The flow of water between rivers and contiguous aquifers influences the quantity and quality of water resources, particularly in regions where precipitation and runoff are unevenly distributed through the year, such as the Columbia Basin (CB) in northwestern United States. Investigations of basin hydrogeology and gains and losses of streamflow for six rivers in the CB were reviewed to characterize general patterns in the timing and location of river-aquifer exchanges at a reach-scale (0.5-150 km) and to identify geologic and geomorphic features associated with the largest exchanges. Ground-water discharge to each river, or the gain in streamflow, was concentrated spatially: more than one-half of the total gains along each river segment were contributed from reaches that represented no more than 30% of the total segment length with the largest and most concentrated gains in rivers in volcanic terrains. Fluvial recharge of aquifers, or losses of streamflow, was largest in rivers in sedimentary basins where unconsolidated sediments form shallow aquifers. Three types of geologic or geomorphic features were associated with the largest exchanges: (1) changes in the thickness of unconsolidated aquifers; (2) contacts between lithologic units that represent contrasts in permeability; and (3) channel forms that increase the hydraulic gradient or cross-sectional area of flow paths between a river and shallow ground-water. The down-valley component of ground-water flow and its vertical convergence on or divergence from a riverbed account for large streamflow gains in some reaches and contrast with the common assumption of lateral ground-water discharge to a river that penetrates completely through the aquifer. Increased ground-water discharge was observed during high-flow periods in reaches of four rivers indicating that changes in ground-water levels can be more important than stage fluctuations in regulating the direction and magnitude of river-aquifer exchanges and that assumptions about ground-water discharge during high flow periods used for base-flow separation must be verified. Given the variety of geologic terrains in the CB, the spatial and temporal patterns of river-aquifer exchanges provide a framework for investigations in other regions that includes a focus on reaches where the largest exchanges are likely to occur, integration of ground-water and surface-water data, and verification of assumptions regarding ground-water flow direction and temporal variation of exchanges. ?? 2006 Elsevier B.V. All rights reserved.
","language":"English","publisher":"Elsevier","doi":"10.1016/j.jhydrol.2006.02.028","issn":"00221694","usgsCitation":"Konrad, C., 2006, Location and timing of river-aquifer exchanges in six tributaries to the Columbia River in the Pacific Northwest of the United States: Journal of Hydrology, v. 329, no. 3-4, p. 444-470, https://doi.org/10.1016/j.jhydrol.2006.02.028.","productDescription":"27 p.","startPage":"444","endPage":"470","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":622,"text":"Washington Water Science Center","active":true,"usgs":true}],"links":[{"id":236433,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":209736,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.jhydrol.2006.02.028"}],"volume":"329","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a490be4b0c8380cd68305","contributors":{"authors":[{"text":"Konrad, C.P.","contributorId":39027,"corporation":false,"usgs":true,"family":"Konrad","given":"C.P.","email":"","affiliations":[],"preferred":false,"id":419121,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70028662,"text":"70028662 - 2006 - Coulomb stress transfer and tectonic loading preceding the 2002 Denali fault earthquake","interactions":[],"lastModifiedDate":"2017-04-26T14:03:11","indexId":"70028662","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","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":"Coulomb stress transfer and tectonic loading preceding the 2002 Denali fault earthquake","docAbstract":"Pre-2002 tectonic loading and Coulomb stress transfer are modeled along the rupture zone of the M 7.9 Denali fault earthquake (DFE) and on adjacent segments of the right-lateral Denali–Totschunda fault system in central Alaska, using a three-dimensional boundary-element program. The segments modeled closely follow, for about 95°, the arc of a circle of radius 375 km centered on an inferred asperity near the northeastern end of the intersection of the Patton Bay fault with the Alaskan megathrust under Prince William Sound. The loading model includes slip of 6 mm/yr below 12 km along the fault system, consistent with rotation of the Wrangell block about the asperity at a rate of about 1°/m.y. as well as slip of the Pacific plate at 5 cm/yr at depth along the Fairweather–Queen Charlotte transform fault system and on the Alaska megathrust. The model is consistent with most available pre-2002 Global Positioning System (GPS) displacement rate data. Coulomb stresses induced on the Denali–Totschunda fault system (locked above 12 km) by slip at depth and by transfer from the M 9.2 Prince William Sound earthquake of 1964 dominated the changing Coulomb stress distribution along the fault. The combination of loading (∼70–85%) and coseismic stress transfer from the great 1964 earthquake (∼15–30%) were the principal post-1900 stress factors building toward strike-slip failure of the northern Denali and Totschunda segments in the M 7.9 earthquake of November 2002. Postseismic stresses transferred from the 1964 earthquake may also have been a significant factor. The M 7.2–7.4 Delta River earthquake of 1912 (Carver et al., 2004) may have delayed or advanced the timing of the DFE, depending on the details and location of its rupture. The initial subevent of the 2002 DFE earthquake was on the 40-km Susitna Glacier thrust fault at the western end of the Denali fault rupture. The Coulomb stress transferred from the 1964 earthquake moved the Susitna Glacier thrust fault uniformly away from thrust failure by about 100 kPa. The initiation of the Denali fault earthquake was advanced by transfer of 30–50 kPa of positive Coulomb stress to the Susitna Glacier fault (Anderson and Ji, 2003) by the nearby M 6.7 Nenana Mountain foreshock of 23 October 2002. The regional tectonic loading model used here suggests that the Semidi (Alaska Peninsula) segment of the megathrust that ruptured in 1938 (M 8.2) may be reloaded and approaching failure.