Anthropogenic features such as urbanization, roads, and power lines, are increasing in western United States landscapes in response to rapidly growing human populations. However, their spatial effects have not been evaluated. Our goal was to model the human footprint across the western United States. We first delineated the actual area occupied by anthropogenic features, the physical effect area. Next, we developed the human footprint model based on the ecological effect area, the zone influenced by features beyond their physical presence, by combining seven input models: three models quantified top-down anthropogenic influences of synanthropic predators (avian predators, domestic dog and cat presence risk), and four models quantified bottom-up anthropogenic influences on habitat (invasion of exotic plants, human-caused fires, energy extraction, and anthropogenic wildland fragmentation). Using independent bird population data, we found bird abundance of four synanthropic species to correlate positively with human footprint intensity and negatively for three of the six species influenced by habitat fragmentation. We then evaluated the extent of the human footprint in relation to terrestrial (ecoregions) and aquatic systems (major rivers and lakes), regional management and conservation status, physical environment, and temporal changes in human actions. The physical effect area of anthropogenic features covered 13% of the western United States with agricultural land (9.8%) being most dominant. High-intensity human footprint areas (class 8–10) overlapped highly productive low-elevation private landholdings and covered 7% of the western United States compared to 48% for low-intensity areas (class 1–3), which were confined to low-productivity high-elevation federal landholdings. Areas within 1 km of rivers were more affected by the human footprint compared to lakes. Percentage human population growth was higher in low-intensity human footprint areas. The disproportional regional effects of the human footprint on landscapes in the western United States create a challenge to management of ecosystems and wildlife populations. Using footprint models, managers can plan land use actions, develop restoration scenarios, and identify areas of high conservation value at local landscapes within a regional context. Moreover, human footprint models serve as a tool to stratify landscapes for studies investigating floral and faunal response to human disturbance intensity gradients.
","language":"English","publisher":"ESA","doi":"10.1890/07-0480.1","usgsCitation":"Leu, M., Hanser, S., and Knick, S., 2008, The human footprint in the west: a large-scale analysis of anthropogenic impacts.: Ecological Applications, v. 18, no. 5, p. 1119-1139, https://doi.org/10.1890/07-0480.1.","productDescription":"21 p.","startPage":"1119","endPage":"1139","costCenters":[{"id":290,"text":"Forest and Rangeland Ecosystem Science Center","active":false,"usgs":true}],"links":[{"id":438856,"rank":1,"type":{"id":30,"text":"Data Release"},"url":"https://doi.org/10.5066/P9BMGEMJ","text":"USGS data release","linkHelpText":"Agricultural Land in the Western United States"},{"id":242118,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"18","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bacc1e4b08c986b323700","contributors":{"authors":[{"text":"Leu, M.","contributorId":90942,"corporation":false,"usgs":true,"family":"Leu","given":"M.","email":"","affiliations":[],"preferred":false,"id":441391,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hanser, S.E.","contributorId":13823,"corporation":false,"usgs":true,"family":"Hanser","given":"S.E.","email":"","affiliations":[],"preferred":false,"id":441389,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Knick, S.T.","contributorId":71290,"corporation":false,"usgs":true,"family":"Knick","given":"S.T.","email":"","affiliations":[],"preferred":false,"id":441390,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033551,"text":"70033551 - 2008 - Rates of zinc and trace metal release from dissolving sphalerite at pH 2.0-4.0","interactions":[],"lastModifiedDate":"2012-03-12T17:21:32","indexId":"70033551","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","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":"Rates of zinc and trace metal release from dissolving sphalerite at pH 2.0-4.0","docAbstract":"High-Fe and low-Fe sphalerite samples were reacted under controlled pH conditions to determine nonoxidative rates of release of Zn and trace metals from the solid-phase. The release (solubilization) of trace metals from dissolving sphalerite to the aqueous phase can be characterized by a kinetic distribution coefficient, (Dtr), which is defined as [(Rtr/X(tr)Sph)/(RZn/X(Zn) Sph)], where R is the trace metal or Zn release rate, and X is the mole fraction of the trace metal or Zn in sphalerite. This coefficient describes the relationship of the sphalerite dissolution rate to the trace metal mole fraction in the solid and its aqueous concentration. The distribution was used to determine some controls on metal release during the dissolution of sphalerite. Departures from the ideal Dtr of 1.0 suggest that some trace metals may be released via different pathways or that other processes (e.g., adsorption, solubility of trace minerals such as galena) affect the observed concentration of metals. Nonoxidative sphalerite dissolution (mediated by H+) is characterized by a \"fast\" stage in the first 24-30 h, followed by a \"slow\" stage for the remainder of the reaction. Over the pH range 2.0-4.0, and for similar extent of reaction (reaction time), sphalerite composition, and surface area, the rates of release of Zn, Fe, Cd, Cu, Mn and Pb from sphalerite generally increase with lower pH. Zinc and Fe exhibit the fastest rates of release, Mn and Pb have intermediate rates of release, and Cd and Cu show the slowest rates of release. The largest variations in metal release rates occur at pH 2.0. At pH 3.0 and 4.0, release rates show less variation and appear less dependent on the metal abundance in the solid. For the same extent of reaction (100 h), rates of Zn release range from 1.53 ?? 10-11 to 5.72 ?? 10-10 mol/m2/s; for Fe, the range is from 4.59 ?? 10-13 to 1.99 ?? 10-10 mol/m2/s. Trace metal release rates are generally 1-5 orders of magnitude slower than the Zn or Fe rates. Results indicate that the distributions of Fe and Cd are directly related to the rate of sphalerite dissolution throughout the reaction at pH 3.0 and 4.0 because these two elements substitute readily into sphalerite. These two metals are likely to be more amenable to usage in predictive acid dissolution models because of this behavior. The Pb distribution shows no strong relation to sphalerite dissolution and appears to be controlled by pH-dependent solubility, most likely related to trace amounts of galena. The distribution of Cu is similar to that of Fe but is the most-dependent of all metals on its mole fraction ratio (Zn:Cu) in sphalerite. The Mn distributions suggest an increase in the rate of Mn release relative to sphalerite dissolution occurs in low Mn samples as pH increases. The Mn distribution in high Mn samples is nearly independent of pH and sphalerite dissolution at pH 2.0 but shows a dependence on these two parameters at higher pH (3.0-4.0).","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Applied Geochemistry","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.apgeochem.2007.10.005","issn":"08832927","usgsCitation":"Stanton, M., Gemery-Hill, P., Shanks, W.C., and Taylor, C., 2008, Rates of zinc and trace metal release from dissolving sphalerite at pH 2.0-4.0: Applied Geochemistry, v. 23, no. 2, p. 136-147, https://doi.org/10.1016/j.apgeochem.2007.10.005.","startPage":"136","endPage":"147","numberOfPages":"12","costCenters":[],"links":[{"id":214459,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.apgeochem.2007.10.005"},{"id":242187,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"23","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a954ae4b0c8380cd81917","contributors":{"authors":[{"text":"Stanton, M.R.","contributorId":103684,"corporation":false,"usgs":true,"family":"Stanton","given":"M.R.","email":"","affiliations":[],"preferred":false,"id":441408,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gemery-Hill, P. A.","contributorId":86575,"corporation":false,"usgs":true,"family":"Gemery-Hill","given":"P. A.","affiliations":[],"preferred":false,"id":441405,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Shanks, Wayne C. III","contributorId":100527,"corporation":false,"usgs":true,"family":"Shanks","given":"Wayne","suffix":"III","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":441407,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Taylor, C. D. 0000-0001-6376-6298","orcid":"https://orcid.org/0000-0001-6376-6298","contributorId":100401,"corporation":false,"usgs":true,"family":"Taylor","given":"C. D.","affiliations":[],"preferred":false,"id":441406,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70033554,"text":"70033554 - 2008 - Sampling considerations for disease surveillance in wildlife populations","interactions":[],"lastModifiedDate":"2012-03-12T17:21:32","indexId":"70033554","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2508,"text":"Journal of Wildlife Management","active":true,"publicationSubtype":{"id":10}},"title":"Sampling considerations for disease surveillance in wildlife populations","docAbstract":"Disease surveillance in wildlife populations involves detecting the presence of a disease, characterizing its prevalence and spread, and subsequent monitoring. A probability sample of animals selected from the population and corresponding estimators of disease prevalence and detection provide estimates with quantifiable statistical properties, but this approach is rarely used. Although wildlife scientists often assume probability sampling and random disease distributions to calculate sample sizes, convenience samples (i.e., samples of readily available animals) are typically used, and disease distributions are rarely random. We demonstrate how landscape-based simulation can be used to explore properties of estimators from convenience samples in relation to probability samples. We used simulation methods to model what is known about the habitat preferences of the wildlife population, the disease distribution, and the potential biases of the convenience-sample approach. Using chronic wasting disease in free-ranging deer (Odocoileus virginianus) as a simple illustration, we show that using probability sample designs with appropriate estimators provides unbiased surveillance parameter estimates but that the selection bias and coverage errors associated with convenience samples can lead to biased and misleading results. We also suggest practical alternatives to convenience samples that mix probability and convenience sampling. For example, a sample of land areas can be selected using a probability design that oversamples areas with larger animal populations, followed by harvesting of individual animals within sampled areas using a convenience sampling method.