier","doi":"10.1016/S0304-4203(98)00088-7","issn":"03044203","usgsCitation":"Hostettler, F., Pereira, W.E., Kvenvolden, K., VanGeen, A., Luoma, S., Fuller, C.C., and Anima, R., 1999, A record of hydrocarbon input to San Francisco Bay as traced by biomarker profiles in surface sediment and sediment cores: Marine Chemistry, v. 64, no. 1-2, p. 115-127, https://doi.org/10.1016/S0304-4203(98)00088-7.","productDescription":"13 p.","startPage":"115","endPage":"127","numberOfPages":"13","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":552,"text":"San Francisco Bay-Delta","active":false,"usgs":true},{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true},{"id":5079,"text":"Pacific Regional Director's Office","active":true,"usgs":true}],"links":[{"id":229421,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","otherGeospatial":"San Francisco Bay","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -123.81591796875,\n 36.56260003738545\n ],\n [\n -120.234375,\n 36.56260003738545\n ],\n [\n -120.234375,\n 39.40224434029275\n ],\n [\n -123.81591796875,\n 39.40224434029275\n ],\n [\n -123.81591796875,\n 36.56260003738545\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"64","issue":"1-2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e53ce4b0c8380cd46c12","contributors":{"authors":[{"text":"Hostettler, F. D.","contributorId":99563,"corporation":false,"usgs":true,"family":"Hostettler","given":"F. D.","affiliations":[],"preferred":false,"id":391760,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Pereira, W. E.","contributorId":46981,"corporation":false,"usgs":true,"family":"Pereira","given":"W.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":391755,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kvenvolden, K.A.","contributorId":80674,"corporation":false,"usgs":true,"family":"Kvenvolden","given":"K.A.","email":"","affiliations":[],"preferred":false,"id":391757,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"VanGeen, A.","contributorId":84086,"corporation":false,"usgs":true,"family":"VanGeen","given":"A.","email":"","affiliations":[],"preferred":false,"id":391758,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Luoma, S. N.","contributorId":86353,"corporation":false,"usgs":true,"family":"Luoma","given":"S. N.","affiliations":[],"preferred":false,"id":391759,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Fuller, C. C.","contributorId":29858,"corporation":false,"usgs":true,"family":"Fuller","given":"C.","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":391754,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Anima, R.","contributorId":77304,"corporation":false,"usgs":true,"family":"Anima","given":"R.","affiliations":[],"preferred":false,"id":391756,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70021574,"text":"70021574 - 1999 - Processes governing phytoplankton blooms in estuaries. I: The local production-loss balance","interactions":[],"lastModifiedDate":"2018-12-19T09:11:44","indexId":"70021574","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2663,"text":"Marine Ecology Progress Series","active":true,"publicationSubtype":{"id":10}},"title":"Processes governing phytoplankton blooms in estuaries. I: The local production-loss balance","docAbstract":"The formation and spatial distribution of phytoplankton blooms in estuaries are controlled by (1) local mechanisms, which determine the production-loss balance for a water column at a particular spatial location (i.e. control if a bloom is possible), and (2) transport-related mechanisms, which govern biomass distribution (i.e. control if and where a bloom actually occurs). In this study, the first of a 2-paper series, we use a depth-averaged numerical model as a theoretical tool to describe how interacting local conditions (water column height, light availability, benthic grazing) influence the local balance between phytoplankton sources and sinks. We also explore trends in the spatial variability of the production-loss balance across the topographic gradients between deep channels and lateral shoals which are characteristic of shallow estuaries. For example, under conditions of high turbidity and slow benthic grazing the highest rates of phytoplankton population growth are found in the shallowest regions. On the other hand, with low turbidity and rapid benthic grazing the highest growth rates occur in the deeper areas. We also explore the effects of semidiurnal tidal variation in water column height, as well as spring-neap variability. Local population growth in the shallowest regions is very sensitive to tidal-scale shallowing and deepening of the water column, especially in the presence of benthic grazing. A spring-neap signal in population growth rate is also prominent in the shallow areas. Population growth in deeper regions is less sensitive to temporal variations in tidal elevation. These results show that both shallow and deep regions of estuaries can act as sources or sinks for phytoplankton biomass, depending on the local conditions of mean water column height, tidal amplitude, light-limited growth rate, and consumption by grazers.
