VALIDATION - ANOTHER PERSPECTIVE   总被引：1，自引：0，他引：1  

C. McCombie  I. McKinley 《Ground water》1993,31(4):530-531

  相似文献   

Discussion on: A mathematical model of permeability alteration around wells     

J. D. McKinley  M. D. Bolton 《国际地质力学数值与分析法杂志》1992,16(12):887-890

  相似文献   

Site fidelity and dispersal patterns of domestic triploid steelhead trout (Oncorhynchus Mykiss Walbaum) released to the wild     

Bridger  C. J.; Booth  R. K.; McKinley  R. S.; Scruton  D. A. 《ICES Journal of Marine Science》2001,58(2):510-516

  相似文献   

Desorption kinetics of radiocesium from subsurface sediments at Hanford Site, USA     

Chongxuan Liu  John M. Zachara  James P. McKinley 《Geochimica et cosmochimica acta》2003,67(16):2893-2912

The desorption of ¹³⁷Cs⁺ was investigated on sediments from the United States Hanford site. Pristine sediments and ones that were contaminated by the accidental release of alkaline ¹³⁷Cs⁺-containing high level nuclear wastes (HLW, 2 × 10⁶ to 6 × 10⁷ pCi ¹³⁷Cs⁺/g) were studied. The desorption of ¹³⁷Cs⁺ was measured in Na⁺, K⁺, Rb⁺, and NH₄⁺electrolytes of variable concentration and pH, and in presence of a strong Cs⁺-specific sorbent (self-assembled monolayer on a mesoporous support, SAMMS). ¹³⁷Cs⁺ desorption from the HLW-contaminated Hanford sediments exhibited two distinct phases: an initial instantaneous release followed by a slow kinetic process. The extent of ¹³⁷Cs⁺ desorption increased with increasing electrolyte concentration and followed a trend of Rb⁺ ≥ K⁺ > Na⁺ at circumneutral pH. This trend followed the respective selectivities of these cations for the sediment. The extent and rate of ¹³⁷Cs⁺ desorption was influenced by surface armoring, intraparticle diffusion, and the collapse of edge-interlayer sites in solutions containing K⁺, Rb⁺, or NH₄⁺. Scanning electron microscopic analysis revealed HLW-induced precipitation of secondary aluminosilicates on the edges and basal planes of micaceous minerals that were primary Cs⁺ sorbents. The removal of these precipitates by acidified ammonium oxalate extraction significantly increased the long-term desorption rate and extent. X-ray microprobe analyses of Cs⁺-sorbed micas showed that the ¹³⁷Cs⁺ distributed not only on mica edges, but also within internal channels parallel to the basal plane, implying intraparticle diffusive migration of ¹³⁷Cs⁺. Controlled desorption experiments using Cs⁺-spiked pristine sediment indicated that the ¹³⁷Cs⁺ diffusion rate was fast in Na⁺-electrolyte, but much slower in the presence of K⁺ or Rb⁺, suggesting an effect of edge-interlayer collapse. An intraparticle diffusion model coupled with a two-site cation exchange model was used to interpret the experimental results. Model simulations suggested that about 40% of total sorbed ¹³⁷Cs⁺ was exchangeable, including equilibrium and kinetic desorbable pools. At pH 3, this ratio increased to 60-80%. The remainder of the sorbed ¹³⁷Cs⁺ was fixed or desorbed at much slower rate than our experiments could detect.  相似文献   

MORPHOMETRIC ANALYSIS OF KARST DEPRESSIONS ON A MEDITERRANEAN KARST MASSIF          下载免费PDF全文

EULOGIO PARDO‐IGÚZQUIZA  ANTONIO PULIDO‐BOSCH  MANUEL LÓPEZ‐CHICANO  JUAN J. DURÁN 《Geografiska Annaler: Series A, Physical Geography》2016,98(3):247-263

Dolines are the most typical landform in karst landscapes. They play an important role in karst hydrogeology; they are effective sediment traps that provide information about past climates and karst evolution, and can also be indicators of tectonic activity. The morphometic analysis of those depressions can help in their study and interpretation. However, detailed identification and delineation of dolines becomes increasingly difficult when the study area is very large, of limited access or covered by vegetation. Here, we have used a method developed by the authors for automatic identification and delineation of karst depressions based on the use of a pit removal algorithm. Next a complete morphometric analysis of the karst depressions has been carried out. The main advantage of the methodology is that by delineating and identifying the depth of each doline from its rim, many morphometric statistics can be obtained, including the relation of doline depth and area with respect to altitude, the main doline orientations, doline density, the fractal dimension of doline area and frequency, and point field analysis, among others. The results are interpreted from a geomorphological point of view and the mapped dolines can be easily integrated into geomorphological mapping. A case study is presented from the large Sierra Gorda karst massif in southern Spain, where 3100 depressions have been identified. A strong structural control of doline shape and orientation is demonstrated; the main areas of doline density are highlighted and doline size is shown to follow a fractal law.  相似文献   

Environmental Monitoring and Peat Assessment Using Multivariate Analysis of Regional-Scale Geochemical Data     

Jennifer M. McKinley  Eric Grunsky  Ute Mueller 《Mathematical Geosciences》2018,50(2):235-246

