Nitrite is an important intermediate species in the biogeochemical cycling of nitrogen, but its role in natural aquatic systems is poorly understood. Isotopic data can be used to study the sources and transformations of NO2- in the environment, but methods for independent isotopic analyses of NO2- in the presence of other N species are still new and evolving. This study demonstrates that isotopic analyses of N and O in NO2- can be done by treating whole freshwater or saltwater samples with the denitrifying bacterium Stenotrophomonas nitritireducens, which selectively reduces NO2- to N2O for isotope ratio mass spectrometry. When calibrated with solutions containing NO2- with known isotopic compositions determined independently, reproducible δ15N and δ18O values were obtained at both natural-abundance levels (±0.2−0.5‰ for δ15N and ±0.4−1.0‰ for δ18O) and moderately enriched 15N tracer levels (±20−50‰ for δ15N near 5000‰) for 5−20 nmol of NO2- (1−20 μmol/L in 1−5 mL aliquots). This method is highly selective for NO2-and was used for mixed samples containing both NO2- and NO3- with little or no measurable cross-contamination. In addition, mixed samples that were analyzed with S. nitritireducens were treated subsequently with Pseudomonas aureofaciens to reduce the NO3- in the absence of NO2-, providing isotopic analyses of NO2- and NO3- separately in the same aliquot. Sequential bacterial reduction methods like this one should be useful for a variety of isotopic studies aimed at understanding nitrogen cycling in aquatic environments. A test of these methods in an agricultural watershed in Indiana provides isotopic evidence for both nitrification and denitrification as sources of NO2- in a small stream.
","language":"English","publisher":"ACS","doi":"10.1021/ac070176k","issn":"00032700","usgsCitation":"Bohlke, J.K., Smith, R.L., and Hannon, J.E., 2007, Isotopic analysis of N and O in nitrite and nitrate by sequential selective bacterial reduction to N2O: Analytical Chemistry, v. 79, no. 15, p. 5888-5895, https://doi.org/10.1021/ac070176k.","productDescription":"8 p.","startPage":"5888","endPage":"5895","numberOfPages":"8","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":238563,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":211294,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1021/ac070176k"}],"country":"United States","state":"Indiana","volume":"79","issue":"15","noUsgsAuthors":false,"publicationDate":"2007-06-21","publicationStatus":"PW","scienceBaseUri":"505a3f93e4b0c8380cd64613","contributors":{"authors":[{"text":"Bohlke, John Karl 0000-0001-5693-6455 jkbohlke@usgs.gov","orcid":"https://orcid.org/0000-0001-5693-6455","contributorId":127841,"corporation":false,"usgs":true,"family":"Bohlke","given":"John","email":"jkbohlke@usgs.gov","middleInitial":"Karl","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":false,"id":429110,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Smith, Richard L. 0000-0002-3829-0125 rlsmith@usgs.gov","orcid":"https://orcid.org/0000-0002-3829-0125","contributorId":1592,"corporation":false,"usgs":true,"family":"Smith","given":"Richard","email":"rlsmith@usgs.gov","middleInitial":"L.","affiliations":[{"id":36183,"text":"Hydro-Ecological Interactions Branch","active":true,"usgs":true},{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true},{"id":37277,"text":"WMA - Earth System Processes Division","active":true,"usgs":true},{"id":38175,"text":"Toxics Substances Hydrology Program","active":true,"usgs":true}],"preferred":true,"id":429109,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hannon, Janet E. jehannon@usgs.gov","contributorId":3177,"corporation":false,"usgs":true,"family":"Hannon","given":"Janet","email":"jehannon@usgs.gov","middleInitial":"E.","affiliations":[],"preferred":true,"id":429108,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70033579,"text":"70033579 - 2007 - Dynamics of newly established elk populations","interactions":[],"lastModifiedDate":"2018-01-05T10:49:35","indexId":"70033579","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","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":"Dynamics of newly established elk populations","docAbstract":"The dynamics of newly established elk (Cervus elaphus) populations can provide insights about maximum sustainable rates of reproduction, survival, and increase. However, data used to estimate rates of increase typically have been limited to counts and rarely have included complementary estimates of vital rates. Complexities of population dynamics cannot be understood without considering population processes as well as population states. We estimated pregnancy rates, survival rates, age ratios, and sex ratios for reintroduced elk at Theodore Roosevelt National Park, North Dakota, USA; combined vital rates in a population projection model; and compared model projections with observed elk numbers and population ratios. Pregnancy rates in January (early in the second trimester of pregnancy) averaged 54.1% (SE = 5.4%) for subadults and 91.0% (SE = 1.7%) for adults, and 91.6% of pregnancies resulted in recruitment at 8 months. Annual survival rates of adult females averaged 0.96 (95% CI = 0.94-0.98) with hunting included and 0.99 (95% CI = 0.97-0.99) with hunting excluded from calculations. Our fitted model explained 99.8% of past variation in population estimates and represents a useful new tool for short-term management planning. Although we found no evidence of temporal variation in vital rates, variation in population composition caused substantial variation in projected rates of increase (??=1.20-1.36). Restoring documented hunter harvests and removals of elk by the National Park Service led to a potential rate of ?? = 1.26. Greater rates of increase substantiated elsewhere were within the expected range of chance variation, given our model and estimates of vital rates. Rates of increase realized by small elk populations are too variable to support inferences about habitat quality or density dependence.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Wildlife Management","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.2193/2006-247","issn":"00225","usgsCitation":"Sargeant, G., and Oehler, M., 2007, Dynamics of newly established elk populations: Journal of Wildlife Management, v. 71, no. 4, p. 1141-1148, https://doi.org/10.2193/2006-247.","productDescription":"8 p.","startPage":"1141","endPage":"1148","costCenters":[{"id":480,"text":"Northern Prairie Wildlife Research Center","active":true,"usgs":true}],"links":[{"id":242089,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":214366,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2193/2006-247"}],"volume":"71","issue":"4","noUsgsAuthors":false,"publicationDate":"2010-12-13","publicationStatus":"PW","scienceBaseUri":"505a0435e4b0c8380cd50858","contributors":{"authors":[{"text":"Sargeant, G.A.","contributorId":51681,"corporation":false,"usgs":true,"family":"Sargeant","given":"G.A.","email":"","affiliations":[],"preferred":false,"id":441517,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Oehler, M.W. Sr.","contributorId":105545,"corporation":false,"usgs":true,"family":"Oehler","given":"M.W.","suffix":"Sr.","email":"","affiliations":[],"preferred":false,"id":441518,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70033408,"text":"70033408 - 2007 - Landscape