Various techniques are available to quantify recharge; however, choosing appropriate techniques is often difficult. Important considerations in choosing a technique include space/time scales, range, and reliability of recharge estimates based on different techniques; other factors may limit the application of particular techniques. The goal of the recharge study is important because it may dictate the required space/time scales of the recharge estimates. Typical study goals include water-resource evaluation, which requires information on recharge over large spatial scales and on decadal time scales; and evaluation of aquifer vulnerability to contamination, which requires detailed information on spatial variability and preferential flow. The range of recharge rates that can be estimated using different approaches should be matched to expected recharge rates at a site. The reliability of recharge estimates using different techniques is variable. Techniques based on surface-water and unsaturated-zone data provide estimates of potential recharge, whereas those based on groundwater data generally provide estimates of actual recharge. Uncertainties in each approach to estimating recharge underscore the need for application of multiple techniques to increase reliability of recharge estimates.
","language":"English","publisher":"Springer","doi":"10.1007/s10040-001-0176-2","usgsCitation":"Scanlon, B., Healy, R.W., and Cook, P.G., 2002, Choosing appropriate techniques for quantifying groundwater recharge: Hydrogeology Journal, v. 10, no. 1, p. 18-39, https://doi.org/10.1007/s10040-001-0176-2.","productDescription":"22 p.","startPage":"18","endPage":"39","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":232867,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"10","issue":"1","noUsgsAuthors":false,"publicationDate":"2002-01-17","publicationStatus":"PW","scienceBaseUri":"5059f5d7e4b0c8380cd4c45b","contributors":{"authors":[{"text":"Scanlon, Bridget R.","contributorId":74093,"corporation":false,"usgs":true,"family":"Scanlon","given":"Bridget R.","affiliations":[],"preferred":false,"id":403368,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Healy, Richard W. 0000-0002-0224-1858 rwhealy@usgs.gov","orcid":"https://orcid.org/0000-0002-0224-1858","contributorId":658,"corporation":false,"usgs":true,"family":"Healy","given":"Richard","email":"rwhealy@usgs.gov","middleInitial":"W.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":403369,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Cook, Peter G.","contributorId":192638,"corporation":false,"usgs":false,"family":"Cook","given":"Peter","email":"","middleInitial":"G.","affiliations":[],"preferred":false,"id":403370,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024834,"text":"70024834 - 2002 - Evaluating remedial alternatives for an acid mine drainage stream: Application of a reactive transport model","interactions":[],"lastModifiedDate":"2018-11-28T09:24:57","indexId":"70024834","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","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":"Evaluating remedial alternatives for an acid mine drainage stream: Application of a reactive transport model","docAbstract":"A reactive transport model based on one-dimensional transport and equilibrium chemistry is applied to synoptic data from an acid mine drainage stream. Model inputs include streamflow estimates based on tracer dilution, inflow chemistry based on synoptic sampling, and equilibrium constants describing acid/base, complexation, precipitation/dissolution, and sorption reactions. The dominant features of observed spatial profiles in pH and metal concentration are reproduced along the 3.5-km study reach by simulating the precipitation of Fe(III) and Al solid phases and the sorption of Cu, As, and Pb onto freshly precipitated iron(III) oxides. Given this quantitative description of existing conditions, additional simulations are conducted to estimate the streamwater quality that could result from two hypothetical remediation plans. Both remediation plans involve the addition of CaCO3 to raise the pH of a small, acidic inflow from ∼2.4 to ∼7.0. This pH increase results in a reduced metal load that is routed downstream by the reactive transport model, thereby providing an estimate of post-remediation water quality. The first remediation plan assumes a closed system wherein inflow Fe(II) is not oxidized by the treatment system; under the second remediation plan, an open system is assumed, and Fe(II) is oxidized within the treatment system. Both plans increase instream pH and substantially reduce total and dissolved concentrations of Al, As, Cu, and Fe(II+III) at the terminus of the study reach. Dissolved Pb concentrations are reduced by ∼18% under the first remediation plan due to sorption onto iron(III) oxides within the treatment system and stream channel. In contrast, iron(III) oxides are limiting under the second remediation plan, and removal of dissolved Pb occurs primarily within the treatment system. This limitation results in an increase in dissolved Pb concentrations over existing conditions as additional downstream sources of Pb are not attenuated by sorption.
Following the aggressive invasion of the bivalve, Potamocorbula amurensis, in the San Francisco Bay-Delta in 1986, selenium contamination in the benthic food web increased. Concentrations in this dominant (exotic) bivalve in North Bay were three times higher in 1995–1997 than in earlier studies, and 1990 concentrations in benthic predators (sturgeon and diving ducks) were also higher than in 1986. The contamination was widespread, varied seasonally and was greater in P. amurensis than in co-occurring and transplanted species. Selenium concentrations in the water column of the Bay were enriched relative to the Sacramento River but were not as high as observed in many contaminated aquatic environments. Total Se concentrations in the dissolved phase never exceeded 0.3 μg Se per l in 1995 and 1996; Se concentrations on particulate material ranged from 0.5 to 2.0 μg Se per g dry weight (dw) in the Bay. Nevertheless, concentrations in P. amurensis reached as high as 20 μg Se per g dw in October 1996. The enriched concentrations in bivalves (6–20 μg Se per g dw) were widespread throughout North San Francisco Bay in October 1995 and October 1996. Concentrations varied seasonally from 5 to 20 μg Se per g dw, and were highest during the periods of lowest river inflows and lowest after extended high river inflows. Transplanted bivalves (oysters, mussels or clams) were not effective indicators of either the degree of Se contamination in P. amurensis or the seasonal increases in contamination in the resident benthos. Se is a potent environmental toxin that threatens higher trophic level species because of its reproductive toxicity and efficient food web transfer. Bivalves concentrate selenium effectively because they bioaccumulate the element strongly and lose it slowly; and they are a direct link in the exposure of predaceous benthivore species. Biological invasions of estuaries are increasing worldwide. Changes in ecological structure and function are well known in response to invasions. This study shows that changes in processes such as cycling and effects of contaminants can accompany such invasions.