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Wildlife Management","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.2193/2007-317","issn":"0022541X","usgsCitation":"Nusser, S., Clark, W., Otis, D.L., and Huang, L., 2008, Sampling considerations for disease surveillance in wildlife populations: Journal of Wildlife Management, v. 72, no. 1, p. 52-60, https://doi.org/10.2193/2007-317.","startPage":"52","endPage":"60","numberOfPages":"9","costCenters":[],"links":[{"id":476660,"rank":10000,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1007&context=stat_las_pubs","text":"External Repository"},{"id":214516,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2193/2007-317"},{"id":242250,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"72","issue":"1","noUsgsAuthors":false,"publicationDate":"2010-12-13","publicationStatus":"PW","scienceBaseUri":"505ab074e4b0c8380cd87b00","contributors":{"authors":[{"text":"Nusser, S.M.","contributorId":49302,"corporation":false,"usgs":true,"family":"Nusser","given":"S.M.","email":"","affiliations":[],"preferred":false,"id":441413,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Clark, W.R.","contributorId":70716,"corporation":false,"usgs":true,"family":"Clark","given":"W.R.","email":"","affiliations":[],"preferred":false,"id":441415,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Otis, David L.","contributorId":64396,"corporation":false,"usgs":true,"family":"Otis","given":"David","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":441414,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Huang, L.","contributorId":19383,"corporation":false,"usgs":true,"family":"Huang","given":"L.","email":"","affiliations":[],"preferred":false,"id":441412,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70033562,"text":"70033562 - 2008 - Relation between species assemblages of fishes and water quality in salt ponds and sloughs in South San Francisco Bay","interactions":[],"lastModifiedDate":"2018-09-26T09:58:11","indexId":"70033562","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3451,"text":"Southwestern Naturalist","active":true,"publicationSubtype":{"id":10}},"title":"Relation between species assemblages of fishes and water quality in salt ponds and sloughs in South San Francisco Bay","docAbstract":"This study was conducted to characterize fishery resources inhabiting salt-evaporation ponds and sloughs in South San Francisco Bay, and to identify key environmental variables that influence distribution of fishes. The ponds, which were originally constructed and operated for commercial production of salt, have undergone preliminary modifications (installation of culverts, gates, and other water-control structures) in preparation for full restoration to mostly tidal wetlands over the next 2 decades. We sampled fish from two salt-pond complexes (Alviso complex and Eden Landing complex), each consisting of several pond systems and their associated sloughs. Cluster analysis of species of fish indicated that at least two species assemblages were present, one characteristic of ponds and the other characteristic of sloughs and slough-like ponds. The slough-like ponds exhibited water-quality conditions (especially salinity) that resembled conditions found in the sloughs. Pond fishes were represented by 12 species, whereas slough fishes were represented by 22 species. Except for bay pipefish (Syngnathus leptorhynchus), which was unique to ponds, all species present in ponds also were in sloughs and slough-like ponds. These results indicated that species of fish in ponds originated from the sloughs. According to canonical-discriminant analysis, four environmental variables were useful for discriminating between the two species assemblages. Most discriminatory power was contributed by the index of habitat connectivity, a measure of minimum distance that a fish must travel to reach a particular pond from the nearest slough. Apparently, as fish from sloughs enter and move through interconnected salt ponds, environmental stress factors increase in severity until only the more tolerant species remain. The most likely source of stress is salinity, because this variable was second in importance to the index of habitat connectivity in discriminating between the two species assemblages. Water temperature and concentration of dissolved oxygen also seemingly influenced spatial distribution of fishes, although they were less important than salinity.","language":"English","publisher":"Southwestern Association of Naturalists","doi":"10.1894/GG-26.1","issn":"00384909","usgsCitation":"Mejia, F., Saiki, M.K., and Takekawa, J.Y., 2008, Relation between species assemblages of fishes and water quality in salt ponds and sloughs in South San Francisco Bay: Southwestern Naturalist, v. 53, no. 3, p. 335-345, https://doi.org/10.1894/GG-26.1.","productDescription":"11 p.","startPage":"335","endPage":"345","costCenters":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"links":[{"id":241823,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214129,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1894/GG-26.1"}],"volume":"53","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"50e4a646e4b0e8fec6cdc15f","contributors":{"authors":[{"text":"Mejia, F.","contributorId":73011,"corporation":false,"usgs":true,"family":"Mejia","given":"F.","email":"","affiliations":[],"preferred":false,"id":441450,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Saiki, M. K.","contributorId":28917,"corporation":false,"usgs":true,"family":"Saiki","given":"M.","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":441448,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Takekawa, John Y. 0000-0003-0217-5907 john_takekawa@usgs.gov","orcid":"https://orcid.org/0000-0003-0217-5907","contributorId":176168,"corporation":false,"usgs":true,"family":"Takekawa","given":"John","email":"john_takekawa@usgs.gov","middleInitial":"Y.","affiliations":[{"id":651,"text":"Western Ecological Research Center","active":true,"usgs":true}],"preferred":false,"id":441449,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033563,"text":"70033563 - 2008 - Biodynamic modeling of PCB uptake by Macoma balthica and Corbicula fluminea from sediment amended with activated carbon","interactions":[],"lastModifiedDate":"2012-03-12T17:21:30","indexId":"70033563","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1565,"text":"Environmental Science & Technology","onlineIssn":"1520-5851","printIssn":"0013-936X","active":true,"publicationSubtype":{"id":10}},"title":"Biodynamic modeling of PCB uptake by Macoma balthica and Corbicula fluminea from sediment amended with activated carbon","docAbstract":"Activated carbon amendment was assessed in the laboratory as a remediation strategy for freshwater sediment contaminated with polychlorinated biphenyls (PCBs) from the Grasse River (near Massena, NY). Three end points were evaluated: aqueous equilibrium PCB concentration, uptake into semipermeable membrane devices (SPMDs), and 28-day bioaccumulation in the clam Corbicula fluminea. PCB uptake by water, SPMDs, and clams followed similar trends, with reductions increasing as a function of carbon dose. Average percent reductions in clam tissue PCBs were 67, 86, and 95% for activated carbon doses of 0.7, 1.3, and 2.5% dry wt, respectively. A biodynamic model that incorporates sediment geochemistry and dietary and aqueous uptake routes was found to agree well with observed uptake by C. fluminea in our laboratory test systems. Results from this study were compared to 28-day bioaccumulation experiments involving PCB-contaminated sediment from Hunters Point Naval Shipyard (San Francisco Bay, CA) and the clam Macoma balthica. Due to differences in feeding strategy, M. balthica deposit-feeds whereas C. fluminea filter-feeds, the relative importance of the aqueous uptake route is predicted to be much higher for C. fluminea than for M. balthica. Whereas M. balthica takes up approximately 90% of its body burden through sediment ingestion, C. fluminea only accumulates approximately 45% via this route. In both cases, results strongly suggest that it is the mass transfer of PCBs from native sediment to added carbon particles, not merely reductions in aqueous PCB concentrations, that effectively reduces PCB bioavailability and uptake by sediment-dwelling organisms. ?? 2008 American Chemical Society.