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/0120050007","issn":"00371106","usgsCitation":"Bufe, C.G., 2006, Coulomb stress transfer and tectonic loading preceding the 2002 Denali fault earthquake: Bulletin of the Seismological Society of America, v. 96, no. 5, p. 1662-1674, https://doi.org/10.1785/0120050007.","productDescription":"13","startPage":"1662","endPage":"1674","costCenters":[],"links":[{"id":236368,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"96","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059fc84e4b0c8380cd4e2c5","contributors":{"authors":[{"text":"Bufe, Charles G. cbufe@usgs.gov","contributorId":1621,"corporation":false,"usgs":true,"family":"Bufe","given":"Charles","email":"cbufe@usgs.gov","middleInitial":"G.","affiliations":[],"preferred":true,"id":419114,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70028661,"text":"70028661 - 2006 - Adsorption site analysis of impurity embedded single-walled carbon nanotube bundles","interactions":[],"lastModifiedDate":"2012-03-12T17:20:56","indexId":"70028661","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1182,"text":"Carbon","active":true,"publicationSubtype":{"id":10}},"title":"Adsorption site analysis of impurity embedded single-walled carbon nanotube bundles","docAbstract":"Bundle morphology and adsorptive contributions from nanotubes and impurities are studied both experimentally and by simulation using a computer-aided methodology, which employs a small physisorbed probe molecule to explore the porosity of nanotube samples. Grand canonical Monte Carlo simulation of nitrogen adsorption on localized sites of a bundle is carried out to predict adsorption in its accessible internal pore volume and on its external surface as a function of tube diameter. External adsorption is split into the contributions from the clean surface of the outermost nanotubes of the bundle and from the surface of the impurities. The site-specific isotherms are then combined into a global isotherm for a given sample using knowledge of its tube-diameter distribution obtained by Raman spectroscopy. The structural parameters of the sample, such as the fraction of open-ended nanotubes and the contributions from impurities and nanotube bundles to total external surface area, are determined by fitting the experimental nitrogen adsorption data to the simulated isotherm. The degree of closure between experimental and calculated adsorption isotherms for samples manufactured by two different methods, to provide different nanotube morphology and contamination level, further strengthens the validity and resulting interpretations based on the proposed approach. The average number of nanotubes per bundle and average bundle size, within a sample, are also quantified. The proposed method allows for extrapolation of adsorption properties to conditions where the purification process is 100% effective at removing all impurities and opening access to all intrabundle adsorption sites. ?? 2006 Elsevier Ltd. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Carbon","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.carbon.2006.05.038","issn":"00086223","usgsCitation":"Agnihotri, S., Mota, J., Rostam-Abadi, M., and Rood, M., 2006, Adsorption site analysis of impurity embedded single-walled carbon nanotube bundles: Carbon, v. 44, no. 12, p. 2376-2383, https://doi.org/10.1016/j.carbon.2006.05.038.","startPage":"2376","endPage":"2383","numberOfPages":"8","costCenters":[],"links":[{"id":209691,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.carbon.2006.05.038"},{"id":236367,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"44","issue":"12","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e6fee4b0c8380cd477a3","contributors":{"authors":[{"text":"Agnihotri, S.","contributorId":19344,"corporation":false,"usgs":true,"family":"Agnihotri","given":"S.","email":"","affiliations":[],"preferred":false,"id":419112,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Mota, J.P.B.","contributorId":18937,"corporation":false,"usgs":true,"family":"Mota","given":"J.P.B.","email":"","affiliations":[],"preferred":false,"id":419111,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Rostam-Abadi, M.","contributorId":37061,"corporation":false,"usgs":true,"family":"Rostam-Abadi","given":"M.","affiliations":[],"preferred":false,"id":419113,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Rood, M.J.","contributorId":15354,"corporation":false,"usgs":true,"family":"Rood","given":"M.J.","email":"","affiliations":[],"preferred":false,"id":419110,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70028660,"text":"70028660 - 2006 - Testing of stack-unit/aquifer sensitivity analysis using contaminant plume distribution in the subsurface of Savannah River Site, South Carolina, USA","interactions":[],"lastModifiedDate":"2017-01-18T12:52:28","indexId":"70028660","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","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":"Testing of stack-unit/aquifer sensitivity analysis using contaminant plume distribution in the subsurface of Savannah River Site, South Carolina, USA","docAbstract":"Published information on the correlation and field-testing of the technique of stack-unit/aquifer sensitivity mapping with documented subsurface contaminant plumes is rare. The inherent characteristic of stack-unit mapping, which makes it a superior technique to other analyses that amalgamate data, is the ability to deconstruct the sensitivity analysis on a unit-by-unit basis. An aquifer sensitivity map, delineating the relative sensitivity of the Crouch Branch aquifer of the Administrative/Manufacturing Area (A/M) at the Savannah River Site (SRS) in South Carolina, USA, incorporates six hydrostratigraphic units, surface soil units, and relevant hydrologic data. When this sensitivity map is compared with the distribution of the contaminant tetrachloroethylene (PCE), PCE is present within the Crouch Branch aquifer within an area classified as highly sensitive, even though the PCE was primarily released on the ground surface within areas classified with low aquifer sensitivity. This phenomenon is explained through analysis of the aquifer sensitivity map, the groundwater potentiometric surface maps, and the plume distributions within the area on a unit-by- unit basis. The results of this correlation show how the paths of the PCE plume are influenced by both the geology and the groundwater flow. ?? Springer-Verlag 2006.