","language":"English","publisher":"Inter-Research","doi":"10.3354/meps187001","issn":"01718630","usgsCitation":"Lucas, L., Koseff, J.R., Cloern, J., Monismith, S., and Thompson, J., 1999, Processes governing phytoplankton blooms in estuaries. I: The local production-loss balance: Marine Ecology Progress Series, v. 187, p. 1-15, https://doi.org/10.3354/meps187001.","productDescription":"15 p.","startPage":"1","endPage":"15","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true},{"id":552,"text":"San Francisco Bay-Delta","active":false,"usgs":true},{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true},{"id":5079,"text":"Pacific Regional Director's Office","active":true,"usgs":true}],"links":[{"id":487397,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.3354/meps187001","text":"Publisher Index Page"},{"id":266010,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.3354/meps187001"},{"id":229286,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"187","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a8db1e4b0c8380cd7ed90","contributors":{"authors":[{"text":"Lucas, L.V.","contributorId":62777,"corporation":false,"usgs":true,"family":"Lucas","given":"L.V.","email":"","affiliations":[],"preferred":false,"id":390343,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Koseff, Jeffrey R.","contributorId":37915,"corporation":false,"usgs":false,"family":"Koseff","given":"Jeffrey","email":"","middleInitial":"R.","affiliations":[{"id":6986,"text":"Stanford University","active":true,"usgs":false}],"preferred":false,"id":390340,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Cloern, J. E.","contributorId":59453,"corporation":false,"usgs":true,"family":"Cloern","given":"J. E.","affiliations":[],"preferred":false,"id":390342,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Monismith, Stephen G.","contributorId":57228,"corporation":false,"usgs":true,"family":"Monismith","given":"Stephen G.","affiliations":[],"preferred":false,"id":390341,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Thompson, J.K.","contributorId":103300,"corporation":false,"usgs":true,"family":"Thompson","given":"J.K.","email":"","affiliations":[],"preferred":false,"id":390344,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70021566,"text":"70021566 - 1999 - Modeling impact of storage zones on stream dissolved oxygen","interactions":[],"lastModifiedDate":"2018-12-19T10:54:45","indexId":"70021566","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2255,"text":"Journal of Environmental Engineering","active":true,"publicationSubtype":{"id":10}},"title":"Modeling impact of storage zones on stream dissolved oxygen","docAbstract":"The Streeter-Phelps dissolved oxygen model is modified to incorporate storage zones. A dimensionless number reflecting enhanced decomposition caused by the increased residence time of the biochemical oxygen demand in the storage zone parameterizes the impact. This result provides a partial explanation for the high decomposition rates observed in shallow streams. An application suggests that the storage zone increases the critical oxygen deficit and moves it closer to the point source. It also indicates that the storage zone should have lower oxygen concentration than the main channel. An analysis of a dimensionless enhancement factor indicates that the biochemical oxygen demand decomposition in small streams could be up to two to three times more than anticipated based on the standard Streeter-Phelps model without storage zones. For larger rivers, enhancements of up to 1.5 could occur.The Streeter-Phelps dissolved oxygen model is modified to incorporate storage zones. A dimensionless number reflecting enhanced decomposition caused by the increased residence time of the biochemical oxygen demand in the storage zone parameterizes the impact. This result provides a partial explanation for the high decomposition rates observed in shallow streams. An application suggests that the storage zone increases the critical oxygen deficit and moves it closer to the point source. It also indicates that the storage zone should have lower oxygen concentration than the main channel. An analysis of a dimensionless enhancement factor indicates that the biochemical oxygen demand decomposition in small streams could be up to two to three times more than anticipated based on the standard Streeter-Phelps model without storage zones. For larger rivers, enhancements of up to 1.5 could occur.","language":"English","publisher":"ASCE","doi":"10.1061/(ASCE)0733-9372(1999)125:5(415)","issn":"07339372","usgsCitation":"Chapra, S., and Runkel, R., 1999, Modeling impact of storage zones on stream dissolved oxygen: Journal of Environmental Engineering, v. 125, no. 5, p. 415-419, https://doi.org/10.1061/(ASCE)0733-9372(1999)125:5(415).","productDescription":"5 