Near Mirror Lake, New Hampshire (USA), hydraulically conductive, fractured bedrock was investigated with the crosswell seismic method to determine whether this method could provide any information about hydraulic conductivity between wells. To this end, crosswell seismic data, acoustic logs from boreholes, image logs from boreholes, and single borehole hydraulic tests were analyzed. The analysis showed that, first, the P-wave velocities from the acoustic logs tended to be higher in schist than they were in granite. (Schist and granite were the dominant rock types). Second, the P-wave velocities from the acoustic logs tended to be low near fractures. Third, the hydraulic conductivity was always low (always less than to 10−8 m/s) where no fractures intersected the borehole, but the hydraulic conductivity ranged from low to high (from less than to 10−10 m/s to 10−4 m/s) where one or more fractures intersected the borehole. Fourth, high hydraulic conductivities were slightly more frequent when the P-wave velocity was low (less than 5200 m/s) than when it was high (greater than or equal to 5200 m/s). The interpretation of this statistical relation was that the fractures tended to increase the hydraulic conductivity and to lower the P-wave velocity. This statistical relation was applied to a velocity tomogram to create a map showing the probability of high hydraulic conductivity; the map was consistent with results from independent hydraulic tests.
Recharge rates of nitrate (NO3−) to groundwater beneath agricultural land commonly are greater than discharge rates of NO3− in nearby streams, but local controls of NO3−distribution in the subsurface generally are poorly known. Groundwater dating (CFC, 3H) was combined with chemical (ions and gases) and stable isotope (N, S, and C) analyses to resolve the effects of land use changes, flow patterns, and water‐aquifer reactions on the distributions of O2, NO3−, SO4=, and other constituents in a two‐dimensional vertical section leading from upland cultivated fields to a riparian wetland and stream in a glacial outwash sand aquifer near Princeton, Minnesota. Within this section a “plume” of oxic NO3−‐rich groundwater was present at shallow depths beneath the fields and part of the wetland but terminated before reaching the stream or the wetland surface. Groundwater dating and hydraulic measurements indicate travel times in the local flow system of 0 to >40 years, with stratified recharge beneath the fields, downward diversion of the shallow NO3−‐bearing plume by semiconfining organic‐rich valley‐filling sediments under the wetland and upward discharge across the valley and stream bottom. The concentrations and δ15N values of NO3− and N2 indicate that the NO3− plume section was bounded in three directions by a curvilinear zone of active denitrification that limited its progress; however, when recalculated to remove the effects of denitrification, the data also indicate changes in both the concentrations and δ15N values of NO3− that was recharged in the past. Isotope data and mass balance calculations indicate that FeS2 and other ferrous Fe phases were the major electron donors for denitrification in at least two settings: (1) within the glacial‐fluvial aquifer sediments beneath the recharge and discharge areas and (2) along the bottom of the valley‐filling sediments in the discharge area. Combined results indicate that the shape and progress of the oxic NO3− plume termination were controlled by a combination of (1) historical and spatial variations in land use practices, (2) contrast in groundwater flow patterns between the agricultural recharge area and riparian wetland discharge area, and (3) distribution and abundance of electron donors in both the sand aquifer and valley‐filling sediments. The data are consistent with slow migration of redox zones through the aquifer in response to recharging oxic groundwater during Holocene time, then an order‐of‐magnitude increase in the flux of electron acceptors as a result of agricultural NO3− contamination in the late twentieth century, to which the redox zone configuration still may be adjusting. The importance of denitrification for NO3− movement through formerly glaciated terrains should depend on the source areas and depositional environments of the glacial sediments, as well as geomorphology and recent stream‐valley sediment history.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/2001WR000663","usgsCitation":"Böhlke, J., Wanty, R., Tuttle, M., Delin, G., and Landon, M.K., 2002, Denitrification in the recharge area and discharge area of a transient agricultural nitrate plume in a glacial outwash sand aquifer, Minnesota: Water Resources Research, v. 38, no. 7, p. 10-1-10-26, https://doi.org/10.1029/2001WR000663.","productDescription":"1105; 26 p.","startPage":"10-1","endPage":"10-26","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":233051,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"38","issue":"7","noUsgsAuthors":false,"publicationDate":"2002-07-17","publicationStatus":"PW","scienceBaseUri":"5059fe9ae4b0c8380cd4ee11","contributors":{"authors":[{"text":"Böhlke, J.K. 0000-0001-5693-6455","orcid":"https://orcid.org/0000-0001-5693-6455","contributorId":96696,"corporation":false,"usgs":true,"family":"Böhlke","given":"J.K.","affiliations":[],"preferred":false,"id":401480,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wanty, R. 0000-0002-2063-6423","orcid":"https://orcid.org/0000-0002-2063-6423","contributorId":99300,"corporation":false,"usgs":true,"family":"Wanty","given":"R.","affiliations":[],"preferred":false,"id":401481,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Tuttle, M.","contributorId":26397,"corporation":false,"usgs":true,"family":"Tuttle","given":"M.","affiliations":[],"preferred":false,"id":401478,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Delin, G.","contributorId":86142,"corporation":false,"usgs":true,"family":"Delin","given":"G.","affiliations":[],"preferred":false,"id":401479,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Landon, Matthew K. 0000-0002-5766-0494 