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrogeology Journal","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1007/s10040-006-0083-7","issn":"14312174","usgsCitation":"Rine, J., Shafer, J., Covington, E., and Berg, R.C., 2006, Testing of stack-unit/aquifer sensitivity analysis using contaminant plume distribution in the subsurface of Savannah River Site, South Carolina, USA: Hydrogeology Journal, v. 14, no. 8, p. 1620-1634, https://doi.org/10.1007/s10040-006-0083-7.","startPage":"1620","endPage":"1634","numberOfPages":"15","costCenters":[{"id":13634,"text":"South Atlantic Water Science Center","active":true,"usgs":true}],"links":[{"id":236331,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":209662,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/s10040-006-0083-7"}],"country":"United 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Carolina\",\"nation\":\"USA \"}}]}","volume":"14","issue":"8","noUsgsAuthors":false,"publicationDate":"2006-08-18","publicationStatus":"PW","scienceBaseUri":"505ba5cbe4b08c986b320ca8","contributors":{"authors":[{"text":"Rine, J.M.","contributorId":53145,"corporation":false,"usgs":true,"family":"Rine","given":"J.M.","email":"","affiliations":[],"preferred":false,"id":419107,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Shafer, J.M.","contributorId":72995,"corporation":false,"usgs":true,"family":"Shafer","given":"J.M.","email":"","affiliations":[],"preferred":false,"id":419108,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Covington, E.","contributorId":92031,"corporation":false,"usgs":true,"family":"Covington","given":"E.","email":"","affiliations":[],"preferred":false,"id":419109,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Berg, R. C.","contributorId":11673,"corporation":false,"usgs":true,"family":"Berg","given":"R.","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":419106,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70028656,"text":"70028656 - 2006 - Slip on the San Andreas fault at Parkfield, California, over two earthquake cycles, and the implications for seismic hazard","interactions":[],"lastModifiedDate":"2012-03-12T17:20:57","indexId":"70028656","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","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":"Slip on the San Andreas fault at Parkfield, California, over two earthquake cycles, and the implications for seismic hazard","docAbstract":"Parkfield, California, which experienced M 6.0 earthquakes in 1934, 1966, and 2004, is one of the few locales for which geodetic observations span multiple earthquake cycles. We undertake a comprehensive study of deformation over the most recent earthquake cycle and explore the results in the context of geodetic data collected prior to the 1966 event. Through joint inversion of the variety of Parkfield geodetic measurements (trilateration, two-color laser, and Global Positioning System), including previously unpublished two-color data, we estimate the spatial distribution of slip and slip rate along the San Andreas using a fault geometry based on precisely relocated seismicity. Although the three most recent Parkfield earthquakes appear complementary in their along-strike distributions of slip, they do not produce uniform strain release along strike over multiple seismic cycles. Since the 1934 earthquake, more than 1 m of slip deficit has accumulated on portions of the fault that slipped in the 1966 and 2004 earthquakes, and an average of 2 m of slip deficit exists on the 33 km of the fault southeast of Gold Hill to be released in a future, perhaps larger, earthquake. It appears that the fault is capable of partially releasing stored strain in moderate earthquakes, maintaining a disequilibrium through multiple earthquake cycles. This complicates the application of simple earthquake recurrence models that assume only the strain accumulated since the most recent event is relevant to the size or timing of an upcoming earthquake. Our findings further emphasize that accumulated slip deficit is not sufficient for earthquake nucleation.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Bulletin of the Seismological Society of America","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1785/0120050820","issn":"00371106","usgsCitation":"Murray, J., and Langbein, J., 2006, Slip on the San Andreas fault at Parkfield, California, over two earthquake cycles, and the implications for seismic hazard: Bulletin of the Seismological Society of America, v. 96, no. 4 B, https://doi.org/10.1785/0120050820.","costCenters":[],"links":[{"id":209603,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1785/0120050820"},{"id":236256,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"96","issue":"4 B","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b914be4b08c986b319811","contributors":{"authors":[{"text":"Murray, J.","contributorId":94837,"corporation":false,"usgs":true,"family":"Murray","given":"J.","affiliations":[],"preferred":false,"id":419093,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Langbein, J.","contributorId":16990,"corporation":false,"usgs":true,"family":"Langbein","given":"J.","affiliations":[],"preferred":false,"id":419092,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70028653,"text":"70028653 - 2006 - Research approach to teaching groundwater biodegradation in karst aquifers","interactions":[],"lastModifiedDate":"2012-03-12T17:20:43","indexId":"70028653","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Research approach to teaching groundwater biodegradation in karst aquifers","docAbstract":"TSU in partnership with the USGS has conducted extensive research regarding biode??gradation of contaminants in karst aquifers. This research resulted in the development of a numerical approach to modeling biodegradation of contaminants in karst aquifers that is taught to environmental engineering students in several steps. First, environmental engineering students are taught chemical-reaction engineering principles relating to a wide variety of environmental fate and transport issues. Second, as part of TSU's engineering course curriculum, students use a non-ideal flow laboratory reactor system and run a tracer study to establish residence time distribution (RTD). Next, the students couple that formula to a first-order biodegradation rate and predict the removal of a biodegradable contaminant as a function of residence time. Following this, students are shown data collected from karst bedrock wells that suggest that karst aquifers are analogous to non-ideal flow reactors. The students are challenged to develop rates of biodegradation through lab studies and use their results to predict biodegradaton at an actual contaminated karst site. Field studies are also conducted to determine the accuracy of the students' predictions. This academic approach teaches biodegradation processes, rate-kinetic processes, hydraulic processes and numerical principles. The students are able to experience how chemical engineering principles can be applied to other situations, such as, modeling biodegradation of contaminants in karst aquifers. This paper provides background on the chemical engineering principles and karst issues used in the research-enhanced curriculum. ?? American Society for Engineering Education, 2006.","largerWorkTitle":"ASEE Annual Conference and Exposition, Conference Proceedings","conferenceTitle":"113th Annual ASEE Conference and Exposition, 2006","conferenceDate":"18 June 2006 through 21 June 2006","conferenceLocation":"Chicago, IL","language":"English","usgsCitation":"King, L., Byl, T., and Painter, R., 2006, Research approach to teaching groundwater biodegradation in karst aquifers, in ASEE Annual Conference and Exposition, Conference Proceedings, Chicago, IL, 18 June 2006 through 21 June 