correlates along mourning dove call-count routes in Mississippi","interactions":[],"lastModifiedDate":"2012-03-12T17:21:38","indexId":"70033408","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","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":"Landscape correlates along mourning dove call-count routes in Mississippi","docAbstract":"Mourning dove (Zenaida macroura) call-count surveys in Mississippi, USA, suggest declining populations. We used available mourning dove call-count data to evaluate long-term mourning dove habitat relationships. Dove routes were located in the Mississippi Alluvial Valley, Deep Loess Province, Mid Coastal Plain, and Hilly Coastal Plain physiographic provinces of Mississippi. We also included routes in the Blackbelt Prairie region of Mississippi and Alabama, USA. We characterized landscape structure and composition within 1.64-km buffers around 10 selected mourning dove call-count routes during 3 time periods. Habitat classes included agriculture, forest, urban, regeneration stands, wetland, and woodlot. We used Akaike's Information Criterion to select the best candidate model. We selected a model containing percent agriculture and edge density that contained approximately 40% of the total variability in the data set. Percent agriculture was positively correlated with relative dove abundance. Interestingly, we found a negative relationship between edge density and dove abundance. Researchers should conduct future research on dove nesting patterns in Mississippi and threshold levels of edge necessary to maximize dove density. During the last 20 years, Mississippi lost more than 800,000 ha of cropland while forest cover represented largely by pine (Pinus taeda) plantations increased by more than 364,000 ha. Our results suggest observed localized declines in mourning dove abundance in Mississippi may be related to the documented conversion of agricultural lands to pine plantations.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Wildlife Management","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.2193/2004-267","issn":"00225","usgsCitation":"Elmore, R., Vilella, F., and Gerard, P., 2007, Landscape correlates along mourning dove call-count routes in Mississippi: Journal of Wildlife Management, v. 71, no. 2, p. 422-427, https://doi.org/10.2193/2004-267.","startPage":"422","endPage":"427","numberOfPages":"6","costCenters":[],"links":[{"id":213142,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.2193/2004-267"},{"id":240737,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"71","issue":"2","noUsgsAuthors":false,"publicationDate":"2010-12-13","publicationStatus":"PW","scienceBaseUri":"505a4409e4b0c8380cd667d2","contributors":{"authors":[{"text":"Elmore, R.D.","contributorId":64450,"corporation":false,"usgs":true,"family":"Elmore","given":"R.D.","email":"","affiliations":[],"preferred":false,"id":440746,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Vilella, F. J.","contributorId":82025,"corporation":false,"usgs":false,"family":"Vilella","given":"F. J.","affiliations":[],"preferred":false,"id":440747,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gerard, P.D.","contributorId":16368,"corporation":false,"usgs":true,"family":"Gerard","given":"P.D.","email":"","affiliations":[],"preferred":false,"id":440745,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70030893,"text":"70030893 - 2007 - Water use regimes: Characterizing direct human interaction with hydrologic systems","interactions":[],"lastModifiedDate":"2018-04-03T11:40:13","indexId":"70030893","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","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":"Water use regimes: Characterizing direct human interaction with hydrologic systems","docAbstract":"The sustainability of human water use practices is a rapidly growing concern in the United States and around the world. To better characterize direct human interaction with hydrologic systems (stream basins and aquifers), we introduce the concept of the water use regime. Unlike scalar indicators of anthropogenic hydrologic stress in the literature, the water use regime is a two‐dimensional, vector indicator that can be depicted on simple x‐y plots of normalized human withdrawals (hout) versus normalized human return flows (hin). Four end‐member regimes, natural‐flow‐dominated (undeveloped), human‐flow‐dominated (churned), withdrawal‐dominated (depleted), and return‐flow‐dominated (surcharged), are defined in relation to limiting values of hout and hin. For illustration, the water use regimes of 19 diverse hydrologic systems are plotted and interpreted. Several of these systems, including the Yellow River Basin, China, and the California Central Valley Aquifer, are shown to approach particular end‐member regimes. Spatial and temporal regime variations, both seasonal and long‐term, are depicted. Practical issues of data availability and regime uncertainty are addressed in relation to the statistical properties of the ratio estimators hout and hin. The water use regime is shown to be a useful tool for comparative water resources assessment and for describing both historic and alternative future pathways of water resource development at a range of scales.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2006WR005062","usgsCitation":"Weiskel, P.K., Vogel, R.M., Steeves, P.A., Zarriello, P.J., DeSimone, L.A., and Ries, K., 2007, Water use regimes: Characterizing direct human interaction with hydrologic systems: Water Resources Research, v. 43, no. 4, Article W04402; 11 p., https://doi.org/10.1029/2006WR005062.","productDescription":"Article W04402; 11 p.","costCenters":[],"links":[{"id":477189,"rank":1,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1029/2006wr005062","text":"Publisher Index Page"},{"id":238597,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"43","issue":"4","noUsgsAuthors":false,"publicationDate":"2007-04-04","publicationStatus":"PW","scienceBaseUri":"505bccbfe4b08c986b32dcdc","contributors":{"authors":[{"text":"Weiskel, Peter K. pweiskel@usgs.gov","contributorId":1099,"corporation":false,"usgs":true,"family":"Weiskel","given":"Peter","email":"pweiskel@usgs.gov","middleInitial":"K.","affiliations":[{"id":466,"text":"New England Water Science Center","active":true,"usgs":true},{"id":376,"text":"Massachusetts Water Science Center","active":true,"usgs":true}],"preferred":true,"id":429116,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Vogel, Richard M.","contributorId":66811,"corporation":false,"usgs":true,"family":"Vogel","given":"Richard","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":429114,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Steeves, Peter A. 0000-0001-7558-9719 psteeves@usgs.gov","orcid":"https://orcid.org/0000-0001-7558-9719","contributorId":1873,"corporation":false,"usgs":true,"family":"Steeves","given":"Peter","email":"psteeves@usgs.gov","middleInitial":"A.","affiliations":[{"id":41514,"text":"Maryland-Delaware-District of Columbia Water Science Center","active":true,"usgs":true}],"preferred":true,"id":429115,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Zarriello, Philip J.","contributorId":21588,"corporation":false,"usgs":false,"family":"Zarriello","given":"Philip","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":429113,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"DeSimone, Leslie