landon@usgs.gov","orcid":"https://orcid.org/0000-0002-5766-0494","contributorId":392,"corporation":false,"usgs":true,"family":"Landon","given":"Matthew","email":"landon@usgs.gov","middleInitial":"K.","affiliations":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"preferred":true,"id":401477,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70024493,"text":"70024493 - 2002 - A passive microwave snow depth algorithm with a proxy for snow metamorphism","interactions":[],"lastModifiedDate":"2012-03-12T17:20:06","indexId":"70024493","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1924,"text":"Hydrological Processes","active":true,"publicationSubtype":{"id":10}},"title":"A passive microwave snow depth algorithm with a proxy for snow metamorphism","docAbstract":"Passive microwave brightness temperatures of snowpacks depend not only on the snow depth, but also on the internal snowpack properties, particularly the grain size, which changes through the winter. Algorithms that assume a constant grain size can yield erroneous estimates of snow depth or water equivalent. For snowpacks that are subject to temperatures well below freezing, the bulk temperature gradient through the snowpack controls the metamorphosis of the snow grains. This study used National Weather Service (NWS) station measurements of snow depth and air temperature from the Northern US Great Plains to determine temporal and spatial variability of the snow depth and bulk snowpack temperature gradient. This region is well suited for this study because it consists primarily of open farmland or prairie, has little relief, is subject to very cold temperatures, and has more than 280 reporting stations. A geostatistical technique called Kriging was used to grid the randomly spaced snow depth measurements. The resulting snow depth maps were then compared with the passive microwave observations from the Special Sensor Microwave Imager (SSM/I). Two snow seasons were examined: 1988-89, a typical snow year, and 1996-97, a record year for snow that was responsible for extensive flooding in the Red River Basin. Inspection of the time series of snow depth and microwave spectral gradient (the difference between the 19 and 37 GHz bands) showed that while the snowpack was constant, the spectral gradient continued to increase. However, there was a strong correlation (0.6 < R2 < 0.9) between the spectral gradient and the cumulative bulk temperature gradient through the snowpack (TGI). Hence, TGI is an index of grain size metamorphism that has occurred within the snowpack. TGI time series from 21 representative sites across the region and the corresponding SSM/I observations were used to develop an algorithm for snow depth that requires daily air temperatures. Copyright ?? 2002 John Wiley & Sons, Ltd.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrological Processes","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1002/hyp.1020","issn":"08856087","usgsCitation":"Josberger, E., and Mognard, N.M., 2002, A passive microwave snow depth algorithm with a proxy for snow metamorphism: Hydrological Processes, v. 16, no. 8, p. 1557-1568, https://doi.org/10.1002/hyp.1020.","startPage":"1557","endPage":"1568","numberOfPages":"12","costCenters":[],"links":[{"id":207775,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/hyp.1020"},{"id":232977,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"16","issue":"8","noUsgsAuthors":false,"publicationDate":"2002-06-11","publicationStatus":"PW","scienceBaseUri":"5059e4d3e4b0c8380cd46964","contributors":{"authors":[{"text":"Josberger, E.G.","contributorId":61161,"corporation":false,"usgs":true,"family":"Josberger","given":"E.G.","email":"","affiliations":[],"preferred":false,"id":401458,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Mognard, N. M.","contributorId":27612,"corporation":false,"usgs":false,"family":"Mognard","given":"N.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":401457,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70024488,"text":"70024488 - 2002 - Influence of an extreme high water event on survival, reproduction, and distribution of snail kites in Florida, USA","interactions":[],"lastModifiedDate":"2022-08-22T16:09:27.922759","indexId":"70024488","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3750,"text":"Wetlands","onlineIssn":"1943-6246","printIssn":"0277-5212","active":true,"publicationSubtype":{"id":10}},"title":"Influence of an extreme high water event on survival, reproduction, and distribution of snail kites in Florida, USA","docAbstract":"Hydrology frequently has been reported as the environmental variable having the greatest influence on Florida snail kite (Rostrhamus sociabilis) populations. Although drought has received the most attention, high-water conditions also have been reported to affect kites. Years of high water generally have been reported to be favorable for nesting, although prolonged high water may be detrimental to sustaining suitable habitat. During 1994 and 1995, southern Florida experienced an extreme high water event. This event enabled us to compare survival, nesting success, number of young per successful nest, and spatial distribution of nesting before, during, and after the event. We found no evidence of an effect (either negative or positive) on survival of adult kites. In contrast, juvenile kites experienced the highest survival during the event, although our data suggest greater annual variability than can be explained by the event alone. We found no evidence of an effect of the high water event on nest success or number of young per successful nest. Nest success was highest during the event in the southern portion of the range but was quite similar to other years, both before and after the event. Our data do indicate a substantial shift in the spatial distribution of nesting birds. During the event, nesting activity shifted to higher elevations (i.e., shallower water) in the major nesting areas of the Everglades region. Nesting also occurred in Big Cypress National Preserve during the event, which is typically too dry to support nesting kites. Thus, our data indicate a potential shortterm benefit of increased juvenile survival and an expansion of nesting habitat. However, the deterioration of habitat quality from prolonged high water precludes any recommendation for such conditions to be maintained for extended periods.