2006.","numberOfPages":"12","costCenters":[],"links":[{"id":236779,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505aa91be4b0c8380cd85c0e","contributors":{"authors":[{"text":"King, L.","contributorId":23744,"corporation":false,"usgs":true,"family":"King","given":"L.","email":"","affiliations":[],"preferred":false,"id":419072,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Byl, T.","contributorId":31967,"corporation":false,"usgs":true,"family":"Byl","given":"T.","email":"","affiliations":[],"preferred":false,"id":419073,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Painter, R.","contributorId":54393,"corporation":false,"usgs":true,"family":"Painter","given":"R.","email":"","affiliations":[],"preferred":false,"id":419074,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70028648,"text":"70028648 - 2006 - Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP","interactions":[],"lastModifiedDate":"2012-03-12T17:20:44","indexId":"70028648","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2033,"text":"International Journal of Coal Geology","active":true,"publicationSubtype":{"id":10}},"title":"Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP","docAbstract":"The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation. The same statistical approach as that followed in the ICCP vitrinite reflectance accreditation program for single seam coals has been used for data evaluation. The results indicated low to medium dispersion for 17 out of 22 participants. This, combined with data from other sets of comparative analyses over a long period, is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter. ?? 2006 ICCP.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"International Journal of Coal Geology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.coal.2006.02.002","issn":"01665162","usgsCitation":"Borrego, A., Araujo, C., Balke, A., Cardott, B., Cook, A., David, P., Flores, D., Hamor-Vido, M., Hiltmann, W., Kalkreuth, W., Koch, J., Kommeren, C., Kus, J., Ligouis, B., Marques, M., Mendonca Filho, J., Misz, M., Oliveira, L., Pickel, W., Reimer, K., Ranasinghe, P., Suarez-Ruiz, I., and Vieth, A., 2006, Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP: International Journal of Coal Geology, v. 68, no. 3-4, p. 151-170, https://doi.org/10.1016/j.coal.2006.02.002.","startPage":"151","endPage":"170","numberOfPages":"20","costCenters":[],"links":[{"id":209922,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.coal.2006.02.002"},{"id":236678,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"68","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3b63e4b0c8380cd624b0","contributors":{"authors":[{"text":"Borrego, A.G.","contributorId":53583,"corporation":false,"usgs":true,"family":"Borrego","given":"A.G.","email":"","affiliations":[],"preferred":false,"id":419020,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Araujo, C.V.","contributorId":36738,"corporation":false,"usgs":true,"family":"Araujo","given":"C.V.","email":"","affiliations":[],"preferred":false,"id":419018,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Balke, A.","contributorId":78524,"corporation":false,"usgs":true,"family":"Balke","given":"A.","email":"","affiliations":[],"preferred":false,"id":419025,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Cardott, B.","contributorId":25342,"corporation":false,"usgs":true,"family":"Cardott","given":"B.","email":"","affiliations":[],"preferred":false,"id":419015,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Cook, A.C.","contributorId":43133,"corporation":false,"usgs":true,"family":"Cook","given":"A.C.","email":"","affiliations":[],"preferred":false,"id":419019,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"David, P.","contributorId":14180,"corporation":false,"usgs":true,"family":"David","given":"P.","email":"","affiliations":[],"preferred":false,"id":419013,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Flores, D.","contributorId":107915,"corporation":false,"usgs":true,"family":"Flores","given":"D.","email":"","affiliations":[],"preferred":false,"id":419032,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Hamor-Vido, M.","contributorId":25343,"corporation":false,"usgs":true,"family":"Hamor-Vido","given":"M.","affiliations":[],"preferred":false,"id":419016,"contributorType":{"id":1,"text":"Authors"},"rank":8},{"text":"Hiltmann, W.","contributorId":71371,"corporation":false,"usgs":true,"family":"Hiltmann","given":"W.","email":"","affiliations":[],"preferred":false,"id":419024,"contributorType":{"id":1,"text":"Authors"},"rank":9},{"text":"Kalkreuth, W.","contributorId":12255,"corporation":false,"usgs":true,"family":"Kalkreuth","given":"W.","email":"","affiliations":[],"preferred":false,"id":419012,"contributorType":{"id":1,"text":"Authors"},"rank":10},{"text":"Koch, J.","contributorId":7065,"corporation":false,"usgs":false,"family":"Koch","given":"J.","affiliations":[],"preferred":false,"id":419010,"contributorType":{"id":1,"text":"Authors"},"rank":11},{"text":"Kommeren, C.J.","contributorId":103852,"corporation":false,"usgs":true,"family":"Kommeren","given":"C.J.","email":"","affiliations":[],"preferred":false,"id":419031,"contributorType":{"id":1,"text":"Authors"},"rank":12},{"text":"Kus, J.","contributorId":98523,"corporation":false,"usgs":true,"family":"Kus","given":"J.","email":"","affiliations":[],"preferred":false,"id":419029,"contributorType":{"id":1,"text":"Authors"},"rank":13},{"text":"Ligouis, B.","contributorId":59228,"corporation":false,"usgs":true,"family":"Ligouis","given":"B.","email":"","affiliations":[],"preferred":false,"id":419021,"contributorType":{"id":1,"text":"Authors"},"rank":14},{"text":"Marques, M.","contributorId":102260,"corporation":false,"usgs":true,"family":"Marques","given":"M.","email":"","affiliations":[],"preferred":false,"id":419030,"contributorType":{"id":1,"text":"Authors"},"rank":15},{"text":"Mendonca Filho, J.G.","contributorId":26128,"corporation":false,"usgs":true,"family":"Mendonca Filho","given":"J.G.","affiliations":[],"preferred":false,"id":419017,"contributorType":{"id":1,"text":"Authors"},"rank":16},{"text":"Misz, M.","contributorId":68524,"corporation":false,"usgs":true,"family":"Misz","given":"M.","email":"","affiliations":[],"preferred":false,"id":419023,"contributorType":{"id":1,"text":"Authors"},"rank":17},{"text":"Oliveira, L.","contributorId":98099,"corporation":false,"usgs":true,"family":"Oliveira","given":"L.","email":"","affiliations":[],"preferred":false,"id":419028,"contributorType":{"id":1,"text":"Authors"},"rank":18},{"text":"Pickel, W.","contributorId":64014,"corporation":false,"usgs":true,"family":"Pickel","given":"W.","affiliations":[],"preferred":false,"id":419022,"contributorType":{"id":1,"text":"Authors"},"rank":19},{"text":"Reimer, K.","contributorId":14998,"corporation":false,"usgs":true,"family":"Reimer","given":"K.","email":"","affiliations":[],"preferred":false,"id":419014,"contributorType":{"id":1,"text":"Authors"},"rank":20},{"text":"Ranasinghe, P.","contributorId":92477,"corporation":false,"usgs":true,"family":"Ranasinghe","given":"P.","affiliations":[],"preferred":false,"id":419027,"contributorType":{"id":1,"text":"Authors"},"rank":21},{"text":"Suarez-Ruiz, I.","contributorId":10598,"corporation":false,"usgs":true,"family":"Suarez-Ruiz","given":"I.","affiliations":[],"preferred":false,"id":419011,"contributorType":{"id":1,"text":"Authors"},"rank":22},{"text":"Vieth, A.","contributorId":92036,"corporation":false,"usgs":true,"family":"Vieth","given":"A.","email":"","affiliations":[],"preferred":false,"id":419026,"contributorType":{"id":1,"text":"Authors"},"rank":23}]}} ,{"id":70028645,"text":"70028645 - 2006 - The ionospheric impact on GPS performance in southern polar region","interactions":[],"lastModifiedDate":"2012-03-12T17:20:44","indexId":"70028645","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"The ionospheric impact on GPS performance in southern polar region","docAbstract":"The primary objective of this paper is to present the results of the study of the effects of varying ionospheric conditions on the GPS signal tracking in the southern polar region. In the first stage of this study, the data collected by the OSU/USGS team in October-November 2003 within the TAMDEF (Transantarctic Mountains Deformation) network were used together with some IGS Antarctic stations to study the effect of severe ionospheric storms on GPS hardware. Note that TAMDEF is a joint USGS/OSU project with the primary objective of measuring crustal motion in the Transantarctic Mountains of Southern Victoria Land using GPS techniques. This study included ten Antarctic stations equipped with different dual-frequency GPS hardware, and the data were evaluated for two 24-hour periods of severe ionospheric storm (2003/10/29) and moderate ionospheric conditions (minor storm of 2003/11/11). The results of this study were presented at the LAG Assembly in Cairns, Australia (Grejner-Brzezinska et al., 2005). Additional tests, in a more controlled environment, were carried out at the US Antarctic station, McMurdo, between January 10 and February 6, 2006, under varying ionospheric conditions, where several different types of receivers were connected to the same antenna located on the rooftop of the Crary Laboratory (the primary test site). In this scenario, each antenna was subject to identical ionospheric effects during each day of the test, and no spatial decorrelation effects were present, as seen in the previous study, due to the spatial separation of the receivers tested. It should be noted, however, that no moderate or severe ionospheric storms occurred during the experiment, so, unfortunately, this type of conditions was not tested here. The test was repeated with different receivers connected to different antenna types; a total of four 5-day sessions were carried out. The following receiver types were used at the primary site: Trimble 5700, Ashtech Z-Surveyor, JNS Euro-80 and Novatel DL-4, with the following antennas: Trimble Zephyr Geodetic, Ashtech D/M and Ashtech E/M chokering. In addition, data collected by the MCM4 IGS station, MCMD UNAVCO station, and CRAR USGS station, all located within 300 m from the primary test site, were used in the analyses. These stations were equipped with the following receiver/antenna combinations: ADA SNR-12/AOAD/MJT chokering (MCM4), Trimble NETRS/AOAD/MJT chokering (MCMD), and TPS ODYSEY_E/JPSREGANT_DD_E (CRAR). The UNAVCO TEQC software was used to carry out the analyses. Depending on the data sampling rate and the mask angle, the expected numbers of observations per receiver/satellite were compared to the actual number of measurements collected during the ionospheric events, with a special emphasis on L2 data. A total number of cycle slips and losses of lock were computed and compared among the hardware types. The results presented here indicate that there is no significant effects on the GPS receivers during minor ionospheric storms (Kp<5). However, the results reported in ibid, indicate significant differences in the hardware performance under severe ionospheric storms. Thus, careful hardware selection is needed to assure data quality/continuity when observations may be affected by severe ionospheric disturbances, while under calm to minor ionospheric activity level there is no significant difference in performance among the hardware tested here.","largerWorkTitle":"Proceedings of the Institute of Navigation - 19th International Technical Meeting of the Satellite Division, ION GNSS 2006","conferenceTitle":"Institute of Navigation - 19th International Technical Meeting of the Satellite Division, ION GNSS 2006","conferenceDate":"26 September 2006 through 29 September 2006","conferenceLocation":"Fort Worth, TX","language":"English","usgsCitation":"Hong, C., Grejner-Brzezinska, D.A., Arslan, N., Willis, M., and Hothem, L., 2006, The ionospheric impact on GPS performance in southern polar region, in Proceedings of the Institute of Navigation - 19th International Technical Meeting of the Satellite Division, ION GNSS 2006, v. 3, Fort Worth, TX, 26 September 2006 through 29 September 2006, p. 1418-1426.","startPage":"1418","endPage":"1426","numberOfPages":"9","costCenters":[],"links":[{"id":236605,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bad64e4b08c986b323bab","contributors":{"authors":[{"text":"Hong, C.-K.","contributorId":90526,"corporation":false,"usgs":true,"family":"Hong","given":"C.-K.","email":"","affiliations":[],"preferred":false,"id":419004,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Grejner-Brzezinska, D. A.","contributorId":42772,"corporation":false,"usgs":true,"family":"Grejner-Brzezinska","given":"D.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":419001,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Arslan, N.","contributorId":86557,"corporation":false,"usgs":true,"family":"Arslan","given":"N.","email":"","affiliations":[],"preferred":false,"id":419003,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Willis, M.","contributorId":82910,"corporation":false,"usgs":true,"family":"Willis","given":"M.","email":"","affiliations":[],"preferred":false,"id":419002,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Hothem, L.","contributorId":13801,"corporation":false,"usgs":true,"family":"Hothem","given":"L.","email":"","affiliations":[],"preferred":false,"id":419000,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70028644,"text":"70028644 - 2006 - Inhibition of coral recruitment by macroalgae and cyanobacteria","interactions":[],"lastModifiedDate":"2012-03-12T17:20:59","indexId":"70028644","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","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":"Inhibition of coral recruitment by macroalgae and cyanobacteria","docAbstract":"Coral recruitment is a key process in the maintenance and recovery of coral reef ecosystems. While intense competition between coral and algae is often assumed on reefs that have undergone phase shifts from coral to algal dominance, data examining the competitive interactions involved, particularly during the larval and immediate post-settlement