p.","startPage":"415","endPage":"419","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":229174,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":206231,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1061/(ASCE)0733-9372(1999)125:5(415)"}],"volume":"125","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a5c05e4b0c8380cd6f98d","contributors":{"authors":[{"text":"Chapra, S.C.","contributorId":11343,"corporation":false,"usgs":true,"family":"Chapra","given":"S.C.","affiliations":[],"preferred":false,"id":390321,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Runkel, R.L.","contributorId":97529,"corporation":false,"usgs":true,"family":"Runkel","given":"R.L.","affiliations":[],"preferred":false,"id":390322,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70020974,"text":"70020974 - 1999 - Butterfly (Papilionoidea and Hesperioidea) assemblages associated with natural, exotic, and restored riparian habitats along the lower Colorado River, USA","interactions":[],"lastModifiedDate":"2018-02-23T14:38:51","indexId":"70020974","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3246,"text":"Regulated Rivers: Research & Management","printIssn":"0886-9375","active":false,"publicationSubtype":{"id":10}},"title":"Butterfly (Papilionoidea and Hesperioidea) assemblages associated with natural, exotic, and restored riparian habitats along the lower Colorado River, USA","docAbstract":"Butterfly assemblages were used to compare revegetated and natural riparian areas along the lower Colorado River. Species richness and correspondence analyses of assemblages showed that revegetated sites had fewer biological elements than more natural sites along the Bill Williams River. Data suggest that revegetated sites do not provide resources needed by some members of the butterfly assemblage, especially those species historically associated with the cottonwood/willow ecosystem. Revegetated sites generally lacked nectar resources, larval host plants, and closed canopies. The riparian system along the regulated river segment that contains these small revegetated sites also appears to have diminished habitat heterogeneity and uncoupled riparian corridors.
Revegetated sites were static environments without the successional stages caused by flooding disturbance found in more natural systems. We hypothesize that revegetation coupled with a more natural hydrology is important for restoration of butterfly assemblages along the lower Colorado River.
","language":"English","publisher":"Wiley","doi":"10.1002/(SICI)1099-1646(199911/12)15:6<485::AID-RRR550>3.0.CO;2-Z","usgsCitation":"Nelson, S.M., and Andersen, D., 1999, Butterfly (Papilionoidea and Hesperioidea) assemblages associated with natural, exotic, and restored riparian habitats along the lower Colorado River, USA: Regulated Rivers: Research & Management, v. 15, no. 6, p. 485-504, https://doi.org/10.1002/(SICI)1099-1646(199911/12)15:6<485::AID-RRR550>3.0.CO;2-Z.","productDescription":"20 p.","startPage":"485","endPage":"504","costCenters":[],"links":[{"id":229925,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","otherGeospatial":"Bill Williams River, Colorado River","volume":"15","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f2bce4b0c8380cd4b322","contributors":{"authors":[{"text":"Nelson, S. M.","contributorId":81853,"corporation":false,"usgs":false,"family":"Nelson","given":"S.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":388164,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Andersen, D.C.","contributorId":19119,"corporation":false,"usgs":true,"family":"Andersen","given":"D.C.","email":"","affiliations":[],"preferred":false,"id":388163,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70021565,"text":"70021565 - 1999 - Indexing the relative abundance of age-0 white sturgeons in an impoundment of the lower Columbia River from highly skewed trawling data","interactions":[],"lastModifiedDate":"2016-01-22T08:10:35","indexId":"70021565","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2886,"text":"North American Journal of Fisheries Management","active":true,"publicationSubtype":{"id":10}},"title":"Indexing the relative abundance of age-0 white sturgeons in an impoundment of the lower Columbia River from highly skewed trawling data","docAbstract":"The development of recruitment monitoring programs for age-0 white sturgeons Acipenser transmontanus is complicated by the statistical properties of catch-per-unit-effort (CPUE) data. We found that age-0 CPUE distributions from bottom trawl surveys violated assumptions of statistical procedures based on normal probability theory. Further, no single data transformation uniformly satisfied these assumptions because CPUE distribution properties varied with the sample mean (??(CPUE)). Given these analytic problems, we propose that an additional index of age-0 white sturgeon relative abundance, the proportion of positive tows (Ep), be used to estimate sample sizes before conducting age-0 recruitment surveys and to evaluate statistical hypothesis tests comparing the relative abundance of age-0 white sturgeons among years. Monte Carlo simulations indicated that Ep was consistently more precise than ??