","language":"English","publisher":"Springer Link","doi":"10.1672/0277-5212(2002)022[0366:IOAEHW]2.0.CO;2","usgsCitation":"Bennetts, R.E., Kitchens, W.M., and Dreitz, V., 2002, Influence of an extreme high water event on survival, reproduction, and distribution of snail kites in Florida, USA: Wetlands, v. 22, no. 2, p. 366-373, https://doi.org/10.1672/0277-5212(2002)022[0366:IOAEHW]2.0.CO;2.","productDescription":"8 p.","startPage":"366","endPage":"373","numberOfPages":"8","costCenters":[],"links":[{"id":232873,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Florida","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -82.90283203125,\n 25.045792240303445\n ],\n [\n -79.91455078125,\n 25.045792240303445\n ],\n [\n -79.91455078125,\n 28.323724553546015\n ],\n [\n -82.90283203125,\n 28.323724553546015\n ],\n [\n -82.90283203125,\n 25.045792240303445\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"22","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3b0ee4b0c8380cd621c1","contributors":{"authors":[{"text":"Bennetts, Robert E.","contributorId":62508,"corporation":false,"usgs":true,"family":"Bennetts","given":"Robert","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":401446,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kitchens, Wiley M. kitchensw@usgs.gov","contributorId":2851,"corporation":false,"usgs":true,"family":"Kitchens","given":"Wiley","email":"kitchensw@usgs.gov","middleInitial":"M.","affiliations":[],"preferred":true,"id":401445,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Dreitz, Victoria","contributorId":172457,"corporation":false,"usgs":false,"family":"Dreitz","given":"Victoria","affiliations":[{"id":5097,"text":"University of Montana, Division of Biological Sciences","active":true,"usgs":false}],"preferred":false,"id":401444,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70024456,"text":"70024456 - 2002 - Characterization of microbial arsenate reduction in the anoxic bottom waters of Mono Lake, California","interactions":[],"lastModifiedDate":"2018-11-28T09:45:05","indexId":"70024456","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1800,"text":"Geomicrobiology Journal","active":true,"publicationSubtype":{"id":10}},"title":"Characterization of microbial arsenate reduction in the anoxic bottom waters of Mono Lake, California","docAbstract":"Dissimilatory reduction of arsenate (DAsR) occurs in the arsenic-rich, anoxic water column of Mono Lake, California, yet the microorganisms responsible for this observed in situ activity have not been identified. To gain insight as to which microorganisms mediate this phenomenon, as well as to some of the biogeochemical constraints on this activity, we conducted incubations of arsenate-enriched bottom water coupled with inhibition/amendment studies and Denaturing Gradient Gel Electrophoresis (DGGE) characterization techniques. DAsR was totally inhibited by filter-sterilization and by nitrate, partially inhibited (~50%) by selenate, but only slightly (~25%) inhibited by oxyanions that block sulfate-reduction (molybdate and tungstate). The apparent inhibition by nitrate, however, was not due to action as a preferred electron acceptor to arsenate. Rather, nitrate addition caused a rapid, microbial re-oxidation of arsenite to arsenate, which gave the overall appearance of no arsenate loss. A similar microbial oxidation of As(III) was also found with Fe(III), a fact that has implications for the recycling of As(V) in Mono Lake's anoxic bottom waters. DAsR could be slightly (10%) stimulated by substrate amendments of lactate, succinate, malate, or glucose, but not by acetate, suggesting that the DAsR microflora is not electron donor limited. DGGE analysis of amplified 16S rDNA gene fragments from incubated arsenate-enriched bottom waters revealed the presence of two bands that were not present in controls without added arsenate. The resolved sequences of these excised bands indicated the presence of members of the epsilon (Sulfurospirillum) and delta (Desulfovibrio) subgroups of the Proteobacteria, both of which have representative species that are capable of anaerobic growth using arsenate as their electron acceptor.","language":"English","publisher":"Taylor & Francis","doi":"10.1080/014904502317246147","issn":"01490451","usgsCitation":"Hoeft, S., Lucas, F., Hollibaugh, J., and Oremland, R., 2002, Characterization of microbial arsenate reduction in the anoxic bottom waters of Mono Lake, California: Geomicrobiology Journal, v. 19, no. 1, p. 23-40, https://doi.org/10.1080/014904502317246147.","productDescription":"18 p.","startPage":"23","endPage":"40","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":231659,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207067,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1080/014904502317246147"}],"country":"United States","state":"California","otherGeospatial":"Mono Lake","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"2010-11-10","publicationStatus":"PW","scienceBaseUri":"5059f4cfe4b0c8380cd4bf32","contributors":{"authors":[{"text":"Hoeft, S.E.","contributorId":24479,"corporation":false,"usgs":true,"family":"Hoeft","given":"S.E.","email":"","affiliations":[],"preferred":false,"id":401355,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Lucas, F.","contributorId":88119,"corporation":false,"usgs":true,"family":"Lucas","given":"F.","email":"","affiliations":[],"preferred":false,"id":401356,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hollibaugh, J.T.","contributorId":22886,"corporation":false,"usgs":true,"family":"Hollibaugh","given":"J.T.","email":"","affiliations":[],"preferred":false,"id":401354,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Oremland, R.S.","contributorId":97512,"corporation":false,"usgs":true,"family":"Oremland","given":"R.S.","email":"","affiliations":[],"preferred":false,"id":401357,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70024455,"text":"70024455 - 2002 - Effects of canopy gaps and flooding on homopterans in a bottomland hardwood forest","interactions":[],"lastModifiedDate":"2019-07-29T07:01:48","indexId":"70024455","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3750,"text":"Wetlands","onlineIssn":"1943-6246","printIssn":"0277-5212","active":true,"publicationSubtype":{"id":10}},"title":"Effects of canopy gaps and flooding on homopterans in a bottomland hardwood forest","docAbstract":"Canopy disturbance is a major factor affecting forest structure and composition and, as a result of habitat alterations, can influence insect communities. We initiated a field study to quantify the effects of canopy disturbance on aerial insect abundance and distribution within a bottomland hardwood forest along the Cache River, Arkansas, USA. We used passive flight-intercept traps to sample insects in canopy gap and forest interior habitats from May to July in 1996, 1997, and 1998. The hydrologic conditions of our study site varied among years: 1996 was relatively dry, 1997 incurred a long-duration flood, and 1998 was moderately wet. Of the 34,000+ Homopterans collected, many groups were distributed in a non-uniform manner among years and between habitats. Total Homopterans, two families of Homopterans, and six morphospecies were more abundant in canopy gaps than interior forest. Many Homopteran taxa were least abundant in 1997 following almost six months of flooding. Alternatively, relatively large Homopteran abundances were associated with the dry conditions of 1996 and the moderately wet conditions of 1998. Differences in Homopteran abundance among years and habitats may be related to differences in vegetation density. Canopy gaps supported more vegetation cover than the interior forest in all but the first sampling interval. In addition, similar to Homopteran abundance, vegetation density was lower in 1997 than in 1998. These results demonstrate that natural disturbance and flooding contribute to Homopteran abundance and distribution patterns in bottomland hardwood forests of the south central United States.