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Environmental Science and Technology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1021/es070139a","issn":"0013936X","usgsCitation":"McLeod, P.B., Luoma, S., and Luthy, R., 2008, Biodynamic modeling of PCB uptake by Macoma balthica and Corbicula fluminea from sediment amended with activated carbon: Environmental Science & Technology, v. 42, no. 2, p. 484-490, https://doi.org/10.1021/es070139a.","startPage":"484","endPage":"490","numberOfPages":"7","costCenters":[],"links":[{"id":214130,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1021/es070139a"},{"id":241824,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"42","issue":"2","noUsgsAuthors":false,"publicationDate":"2007-12-12","publicationStatus":"PW","scienceBaseUri":"5059f14be4b0c8380cd4ab7b","contributors":{"authors":[{"text":"McLeod, Pamela B.","contributorId":76913,"corporation":false,"usgs":true,"family":"McLeod","given":"Pamela","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":441452,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Luoma, S. N.","contributorId":86353,"corporation":false,"usgs":true,"family":"Luoma","given":"S. N.","affiliations":[],"preferred":false,"id":441453,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Luthy, R.G.","contributorId":36335,"corporation":false,"usgs":true,"family":"Luthy","given":"R.G.","email":"","affiliations":[],"preferred":false,"id":441451,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033564,"text":"70033564 - 2008 - Structural equation modeling for observational studies","interactions":[],"lastModifiedDate":"2012-03-12T17:21:30","indexId":"70033564","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2508,"text":"Journal of Wildlife Management","active":true,"publicationSubtype":{"id":10}},"title":"Structural equation modeling for observational studies","docAbstract":"Structural equation modeling (SEM) represents a framework for developing and evaluating complex hypotheses about systems. This method of data analysis differs from conventional univariate and multivariate approaches familiar to most biologists in several ways. First, SEMs are multiequational and capable of representing a wide array of complex hypotheses about how system components interrelate. Second, models are typically developed based on theoretical knowledge and designed to represent competing hypotheses about the processes responsible for data structure. Third, SEM is conceptually based on the analysis of covariance relations. Most commonly, solutions are obtained using maximum-likelihood solution procedures, although a variety of solution procedures are used, including Bayesian estimation. Numerous extensions give SEM a very high degree of flexibility in dealing with nonnormal data, categorical responses, latent variables, hierarchical structure, multigroup comparisons, nonlinearities, and other complicating factors. Structural equation modeling allows researchers to address a variety of questions about systems, such as how different processes work in concert, how the influences of perturbations cascade through systems, and about the relative importance of different influences. I present 2 example applications of SEM, one involving interactions among lynx (Lynx pardinus), mongooses (Herpestes ichneumon), and rabbits (Oryctolagus cuniculus), and the second involving anuran species richness. Many wildlife ecologists may find SEM useful for understanding how populations function within their environments. Along with the capability of the methodology comes a need for care in the proper application of SEM.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Wildlife Management","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.2193/2007-307","issn":"0022541X","usgsCitation":"Grace, J., 2008, Structural equation modeling for observational studies: Journal of Wildlife Management, v. 72, no. 1, p. 14-22, https://doi.org/10.2193/2007-307.","startPage":"14","endPage":"22","numberOfPages":"9","costCenters":[],"links":[{"id":214163,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2193/2007-307"},{"id":241857,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"72","issue":"1","noUsgsAuthors":false,"publicationDate":"2010-12-13","publicationStatus":"PW","scienceBaseUri":"505b9be4e4b08c986b31d157","contributors":{"authors":[{"text":"Grace, J.B. 0000-0001-6374-4726","orcid":"https://orcid.org/0000-0001-6374-4726","contributorId":38938,"corporation":false,"usgs":true,"family":"Grace","given":"J.B.","affiliations":[],"preferred":false,"id":441454,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70033565,"text":"70033565 - 2008 - A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA","interactions":[],"lastModifiedDate":"2020-07-30T14:41:50.434855","indexId":"70033565","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1109,"text":"Bulletin of Volcanology","active":true,"publicationSubtype":{"id":10}},"title":"A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA","docAbstract":"We mapped the geometry of 13 silicic dikes at Summer Coon, an eroded Oligocene stratovolcano in southern Colorado, to investigate various characteristics of radial dike emplacement in composite volcanoes. Exposed dikes are up to about 7 km in length and have numerous offset segments along their upper peripheries. Surprisingly, most dikes at Summer Coon increase in thickness with distance from the center of the volcano. Magma pressure in a dike is expected to lessen away from the pressurized source region, which would encourage a blade-like dike to decrease in thickness with distance from the center of the volcano. We attribute the observed thickness pattern as evidence of a driving pressure gradient, which is caused by decreasing host rock shear modulus and horizontal stress, both due to decreasing emplacement depths beneath the sloping flanks of the volcano. Based on data from Summer Coon, we propose that radial dikes originate at depth below the summit of a host volcano and follow steeply inclined paths towards the surface. Near the interface between volcanic cone and basement, which may represent a neutral buoyancy surface or stress barrier, magma is transported subhorizontally and radially away from the center of the volcano in blade-like dikes. The dikes thicken with increasing radial distance, and offset segments and fingers form along the upper peripheries of the intrusions. Eruptions may occur anywhere along the length of the dikes, but the erupted volume will generally be greater for dike-fed eruptions far from the center of the host volcano owing to the increase in driving pressure with distance from the source. Observed eruptive volumes, vent locations, and vent-area intrusions from inferred post-glacial dike-fed eruptions at Mount Adams, Washington, USA, support the proposed model. Hazards associated with radial dike emplacement are therefore greater for longer dikes that propagate to the outer flanks of a volcano.
","language":"English","publisher":"Springer","doi":"10.1007/s00445-007-0175-9","issn":"02588900","usgsCitation":"Poland, M.P., Moats, W., and Fink, J., 2008, A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA: Bulletin of Volcanology, v. 70, no. 7, p. 861-875, https://doi.org/10.1007/s00445-007-0175-9.","productDescription":"15 p.","startPage":"861","endPage":"875","numberOfPages":"15","costCenters":[{"id":336,"text":"Hawaiian Volcano Observatory","active":false,"usgs":true},{"id":616,"text":"Volcano Hazards Team","active":false,"usgs":true}],"links":[{"id":241858,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Colorado","otherGeospatial":"Summer Coon volcano","geographicExtents":"{\n\n\"type\": \"FeatureCollection\",\n\n\"features\": [\n\n{\n\n\"type\": \"Feature\",\n\n\"properties\": {},\n\n\"geometry\": {\n\n\"type\": \"Polygon\",\n\n\"coordinates\": [\n\n[\n\n[\n\n-106.3916015625,\n\n37.693601037244406\n\n],\n\n[\n\n-106.10733032226562,\n\n37.693601037244406\n\n],\n\n[\n\n-106.10733032226562,\n\n37.835818618104156\n\n],\n\n[\n\n-106.3916015625,\n\n37.835818618104156\n\n],\n\n[\n\n-106.3916015625,\n\n37.693601037244406\n\n]\n\n]\n\n]\n\n}\n\n}\n\n]\n\n}","volume":"70","issue":"7","noUsgsAuthors":false,"publicationDate":"2007-11-06","publicationStatus":"PW","scienceBaseUri":"5059e46be4b0c8380cd46655","contributors":{"authors":[{"text":"Poland, Michael P. 0000-0001-5240-6123 mpoland@usgs.gov","orcid":"https://orcid.org/0000-0001-5240-6123","contributorId":146118,"corporation":false,"usgs":true,"family":"Poland","given":"Michael","email":"mpoland@usgs.gov","middleInitial":"P.","affiliations":[{"id":617,"text":"Volcano Science Center","active":true,"usgs":true}],"preferred":true,"id":441457,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Moats, W.P.","contributorId":7923,"corporation":false,"usgs":true,"family":"Moats","given":"W.P.","email":"","affiliations":[],"preferred":false,"id":441455,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Fink, J.H.","contributorId":44367,"corporation":false,"usgs":true,"family":"Fink","given":"J.H.","email":"","affiliations":[],"preferred":false,"id":441456,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033568,"text":"70033568 - 2008 - Long-period building response to earthquakes in the San Francisco Bay Area","interactions":[],"lastModifiedDate":"2017-11-27T13:06:50","indexId":"70033568","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Long-period building response to earthquakes in the San Francisco Bay Area","docAbstract":"This article reports a study of modeled, long-period building responses to ground-motion simulations of earthquakes in the San Francisco Bay Area. The earthquakes include the 1989 magnitude 6.9 Loma Prieta earthquake, a magnitude 7.8 simulation of the 1906 San Francisco earthquake, and two hypothetical magnitude 7.8 northern San Andreas fault earthquakes with hypocenters north and south of San Francisco. We use the simulated ground motions to excite nonlinear models of 20-story, steel, welded moment-resisting frame (MRF) buildings. We consider MRF buildings designed with two different strengths and modeled with either ductile or brittle welds. Using peak interstory drift ratio (IDR) as a performance