A. 0000-0003-0774-9607 ldesimon@usgs.gov","orcid":"https://orcid.org/0000-0003-0774-9607","contributorId":195635,"corporation":false,"usgs":true,"family":"DeSimone","given":"Leslie","email":"ldesimon@usgs.gov","middleInitial":"A.","affiliations":[{"id":376,"text":"Massachusetts Water Science Center","active":true,"usgs":true},{"id":466,"text":"New England Water Science Center","active":true,"usgs":true}],"preferred":true,"id":429117,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Ries, Kernell G. III kries@usgs.gov","contributorId":1913,"corporation":false,"usgs":true,"family":"Ries","given":"Kernell G.","suffix":"III","email":"kries@usgs.gov","affiliations":[{"id":502,"text":"Office of Surface Water","active":true,"usgs":true}],"preferred":false,"id":429112,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70030788,"text":"70030788 - 2007 - Multiple-methods investigation of recharge at a humid-region fractured rock site, Pennsylvania, USA","interactions":[],"lastModifiedDate":"2023-07-31T12:25:02.159277","indexId":"70030788","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","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":"Multiple-methods investigation of recharge at a humid-region fractured rock site, Pennsylvania, USA","docAbstract":"Lysimeter-percolate and well-hydrograph analyses were combined to evaluate recharge for the Masser Recharge Site (central Pennsylvania, USA). In humid regions, aquifer recharge through an unconfined low-porosity fractured-rock aquifer can cause large magnitude water-table fluctuations over short time scales. The unsaturated hydraulic characteristics of the subsurface porous media control the magnitude and timing of these fluctuations. Data from multiple sets of lysimeters at the site show a highly seasonal pattern of percolate and exhibit variability due to both installation factors and hydraulic property heterogeneity. Individual event analysis of well hydrograph data reveals the primary influences on water-table response, namely rainfall depth, rainfall intensity, and initial water-table depth. Spatial and seasonal variability in well response is also evident. A new approach for calculating recharge from continuous water-table elevation records using a master recession curve (MRC) is demonstrated. The recharge estimated by the MRC approach when assuming a constant specific yield is seasonal to a lesser degree than the recharge estimate resulting from the lysimeter analysis. Partial reconciliation of the two recharge estimates is achieved by considering a conceptual model of flow processes in the highly-heterogeneous underlying fractured porous medium.
Regional wildlife–habitat models are commonly developed but rarely tested with truly independent data. We tested a published habitat model for black bears (Ursus americanus) with new data collected in a different site in the same ecological region (i.e., Ouachita Mountains of Arkansas and Oklahoma, USA). We used a Mahalanobis distance model developed from relocations of black bears in Arkansas to produce a map layer of Mahalanobis distances on a study area in neighboring Oklahoma. We tested this modeled map layer with relocations of black bears on the Oklahoma area. The distributions of relocations of female black bears were consistent with model predictions. We conclude that this modeling approach can be used to predict regional suitability for a species of interest.
","language":"English","publisher":"Wildlife Society","doi":"10.2193/2006-031","issn":"00225","usgsCitation":"Hellgren, E.C., Bales, S., Gregory, M., Leslie, D., and Clark, J.D., 2007, Testing a Mahalanobis distance model of black bear habitat use in the Ouachita Mountains of Oklahoma: Journal of Wildlife Management, v. 71, no. 3, p. 924-928, https://doi.org/10.2193/2006-031.","productDescription":"5 p.","startPage":"924","endPage":"928","numberOfPages":"5","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":481,"text":"Northern Rocky Mountain Science Center","active":true,"usgs":true}],"links":[{"id":239508,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Oklahoma","county":"LeFlore County","otherGeospatial":"Ouachita National Forest","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -94.4384765625,\n 34.97375095431689\n ],\n [\n -94.50164794921875,\n 34.97375095431689\n ],\n [\n -94.57855224609375,\n 34.939985151560435\n ],\n [\n -94.61700439453125,\n 34.88142481679758\n ],\n [\n -94.72412109375,\n 34.88142481679758\n ],\n [\n -94.8394775390625,\n 34.89268966339912\n ],\n [\n -94.93011474609375,\n 34.908457853981396\n ],\n [\n -95.00701904296875,\n 34.89043681762452\n ],\n [\n -95.06744384765625,\n 34.827332061981586\n ],\n [\n -95.0537109375,\n 34.7461262752594\n ],\n [\n -94.98504638671875,\n 34.70097741472011\n ],\n [\n -94.86145019531249,\n 34.67613503380097\n ],\n [\n -94.73236083984375,\n 34.655803905058974\n ],\n [\n -94.6636962890625,\n 34.6241677899049\n ],\n [\n -94.7021484375,\n 34.56085936708384\n ],\n [\n -94.66094970703125,\n 34.472599425831355\n ],\n [\n -94.69940185546875,\n 34.40011121603371\n ],\n [\n -94.7625732421875,\n 34.36837785748377\n ],\n [\n -94.82025146484375,\n 34.35477416538757\n ],\n [\n -94.833984375,\n 34.279914398549934\n ],\n [\n -94.79827880859375,\n 34.23905366851639\n ],\n [\n -94.7735595703125,\n 34.1890858311724\n ],\n [\n -94.7515869140625,\n 34.129994745824746\n ],\n [\n -94.72686767578125,\n 34.08906131584996\n ],\n [\n -94.63623046875,\n 34.066311964721045\n ],\n [\n -94.52911376953125,\n 34.066311964721045\n ],\n [\n -94.47418212890625,\n 34.068587174791965\n ],\n [\n -94.4384765625,\n 34.97375095431689\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"71","issue":"3","noUsgsAuthors":false,"publicationDate":"2010-12-13","publicationStatus":"PW","scienceBaseUri":"505ba5b5e4b08c986b320c01","contributors":{"authors":[{"text":"Hellgren, E. C.","contributorId":40327,"corporation":false,"usgs":true,"family":"Hellgren","given":"E.","email":"","middleInitial":"C.","affiliations":[],"preferred":false,"id":426548,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Bales, S.L.","contributorId":34312,"corporation":false,"usgs":true,"family":"Bales","given":"S.L.","email":"","affiliations":[],"preferred":false,"id":426547,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gregory, M.S.","contributorId":96476,"corporation":false,"usgs":true,"family":"Gregory","given":"M.S.","email":"","affiliations":[],"preferred":false,"id":426551,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Leslie, David M. Jr.","contributorId":52514,"corporation":false,"usgs":true,"family":"Leslie","given":"David M.","suffix":"Jr.","affiliations":[],"preferred":false,"id":426549,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Clark, J. D.","contributorId":85911,"corporation":false,"usgs":true,"family":"Clark","given":"J.","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":426550,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70030291,"text":"70030291 - 2007 - A simulation of groundwater discharge and nitrate delivery to chesapeake bay from the lowermost delmarva peninsula, USA","interactions":[],"lastModifiedDate":"2012-03-12T17:21:01","indexId":"70030291","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"A simulation of groundwater discharge and nitrate delivery to chesapeake bay from the lowermost delmarva