","language":"English","publisher":"Springer","doi":"10.1672/0277-5212(2002)022[0541:EOCGAF]2.0.CO;2","issn":"02775212","usgsCitation":"Gorham, L., King, S., Keeland, B.D., and Mopper, S., 2002, Effects of canopy gaps and flooding on homopterans in a bottomland hardwood forest: Wetlands, v. 22, no. 3, p. 541-549, https://doi.org/10.1672/0277-5212(2002)022[0541:EOCGAF]2.0.CO;2.","productDescription":"9 p.","startPage":"541","endPage":"549","numberOfPages":"9","costCenters":[{"id":455,"text":"National Wetlands Research Center","active":true,"usgs":true},{"id":17705,"text":"Wetland and Aquatic Research Center","active":true,"usgs":true}],"links":[{"id":231658,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Arkansas","otherGeospatial":"Cache 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\"}}]}","volume":"22","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a06a1e4b0c8380cd51342","contributors":{"authors":[{"text":"Gorham, L.E.","contributorId":12652,"corporation":false,"usgs":true,"family":"Gorham","given":"L.E.","email":"","affiliations":[],"preferred":false,"id":401350,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"King, S.L.","contributorId":105663,"corporation":false,"usgs":true,"family":"King","given":"S.L.","email":"","affiliations":[],"preferred":false,"id":401353,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Keeland, B. D.","contributorId":45275,"corporation":false,"usgs":true,"family":"Keeland","given":"B.","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":401352,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Mopper, S.","contributorId":33489,"corporation":false,"usgs":true,"family":"Mopper","given":"S.","email":"","affiliations":[],"preferred":false,"id":401351,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70024387,"text":"70024387 - 2002 - Mercury deposition in snow near an industrial emission source in the western U.S. and comparison to ISC3 model predictions","interactions":[],"lastModifiedDate":"2018-11-26T10:57:51","indexId":"70024387","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3728,"text":"Water, Air, & Soil Pollution","onlineIssn":"1573-2932","printIssn":"0049-6979","active":true,"publicationSubtype":{"id":10}},"title":"Mercury deposition in snow near an industrial emission source in the western U.S. and comparison to ISC3 model predictions","docAbstract":"Mercury (total and methyl) was evaluated in snow samples collected near a major mercury emission source on the Idaho National Engineering and Environmental Laboratory (INEEL) insoutheastern Idaho and 160 km downwind in Teton Range in westernWyoming. The sampling was done to assess near-field (<12 km)deposition rates around the source, compare them to those measured in a relatively remote, pristine downwind location, andto use the measurements to develop improved, site-specific modelinput parameters for precipitation scavenging coefficient and thefraction of Hg emissions deposited locally. Measured snow waterconcentrations (ng L-1) were converted to deposition (ugm-2) using the sample location snow water equivalent. Thedeposition was then compared to that predicted using the ISC3 airdispersion/deposition model which was run with a range ofparticle and vapor scavenging coefficient input values. Acceptedmodel statistical performance measures (fractional bias andnormalized mean square error) were calculated for the differentmodeling runs, and the best model performance was selected. Measured concentrations close to the source (average = 5.3 ngL-1) were about twice those measured in the Teton Range(average = 2.7 ng L-1) which were within the expected rangeof values for remote background areas. For most of the samplinglocations, the ISC3 model predicted within a factor of two of theobserved deposition. The best modeling performance was obtainedusing a scavenging coefficient value for 0.25 μm diameterparticulate and the assumption that all of the mercury isreactive Hg(II) and subject to local deposition. A 0.1 μm particle assumption provided conservative overprediction of thedata, while a vapor assumption resulted in highly variable predictions. Partitioning a fraction of the Hg emissions to elemental Hg(0) (a U.S. EPA default assumption for combustion facility risk assessments) would have underpredicted the observed fallout.