measure, the stiffer, higher strength building models outperform the equivalent more flexible, lower strength designs. The hypothetical magnitude 7.8 earthquake with hypocenter north of San Francisco produces the most severe ground motions. In this simulation, the responses of the more flexible, lower strength building model with brittle welds exceed an IDR of 2.5% (that is, threaten life safety) on 54% of the urban area, compared to 4.6% of the urban area for the stiffer, higher strength building with ductile welds. We also use the simulated ground motions to predict the maximum isolator displacement of base-isolated buildings with linear, single-degree-of-freedom (SDOF) models. For two existing 3-sec isolator systems near San Francisco, the design maximum displacement is 0.5 m, and our simulations predict isolator displacements for this type of system in excess of 0.5 m in many urban areas. This article demonstrates that a large, 1906-like earthquake could cause significant damage to long-period buildings in the San Francisco Bay Area.","largerWorkTitle":"Bulletin of the Seismological Society of America","language":"English","doi":"10.1785/0120060408","issn":"00371106","usgsCitation":"Olsen, A., Aagaard, B.T., and Heaton, T.H., 2008, Long-period building response to earthquakes in the San Francisco Bay Area, in Bulletin of the Seismological Society of America, v. 98, no. 2, p. 1047-1065, https://doi.org/10.1785/0120060408.","startPage":"1047","endPage":"1065","numberOfPages":"19","costCenters":[],"links":[{"id":241922,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214223,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1785/0120060408"}],"volume":"98","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a496ce4b0c8380cd685bd","contributors":{"authors":[{"text":"Olsen, A.H.","contributorId":95706,"corporation":false,"usgs":true,"family":"Olsen","given":"A.H.","email":"","affiliations":[],"preferred":false,"id":441464,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Aagaard, Brad T. 0000-0002-8795-9833 baagaard@usgs.gov","orcid":"https://orcid.org/0000-0002-8795-9833","contributorId":192869,"corporation":false,"usgs":true,"family":"Aagaard","given":"Brad","email":"baagaard@usgs.gov","middleInitial":"T.","affiliations":[{"id":237,"text":"Earthquake Science Center","active":true,"usgs":true},{"id":300,"text":"Geologic Hazards Science Center","active":true,"usgs":true}],"preferred":false,"id":441462,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Heaton, T. H.","contributorId":64671,"corporation":false,"usgs":false,"family":"Heaton","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":441463,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033574,"text":"70033574 - 2008 - Holocene depositional environments and surface-level changes at Lake Fryxell, Antarctica","interactions":[],"lastModifiedDate":"2012-03-12T17:21:29","indexId":"70033574","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1905,"text":"Holocene","active":true,"publicationSubtype":{"id":10}},"title":"Holocene depositional environments and surface-level changes at Lake Fryxell, Antarctica","docAbstract":"We report on Holocene surface-level variations of Lake Fryxell, Antarctica, as determined from multi-proxy analyses of 18 sediment cores. During this time accumulating sediments were predominantly aeolian sand with algal and carbonate laminae. Based on stratigraphy, mineralogy and diatom assemblages we suggest some carbonate laminae were deposited when lake level dropped, leading to concentration and subsequent precipitation of salts. Although lake level appears to have remained relatively stable throughout the Holocene, minor (<4.5 m below present) lowstands occurred at approximately 6400, 4700, 3800 and ??? 1600 cal. yr BP. The stability of Lake Fryxell during the Holocene contrasts with large-scale variability at other Dry Valleys lakes (eg, Lake Vanda) and with suggestions from chemical diffusion models of a near-desiccation at ???1200 cal. yr BP. The reason for the comparative stability of Lake Fryxell is uncertain, but may be the result of basin morphology and the number, aspect and proximity of meltwater sources. ?? 2008 SAGE Publications.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Holocene","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1177/0959683608091797","issn":"09596","usgsCitation":"Whittaker, T., Hall, B., Hendy, C., and Spaulding, S., 2008, Holocene depositional environments and surface-level changes at Lake Fryxell, Antarctica: Holocene, v. 18, no. 5, p. 775-786, https://doi.org/10.1177/0959683608091797.","startPage":"775","endPage":"786","numberOfPages":"12","costCenters":[],"links":[{"id":214308,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1177/0959683608091797"},{"id":242020,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"18","issue":"5","noUsgsAuthors":false,"publicationDate":"2008-08-01","publicationStatus":"PW","scienceBaseUri":"505a31dde4b0c8380cd5e2d0","contributors":{"authors":[{"text":"Whittaker, T.E.","contributorId":54417,"corporation":false,"usgs":true,"family":"Whittaker","given":"T.E.","email":"","affiliations":[],"preferred":false,"id":441494,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hall, B.L.","contributorId":92502,"corporation":false,"usgs":true,"family":"Hall","given":"B.L.","email":"","affiliations":[],"preferred":false,"id":441496,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hendy, C.H.","contributorId":94511,"corporation":false,"usgs":true,"family":"Hendy","given":"C.H.","email":"","affiliations":[],"preferred":false,"id":441497,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Spaulding, S. A. 0000-0002-9787-7743","orcid":"https://orcid.org/0000-0002-9787-7743","contributorId":74390,"corporation":false,"usgs":true,"family":"Spaulding","given":"S. A.","affiliations":[],"preferred":false,"id":441495,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70033575,"text":"70033575 - 2008 - Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow","interactions":[],"lastModifiedDate":"2018-10-22T08:41:54","indexId":"70033575","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3722,"text":"Water Resources Research","onlineIssn":"1944-7973","printIssn":"0043-1397","active":true,"publicationSubtype":{"id":10}},"title":"Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow","docAbstract":"The Biscayne aquifer is a highly transmissive karst limestone that serves as the sole source of drinking water to over two million residents in south Florida. The aquifer is characterized by eogenetic karst, where the most transmissive void space can be an interconnected, touching‐vug, biogenically influenced porosity of biogenic origin. Public supply wells in the aquifer are in close proximity to lakes established by surface mining. The mining of the limestone has occurred to the same depths as the production wells, which has raised concerns about pathogen and chemical transport from these surface water bodies. Hydraulic and forced gradient tracer tests were conducted to augment geologic and geophysical studies and to develop a hydrogeologic conceptual model of groundwater flow and chemical transport in the Biscayne aquifer. Geologic and geophysical data indicate multiple, areally extensive subhorizontal preferential flow zones of vuggy limestone separated by rock with a matrix pore system. The hydraulic response from an aquifer test suggests that the Biscayne aquifer behaves as a dual‐porosity medium; however, the results of the tracer test showed rapid transport similar to other types of karst. The tracer test and concurrent temperature logging revealed that only one of the touching‐vug flow zones dominates transport near the production wells. On the basis of the rising limb of the breakthrough curve, the dispersivity is estimated to be less than 3% of the tracer travel distance, which suggests that the fastest flow paths in the formation are likely to yield limited dilution of chemical constituents.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2007WR006058","usgsCitation":"Renken, R.A., Cunningham, K.J., Shapiro, A.M., Harvey, R.W., Zygnerski, M.R., Metge, D.W., and Wacker, M.A., 2008, Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 1. Revised conceptualization of groundwater flow: Water Resources Research, v. 44, no. 8, W08429; 16 p., https://doi.org/10.1029/2007WR006058.","productDescription":"W08429; 16 p.","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":476744,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/2007wr006058","text":"Publisher Index Page"},{"id":242021,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"44","issue":"8","noUsgsAuthors":false,"publicationDate":"2008-08-23","publicationStatus":"PW","scienceBaseUri":"505a7595e4b0c8380cd77c14","contributors":{"authors":[{"text":"Renken, Robert A. rarenken@usgs.gov","contributorId":269,"corporation":false,"usgs":true,"family":"Renken","given":"Robert","email":"rarenken@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":441504,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Cunningham, Kevin J. 0000-0002-2179-8686 kcunning@usgs.gov","orcid":"https://orcid.org/0000-0002-2179-8686","contributorId":1689,"corporation":false,"usgs":true,"family":"Cunningham","given":"Kevin","email":"kcunning@usgs.gov","middleInitial":"J.","affiliations":[{"id":269,"text":"FLWSC-Ft. Lauderdale","active":true,"usgs":true}],"preferred":true,"id":441499,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Shapiro, Allen M. 0000-0002-6425-9607 ashapiro@usgs.gov","orcid":"https://orcid.org/0000-0002-6425-9607","contributorId":2164,"corporation":false,"usgs":true,"family":"Shapiro","given":"Allen","email":"ashapiro@usgs.gov","middleInitial":"M.","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true},{"id":37277,"text":"WMA - Earth System Processes Division","active":true,"usgs":true}],"preferred":true,"id":441502,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Harvey, Ronald