(CPUE), and because Ep is binomially rather than normally distributed, surveys can be planned and analyzed without violating the assumptions of procedures based on normal probability theory. However, we show that Ep may underestimate changes in relative abundance at high levels and confound our ability to quantify responses to management actions if relative abundance is consistently high. If data suggest that most samples will contain age-0 white sturgeons, estimators of relative abundance other than Ep should be considered. Because Ep may also obscure correlations to climatic and hydrologic variables if high abundance levels are present in time series data, we recommend ??(CPUE) be used to describe relations to environmental variables. The use of both Ep and ??(CPUE) will facilitate the evaluation of hypothesis tests comparing relative abundance levels and correlations to variables affecting age-0 recruitment. Estimated sample sizes for surveys should therefore be based on detecting predetermined differences in Ep, but data necessary to calculate ??(CPUE) should also be collected.","language":"English","publisher":"American Fisheries Society","doi":"10.1577/1548-8675(1999)019<0520:ITRAOA>2.0.CO;2","issn":"02755947","usgsCitation":"Counihan, T., Miller, A.I., and Parsley, M., 1999, Indexing the relative abundance of age-0 white sturgeons in an impoundment of the lower Columbia River from highly skewed trawling data: North American Journal of Fisheries Management, v. 19, no. 2, p. 520-529, https://doi.org/10.1577/1548-8675(1999)019<0520:ITRAOA>2.0.CO;2.","productDescription":"10 p.","startPage":"520","endPage":"529","numberOfPages":"10","costCenters":[{"id":654,"text":"Western Fisheries Research Center","active":true,"usgs":true}],"links":[{"id":229140,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","otherGeospatial":"Columbia River","volume":"19","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3a82e4b0c8380cd61d2f","contributors":{"authors":[{"text":"Counihan, T.D.","contributorId":9789,"corporation":false,"usgs":true,"family":"Counihan","given":"T.D.","email":"","affiliations":[],"preferred":false,"id":390318,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Miller, Allen I.","contributorId":31544,"corporation":false,"usgs":true,"family":"Miller","given":"Allen","email":"","middleInitial":"I.","affiliations":[],"preferred":false,"id":390319,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Parsley, M.J.","contributorId":59542,"corporation":false,"usgs":true,"family":"Parsley","given":"M.J.","email":"","affiliations":[],"preferred":false,"id":390320,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70021556,"text":"70021556 - 1999 - Hydraulic and geochemical performance of a permeable reactive barrier containing zero-valent iron, Denver Federal Center","interactions":[],"lastModifiedDate":"2021-05-28T16:57:02.113331","indexId":"70021556","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","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":"Hydraulic and geochemical performance of a permeable reactive barrier containing zero-valent iron, Denver Federal Center","docAbstract":"The hydraulic and geochemical performance of a 366 m long permeable reactive barrier (PRB) at the Denver Federal Center, Denver, Colorado, was evaluated. The funnel and gate system, which was installed in 1996 to intercept and remediate ground water contaminated with chlorinated aliphatic hydrocarbons (CAHs), contained four 12.2 m wide gates filled with zero‐valent iron. Ground water mounding on the upgradient side of the PRB resulted in a tenfold increase in the hydraulic gradient and ground water velocity through the gates compared to areas of the aquifer unaffected by the PRB. Water balance calculations for April 1997 indicate that about 75 % of the ground water moving toward the PRB from upgradient areas moved through the gates. The rest of the water either accumulated on the upgradient side of the PRB or bypassed the PRB. Chemical data from monitoring wells screened down‐gradient, beneath, and at the ends of the PRB indicate that contaminants had not bypassed the PRB, except in a few isolated areas. Greater than 99 % of the CAH mass entering the gates was retained by the iron. Fifty‐one percent of the CAH carbon entering one gate was accounted for in dissolved C1 and C2 hydrocarbons, primarily ethane and ethene, which indicates that CAHs may adsorb to the iron prior to being dehalogenated. Treated water exiting the gates displaced contaminated ground water at a distance of at least 3 m downgradient from the PRB by the end of 1997. Measurements of dissolved inorganic ions in one gate indicate that calcite and siderite precipitation in the gate could reduce gate porosity by about 0.35 % per year. Results from this study indicate that funnel and gate systems containing zero‐valent iron can effectively treat ground water contaminated with CAHs. However, the hydrologic impacts of the PRB on the flow system need to be fully understood to prevent contaminants from bypassing the PRB.