stage, are scarce. Using a series of field and outdoor seawater table experiments, we tested the hypothesis that common species of macroalgae and cyanobacteria inhibit coral recruitment. We examined the effects of Lyngbya spp., Dictyota spp., Lobophora variegata (J. V. Lamouroux) Womersley, and Chondrophycus poiteaui (J. V. Lamouroux) Nam (formerly Laurencia poiteaui) on the recruitment success of Porites astreoides larvae. All species but C. poiteaui caused either recruitment inhibition or avoidance behavior in P. astreoides larvae, while L. confervoides and D. menstrualis significantly increased mortality rates of P. astreoides recruits. We also tested the effect of some of these macrophytes on larvae of the gorgonian octocoral Briareum asbestinum. Exposure to Lyngbya majuscula reduced survival and recruitment in the octocoral larvae. Our results provide evidence that algae and cyanobacteria use tactics beyond space occupation to inhibit coral recruitment. On reefs experiencing phase shifts or temporary algal blooms, the restocking of adult coral populations may be slowed due to recruitment inhibition, thereby perpetuating reduced coral cover and limiting coral community recovery. ?? Inter-Research 2006.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Marine Ecology Progress Series","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.3354/meps323107","issn":"01718630","usgsCitation":"Kuffner, I., Walters, L., Becerro, M., Paul, V., Ritson-Williams, R., and Beach, K., 2006, Inhibition of coral recruitment by macroalgae and cyanobacteria: Marine Ecology Progress Series, v. 323, p. 107-117, https://doi.org/10.3354/meps323107.","startPage":"107","endPage":"117","numberOfPages":"11","costCenters":[],"links":[{"id":477687,"rank":10000,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://doi.org/10.3354/meps323107","text":"External Repository"},{"id":209842,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.3354/meps323107"},{"id":236573,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"323","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3bd7e4b0c8380cd62878","contributors":{"authors":[{"text":"Kuffner, I. B.","contributorId":40328,"corporation":false,"usgs":true,"family":"Kuffner","given":"I. B.","affiliations":[],"preferred":false,"id":418996,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Walters, L.J.","contributorId":107081,"corporation":false,"usgs":true,"family":"Walters","given":"L.J.","email":"","affiliations":[],"preferred":false,"id":418999,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Becerro, M.A.","contributorId":18956,"corporation":false,"usgs":true,"family":"Becerro","given":"M.A.","affiliations":[],"preferred":false,"id":418994,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Paul, V.J.","contributorId":40782,"corporation":false,"usgs":true,"family":"Paul","given":"V.J.","email":"","affiliations":[],"preferred":false,"id":418997,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Ritson-Williams, R.","contributorId":88546,"corporation":false,"usgs":true,"family":"Ritson-Williams","given":"R.","affiliations":[],"preferred":false,"id":418998,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Beach, K.S.","contributorId":37134,"corporation":false,"usgs":true,"family":"Beach","given":"K.S.","email":"","affiliations":[],"preferred":false,"id":418995,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70028642,"text":"70028642 - 2006 - Pelagic seabird surveys in the Tuamotu and Gambier Archipelagos, French Polynesia","interactions":[],"lastModifiedDate":"2018-08-21T13:08:10","indexId":"70028642","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2675,"text":"Marine Ornithology: Journal of Seabird Research and Conservation","onlineIssn":"2074-1235","printIssn":"1018-3337","active":true,"publicationSubtype":{"id":10}},"title":"Pelagic seabird surveys in the Tuamotu and Gambier Archipelagos, French Polynesia","docAbstract":"We conducted pelagic seabird surveys in the Gambier and Tuamotu Archipelagos in the southeastern Pacific Ocean totaling 40 hours during 7-27 March 2003 and 22.5 hours during 22-27 July 2001. We used a 300-m-wide strip transect to estimate seabird density, and we estimated relative abundance of birds at all distances. In 2001, we observed a total of 326 birds of 18 species. The mean relative abundance of all birds was 14.3 ?? 3.1/h. Red-footed Booby Sula sula was the most abundant species (5.6/h), followed by White Tern Gygis alba (3.4/h), and Great Crested or Swift Tern Sterna bergii (1.2/h). In 2003, we observed a total of 1463 birds of 25 species. The mean relative abundance of all birds was 36.6 ?? 11.4/h and the mean density of all birds was 4.14 ?? 0.72/km2. Brown Noddy Anous stolidus was the most abundant species (17.6/h, 1.5/km2), followed by White Tern (8.4/h, 1.3/km2), and Red-footed Booby (4.6/h, 0.8/km2). Several globally or locally rare species were observed infrequently, including Phoenix Petrel Pterodroma alba (0.1/h, 0.03/km2). Distribution of birds was uneven, with long periods of no birds punctuated by occasional feeding flocks. In 2003, species diversity was related to length of observation period, with more species observed on longer segments (r2 = 0.58, F1.5 = 6.03, P = 0.05). Although the duration and extent of our surveys were limited, these data are valuable because little published information is available on pelagic seabirds in southeastern Polynesia.","language":"English","publisher":"Pacific Seabird Group","issn":"10183337","usgsCitation":"Vanderwerf, E.A., Pierce, R.J., Gill, V., Wragg, G., Raust, P., and Tibbitts, T.L., 2006, Pelagic seabird surveys in the Tuamotu and Gambier Archipelagos, French Polynesia: Marine Ornithology: Journal of Seabird Research and Conservation, v. 34, no. 1, p. 65-70.","productDescription":"6 p.","startPage":"65","endPage":"70","costCenters":[{"id":114,"text":"Alaska Science Center","active":true,"usgs":true},{"id":117,"text":"Alaska Science Center Biology WTEB","active":true,"usgs":true}],"links":[{"id":236538,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":337053,"rank":2,"type":{"id":15,"text":"Index Page"},"url":"https://www.marineornithology.org/content/get.cgi?rn=684"}],"country":"France","state":"French Polynesia","otherGeospatial":"Gambier Archipelago, Tuamotu Archipelago","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -150,\n -10\n ],\n [\n -134,\n -10\n ],\n [\n -134,\n -25\n ],\n [\n -150,\n -25\n ],\n [\n -150,\n -10\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"34","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a763ce4b0c8380cd77fd7","contributors":{"authors":[{"text":"Vanderwerf, Eric A.","contributorId":104689,"corporation":false,"usgs":false,"family":"Vanderwerf","given":"Eric","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":418988,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Pierce, Ray J.","contributorId":16635,"corporation":false,"usgs":false,"family":"Pierce","given":"Ray","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":418984,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gill, Verena