W. 0000-0002-2791-8503 rwharvey@usgs.gov","orcid":"https://orcid.org/0000-0002-2791-8503","contributorId":564,"corporation":false,"usgs":true,"family":"Harvey","given":"Ronald","email":"rwharvey@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441498,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Zygnerski, Michael R.","contributorId":25469,"corporation":false,"usgs":true,"family":"Zygnerski","given":"Michael","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":441500,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Metge, David W. dwmetge@usgs.gov","contributorId":663,"corporation":false,"usgs":true,"family":"Metge","given":"David","email":"dwmetge@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441501,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Wacker, Michael A. mwacker@usgs.gov","contributorId":2162,"corporation":false,"usgs":true,"family":"Wacker","given":"Michael","email":"mwacker@usgs.gov","middleInitial":"A.","affiliations":[{"id":269,"text":"FLWSC-Ft. Lauderdale","active":true,"usgs":true}],"preferred":true,"id":441503,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70033580,"text":"70033580 - 2008 - Relationship of floodplain ichnocoenoses to paleopedology, paleohydrology, and paleoclimate in the Willwood Formation, Wyoming, during the Paleocene-Eocene Thermal Maximum","interactions":[],"lastModifiedDate":"2012-03-12T17:21:33","indexId":"70033580","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3000,"text":"Palaios","active":true,"publicationSubtype":{"id":10}},"title":"Relationship of floodplain ichnocoenoses to paleopedology, paleohydrology, and paleoclimate in the Willwood Formation, Wyoming, during the Paleocene-Eocene Thermal Maximum","docAbstract":"Vertical changes in distribution, abundance, and ichnodiversity of ichnocoenoses in alluvial deposits of the Willwood Formation suggest significantly drier moisture regimes in the Bighorn Basin, Wyoming, during the Paleocene-Eocene Thermal Maximum (PETM), a transient period of global warming. The Willwood Formation at Polecat Bench contains an abundant assemblage of ichnofossils, including various types of rhizoliths and invertebrate trace fossils, such as Naktodemasis bowni, Camborygma litonomos, Edaphichnium lumbricatum, cf. Cylindricum isp., cf. Planolites isp., cf. Steinichnus, and cocoon traces. These comprise six distinct ichnocoenoses, which are categorized as dominantly terraphilic, hygrophilic, or hydrophilic based on the inferred moisture regimes of their most abundant ichnofossil morphotypes and associated pedogenic features, including other trace fossils and rhizoliths. The interpreted moisture regimes correlate well with the paleoenvironments of their host lithofacies, as inferred from sedimentology and paleopedology. Outside the PETM interval at Polecat Bench, abundant avulsion deposits and thin, compound paleosols containing hygrophilic and hydrophilic ichnocoenoses suggest frequent depositional events and predominantly poor to imperfect soil-drainage conditions. Within the PETM interval, thick, cumulative paleosol profiles with abundant terraphilic to hygrophilic ichnocoenoses suggest significantly improved drainage conditions. Lithofacies and ichnocoenoses above the PETM interval are not significantly different from those below the interval, indicating a return to pre-PETM moisture regimes. These conclusions support previous studies that suggest the Bighorn Basin experienced transient drying during this interval. This study demonstrates that ichnocoenoses and their ichnopedologic associations can be used to refine paleohydrologic and paleoclimatic generalizations inferred from paleoclimate models. Copyright ?? 2008, SEPM (Society for Sedimentary Geology).","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Palaios","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.2110/palo.2007.p07-080r","issn":"08831","usgsCitation":"Smith, J., Hasiotis, S., Kraus, M.J., and Woody, D., 2008, Relationship of floodplain ichnocoenoses to paleopedology, paleohydrology, and paleoclimate in the Willwood Formation, Wyoming, during the Paleocene-Eocene Thermal Maximum: Palaios, v. 23, no. 9-10, p. 683-699, https://doi.org/10.2110/palo.2007.p07-080r.","startPage":"683","endPage":"699","numberOfPages":"17","costCenters":[],"links":[{"id":214396,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2110/palo.2007.p07-080r"},{"id":242119,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"23","issue":"9-10","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"50e4a76de4b0e8fec6cdc460","contributors":{"authors":[{"text":"Smith, J.J.","contributorId":106175,"corporation":false,"usgs":true,"family":"Smith","given":"J.J.","email":"","affiliations":[],"preferred":false,"id":441521,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hasiotis, S.T.","contributorId":107020,"corporation":false,"usgs":true,"family":"Hasiotis","given":"S.T.","affiliations":[],"preferred":false,"id":441522,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Kraus, M. J.","contributorId":44605,"corporation":false,"usgs":false,"family":"Kraus","given":"M.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":441520,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Woody, D.T.","contributorId":39207,"corporation":false,"usgs":true,"family":"Woody","given":"D.T.","email":"","affiliations":[],"preferred":false,"id":441519,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70033585,"text":"70033585 - 2008 - A close look at Saturn's rings with Cassini VIMS","interactions":[],"lastModifiedDate":"2012-03-12T17:21:33","indexId":"70033585","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1963,"text":"Icarus","active":true,"publicationSubtype":{"id":10}},"title":"A close look at Saturn's rings with Cassini VIMS","docAbstract":"Soon after the Cassini-Huygens spacecraft entered orbit about Saturn on 1 July 2004, its Visual and Infrared Mapping Spectrometer obtained two continuous spectral scans across the rings, covering the wavelength range 0.35-5.1 ??m, at a spatial resolution of 15-25 km. The first scan covers the outer C and inner B rings, while the second covers the Cassini Division and the entire A ring. Comparisons of the VIMS radial reflectance profile at 1.08 ??m with similar profiles at a wavelength of 0.45 ??m assembled from Voyager images show very little change in ring structure over the intervening 24 years, with the exception of a few features already known to be noncircular. A model for single-scattering by a classical, many-particle-thick slab of material with normal optical depths derived from the Voyager photopolarimeter stellar occultation is found to provide an excellent fit to the observed VIMS reflectance profiles for the C ring and Cassini Division, and an acceptable fit for the inner B ring. The A ring deviates significantly from such a model, consistent with previous suggestions that this region may be closer to a monolayer. An additional complication here is the azimuthally-variable average optical depth associated with \"self-gravity wakes\" in this region and the fact that much of the A ring may be a mixture of almost opaque wakes and relatively transparent interwake zones. Consistently with previous studies, we find that the near-infrared spectra of all main ring regions are dominated by water ice, with a typical regolith grain radius of 5-20 ??m, while the steep decrease in visual reflectance shortward of 0.6 ??m is suggestive of an organic contaminant, perhaps tholin-like. Although no materials other than H2O ice have been identified with any certainty in the VIMS spectra of the rings, significant radial variations are seen in the strength of the water-ice absorption bands. Across the boundary between the C and B rings, over a radial range of ???7000 km, the near-IR band depths strengthen considerably. A very similar pattern is seen across the outer half of the Cassini Division and into the inner A ring, accompanied by a steepening of the red slope in the visible spectrum shortward of 0.55 ??m. We attribute these trends-as well as smaller-scale variations associated with strong density waves in the A ring-to differing grain sizes in the tholin-contaminated icy regolith that covers the surfaces of the decimeter-to-meter sized ring particles. On the largest scale, the spectral variations seen by VIMS suggest that the rings may be divided into two larger 'ring complexes,' with similar internal variations in structure, optical depth, particle size, regolith texture and composition. The inner complex comprises the C and B rings, while the outer comprises the Cassini Division and A ring. ?? 2007 Elsevier Inc. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Icarus","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.icarus.2007.08.036","issn":"00191035","usgsCitation":"Nicholson, P.D., Hedman, M., Clark, R.N., Showalter, M., Cruikshank, D.P., Cuzzi, J., Filacchione, G., Capaccioni, F., Cerroni, P., Hansen, G.B., Sicardy, B., Drossart, P., Brown, R.H., Buratti, B.J., Baines, K.H., and Coradini, A., 2008, A close look at Saturn's rings with Cassini VIMS: Icarus, v. 193, no. 1, p. 182-212, https://doi.org/10.1016/j.icarus.2007.08.036.","startPage":"182","endPage":"212","numberOfPages":"31","costCenters":[],"links":[{"id":214461,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.icarus.2007.08.036"},{"id":242189,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"193","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e345e4b0c8380cd45f17","contributors":{"authors":[{"text":"Nicholson, P. D.","contributorId":54330,"corporation":false,"usgs":false,"family":"Nicholson","given":"P.","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":441549,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hedman, M.M.","contributorId":91694,"corporation":false,"usgs":true,"family":"Hedman","given":"M.M.","email":"","affiliations":[],"preferred":false,"id":441553,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Clark, R. N.","contributorId":6568,"corporation":false,"usgs":true,"family":"Clark","given":"R.","email":"","middleInitial":"N.","affiliations":[],"preferred":false,"id":441539,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Showalter, M.R.","contributorId":24992,"corporation":false,"usgs":true,"family":"Showalter","given":"M.R.","email":"","affiliations":[],"preferred":false,"id":441542,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Cruikshank, D. P.","contributorId":51434,"corporation":false,"usgs":false,"family":"Cruikshank","given":"D.