","language":"English","publisher":"Springer","doi":"10.1023/A:1015856717964","issn":"00496979","usgsCitation":"Abbott, M., Susong, D., Krabbenhoft, D., and Rood, A., 2002, Mercury deposition in snow near an industrial emission source in the western U.S. and comparison to ISC3 model predictions: Water, Air, & Soil Pollution, v. 139, no. 1-4, p. 95-114, https://doi.org/10.1023/A:1015856717964.","productDescription":"20 p.","startPage":"95","endPage":"114","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":231929,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207197,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1023/A:1015856717964"}],"country":"United States","state":"Idaho","otherGeospatial":"Idaho National Engineering and Environmental Laboratory","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -114.4556,42.0085 ], [ -114.4556,44.4397 ], [ -111.6129,44.4397 ], [ -111.6129,42.0085 ], [ -114.4556,42.0085 ] ] ] } } ] }","volume":"139","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a53fee4b0c8380cd6ce55","contributors":{"authors":[{"text":"Abbott, M.L.","contributorId":76090,"corporation":false,"usgs":true,"family":"Abbott","given":"M.L.","email":"","affiliations":[],"preferred":false,"id":401083,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Susong, D. D.","contributorId":12868,"corporation":false,"usgs":true,"family":"Susong","given":"D. D.","affiliations":[],"preferred":false,"id":401082,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Krabbenhoft, D. P. 0000-0003-1964-5020","orcid":"https://orcid.org/0000-0003-1964-5020","contributorId":90765,"corporation":false,"usgs":true,"family":"Krabbenhoft","given":"D. P.","affiliations":[],"preferred":false,"id":401085,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Rood, A.S.","contributorId":76906,"corporation":false,"usgs":true,"family":"Rood","given":"A.S.","email":"","affiliations":[],"preferred":false,"id":401084,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70024386,"text":"70024386 - 2002 - Relations between soil moisture and satellite vegetation indices in the U.S. Corn Belt","interactions":[],"lastModifiedDate":"2017-04-10T10:08:49","indexId":"70024386","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2344,"text":"Journal of Hydrometeorology","active":true,"publicationSubtype":{"id":10}},"title":"Relations between soil moisture and satellite vegetation indices in the U.S. Corn Belt","docAbstract":"Satellite-derived vegetation indices extracted over locations representative of midwestern U.S. cropland and forest for the period 1990–94 are analyzed to determine the sensitivity of the indices to neutron probe soil moisture measurements of the Illinois Climate Network (ICN). The deseasoned (i.e., departures from multiyear mean annual cycle) soil moisture measurements are shown to be weakly correlated with the deseasoned full resolution (1 km × 1 km) normalized difference vegetation index (NDVI) and fractional vegetation cover (FVC) data over both land cover types. The association, measured by the Pearson-moment-correlation coefficient, is stronger over forest than over cropland during the growing season (April–September). The correlations improve successively when the NDVI and FVC pixel data are aggregated to 3 km × 3 km, 5 km × 5 km, and 7 km × 7 km areas. The improved correlations are partly explained by the reduction in satellite navigation errors as spatial aggregation occurs, as well as the apparent scale dependence of the NDVI–soil moisture association. Similarly, stronger relations are obtained with soil moisture data that are lagged by up to 8 weeks with respect to the vegetation indices, implying that soil moisture may be a useful predictor of warm season satellite-derived vegetation conditions. This study suggests that a “long-term” memory of several weeks is present in the near-surface hydrological characteristics, especially soil water content, of the Midwest Corn Belt. The memory is integrated into the satellite vegetation indices and may be useful for predicting crop yield estimates and surface temperature anomalies.
","language":"English","publisher":"American Meteorological Society","doi":"10.1175/1525-7541(2002)003<0395:RBSMAS>2.0.CO;2","issn":"1525755X","usgsCitation":"Adegoke, J.O., and Carleton, A., 2002, Relations between soil moisture and satellite vegetation indices in the U.S. Corn Belt: Journal of Hydrometeorology, v. 3, no. 4, p. 395-405, https://doi.org/10.1175/1525-7541(2002)003<0395:RBSMAS>2.0.CO;2.","productDescription":"11 p.","startPage":"395","endPage":"405","numberOfPages":"11","costCenters":[{"id":222,"text":"Earth Resources Observation and Science (EROS) Center","active":true,"usgs":true}],"links":[{"id":478723,"rank":10000,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.1175/1525-7541(2002)003<0395:rbsmas>2.0.co;2","text":"Publisher Index Page"},{"id":231964,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":207210,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1175/1525-7541(2002)003<0395:RBSMAS>2.0.CO;2"}],"volume":"3","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"50e4a703e4b0e8fec6cdc33a","contributors":{"authors":[{"text":"Adegoke, Jimmy O.","contributorId":94816,"corporation":false,"usgs":true,"family":"Adegoke","given":"Jimmy","email":"","middleInitial":"O.","affiliations":[],"preferred":false,"id":401081,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Carleton, A.M.","contributorId":87330,"corporation":false,"usgs":true,"family":"Carleton","given":"A.M.","email":"","affiliations":[],"preferred":false,"id":401080,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70024384,"text":"70024384 - 2002 - Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance","interactions":[],"lastModifiedDate":"2018-11-26T08:30:56","indexId":"70024384","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","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":"Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance","docAbstract":"To provide the first nationwide reconnaissance of the occurrence of pharmaceuticals, hormones, and other organic wastewater contaminants (OWCs) in water resources, the U.S. Geological Survey used five newly developed analytical methods to measure concentrations of 95 OWCs in water samples from a network of 139 streams across 30 states during 1999 and 2000. The selection of sampling sites was biased toward streams susceptible to contamination (i.e. downstream of intense urbanization and livestock production). OWCs were prevalent during this study, being found in 80% of the streams sampled. The compounds detected represent a wide range of residential, industrial, and agricultural origins and uses with 82 of the 95 OWCs being found during this study. The most frequently detected compounds were coprostanol (fecal steroid), cholesterol (plant and animal steroid), N,N-diethyltoluamide (insect repellant), caffeine (stimulant), triclosan (antimicrobial disinfectant), tri(2-chloroethyl)phosphate (fire retardant), and 4-nonylphenol (nonionic detergent metabolite). Measured concentrations for this study were generally low and rarely exceeded drinking-water guidelines, drinking-water health advisories, or aquatic-life criteria. Many compounds, however, do not have such guidelines established. The detection of multiple OWCs was common for this study, with a median of seven and as many as 38 OWCs being found in a given water sample. Little is known about the potential interactive effects (such as synergistic or antagonistic toxicity) that may occur from complex mixtures of OWCs in the environment. In addition, results of this study demonstrate the importance of obtaining data on metabolites to fully understand not only the fate and transport of OWCs in the hydrologic system but also their ultimate overall effect on human health and the environment.