","language":"English","publisher":"National Ground Water Association","doi":"10.1111/j.1745-6584.1999.tb01117.x","usgsCitation":"McMahon, P., Dennehy, K., and Sandstrom, M.W., 1999, Hydraulic and geochemical performance of a permeable reactive barrier containing zero-valent iron, Denver Federal Center: Ground Water, v. 37, no. 3, p. 396-404, https://doi.org/10.1111/j.1745-6584.1999.tb01117.x.","productDescription":"9 p.","startPage":"396","endPage":"404","numberOfPages":"9","costCenters":[{"id":452,"text":"National Water Quality Laboratory","active":true,"usgs":true}],"links":[{"id":229583,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Colorado","city":"Denver","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -105.12976169586182,\n 39.71190772724697\n ],\n [\n -105.11053562164307,\n 39.71190772724697\n ],\n [\n -105.11053562164307,\n 39.72511180282315\n ],\n [\n -105.12976169586182,\n 39.72511180282315\n ],\n [\n -105.12976169586182,\n 39.71190772724697\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"37","issue":"3","noUsgsAuthors":false,"publicationDate":"2005-08-04","publicationStatus":"PW","scienceBaseUri":"505a32d6e4b0c8380cd5eb01","contributors":{"authors":[{"text":"McMahon, P.B. 0000-0001-7452-2379","orcid":"https://orcid.org/0000-0001-7452-2379","contributorId":10762,"corporation":false,"usgs":true,"family":"McMahon","given":"P.B.","affiliations":[],"preferred":false,"id":390285,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Dennehy, K.F.","contributorId":41841,"corporation":false,"usgs":true,"family":"Dennehy","given":"K.F.","affiliations":[],"preferred":false,"id":390287,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Sandstrom, Mark W. 0000-0003-0006-5675 sandstro@usgs.gov","orcid":"https://orcid.org/0000-0003-0006-5675","contributorId":706,"corporation":false,"usgs":true,"family":"Sandstrom","given":"Mark","email":"sandstro@usgs.gov","middleInitial":"W.","affiliations":[{"id":37464,"text":"WMA - Laboratory & Analytical Services Division","active":true,"usgs":true},{"id":5046,"text":"Branch of Analytical Serv (NWQL)","active":true,"usgs":true},{"id":503,"text":"Office of Water Quality","active":true,"usgs":true},{"id":452,"text":"National Water Quality Laboratory","active":true,"usgs":true}],"preferred":true,"id":390286,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70021540,"text":"70021540 - 1999 - Dissolved sulfide distributions in the water column and sediment pore waters of the Santa Barbara Basin","interactions":[],"lastModifiedDate":"2018-12-19T08:56:58","indexId":"70021540","displayToPublicDate":"1999-01-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1759,"text":"Geochimica et Cosmochimica Acta","active":true,"publicationSubtype":{"id":10}},"title":"Dissolved sulfide distributions in the water column and sediment pore waters of the Santa Barbara Basin","docAbstract":"Dissolved sulfide concentrations in the water column and in sediment pore waters were measured by square-wave voltammetry (nanomolar detection limit) during three cruises to the Santa Barbara Basin in February 1995, November–December 1995, and April 1997. In the water column, sulfide concentrations measured outside the basin averaged 3 ± 1 nM (n= 28) in the 0 to 600 m depth range. Inside the basin, dissolved sulfides increased to reach values of up to 15 nM at depths >400 m. A suite of box cores and multicores collected at four sites along the northeastern flank of the basin showed considerable range in surficial (<0.5 cm) pore-water sulfide concentrations: <0.008, 0.01, 0.02, to as much as 0.4 μM at the 340, 430, 550, and 590 m sites, respectively. At a core depth of 10 cm, however, pore–water sulfides exhibited an even wider range: 0.005, 0.05, 0.1, and 100 μM at the same sites, respectively. The sulfide flux into the deep basin, estimated from water-column profiles during three cruises, suggests a fairly consistent input of 100–300 nmole m−2 h−1. In contrast, sulfide fluxes estimated