A.","contributorId":140658,"corporation":false,"usgs":false,"family":"Gill","given":"Verena A.","affiliations":[{"id":6678,"text":"U.S. Fish and Wildlife Service, Alaska Maritime National Wildlife Refuge","active":true,"usgs":false}],"preferred":false,"id":418986,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Wragg, Graham","contributorId":8272,"corporation":false,"usgs":false,"family":"Wragg","given":"Graham","email":"","affiliations":[],"preferred":false,"id":418983,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Raust, Philippe","contributorId":46288,"corporation":false,"usgs":false,"family":"Raust","given":"Philippe","email":"","affiliations":[],"preferred":false,"id":418987,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Tibbitts, T. Lee 0000-0002-0290-7592 ltibbitts@usgs.gov","orcid":"https://orcid.org/0000-0002-0290-7592","contributorId":140455,"corporation":false,"usgs":true,"family":"Tibbitts","given":"T.","email":"ltibbitts@usgs.gov","middleInitial":"Lee","affiliations":[{"id":114,"text":"Alaska Science Center","active":true,"usgs":true},{"id":117,"text":"Alaska Science Center Biology WTEB","active":true,"usgs":true}],"preferred":false,"id":418985,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70028635,"text":"70028635 - 2006 - Importance of spatial autocorrelation in modeling bird distributions at a continental scale","interactions":[],"lastModifiedDate":"2012-03-12T17:20:59","indexId":"70028635","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1445,"text":"Ecography","active":true,"publicationSubtype":{"id":10}},"title":"Importance of spatial autocorrelation in modeling bird distributions at a continental scale","docAbstract":"Spatial autocorrelation in species' distributions has been recognized as inflating the probability of a type I error in hypotheses tests, causing biases in variable selection, and violating the assumption of independence of error terms in models such as correlation or regression. However, it remains unclear whether these problems occur at all spatial resolutions and extents, and under which conditions spatially explicit modeling techniques are superior. Our goal was to determine whether spatial models were superior at large extents and across many different species. In addition, we investigated the importance of purely spatial effects in distribution patterns relative to the variation that could be explained through environmental conditions. We studied distribution patterns of 108 bird species in the conterminous United States using ten years of data from the Breeding Bird Survey. We compared the performance of spatially explicit regression models with non-spatial regression models using Akaike's information criterion. In addition, we partitioned the variance in species distributions into an environmental, a pure spatial and a shared component. The spatially-explicit conditional autoregressive regression models strongly outperformed the ordinary least squares regression models. In addition, partialling out the spatial component underlying the species' distributions showed that an average of 17% of the explained variation could be attributed to purely spatial effects independent of the spatial autocorrelation induced by the underlying environmental variables. We concluded that location in the range and neighborhood play an important role in the distribution of species. Spatially explicit models are expected to yield better predictions especially for mobile species such as birds, even in coarse-grained models with a large extent. ?? Ecography.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Ecography","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1111/j.2006.0906-7590.04621.x","issn":"09067590","usgsCitation":"Bahn, V., O’Connor, R., and Krohn, W., 2006, Importance of spatial autocorrelation in modeling bird distributions at a continental scale: Ecography, v. 29, no. 6, p. 835-844, https://doi.org/10.1111/j.2006.0906-7590.04621.x.","startPage":"835","endPage":"844","numberOfPages":"10","costCenters":[],"links":[{"id":209734,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1111/j.2006.0906-7590.04621.x"},{"id":236431,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"29","issue":"6","noUsgsAuthors":false,"publicationDate":"2006-12-13","publicationStatus":"PW","scienceBaseUri":"505a3943e4b0c8380cd61876","contributors":{"authors":[{"text":"Bahn, V.","contributorId":23741,"corporation":false,"usgs":true,"family":"Bahn","given":"V.","email":"","affiliations":[],"preferred":false,"id":418952,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"O’Connor, R.J.","contributorId":37861,"corporation":false,"usgs":true,"family":"O’Connor","given":"R.J.","email":"","affiliations":[],"preferred":false,"id":418953,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Krohn, W.B.","contributorId":64355,"corporation":false,"usgs":true,"family":"Krohn","given":"W.B.","email":"","affiliations":[],"preferred":false,"id":418954,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70028630,"text":"70028630 - 2006 - The importance of physiological ecology in conservation biology","interactions":[],"lastModifiedDate":"2012-03-12T17:20:56","indexId":"70028630","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"The importance of physiological ecology in conservation biology","docAbstract":"Many of the threats to the persistence of populations of sensitive species have physiological or pathological mechanisms, and those mechanisms are best understood through the inherently integrative discipline of physiological ecology. The desert tortoise was listed under the Endangered Species Act largely due to a newly recognized upper respiratory disease thought to cause mortality in individuals and severe declines in populations. Numerous hypotheses about the threats to the persistence of desert tortoise populations involve acquisition of nutrients, and its connection to stress and disease. The nutritional wisdom hypothesis posits that animals should forage not for particular food items, but instead, for particular nutrients such as calcium and phosphorus used in building bones. The optimal foraging hypothesis suggests that, in circumstances of resource abundance, tortoises should forage as dietary specialists as a means of maximizing intake of resources. The optimal digestion hypothesis suggests that tortoises should process ingesta in ways that regulate assimilation rate. Finally, the cost-of-switching hypothesis suggests that herbivores, like the desert tortoise, should avoid switching food types to avoid negatively affecting the microbe community responsible for fermenting plants into energy and nutrients. Combining hypotheses into a resource acquisition theory leads to novel predictions that are generally supported by data presented here. Testing hypotheses, and synthesizing test results into a theory, provides a robust