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":441547,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Cuzzi, J.N.","contributorId":53962,"corporation":false,"usgs":true,"family":"Cuzzi","given":"J.N.","email":"","affiliations":[],"preferred":false,"id":441548,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Filacchione, G.","contributorId":48740,"corporation":false,"usgs":true,"family":"Filacchione","given":"G.","affiliations":[],"preferred":false,"id":441546,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Capaccioni, F.","contributorId":90900,"corporation":false,"usgs":true,"family":"Capaccioni","given":"F.","email":"","affiliations":[],"preferred":false,"id":441552,"contributorType":{"id":1,"text":"Authors"},"rank":8},{"text":"Cerroni, P.","contributorId":7869,"corporation":false,"usgs":true,"family":"Cerroni","given":"P.","affiliations":[],"preferred":false,"id":441540,"contributorType":{"id":1,"text":"Authors"},"rank":9},{"text":"Hansen, G. B.","contributorId":98478,"corporation":false,"usgs":false,"family":"Hansen","given":"G.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":441554,"contributorType":{"id":1,"text":"Authors"},"rank":10},{"text":"Sicardy, B.","contributorId":57622,"corporation":false,"usgs":true,"family":"Sicardy","given":"B.","affiliations":[],"preferred":false,"id":441550,"contributorType":{"id":1,"text":"Authors"},"rank":11},{"text":"Drossart, P.","contributorId":29574,"corporation":false,"usgs":true,"family":"Drossart","given":"P.","affiliations":[],"preferred":false,"id":441543,"contributorType":{"id":1,"text":"Authors"},"rank":12},{"text":"Brown, R. H.","contributorId":19931,"corporation":false,"usgs":false,"family":"Brown","given":"R.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":441541,"contributorType":{"id":1,"text":"Authors"},"rank":13},{"text":"Buratti, B. J.","contributorId":69280,"corporation":false,"usgs":false,"family":"Buratti","given":"B.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":441551,"contributorType":{"id":1,"text":"Authors"},"rank":14},{"text":"Baines, K. H.","contributorId":37868,"corporation":false,"usgs":false,"family":"Baines","given":"K.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":441545,"contributorType":{"id":1,"text":"Authors"},"rank":15},{"text":"Coradini, A.","contributorId":34679,"corporation":false,"usgs":true,"family":"Coradini","given":"A.","affiliations":[],"preferred":false,"id":441544,"contributorType":{"id":1,"text":"Authors"},"rank":16}]}} ,{"id":70033587,"text":"70033587 - 2008 - Collaboration tools and techniques for large model datasets","interactions":[],"lastModifiedDate":"2017-08-23T12:24:46","indexId":"70033587","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2381,"text":"Journal of Marine Systems","active":true,"publicationSubtype":{"id":10}},"title":"Collaboration tools and techniques for large model datasets","docAbstract":"In MREA and many other marine applications, it is common to have multiple models running with different grids, run by different institutions. Techniques and tools are described for low-bandwidth delivery of data from large multidimensional datasets, such as those from meteorological and oceanographic models, directly into generic analysis and visualization tools. Output is stored using the NetCDF CF Metadata Conventions, and then delivered to collaborators over the web via OPeNDAP. OPeNDAP datasets served by different institutions are then organized via THREDDS catalogs. Tools and procedures are then used which enable scientists to explore data on the original model grids using tools they are familiar with. It is also low-bandwidth, enabling users to extract just the data they require, an important feature for access from ship or remote areas. The entire implementation is simple enough to be handled by modelers working with their webmasters - no advanced programming support is necessary. ?? 2007 Elsevier B.V. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Marine Systems","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.jmarsys.2007.02.013","issn":"09247963","usgsCitation":"Signell, R.P., Carniel, S., Chiggiato, J., Janekovic, I., Pullen, J., and Sherwood, C.R., 2008, Collaboration tools and techniques for large model datasets: Journal of Marine Systems, v. 69, no. 1-2, p. 154-161, https://doi.org/10.1016/j.jmarsys.2007.02.013.","productDescription":"8 p.","startPage":"154","endPage":"161","costCenters":[{"id":678,"text":"Woods Hole Coastal and Marine Science Center","active":true,"usgs":true}],"links":[{"id":476753,"rank":1,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://hdl.handle.net/1912/2050","text":"External Repository"},{"id":242220,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"69","issue":"1-2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f7abe4b0c8380cd4cc3d","contributors":{"authors":[{"text":"Signell, R. P.","contributorId":89147,"corporation":false,"usgs":true,"family":"Signell","given":"R.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":441567,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Carniel, S.","contributorId":47504,"corporation":false,"usgs":true,"family":"Carniel","given":"S.","email":"","affiliations":[],"preferred":false,"id":441564,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Chiggiato, J.","contributorId":47065,"corporation":false,"usgs":true,"family":"Chiggiato","given":"J.","affiliations":[],"preferred":false,"id":441563,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Janekovic, I.","contributorId":69796,"corporation":false,"usgs":true,"family":"Janekovic","given":"I.","email":"","affiliations":[],"preferred":false,"id":441566,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Pullen, J.","contributorId":34339,"corporation":false,"usgs":true,"family":"Pullen","given":"J.","email":"","affiliations":[],"preferred":false,"id":441562,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Sherwood, C. R.","contributorId":48235,"corporation":false,"usgs":true,"family":"Sherwood","given":"C.","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":441565,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70033592,"text":"70033592 - 2008 - Dating groundwater with trifluoromethyl sulfurpentafluoride (SF 5CF3), sulfur hexafluoride (SF6), CF 3Cl (CFC-13), and CF2Cl2 (CFC-12)","interactions":[],"lastModifiedDate":"2018-03-21T15:19:45","indexId":"70033592","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3722,"text":"Water Resources Research","onlineIssn":"1944-7973","printIssn":"0043-1397","active":true,"publicationSubtype":{"id":10}},"title":"Dating groundwater with trifluoromethyl sulfurpentafluoride (SF 5CF3), sulfur hexafluoride (SF6), CF 3Cl (CFC-13), and CF2Cl2 (CFC-12)","docAbstract":"[1] A new groundwater dating procedure using the transient atmospheric signal of the environmental tracers SF5CF3, CFC-13, SF6, and CFC-12 was developed. The analytical procedure determines concentrations of the four tracers in air and water samples. SF 5CF3 and CFC-13 can be used to date groundwaters in some environments where the CFCs and SF6 have previously failed because these new tracers have increasing atmospheric input functions, no known terrigenic source, and are believed to be stable under reducing conditions. SF5CF3 has a dating range from 1970 to modern; the mixing ratio (mole fraction) in North American air has increased from the detection limit of 0.005 parts per trillion (ppt) to the 2006 mole fraction of about 0.16 ppt. No evidence was found for degradation of SF5CF3 in laboratory anaerobic systems. The solubility of SF5CF3 was measured in water from 1 to 35??C. Groundwater samples that contained large amounts of terrigenic SF6 did not contain terrigenic SF 5CF3. CFC-13 is a trace atmospheric gas with a dating range in groundwater of about 1965 to modem. CFC-13 has been used primarily in very low-temperature refrigeration; thus groundwater environments are less likely to be contaminated with nonatmospheric sources as compared to other widely used CFCs. Because of the low solubility of SF5CF3 and CFC-13 in water, an excess air correction must be applied to the apparent ages. The new dating procedure was tested in water samples from wells and springs from Maryland, Virginia, and West Virginia.