peninsula, USA","docAbstract":"A groundwater model has been developed for the lowermost Delmarva Peninsula, USA, that simulates saltwater intrusion into local confined aquifers and nitrate delivery to the Chesapeake Bay from the surficial aquifer. A flow path and groundwater-age analysis was performed using the model to estimate the timing of nitrate delivery to the bay over the next several decades. The simulated mean and median residence times of groundwater in the lowermost peninsula are 30 and 15 years, respectively. Current and future nitrate concentrations in coastal groundwater discharge were simulated based on local well data that include nitrate concentrations and groundwater age. A simulated future-trends analysis indicates that nitrate that has been applied to agricultural regions over the last few decades will continue to discharge into the bay for several decades to come. This study highlights the importance of considering the groundwater lag time that affects the mean transport time from diffuse contamination sources.","largerWorkTitle":"IAHS-AISH Publication","conferenceTitle":"International Symposium: A New Focus on Groundwater - Seawater Interactions - 24th General Assembly of the In","conferenceDate":"2 July 2007 through 13 July 2007","conferenceLocation":"Perugia","language":"English","issn":"01447","isbn":"9781901502046","usgsCitation":"Sanford, W., and Pope, J., 2007, A simulation of groundwater discharge and nitrate delivery to chesapeake bay from the lowermost delmarva peninsula, USA, in IAHS-AISH Publication, no. 312, Perugia, 2 July 2007 through 13 July 2007, p. 326-333.","startPage":"326","endPage":"333","numberOfPages":"8","costCenters":[],"links":[{"id":239475,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"issue":"312","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e596e4b0c8380cd46e52","contributors":{"authors":[{"text":"Sanford, W. E. 0000-0002-6624-0280","orcid":"https://orcid.org/0000-0002-6624-0280","contributorId":102112,"corporation":false,"usgs":true,"family":"Sanford","given":"W. E.","affiliations":[],"preferred":false,"id":426542,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Pope, J.P.","contributorId":25352,"corporation":false,"usgs":true,"family":"Pope","given":"J.P.","email":"","affiliations":[],"preferred":false,"id":426541,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70030902,"text":"70030902 - 2007 - Composite analysis for Escherichia coli at coastal beaches","interactions":[],"lastModifiedDate":"2012-03-12T17:21:15","indexId":"70030902","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2330,"text":"Journal of Great Lakes Research","active":true,"publicationSubtype":{"id":10}},"title":"Composite analysis for Escherichia coli at coastal beaches","docAbstract":"At some coastal beaches, concentrations of fecal-indicator bacteria can differ substantially between multiple points at the same beach at the same time. Because of this spatial variability, the recreational water quality at beaches is sometimes determined by stratifying a beach into several areas and collecting a sample from each area to analyze for the concentration of fecal-indicator bacteria. The average concentration of bacteria from those points is often used to compare to the recreational standard for advisory postings. Alternatively, if funds are limited, a single sample is collected to represent the beach. Compositing the samples collected from each section of the beach may yield equally accurate data as averaging concentrations from multiple points, at a reduced cost. In the study described herein, water samples were collected at multiple points from three Lake Erie beaches and analyzed for Escherichia coli on modified mTEC agar (EPA Method 1603). From the multiple-point samples, a composite sample (n = 116) was formed at each beach by combining equal aliquots of well-mixed water from each point. Results from this study indicate that E. coli concentrations from the arithmetic average of multiple-point samples and from composited samples are not significantly different (t = 1.59, p = 0.1139) and yield similar measures of recreational water quality; additionally, composite samples could result in a significant cost savings.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Great Lakes Research","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.3394/0380-1330(2007)33[335:CAFECA]2.0.CO;2","issn":"03801330","usgsCitation":"Bertke, E., 2007, Composite analysis for Escherichia coli at coastal beaches: Journal of Great Lakes Research, v. 33, no. 2, p. 335-341, https://doi.org/10.3394/0380-1330(2007)33[335:CAFECA]2.0.CO;2.","startPage":"335","endPage":"341","numberOfPages":"7","costCenters":[],"links":[{"id":211444,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.3394/0380-1330(2007)33[335:CAFECA]2.0.CO;2"},{"id":238735,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"33","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f916e4b0c8380cd4d417","contributors":{"authors":[{"text":"Bertke, E.E.","contributorId":24990,"corporation":false,"usgs":true,"family":"Bertke","given":"E.E.","email":"","affiliations":[],"preferred":false,"id":429145,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70030065,"text":"70030065 - 2007 - Sea level fluctuations in central California at subtidal to decadal and longer time scales with implications for San Francisco Bay, California","interactions":[],"lastModifiedDate":"2023-08-02T12:16:40.648602","indexId":"70030065","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1587,"text":"Estuarine, Coastal and Shelf Science","active":true,"publicationSubtype":{"id":10}},"title":"Sea level fluctuations in central California at subtidal to decadal and longer time scales with implications for San Francisco Bay, California","docAbstract":"Sea level elevations from near the mouth of San Francisco Bay are used to describe the low-frequency variability of forcing of the coastal ocean on the Bay at a variety of temporal scales. About 90% of subtidal fluctuations in sea level in San Francisco Bay are driven by the sea level variations in the coastal ocean that propagate into the Bay at the estuary mouth. We use the 100-year sea level record available at San Francisco to document a 1.9 mm/yr mean sea level rise, and to determine fluctuations related to El Nino-Southern Oscillation (ENSO) and other climatic events. At time scales greater than 1 year, ENSO dominates the sea level signal and can result in fluctuations in sea level of 10–15 cm. Alongshore wind stress data from central California are also analyzed to determine the impact of changes in coastal elevation at the mouth of San Francisco Bay within the synoptic wind band of 2–30 days. At least 40% of the subtidal fluctuations in sea level of the Bay are tied to the large-scale regional wind field affecting sea level variations in the coastal ocean, with little local, direct wind forcing of the Bay itself. The majority of the subtidal sea level fluctuations within the Bay that are not related to the coastal ocean sea level signal are forced by an east–west sea level gradient resulting from tidally induced variations in sea level at specific beat frequencies that are enhanced in the northern reach of the Bay. River discharge into the Bay through the Sacramento and San Joaquin River Delta also contributes to the east–west gradient, but to a lesser degree.