scientific alternative to the popular use of untested hypotheses and unanalyzed data to assert the needs of species. The scientific approach should focus on hypotheses concerning anthropogenic modifications of the environment that impact physiological processes ultimately important to population phenomena. We show how measurements of such impacts as nutrient starvation, can cause physiological stress, and that the endocrine mechanisms involved with stress can result in disease. Finally, our new syntheses evince a new hypothesis. Free molecules of the stress hormone corticosterone can inhibit immunity, and the abundance of \"free corticosterone\" in the blood (thought to be the active form of the hormone) is regulated when the corticosterone molecules combine with binding globulins. The sex hormone, testosterone, combines with the same binding globulin. High levels of testosterone, naturally occurring in the breeding season, may be further enhanced in populations at high densities, and the resulting excess testosterone may compete with binding globulins, thereby releasing corticosterone and reducing immunity to disease. This sequence could result in physiological and pathological phenomena leading to population cycles with a period that would be essentially impossible to observe in desert tortoise. Such cycles could obscure population fluctuations of anthropogenic origin. ?? 2006 The Author(s).","largerWorkTitle":"Integrative and Comparative Biology","language":"English","doi":"10.1093/icb/icl054","issn":"15407063","usgsCitation":"Tracy, C., Nussear, K., Esque, T., Dean-Bradley, K., DeFalco, L., Castle, K., Zimmerman, L., Espinoza, R., and Barber, A., 2006, The importance of physiological ecology in conservation biology, in Integrative and Comparative Biology, v. 46, no. 6, p. 1191-1205, https://doi.org/10.1093/icb/icl054.","startPage":"1191","endPage":"1205","numberOfPages":"15","costCenters":[],"links":[{"id":477395,"rank":10000,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1093/icb/icl054","text":"Publisher Index Page"},{"id":209690,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1093/icb/icl054"},{"id":236365,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"46","issue":"6","noUsgsAuthors":false,"publicationDate":"2006-10-11","publicationStatus":"PW","scienceBaseUri":"505bacfbe4b08c986b3238c3","contributors":{"authors":[{"text":"Tracy, C.R.","contributorId":73524,"corporation":false,"usgs":true,"family":"Tracy","given":"C.R.","email":"","affiliations":[],"preferred":false,"id":418912,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Nussear, K.E.","contributorId":80227,"corporation":false,"usgs":true,"family":"Nussear","given":"K.E.","affiliations":[],"preferred":false,"id":418914,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Esque, T. C. 0000-0002-4166-6234","orcid":"https://orcid.org/0000-0002-4166-6234","contributorId":76250,"corporation":false,"usgs":true,"family":"Esque","given":"T. C.","affiliations":[],"preferred":false,"id":418913,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Dean-Bradley, K.","contributorId":35268,"corporation":false,"usgs":true,"family":"Dean-Bradley","given":"K.","affiliations":[],"preferred":false,"id":418908,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"DeFalco, L.A.","contributorId":46032,"corporation":false,"usgs":true,"family":"DeFalco","given":"L.A.","affiliations":[],"preferred":false,"id":418909,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Castle, K.T.","contributorId":60592,"corporation":false,"usgs":true,"family":"Castle","given":"K.T.","email":"","affiliations":[],"preferred":false,"id":418911,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Zimmerman, L.C.","contributorId":55784,"corporation":false,"usgs":true,"family":"Zimmerman","given":"L.C.","email":"","affiliations":[],"preferred":false,"id":418910,"contributorType":{"id":1,"text":"Authors"},"rank":8},{"text":"Espinoza, R.E.","contributorId":9048,"corporation":false,"usgs":true,"family":"Espinoza","given":"R.E.","email":"","affiliations":[],"preferred":false,"id":418907,"contributorType":{"id":1,"text":"Authors"},"rank":9},{"text":"Barber, A.M.","contributorId":6238,"corporation":false,"usgs":true,"family":"Barber","given":"A.M.","email":"","affiliations":[],"preferred":false,"id":418906,"contributorType":{"id":1,"text":"Authors"},"rank":10}]}} ,{"id":70028629,"text":"70028629 - 2006 - Denitrification in nitrate-rich streams: Application of N2:Ar and 15N-tracer methods in intact cores","interactions":[],"lastModifiedDate":"2018-10-26T10:47:56","indexId":"70028629","displayToPublicDate":"2006-01-01T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1450,"text":"Ecological Applications","active":true,"publicationSubtype":{"id":10}},"displayTitle":"Denitrification in nitrate-rich streams: Application of N2:Ar and 15N-tracer methods in intact cores","title":"Denitrification in nitrate-rich streams: Application of N2:Ar and 15N-tracer methods in intact cores","docAbstract":"Rates of benthic denitrification were measured using two techniques, membrane inlet mass spectrometry (MIMS) and isotope ratio mass spectrometry (IRMS), applied to sediment cores from two NO3−‐rich streams draining agricultural land in the upper Mississippi River Basin. Denitrification was estimated simultaneously from measurements of N2:Ar (MIMS) and 15N[N2] (IRMS) after the addition of low‐level 15NO3− tracer (15N:N = 0.03–0.08) in stream water overlying intact sediment cores. Denitrification rates ranged from about 0 to 4400 μmol N·m−2·h−1 in Sugar Creek and from 0 to 1300 μmol N·m−2·h−1 in Iroquois River, the latter of which possesses greater streamflow discharge and a more homogeneous streambed and water column. Within the uncertainties of the two techniques, there is good agreement between the MIMS and IRMS results, which indicates that the production of N2 by the coupled process of nitrification/denitrification was relatively unimportant and surface‐water NO3− was the dominant source of NO3− for benthic denitrification in these streams. Variation in stream NO3− concentration (from about 20 μmol/L during low discharge to 1000 μmol/L during high discharge) was a significant control of benthic denitrification rates, judging from the more abundant MIMS data. The interpretation that NO3− concentration directly affects denitrification rate was corroborated by increased rates of denitrification in cores amended with NO3−. Denitrification in Sugar Creek removed ≤11% per day of the in‐stream NO3− in late spring and removed roughly 15–20% in late summer. The fraction of NO3− removed in Iroquois River was less than that of Sugar Creek. Although benthic denitrification rates were relatively high during periods of high stream flow, when NO3concentrations were also high, the increase in benthic denitrification could not compensate for the much larger increase in stream NO3− fluxes during high flow. Consequently, fractional NO3− losses were relatively low during high flow.