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Water Resources Research","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1029/2007WR006150","issn":"00431397","usgsCitation":"Busenberg, E., and Plummer, N., 2008, Dating groundwater with trifluoromethyl sulfurpentafluoride (SF 5CF3), sulfur hexafluoride (SF6), CF 3Cl (CFC-13), and CF2Cl2 (CFC-12): Water Resources Research, v. 44, no. 2, https://doi.org/10.1029/2007WR006150.","costCenters":[],"links":[{"id":487125,"rank":10000,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/2007wr006150","text":"Publisher Index Page"},{"id":214101,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1029/2007WR006150"},{"id":241791,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"44","issue":"2","noUsgsAuthors":false,"publicationDate":"2008-02-22","publicationStatus":"PW","scienceBaseUri":"5059fde0e4b0c8380cd4e9aa","contributors":{"authors":[{"text":"Busenberg, E.","contributorId":56796,"corporation":false,"usgs":true,"family":"Busenberg","given":"E.","affiliations":[],"preferred":false,"id":441588,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Plummer, Niel 0000-0002-4020-1013 nplummer@usgs.gov","orcid":"https://orcid.org/0000-0002-4020-1013","contributorId":190100,"corporation":false,"usgs":true,"family":"Plummer","given":"Niel","email":"nplummer@usgs.gov","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":true,"id":441589,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70033593,"text":"70033593 - 2008 - Dynamic stresses, Coulomb failure, and remote triggering","interactions":[],"lastModifiedDate":"2019-03-20T08:03:12","indexId":"70033593","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1135,"text":"Bulletin of the Seismological Society of America","onlineIssn":"1943-3573","printIssn":"0037-1106","active":true,"publicationSubtype":{"id":10}},"title":"Dynamic stresses, Coulomb failure, and remote triggering","docAbstract":"Dynamic stresses associated with crustal surface waves with 15-30-sec periods and peak amplitudes < 1 MPa are capable of triggering seismicity at sites remote from the generating mainshock under appropriate conditions. Coulomb failure models based on a frictional strength threshold offer one explanation for instances of rapid-onset triggered seismicity that develop during the surface-wave peak dynamic stressing. Evaluation of the triggering potential of surface-wave dynamic stresses acting on critically stressed faults using a Mohr's circle representation together with the Coulomb failure criteria indicates that Love waves should have a higher triggering potential than Rayleigh waves when incident on vertical, strike-slip faults. That (1) the onset of triggered seismicity often appears to begin during the Rayleigh wave rather than the earher-arriving Love wave, (2) vertical strike-slip faults pervade the crust in most tectonic regimes, and (3) Love-wave amplitudes typically exceed those for Rayleigh waves suggests that the explanation for rapid-onset dynamic triggering may not reside solely with a simple static-threshold friction mode. The results also indicate that thrust faults should be more susceptible to dynamic triggering by Rayleigh-wave stresses than normal faults in the shallow seismogenic crust (< 5 km), while the reverse should be true in the lower seismogenic crust (> 5 km). The latter is consistent with the observation that extensional or transtensional tectonic regimes are more susceptible to remote triggering by Rayleigh-wave dynamic stresses than compressional or transpressional regimes. Locally elevated pore pressures may have a role in the observed prevalence of dynamic triggering in extensional regimes and geothermal/volcanic systems.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Bulletin of the Seismological Society of America","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1785/0120070049","issn":"00371106","usgsCitation":"Hill, D.P., 2008, Dynamic stresses, Coulomb failure, and remote triggering: Bulletin of the Seismological Society of America, v. 98, no. 1, p. 66-92, https://doi.org/10.1785/0120070049.","startPage":"66","endPage":"92","numberOfPages":"27","costCenters":[{"id":615,"text":"Volcano Hazards Program","active":true,"usgs":true}],"links":[{"id":241792,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214102,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1785/0120070049"}],"volume":"98","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a042be4b0c8380cd50820","contributors":{"authors":[{"text":"Hill, David P. 0000-0002-1619-2006 dhill@usgs.gov","orcid":"https://orcid.org/0000-0002-1619-2006","contributorId":206752,"corporation":false,"usgs":true,"family":"Hill","given":"David","email":"dhill@usgs.gov","middleInitial":"P.","affiliations":[{"id":617,"text":"Volcano Science Center","active":true,"usgs":true}],"preferred":true,"id":759551,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70033596,"text":"70033596 - 2008 - Permeability of continental crust influenced by internal and external forcing","interactions":[],"lastModifiedDate":"2019-03-28T16:50:15","indexId":"70033596","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1765,"text":"Geofluids","active":true,"publicationSubtype":{"id":10}},"title":"Permeability of continental crust influenced by internal and external forcing","docAbstract":"The permeability of continental crust is so highly variable that it is often considered to defy systematic characterization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability–depth relations) on a very large scale? Here we argue that large‐scale crustal permeability adjusts to accommodate rates of internal and external forcing. In the deeper crust, internal forcing – fluxes induced by metamorphism, magmatism, and mantle degassing – is dominant, whereas in the shallow crust, external forcing – the vigor of the hydrologic cycle – is a primary control. Crustal petrologists have long recognized the likelihood of a causal relation between fluid flux and permeability in the deep, ductile crust, where fluid pressures are typically near‐lithostatic. It is less obvious that such a relation should pertain in the relatively cool, brittle upper crust, where near‐hydrostatic fluid pressures are the norm. We use first‐order calculations and numerical modeling to explore the hypothesis that upper‐crustal permeability is influenced by the magnitude of external fluid sources, much as lower‐crustal permeability is influenced by the magnitude of internal fluid sources. We compare model‐generated permeability structures with various observations of crustal permeability.
","language":"English","publisher":"Wiley","doi":"10.1111/j.1468-8123.2008.00211.x","issn":"14688115","usgsCitation":"Rojstaczer, S., Ingebritsen, S.E., and Hayba, D., 2008, Permeability of continental crust influenced by internal and external forcing: Geofluids, v. 8, no. 2, p. 128-139, https://doi.org/10.1111/j.1468-8123.2008.00211.x.","productDescription":"12 p.","startPage":"128","endPage":"139","costCenters":[{"id":245,"text":"Eastern Mineral and Environmental Resources Science Center","active":true,"usgs":true},{"id":615,"text":"Volcano Hazards Program","active":true,"usgs":true}],"links":[{"id":214165,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1111/j.1468-8123.2008.00211.x"},{"id":241859,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"8","issue":"2","noUsgsAuthors":false,"publicationDate":"2008-05-20","publicationStatus":"PW","scienceBaseUri":"505a76ade4b0c8380cd78259","contributors":{"authors":[{"text":"Rojstaczer, S.A.","contributorId":54620,"corporation":false,"usgs":true,"family":"Rojstaczer","given":"S.A.","email":"","affiliations":[],"preferred":false,"id":441599,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ingebritsen, S. E.","contributorId":8078,"corporation":false,"usgs":true,"family":"Ingebritsen","given":"S.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":441598,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hayba, D.O. 0000-0003-4092-1894","orcid":"https://orcid.org/0000-0003-4092-1894","contributorId":57850,"corporation":false,"usgs":true,"family":"Hayba","given":"D.O.","affiliations":[],"preferred":false,"id":441600,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033598,"text":"70033598 - 2008 - High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA","interactions":[],"lastModifiedDate":"2012-03-12T17:21:30","indexId":"70033598","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3443,"text":"Southeastern Geology","active":true,"publicationSubtype":{"id":10}},"title":"High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA","docAbstract":"Geophysical surveys, sedimentology, and optically-stimulated luminescence age analyses were used to assess the geologic development of a coastal system near Swansboro, NC. This area is a significant Woodland Period Native American habitation and is designated the \"Broad Reach\" archaeological site. 2-d and 3-d subsurface geophysical surveys were performed using a ground penetrating radar system to define the stratigraphic framework and depositional facies. Sediment samples were collected and analyzed for grain-size to determine depositional environments. Samples were acquired and analyzed using optically stimulated luminescence techniques to derive the depositional age of the various features. The data support a low eolian to shallow subtidal coastal depositional setting for this area. Li-DAR data reveal ridge and swale topography, most likely related to beach ridges, and eolian features including low-relief, low-angle transverse and parabolic dunes, blowouts, and a low-relief eolian sand sheet. Geophysical data reveal dominantly seaward dipping units, and low-angle mounded features. Sedimentological data reveal mostly moderately-well to well-sorted fine-grained symmetrical to coarse skewed sands, suggesting initial aqueous transport and deposition, followed by eolian reworking and bioturbation. OSL data indicate initial coastal deposition prior to ca. 45,000 yBP, followed by eolian reworking and low dune stabilization at ca. 13,000 to 11,500 yBP, and again at ca. 10,000 yBP (during, and slightly after the Younger Dryas chronozone).","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Southeastern Geology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","issn":"00383678","usgsCitation":"Mallinson, D., Mahan, S., and Moore, C., 2008, High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA: Southeastern Geology, v. 45, no. 3, p. 