","language":"English","publisher":"American Chemical Society","doi":"10.1021/es011055j","issn":"0013936X","usgsCitation":"Kolpin, D., Furlong, E., Meyer, M.T., Thurman, E., Zaugg, S., Barber, L.B., and Buxton, H., 2002, Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance: Environmental Science & Technology, v. 36, no. 6, p. 1202-1211, https://doi.org/10.1021/es011055j.","productDescription":"10 p.","startPage":"1202","endPage":"1211","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":351,"text":"Iowa Water Science Center","active":true,"usgs":true},{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":231928,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": 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]\n}","volume":"36","issue":"6","noUsgsAuthors":false,"publicationDate":"2002-03-13","publicationStatus":"PW","scienceBaseUri":"505a786fe4b0c8380cd786cb","contributors":{"authors":[{"text":"Kolpin, D.W.","contributorId":87565,"corporation":false,"usgs":true,"family":"Kolpin","given":"D.W.","email":"","affiliations":[],"preferred":false,"id":401073,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Furlong, E. T. 0000-0002-7305-4603","orcid":"https://orcid.org/0000-0002-7305-4603","contributorId":98346,"corporation":false,"usgs":true,"family":"Furlong","given":"E. T.","affiliations":[],"preferred":false,"id":401075,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Meyer, M. T.","contributorId":92279,"corporation":false,"usgs":true,"family":"Meyer","given":"M.","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":401074,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Thurman, E.M.","contributorId":102864,"corporation":false,"usgs":true,"family":"Thurman","given":"E.M.","affiliations":[],"preferred":false,"id":401076,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Zaugg, S.D.","contributorId":82811,"corporation":false,"usgs":true,"family":"Zaugg","given":"S.D.","email":"","affiliations":[],"preferred":false,"id":401072,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Barber, L. B.","contributorId":64602,"corporation":false,"usgs":true,"family":"Barber","given":"L.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":401070,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Buxton, H. T.","contributorId":67873,"corporation":false,"usgs":true,"family":"Buxton","given":"H. T.","affiliations":[],"preferred":false,"id":401071,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70024381,"text":"70024381 - 2002 - The lacustrine carbon cycle as illuminated by the waters and sediments of two hydrologically distinct headwater lakes in north-central Minnesota, U.S.A","interactions":[],"lastModifiedDate":"2022-08-03T16:03:30.533493","indexId":"70024381","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2451,"text":"Journal of Sedimentary Research","onlineIssn":"1938-3681","printIssn":"1527-1404","active":true,"publicationSubtype":{"id":10}},"title":"The lacustrine carbon cycle as illuminated by the waters and sediments of two hydrologically distinct headwater lakes in north-central Minnesota, U.S.A","docAbstract":"The accumulation rates of CaCO3 and organic carbon (OC) in lake sediments are delicately balanced between production in the epilimnion and destruction in the hypolimnion. The cycling of these two forms of carbon makes a \"carbon pump\" that greatly affects the biogeochemical cycles of other elements. To further understand these biogeochemical dynamics, the lakes, streams, and wetlands of the Shingobee River headwater area of north-central Minnesota have been subjected to intensive hydrologic and biogeochemical studies. Williams Lake, situated close to the highest point in the regional flow system, is hydrologically closed, with no surface inlet or outlet, and ground water and precipitation as the only sources of water. Shingobee Lake, situated at the lowest point in the regional flow system, has the Shingobee River as an inlet and outlet. The surface waters of both lakes are oversaturated, and the bottom waters undersaturated, with respect to CaCO3 during the summer. The small amount of CaCO3 that is precipitated in the epilimnion of Williams Lake during the summer is dissolved in the undersaturated hypolimnion and sediments with the result that no CaCO3 is incorporated into the profundal surface sediments. Because of the high phytoplankton productivity of Shingobee Lake, sufficient CaCO3 is produced in the epilimnion that large amounts survive the corrosive hypolimnion and sediments, and an average of 46 wt. % accumulates in surface sediments.
Another consequence of higher phytoplankton productivity in Shingobee Lake is that the hypolimnion becomes oxygen deficient within a month after overturn in both the spring and fall. Because of reducing conditions that develop in the hypolimnion of Shingobee Lake, high concentrations of dissolved Fe and Mn accumulate there during summer stratification. Precipitation of Fe and Mn oxyhydroxides during periods of fall and spring overturn results in high concentrations of Fe and Mn in surface sediments. In Williams Lake, high concentrations of Fe and Mn do not build up in the hypolimnion.