Recognition of arsenic (As) contamination of shallow fluvio-deltaic aquifers in the Bengal Basin has resulted in increasing exploitation of groundwater from deeper aquifers that generally contain low concentrations of dissolved As. Pumping-induced infiltration of high-As groundwater could eventually cause As concentrations in these aquifers to increase. This study investigates the adsorption capacity for As of sediment from a low-As aquifer near Dhaka, Bangladesh. A shallow, chemically-reducing aquifer at this site extends to a depth of 50 m and has maximum As concentrations in groundwater of 900 μg/L. At depths greater than 50 m, geochemical conditions are more oxidizing and groundwater has < 5 μg/L As. There is no thick layer of clay at this site to inhibit vertical transport of groundwater.
Arsenite [As(III)] is the dominant oxidation state in contaminated groundwater; however, data from laboratory batch experiments show that As(III) is oxidized to arsenate [As(V)] by manganese (Mn) minerals that are present in the oxidized sediment. Thus, the long-term viability of the deeper aquifers as a source of water supply is likely to depend on As(V) adsorption. The adsorption capacity of these sediments is a function of the oxidation state of As and the concentration of other solutes that compete for adsorption sites. Arsenite that was not oxidized did adsorb, but to a much lesser extent than As(V). Phosphate (P) caused a substantial decrease in As(V) adsorption. Increasing pH and concentrations of silica (Si) had lesser effects on As(V) adsorption. The effect of bicarbonate (HCO3) on As(V) adsorption was negligible. Equilibrium constants for adsorption of As(V), As(III), P, Si, HCO3, and H were determined from the experimental data and a quantitative model developed. Oxidation of As(III) was modeled with a first-order rate constant. This model was used to successfully simulate As(V) adsorption in the presence of multiple competing solutes. Results from these experiments show that oxidized sediments have a substantial but limited capacity for removal of As from groundwater.
","language":"English","publisher":"Elsevier","doi":"10.1016/j.scitotenv.2006.11.029","issn":"00489697","usgsCitation":"Stollenwerk, K.G., Breit, G.N., Welch, A.H., Yount, J., Whitney, J.W., Foster, A.L., Uddin, M., Majumder, R., and Ahmed, N., 2007, Arsenic attenuation by oxidized aquifer sediments in Bangladesh: Science of the Total Environment, v. 379, no. 2-3, p. 133-150, https://doi.org/10.1016/j.scitotenv.2006.11.029.","productDescription":"18 p.","startPage":"133","endPage":"150","numberOfPages":"18","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":477071,"rank":2,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1016/j.scitotenv.2006.11.029","text":"Publisher Index Page"},{"id":240253,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Bangladesh","city":"Dhaka","otherGeospatial":"Bengal Basin","geographicExtents":"{\"type\":\"FeatureCollection\",\"features\":[{\"type\":\"Feature\",\"geometry\":{\"type\":\"Polygon\",\"coordinates\":[[[92.67272,22.04124],[92.65226,21.32405],[92.30323,21.47549],[92.36855,20.67088],[92.08289,21.1922],[92.02522,21.70157],[91.83489,22.18294],[91.41709,22.76502],[90.49601,22.80502],[90.58696,22.39279],[90.27297,21.83637],[89.84747,22.03915],[89.70205,21.85712],[89.41886,21.96618],[89.03196,22.05571],[88.87631,22.87915],[88.52977,23.63114],[88.69994,24.23371],[88.08442,24.50166],[88.30637,24.86608],[88.93155,25.23869],[88.20979,25.76807],[88.56305,26.44653],[89.35509,26.01441],[89.83248,25.96508],[89.92069,25.26975],[90.87221,25.1326],[91.7996,25.14743],[92.3762,24.97669],[91.91509,24.13041],[91.46773,24.07264],[91.15896,23.50353],[91.70648,22.98526],[91.86993,23.62435],[92.14603,23.6275],[92.67272,22.04124]]]},\"properties\":{\"name\":\"Bangladesh\"}}]}","volume":"379","issue":"2-3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ed8be4b0c8380cd49882","contributors":{"authors":[{"text":"Stollenwerk, Kenneth G. kgstolle@usgs.gov","contributorId":578,"corporation":false,"usgs":true,"family":"Stollenwerk","given":"Kenneth","email":"kgstolle@usgs.gov","middleInitial":"G.","affiliations":[],"preferred":true,"id":425109,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Breit, George N. 0000-0003-2188-6798 gbreit@usgs.gov","orcid":"https://orcid.org/0000-0003-2188-6798","contributorId":1480,"corporation":false,"usgs":true,"family":"Breit","given":"George","email":"gbreit@usgs.gov","middleInitial":"N.","affiliations":[{"id":211,"text":"Crustal Geophysics and Geochemistry Science Center","active":true,"usgs":true},{"id":171,"text":"Central Mineral and Environmental Resources Science Center","active":true,"usgs":true}],"preferred":true,"id":425111,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Welch, Alan H.","contributorId":35399,"corporation":false,"usgs":true,"family":"Welch","given":"Alan","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":425105,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Yount, James C.","contributorId":39341,"corporation":false,"usgs":true,"family":"Yount","given":"James C.","affiliations":[],"preferred":false,"id":425108,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Whitney, John W. 0000-0003-3824-3692 jwhitney@usgs.gov","orcid":"https://orcid.org/0000-0003-3824-3692","contributorId":804,"corporation":false,"usgs":true,"family":"Whitney","given":"John","email":"jwhitney@usgs.gov","middleInitial":"W.","affiliations":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"preferred":true,"id":425107,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Foster, Andrea L. 0000-0003-1362-0068 afoster@usgs.gov","orcid":"https://orcid.org/0000-0003-1362-0068","contributorId":1740,"corporation":false,"usgs":true,"family":"Foster","given":"Andrea","email":"afoster@usgs.gov","middleInitial":"L.","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true},{"id":662,"text":"Western Mineral and Environmental Resources Science Center","active":true,"usgs":true}],"preferred":true,"id":425106,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Uddin, M.N.","contributorId":105979,"corporation":false,"usgs":true,"family":"Uddin","given":"M.N.","email":"","affiliations":[],"preferred":false,"id":425113,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Majumder, R.K.","contributorId":94929,"corporation":false,"usgs":true,"family":"Majumder","given":"R.K.","email":"","affiliations":[],"preferred":false,"id":425112,"contributorType":{"id":1,"text":"Authors"},"rank":8},{"text":"Ahmed, N.","contributorId":71846,"corporation":false,"usgs":true,"family":"Ahmed","given":"N.","email":"","affiliations":[],"preferred":false,"id":425110,"contributorType":{"id":1,"text":"Authors"},"rank":9}]}} ,{"id":70030198,"text":"70030198 - 2007 - Factors associated with sources, transport, and fate of volatile organic