161-177.","startPage":"161","endPage":"177","numberOfPages":"17","costCenters":[],"links":[{"id":241892,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"45","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a30d1e4b0c8380cd5d991","contributors":{"authors":[{"text":"Mallinson, D.","contributorId":93686,"corporation":false,"usgs":true,"family":"Mallinson","given":"D.","affiliations":[],"preferred":false,"id":441607,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Mahan, S.","contributorId":98894,"corporation":false,"usgs":true,"family":"Mahan","given":"S.","email":"","affiliations":[],"preferred":false,"id":441608,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Moore, Christine","contributorId":21774,"corporation":false,"usgs":true,"family":"Moore","given":"Christine","email":"","affiliations":[],"preferred":false,"id":441606,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033611,"text":"70033611 - 2008 - Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 3. Use of microspheres to estimate the transport potential of Cryptosporidium parvum oocysts","interactions":[],"lastModifiedDate":"2018-10-22T09:08:08","indexId":"70033611","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3722,"text":"Water Resources Research","onlineIssn":"1944-7973","printIssn":"0043-1397","active":true,"publicationSubtype":{"id":10}},"displayTitle":"Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 3. Use of microspheres to estimate the transport potential of Cryptosporidium parvum oocysts","title":"Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 3. Use of microspheres to estimate the transport potential of Cryptosporidium parvum oocysts","docAbstract":"The vulnerability of a municipal well in the Northwest well field in southeastern Florida to potential contamination by Cryptosporidium parvum oocysts was assessed in a large‐scale, forced‐gradient (convergent) injection and recovery test. The field study involved a simultaneous pulse introduction of a nonreactive tracer (SF6, an inert gas) and oocyst‐sized (1.6, 2.9, and 4.9 μm diameter) carboxylated polystyrene microspheres into karst limestone of the Biscayne aquifer characterized by a complex triple (matrix, touching‐vug, and conduit) porosity. Fractional recoveries 97 m down gradient were inversely related to diameter and ranged from 2.9% for the 4.9 μm microspheres to 5.8% for 1.6 μm microspheres. Their centers of mass arrived at the pumping well approximately threefold earlier than that of the nonreactive tracer SF6 (gas), underscoring the need for use of colloid tracers and field‐scale tracer tests for these kinds of evaluations. In a modified triaxial cell using near in situ chemical conditions, 2.9 and 4.9 μm microspheres underestimated by fourfold to sixfold the attachment potential of the less electronegative 2.9–4.1 μm oocysts in the matrix porosity of limestone core samples. The field and laboratory results collectively suggested that it may take 200–300 m of transport to ensure even a 1‐log unit removal of oocysts, even though the limestone surfaces exhibited a substantive capability for their sorptive removal. The study further demonstrated the utility of microspheres as oocyst surrogates in field‐scale assessments of well vulnerability in limestone, provided that differences in attachment behaviors between oocysts and microspheres are taken into account.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2007WR006060","usgsCitation":"Harvey, R.W., Metge, D.W., Shapiro, A.M., Renken, R.A., Osborn, C.L., Ryan, J.N., Cunningham, K.J., and Landkamer, L.L., 2008, Pathogen and chemical transport in the karst limestone of the Biscayne aquifer: 3. Use of microspheres to estimate the transport potential of Cryptosporidium parvum oocysts: Water Resources Research, v. 44, no. 8, W08431; 12 p., https://doi.org/10.1029/2007WR006060.","productDescription":"W08431; 12 p.","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":476722,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/2007wr006060","text":"Publisher Index Page"},{"id":242057,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"44","issue":"8","noUsgsAuthors":false,"publicationDate":"2008-08-23","publicationStatus":"PW","scienceBaseUri":"505a7596e4b0c8380cd77c20","contributors":{"authors":[{"text":"Harvey, Ronald W. 0000-0002-2791-8503 rwharvey@usgs.gov","orcid":"https://orcid.org/0000-0002-2791-8503","contributorId":564,"corporation":false,"usgs":true,"family":"Harvey","given":"Ronald","email":"rwharvey@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441663,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Metge, David W. dwmetge@usgs.gov","contributorId":663,"corporation":false,"usgs":true,"family":"Metge","given":"David","email":"dwmetge@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":441665,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Shapiro, Allen M. 0000-0002-6425-9607 ashapiro@usgs.gov","orcid":"https://orcid.org/0000-0002-6425-9607","contributorId":2164,"corporation":false,"usgs":true,"family":"Shapiro","given":"Allen","email":"ashapiro@usgs.gov","middleInitial":"M.","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true},{"id":37277,"text":"WMA - Earth System Processes Division","active":true,"usgs":true}],"preferred":true,"id":441667,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Renken, Robert A. rarenken@usgs.gov","contributorId":269,"corporation":false,"usgs":true,"family":"Renken","given":"Robert","email":"rarenken@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":441668,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Osborn, Christina L.","contributorId":118702,"corporation":false,"usgs":false,"family":"Osborn","given":"Christina","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":441662,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Ryan, Joseph N.","contributorId":54290,"corporation":false,"usgs":false,"family":"Ryan","given":"Joseph","email":"","middleInitial":"N.","affiliations":[{"id":604,"text":"University of Colorado- Boulder","active":false,"usgs":true}],"preferred":false,"id":441669,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Cunningham, Kevin J. 0000-0002-2179-8686 kcunning@usgs.gov","orcid":"https://orcid.org/0000-0002-2179-8686","contributorId":1689,"corporation":false,"usgs":true,"family":"Cunningham","given":"Kevin","email":"kcunning@usgs.gov","middleInitial":"J.","affiliations":[{"id":269,"text":"FLWSC-Ft. Lauderdale","active":true,"usgs":true}],"preferred":true,"id":441664,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Landkamer, Lee L.","contributorId":65679,"corporation":false,"usgs":true,"family":"Landkamer","given":"Lee","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":441666,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70033612,"text":"70033612 - 2008 - Rain‐induced subsurface airflow and Lisse effect","interactions":[],"lastModifiedDate":"2018-04-03T11:48:56","indexId":"70033612","displayToPublicDate":"2008-01-01T00:00:00","publicationYear":"2008","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3722,"text":"Water Resources Research","onlineIssn":"1944-7973","printIssn":"0043-1397","active":true,"publicationSubtype":{"id":10}},"title":"Rain‐induced subsurface airflow and Lisse effect","docAbstract":"Water‐level increase after rainfall is usually indicative of rainfall recharge to groundwater. This, however, may not be true if the Lisse effect occurs. This effect represents the water‐level increase in a well driven by airflow induced by an advancing wetting front during highly intensive rains. The rainwater, which may behave like a low‐permeability lid, seals the ground surface so that the air pressure beneath the wetting front is increased because of air compression due to downward movement of the wetting front. A rapid and substantial rise of the water level in the well screened below water table, which bears no relationship to groundwater recharge, can be induced when various factors such as soil properties and the rain‐runoff condition combine favorably. A transient, three‐dimensional and variably saturated flow model was employed to study the air and groundwater flows in the soil under rain conditions. The objectives of this paper are two‐fold: to evaluate the reliability of the theory of the Lisse effect presented by Weeks to predict its magnitude in modeled situations that mimic the physical complexity of real aquifers, and to conduct parametric studies on the sensitivity of the water‐level rise in the well to soil properties and the rain event. The simulation results reveal that the magnitude of the Lisse effect increases with the ponding depth. Soil permeability plays a key role in generating the Lisse effect. The water‐level rise in the well is delayed relative to the air‐pressure rise in the unsaturated zone when the soil permeability is low, and the maximum water‐level rise is less than the maximum air pressure induced by rain infiltration. The simulation also explores the sensitivity of the Lisse effect to the van Genuchten parameters and the water table depth.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2007WR006294","usgsCitation":"Guo, H., Jiao, J.J., and Weeks, E.P., 2008, Rain‐induced subsurface airflow and Lisse effect: Water Resources Research, v. 44, no. 7, Article W07409; 9 p., https://doi.org/10.1029/2007WR006294.","productDescription":"Article W07409; 9 p.","costCenters":[],"links":[{"id":242090,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"44","issue":"7","noUsgsAuthors":false,"publicationDate":"2008-07-18","publicationStatus":"PW","scienceBaseUri":"505a944ae4b0c8380cd81301","contributors":{"authors":[{"text":"Guo, Haipeng","contributorId":152547,"corporation":false,"usgs":false,"family":"Guo","given":"Haipeng","email":"","affiliations":[],"preferred":false,"id":441670,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Jiao, Jiu J.","contributorId":80132,"corporation":false,"usgs":false,"family":"Jiao","given":"Jiu","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":441672,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Weeks, Edwin P. epweeks@usgs.gov","contributorId":2576,"corporation":false,"usgs":true,"family":"Weeks","given":"Edwin","email":"epweeks@usgs.gov","middleInitial":"P.","affiliations":[],"preferred":true,"id":441671,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ]}