The concentration of CaCO3 is about 80 wt. % in lower Holocene sediments of both lakes. The lower Holocene sediments in both lakes also contain high concentrations of Fe and Mn, and the lower Holocene sediments of Shingobee are laminated. The waters of both lakes had identical values of δ13C and δ18O during the early Holocene, but the waters of Williams Lake \"evolved\" during the early Holocene, increasing about 10‰ in both δ13C and δ18O. Deposits of lacustrine marl occur as much as seven meters above the present elevation of Williams Lake, the highest of the two lakes. Taken together, these observations suggest that the lakes were once connected to form a larger lake called Lake Willobee with a hypolimnion that was anoxic, at least seasonally.
","language":"English","publisher":"SEPM Society for Sedimentary Geology","doi":"10.1306/101801720416","usgsCitation":"Dean, W.E., and Schwalb, A., 2002, The lacustrine carbon cycle as illuminated by the waters and sediments of two hydrologically distinct headwater lakes in north-central Minnesota, U.S.A: Journal of Sedimentary Research, v. 72, no. 3, p. 416-431, https://doi.org/10.1306/101801720416.","productDescription":"16 p.","startPage":"416","endPage":"431","numberOfPages":"16","costCenters":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"links":[{"id":231890,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Minnesota","otherGeospatial":"Shingobee Lake, Williams Lake","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -94.69712734222412,\n 46.998607143063424\n ],\n [\n -94.67936038970947,\n 46.998607143063424\n ],\n [\n -94.67936038970947,\n 47.01043049343728\n ],\n [\n -94.69712734222412,\n 47.01043049343728\n ],\n [\n -94.69712734222412,\n 46.998607143063424\n ]\n ]\n ]\n }\n },\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -94.67605590820312,\n 46.949383372087425\n ],\n [\n -94.66292381286621,\n 46.949383372087425\n ],\n [\n -94.66292381286621,\n 46.958288587932536\n ],\n [\n -94.67605590820312,\n 46.958288587932536\n ],\n [\n -94.67605590820312,\n 46.949383372087425\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"72","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bad76e4b08c986b323c18","contributors":{"authors":[{"text":"Dean, Walter E. dean@usgs.gov","contributorId":1801,"corporation":false,"usgs":true,"family":"Dean","given":"Walter","email":"dean@usgs.gov","middleInitial":"E.","affiliations":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"preferred":true,"id":401063,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Schwalb, Antje","contributorId":20457,"corporation":false,"usgs":true,"family":"Schwalb","given":"Antje","email":"","affiliations":[],"preferred":false,"id":401062,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70024366,"text":"70024366 - 2002 - Effects of surface run-off on the transport of agricultural chemicals to ground water in a sandplain setting","interactions":[],"lastModifiedDate":"2018-11-26T09:08:13","indexId":"70024366","displayToPublicDate":"2002-01-01T00:00:00","publicationYear":"2002","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3352,"text":"Science of the Total Environment","active":true,"publicationSubtype":{"id":10}},"title":"Effects of surface run-off on the transport of agricultural chemicals to ground water in a sandplain setting","docAbstract":"An experiment was conducted at a depressional (lowland) and an upland site in sandy soils to evaluate the effects of surface run-off on the transport of agricultural chemicals to ground water. Approximately 16.5 cm of water was applied to both sites during the experiment, representing a natural precipitation event with a recurrence interval of approximately 100 years. Run-off was quantified at the lowland site and was not detected at the upland site during the experiment. Run-off of water to the lowland site was the most important factor affecting differences in the concentrations and fluxes of the agricultural chemicals between the two sites. Run-off of water to the lowland site appears to have played a dual role by diluting chemical concentrations in the unsaturated zone as well as increasing the concentrations at the water table, compared to the upland site. Concentrations of chloride, nitrate and atrazine plus metabolites were noticeably greater at the water table than in the unsaturated zone at both sites. The estimated mass flux of chloride and nitrate to the water table during the test were 5–2 times greater, respectively, at the lowland site compared to the upland site, whereas the flux of sulfate and atrazine plus metabolites was slightly greater at the upland site. Results indicate that matrix flow of water and chemicals was the primary process causing the observed differences between the two sites. Results of the experiment illustrate the effects of heterogeneity and the complexity of evaluating chemical transport through the unsaturated zone.
Ground water chemistry data collected over a six‐year period show that the distribution of contaminants and redox processes in a shallow petroleum hydrocarbon‐contaminated aquifer has changed rapidly over time. Shortly after a gasoline release occurred in 1990, high concentrations of benzene were present near the contaminant source area. In this contaminated zone, dissolved oxygen in ground water was depleted, and by 1994 Fe(lll) reduction and sulfate reduction were the predominant terminal electron accepting processes. Significantly, dissolved methane was below measurable levels in 1994, indicating the absence of significant methanogenesis. By 1996, however, depletion of solid‐phase Fe(lll)‐oxyhydroxides in aquifer sediments and depletion of dissolved sulfate in ground water resulted in the onset of methanogenesis. Between 1996 and 2000, water‐chemistry data indicated that methanogenic metabolism became increasingly prevalent. Molecular analysis of 16S‐rDNA extracted from sediments shows the presence of a more diverse methanogenic community inside as opposed to outside the plume core, and is consistent with water‐chemistry data indicating a shift toward methanogenesis over time. This rapid evolution of redox processes reflects several factors including the large amounts of contaminants, relatively rapid ground water flow (∼0.3 m/day [∼1 foot/day]), and low concentrations of microbially reducible Fe(lll) oxyhydroxides (∼ 1 umol/g) initially present in aquifer sediments. These results illustrate that, under certain hydrologic conditions, redox conditions in petroleum hydrocarbon‐contaminated aquifers can change rapidly in time and space, and that the availability of solid‐phase Fe(lll)‐oxyhydroxides affects this rate of change.