compounds and their mixtures in aquifers of the United States","interactions":[],"lastModifiedDate":"2012-03-12T17:21:01","indexId":"70030198","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","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":"Factors associated with sources, transport, and fate of volatile organic compounds and their mixtures in aquifers of the United States","docAbstract":"Factors associated with sources, transport, and fate of volatile organic compounds (VOCs) in groundwater from aquifers throughout the United States were evaluated using statistical methods. Samples were collected from 1631 wells throughout the conterminous United States between 1996 and 2002 as part of the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey. Water samples from wells completed in aquifers used to supply drinking water were analyzed for more than 50 VOCs. Wells were primarily rural domestic water supplies (1184), followed by public water supplies (216); the remaining wells (231) supplied a variety of uses. The median well depth was 50 meters. Age-date information shows that about 60% of the samples had a fraction of water recharged after 1953. Chloroform, toluene, 1,2,4-trimethylbenzene, and perchloroethene were some of the frequently detected VOCs. Concentrations generally were less than 1 ??g/L. Source factors include, in order of importance, general land-use activity, septic/sewer density, and sites where large concentrations of VOCs are potentially released, such as leaking underground storage tanks. About 10% of all samples had VOC mixtures that were associated with concentrated sources; 20% were associated with dispersed sources. Important transport factors included well/screen depth, precipitation/groundwater recharge, air temperature, and various soil characteristics. Dissolved oxygen was strongly associated with VOCs and represents the fate of many VOCs in groundwater. Well type (domestic or public water supply) was also an important explanatory factor. Results of multiple analyses show the importance of (1) accounting for both dispersed and concentrated sources of VOCs, (2) measuring dissolved oxygen when sampling wells to help explain the fate of VOCs, and (3) limiting the type of wells sampled in monitoring networks to avoid unnecessary variance in the data, or controlling for this variance during data analysis.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Environmental Science and Technology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1021/es061079w","issn":"0013936X","usgsCitation":"Squillace, P.J., and Moran, M., 2007, Factors associated with sources, transport, and fate of volatile organic compounds and their mixtures in aquifers of the United States: Environmental Science & Technology, v. 41, no. 7, p. 2123-2130, https://doi.org/10.1021/es061079w.","startPage":"2123","endPage":"2130","numberOfPages":"8","costCenters":[],"links":[{"id":239086,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":211738,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1021/es061079w"}],"volume":"41","issue":"7","noUsgsAuthors":false,"publicationDate":"2007-03-06","publicationStatus":"PW","scienceBaseUri":"505a0eb4e4b0c8380cd535a3","contributors":{"authors":[{"text":"Squillace, P. J.","contributorId":8878,"corporation":false,"usgs":true,"family":"Squillace","given":"P.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":426098,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Moran, M.J.","contributorId":7862,"corporation":false,"usgs":true,"family":"Moran","given":"M.J.","email":"","affiliations":[],"preferred":false,"id":426097,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70046035,"text":"70046035 - 2007 - Anza-Terwilliger study wells in Riverside County, California","interactions":[],"lastModifiedDate":"2013-05-21T10:32:40","indexId":"70046035","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":6,"text":"USGS Unnumbered Series"},"title":"Anza-Terwilliger study wells in Riverside County, California","docAbstract":"This digital data set contains the locations, water-level altitude, and water-level differences of 70 wells selected to document water-level changes between fall 2004 and spring 2005 in the Anza-Terwilliger area of Riverside County, California. The winter of 2005 was one of the wettest periods on record. Links to the U.S. Geological Survey National Water Information Systems Website (NWISWeb) have been established to interactively view recent water-level information via the internet by clicking on a specific well.","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Reston, VA","doi":"10.3133/70046035","usgsCitation":"Morita, A., Clark, D.A., and Martin, P., 2007, Anza-Terwilliger study wells in Riverside County, California, Dataset, https://doi.org/10.3133/70046035.","productDescription":"Dataset","onlineOnly":"Y","additionalOnlineFiles":"Y","costCenters":[],"links":[{"id":272520,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"}],"country":"United States","state":"California","county":"Riverside","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -116.803944,33.480553 ], [ -116.803944,33.583648 ], [ -116.624364,33.583648 ], [ -116.624364,33.480553 ], [ -116.803944,33.480553 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"519c9762e4b0ce6c26df819e","contributors":{"authors":[{"text":"Morita, Andrew 0000-0002-8120-996X","orcid":"https://orcid.org/0000-0002-8120-996X","contributorId":52292,"corporation":false,"usgs":true,"family":"Morita","given":"Andrew","affiliations":[],"preferred":false,"id":478732,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Clark, Dennis A. daclark@usgs.gov","contributorId":1477,"corporation":false,"usgs":true,"family":"Clark","given":"Dennis","email":"daclark@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":478731,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Martin, Peter pmmartin@usgs.gov","contributorId":799,"corporation":false,"usgs":true,"family":"Martin","given":"Peter","email":"pmmartin@usgs.gov","affiliations":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"preferred":true,"id":478730,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70030790,"text":"70030790 - 2007 - Alternative community structures in a kelp-urchin community: A qualitative modeling approach","interactions":[],"lastModifiedDate":"2012-03-12T17:21:15","indexId":"70030790","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1458,"text":"Ecological Modelling","active":true,"publicationSubtype":{"id":10}},"title":"Alternative community structures in a kelp-urchin community: A qualitative modeling approach","docAbstract":"Shifts in interaction patterns within a community may result from periodic disturbances and climate. The question arises as to the extent and significance of these shifting patterns. Using a novel approach to link