from pore-water sulfide gradients at the sediment water interface were much more variable (−4 to 13,000 nmole m−2 h−1). Dissolved silicate profiles show clear indications of irrigation at shallow sites (340 and 430 m) in comparison to deeper basin sites (550 and 590 m) with low (<10 μM) bottom-water dissolved-oxygen concentrations. Pore-water profiles indicate ammonia generation at all sites, but particularly at the deep-basin 590 m site with concentrations increasing with sediment depth to >400 μM at 10 cm. Decreases in water-column nitrate below the sill depth indicate nitrate consumption (−55 to −137 μmole m−2 h−1) similar to nearby Santa Monica Basin. Peaks in pore-water iron concentrations were generally observed between 2 and 5 cm depth with shallowest peaks at the 590 m site. These observations, including observations of the benthic microfauna, suggest that the extent to which the sulfide flux, sustained by elevated pore-water concentrations, reaches the water column may be modulated by the abundance of sulfide-oxidizing bacteria in addition to iron redox and precipitation reactions.
Sediments sampled at a hydrocarbon-contaminated, glacial-outwash, sandy aquifer near Bemidji, Minnesota, were analyzed for sediment-associated Fe with several techniques. Extraction with 0.5 M HCl dissolved poorly crystalline Fe oxides and small amounts of Fe in crystalline Fe oxides, and extracted Fe from phyllosilicates. Use of Ti-citrate-EDTA-bicarbonate results in more complete removal of crystalline Fe oxides. The average HCl-extractable Fe(III) concentration in the sediments closest to the crude-oil contamination (16.2 μmol/g) has been reduced by up to 30% from background values (23.8 μmol/g) as a result of Fe(III) reduction in contaminated anoxic groundwater. Iron(II) concentrations are elevated in sediments within an anoxic plume in the aquifer. Iron(II) values under the oil body (19.2 μmol/g) are as much as 4 times those in the background sediments (4.6 μmol/g), indicating incorporation of reduced Fe in the contaminated sediments. A 70% increase in total extractable Fe at the anoxic/oxic transition zone indicates reoxidation and precipitation of Fe mobilized from sediment in the anoxic plume. Scanning electron microscopy detected authigenic ferroan calcite in the anoxic sediments and confirmed abundant Fe(III) oxyhydroxides at the anoxic/oxic boundary. The redox biogeochemistry of Fe in this system is coupled to contaminant degradation and is important in predicting processes of hydrocarbon degradation.
Snowmelt is the principal source for soil moisture, ground-water re-charge, and stream-flow in mountainous regions of the western US, Canada, and other similar regions of the world. Information on the timing, magnitude, and contributing area of melt under variable or changing climate conditions is required for successful water and resource management. A coupled energy and mass-balance model ISNOBAL is used to simulate the development and melting of the seasonal snowcover in several mountain basins in California, Idaho, and Utah. Simulations are done over basins varying from 1 to 2500 km2, with simulation periods varying from a few days for the smallest basin, Emerald Lake watershed in California, to multiple snow seasons for the Park City area in Utah. The model is driven by topographically corrected estimates of radiation, temperature, humidity, wind, and precipitation. Simulation results in all basins closely match independently measured snow water equivalent, snow depth, or runoff during both the development and depletion of the snowcover. Spatially distributed estimates of snow deposition and melt allow us to better understand the interaction between topographic structure, climate, and moisture availability in mountain basins of the western US. Application of topographically distributed models such as this will lead to improved water resource and watershed management. Copyright © 1999 John Wiley & Sons, Ltd.