qualitative mathematical models and field data, namely using the inverse matrix to identify the community matrix, we reconstructed community networks from kelp forests off the Oregon Coast. We simulated all ecologically plausible interactions among community members, selected the models whose outcomes match field observations, and identified highly frequent links to characterize the community network from a particular site. We tested all possible biologically reasonable community networks through qualitative simulations, selected those that matched patterns observed in the field, and further reduced the set of possibilities by retaining those that were stable. We found that a community can be represented by a set of alternative structures, or scenarios. From 11,943,936 simulated models, 0.23% matched the field observations; moreover, only 0.006%, or 748 models, were highly reliable in their predictions and met conditions for stability. Predator-prey interactions as well as non-predatory relationships were consistently found in most of the 748 models. These highly frequent connections were useful to characterize the community network in the study site. We suggest that alternative networks provide the community with a buffer to disturbance, allowing it to continuously reorganize to adapt to a variable environment. This is possible due to the fluctuating capacities of foraging species to consume alternate resources. This suggestion is sustained by our results, which indicate that none of the models that matched field observations were fully connected. This plasticity may contribute to the persistence of these communities. We propose that qualitative simulations represent a powerful technique to raise new hypotheses concerning community dynamics and to reconstruct guidelines that may govern community patterns. ?? 2007 Elsevier B.V. All rights reserved.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Ecological Modelling","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.ecolmodel.2007.02.031","issn":"03043800","usgsCitation":"Montano-Moctezuma, G., Li, H., and Rossignol, P., 2007, Alternative community structures in a kelp-urchin community: A qualitative modeling approach: Ecological Modelling, v. 205, no. 3-4, p. 343-354, https://doi.org/10.1016/j.ecolmodel.2007.02.031.","startPage":"343","endPage":"354","numberOfPages":"12","costCenters":[],"links":[{"id":211322,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.ecolmodel.2007.02.031"},{"id":238591,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"205","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059e97ee4b0c8380cd48304","contributors":{"authors":[{"text":"Montano-Moctezuma, G.","contributorId":45041,"corporation":false,"usgs":true,"family":"Montano-Moctezuma","given":"G.","affiliations":[],"preferred":false,"id":428689,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Li, H.W.","contributorId":23261,"corporation":false,"usgs":true,"family":"Li","given":"H.W.","email":"","affiliations":[],"preferred":false,"id":428688,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Rossignol, P.A.","contributorId":90019,"corporation":false,"usgs":true,"family":"Rossignol","given":"P.A.","affiliations":[],"preferred":false,"id":428690,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70030724,"text":"70030724 - 2007 - Joint inversion of high-frequency surface waves with fundamental and higher modes","interactions":[],"lastModifiedDate":"2012-03-12T17:21:01","indexId":"70030724","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2165,"text":"Journal of Applied Geophysics","active":true,"publicationSubtype":{"id":10}},"title":"Joint inversion of high-frequency surface waves with fundamental and higher modes","docAbstract":"Joint inversion of multimode surface waves for estimating the shear (S)-wave velocity has received much attention in recent years. In this paper, we first analyze sensitivity of phase velocities of multimodes of surface waves for a six-layer earth model, and then we invert surface-wave dispersion curves of the theoretical model and a real-world example. Sensitivity analysis shows that fundamental mode data are more sensitive to the S-wave velocities of shallow layers and are concentrated on a very narrow frequency band, while higher mode data are more sensitive to the parameters of relatively deeper layers and are distributed over a wider frequency band. These properties provide a foundation of using a multimode joint inversion to define S-wave velocities. Inversion results of both synthetic data and a real-world example demonstrate that joint inversion with the damped least-square method and the singular-value decomposition technique to invert high-frequency surface waves with fundamental and higher mode data simultaneously can effectively reduce the ambiguity and improve the accuracy of S-wave velocities. ?? 2007.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Applied Geophysics","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/j.jappgeo.2007.02.004","issn":"09269851","usgsCitation":"Luo, Y., Xia, J., Liu, J., Liu, Q., and Xu, S., 2007, Joint inversion of high-frequency surface waves with fundamental and higher modes: Journal of Applied Geophysics, v. 62, no. 4, p. 375-384, https://doi.org/10.1016/j.jappgeo.2007.02.004.","startPage":"375","endPage":"384","numberOfPages":"10","costCenters":[],"links":[{"id":239084,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":211737,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/j.jappgeo.2007.02.004"}],"volume":"62","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a4003e4b0c8380cd649d1","contributors":{"authors":[{"text":"Luo, Y.","contributorId":28417,"corporation":false,"usgs":true,"family":"Luo","given":"Y.","email":"","affiliations":[],"preferred":false,"id":428399,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Xia, J.","contributorId":63513,"corporation":false,"usgs":true,"family":"Xia","given":"J.","email":"","affiliations":[],"preferred":false,"id":428400,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Liu, J.","contributorId":23672,"corporation":false,"usgs":false,"family":"Liu","given":"J.","affiliations":[],"preferred":false,"id":428398,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Liu, Q.","contributorId":17827,"corporation":false,"usgs":true,"family":"Liu","given":"Q.","email":"","affiliations":[],"preferred":false,"id":428397,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Xu, S.","contributorId":84954,"corporation":false,"usgs":true,"family":"Xu","given":"S.","email":"","affiliations":[],"preferred":false,"id":428401,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70046026,"text":"70046026 - 2007 - Grids of Agricultural Pesticide Use in the Conterminous United States, 1992","interactions":[],"lastModifiedDate":"2013-05-20T15:04:06","indexId":"70046026","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":6,"text":"USGS Unnumbered Series"},"title":"Grids of Agricultural Pesticide Use in the Conterminous United States, 1992","docAbstract":"This spatial dataset consists of 199 1-kilometer (km) resolution grids depicting estimated agricultural use of 199 pesticides in 1992 for the conterminous United States. Each grid cell value in the national grids of this dataset is the estimated total kilograms (kg) of a pesticide applied to row crops, small grain crops and fallow land,pasture and hay crops, and orchard and vineyard crops within the 1- by 1-km area. Nonagricultural uses of pesticides are not included in this dataset. Of the 199 pesticides represented in the grids, 92 are herbicides, 58 are insecticides, and 32 are fungicides. The remaining 17 grids are composed of the category \"other pesticides\", which consists of fumigants, growth regulators, and defoliants. Although this data set is referenced to 1992, it generally represents a composite of estimated pesticide use during the early 1990s.","language":"English","publisher":"Geological Survey","publisherLocation":"Reston, VA","doi":"10.3133/70046026","usgsCitation":"Nakagaki, N., 2007, Grids of Agricultural Pesticide Use in the Conterminous United States, 1992, Dataset, https://doi.org/10.3133/70046026.","productDescription":"Dataset","onlineOnly":"Y","temporalStart":"1992-01-01","temporalEnd":"1992-12-31","costCenters":[],"links":[{"id":272513,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":272512,"type":{"id":16,"text":"Metadata"},"url":"https://water.usgs.gov/GIS/metadata/usgswrd/XML/agpest92grd.xml"}],"country":"United States","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -124.8,24.5 ], [ -124.8,49.383333 ], [ -66.95,49.383333 ], [ -66.95,24.5 ], [ -124.8,24.5 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"519b45eae4b0e4e151ef5d2b","contributors":{"authors":[{"text":"Nakagaki, Naomi 0000-0003-3653-0540 nakagaki@usgs.gov","orcid":"https://orcid.org/0000-0003-3653-0540","contributorId":1067,"corporation":false,"usgs":true,"family":"Nakagaki","given":"Naomi","email":"nakagaki@usgs.gov","affiliations":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"preferred":true,"id":478717,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70032179,"text":"70032179 - 2007 - Aquifer-scale controls on the distribution of nitrate and ammonium in ground water near La Pine, Oregon, USA","interactions":[],"lastModifiedDate":"2023-10-03T11:25:27.364711","indexId":"70032179","displayToPublicDate":"2007-01-01T00:00:00","publicationYear":"2007","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2342,"text":"Journal of Hydrology","active":true,"publicationSubtype":{"id":10}},"title":"Aquifer-scale controls on the distribution of nitrate and ammonium in ground water near La Pine, Oregon, USA","docAbstract":"Geochemical and isotopic tools were applied at aquifer, transect, and subtransect scales to provide a framework for understanding sources, transport, and fate of dissolved inorganic N in a sandy aquifer near La Pine, Oregon. NO3 is a common contaminant in shallow ground water in this area, whereas high concentrations of NH4-N (up to 39 mg/L) are present in deep ground water. N concentrations, N/Cl ratios, tracer-based apparent ground-water ages, N isotope data, and hydraulic gradients indicate that septic tank effluent is the primary source of NO3. N isotope data, N/Cl and N/C relations, 3H data, and hydraulic considerations point to a natural, sedimentary organic matter source for the high concentrations of NH4, and are inconsistent with an origin as septic tank N. Low recharge rates and flow velocities have largely restricted anthropogenic NO3 to isolated plumes within several meters of the water table. A variety of geochemical and isotopic data indicate that denitrification also affects NO3 gradients in the aquifer. Ground water in the La Pine aquifer evolves from oxic to increasingly reduced conditions. Suboxic conditions are achieved after about 15-30 y of transport below the water table. NO3 is denitrified near the oxic/suboxic boundary. Denitrification in the La Pine aquifer is characterized well at the aquifer scale with a redox boundary approach that inherently captures spatial variability in the distribution of electron donors.
","language":"English","publisher":"Elsevier","doi":"10.1016/j.jhydrol.2006.09.013","issn":"00221694","usgsCitation":"Hinkle, S.R., Bohlke, J.K., Duff, J.H., Morgan, D.S., and Weick, R.J., 2007, Aquifer-scale controls on the distribution of nitrate and ammonium in ground water near La Pine, Oregon, USA: Journal of Hydrology, v. 333, no. 2-4, p. 486-503, https://doi.org/10.1016/j.jhydrol.2006.09.013.","productDescription":"18 p.","startPage":"486","endPage":"503","numberOfPages":"18","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":242337,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Oregon","city":"La Pine","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -121.75,43.5 ], [ -121.75,44 ], [ -121.33333333333333,44 ], [ -121.33333333333333,43.5 ], [ -121.75,43.5 ] ] ] } } ] }","volume":"333","issue":"2-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ed25e4b0c8380cd4965e","contributors":{"authors":[{"text":"Hinkle, Stephen R. srhinkle@usgs.gov","contributorId":1171,"corporation":false,"usgs":true,"family":"Hinkle","given":"Stephen","email":"srhinkle@usgs.gov","middleInitial":"R.","affiliations":[{"id":518,"text":"Oregon Water Science Center","active":true,"usgs":true}],"preferred":true,"id":434887,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Bohlke, John Karl 0000-0001-5693-6455 jkbohlke@usgs.gov","orcid":"https://orcid.org/0000-0001-5693-6455","contributorId":127841,"corporation":false,"usgs":true,"family":"Bohlke","given":"John","email":"jkbohlke@usgs.gov","middleInitial":"Karl","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":false,"id":434888,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Duff, John H. jhduff@usgs.gov","contributorId":961,"corporation":false,"usgs":true,"family":"Duff","given":"John","email":"jhduff@usgs.gov","middleInitial":"H.","affiliations":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true},{"id":438,"text":"National Research Program - Western Branch","active":true,"usgs":true}],"preferred":true,"id":434886,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Morgan, David S.","contributorId":73181,"corporation":false,"usgs":true,"family":"Morgan","given":"David","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":434885,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Weick, Rodney J.","contributorId":79560,"corporation":false,"usgs":true,"family":"Weick","given":"Rodney","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":434889,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ]}