A compositional multivariate approach was used to analyse regional-scale soil geochemical data obtained as part of the Tellus Project generated by the Geological Survey of Northern Ireland. The multi-element total concentration data presented comprise X-ray fluorescence (XRF) analyses of 6862 rural soil samples collected at 20-cm depth on a non-aligned grid at one site per \(2\,\hbox {km}^{2}\). Censored data were imputed using published detection limits. Each soil sample site was assigned to the regional geology map, resulting in spatial data for one categorical variable and 35 continuous variables comprised of individual and amalgamated elements. This paper examines the extent to which soil geochemistry reflects the underlying geology or superficial deposits. Since the soil geochemistry is compositional, log-ratios were computed to adequately evaluate the data using multivariate statistical methods. Principal component analysis (PCA) and minimum/maximum autocorrelation factors (MAF) were used to carry out linear discriminant analysis (LDA) as a means to discover and validate processes related to the geologic assemblages coded as age bracket. Peat cover was introduced as an additional category to measure the ability to predict and monitor fragile ecosystems. Overall prediction accuracies for the age bracket categories were 68.4 % using PCA and 74.7 % using MAF. With inclusion of peat, the accuracy for LDA classification decreased to 65.0 and 69.9 %, respectively. The increase in misclassification due to the presence of peat may reflect degradation of peat-covered areas since the creation of superficial deposit classification.  相似文献   

Individual responsibility for the oceans? An evaluation of marine citizenship by UK marine practitioners     

Emma McKinley  Stephen Fletcher 《Ocean & Coastal Management》2010,53(7):379-384

In recent times, the governance of the marine environment has evolved from being primarily top down and state directed to being more participatory and community based. This paper proposes that an extension of this trend would be the inculcation of a societal sense of marine citizenship to deliver the sustainable management and protection of the marine environment through enhanced individual involvement in policy development and implementation. The potential role of marine citizenship in UK marine governance was examined by surveying UK marine practitioner’s views on both the current and future role of marine citizenship. Observations from this study identified three key factors for discussion including conflicting opinions over the implementation of marine citizenship into policy; that marine-focused education and a sense of personal attachment are integral to the development of marine citizenship; and that as yet, the potential implications of an enhanced sense of marine citizenship are uncertain. This research highlights the recognition amongst marine practitioners that higher levels of citizen involvement in the management of the marine environment would greatly benefit the marine environment, with additional benefits possible through an increased sense of marine citizenship.  相似文献   

Generation of Hydrogen Gas as a Result of Drilling Within the Saturated Zone   总被引：1，自引：0，他引：1  

Bruce N. Bjornstad  James P. McKinley  Todd O. Stevens  Shirley A. Rawson  James K. Fredrickson  Philip E. Long 《Ground Water Monitoring & Remediation》1994,14(4):140-147

Hydrogen gas was discovered within the steel casing above standing water in a percussion-drilled borehole on the Hanlord Site in south-central Washington state. In situ measurements of the borehole fluids indicated anoxic, low-Eh (<-400 mV) conditions. Ground water sampled from adjacent wells in the same formation indicated that the ground water was oxygenated. H₂ was generated during percussion drilling, due to the decomposition of borehole waters as a result of aqueous reactions with drilled sediment and steel from the drilling tools or casing. The generation of H₂ within percussion-drilled boreholes that extend below the water table may be more common than previously realized. The ambient concentration of H₂ produced during drilling was limited by microbial activity within the casing-resident fluids. H₂ was generated abiotically in the laboratory, whereby sterilized borehole slurry samples produced 100 times more H₂ than unsterilizcd samples. It appears that H₂ is metabolized by microorganisms and concentrations might be significantly greater if not for microbial metabolism.  相似文献   

Ferrous phosphate surface precipitates resulting from the reduction of intragrain 6-line ferrihydrite by Shewanella oneidensis MR-1     

T.S. Peretyazhko  J.M. Zachara  D.W. Kennedy  J.K. Fredrickson  B.W. Arey  J.P. McKinley  C.M. Wang  A.C. Dohnalkova  Y. Xia 《Geochimica et cosmochimica acta》2010,74(13):3751-60

The reductive biotransformation of 6-line ferrihydrite located within porous silica (intragrain ferrihydrite) by Shewanella oneidensis MR-1 was investigated and compared to the behavior of 6-line ferrihydrite in suspension (free ferrihydrite). The effect of buffer type (PIPES and NaHCO₃), phosphate (P), and an electron shuttle (AQDS) on the extent of reduction and formation of Fe(II) secondary phases was investigated under anoxic conditions. Electron microscopy and micro X-ray diffraction were applied to evaluate the morphology and mineralogy of the biogenic precipitates and to study the distribution of microorganisms on the surface of porous silica after bioreduction. Kinetic reduction experiments with free and intragrain ferrihydrite revealed contrasting behavior with respect to the buffer and presence of P. The overall amount of intragrain ferrihydrite reduction was less than that of free ferrihydrite [at 5 mmol L⁻¹ Fe(III)_T]. Reductive mineralization was not observed in the intragrain ferrihydrite incubations without P, and all biogenic Fe(II) concentrated in the aqueous phase. Irrespective of buffer and AQDS addition, rosettes of Fe(II) phosphate of approximate 20-30 μm size were observed on porous silica when P was present. The rosettes grew not only on the silica surface but also within it, forming a coherent spherical structure. These precipitates were well colonized by microorganisms and contained extracellular materials at the end of incubation. Microbial extracellular polymeric substances may have adsorbed Fe(II) promoting Fe(II) phosphate nucleation with subsequent crystal growth proceeding in different directions from a common center.  相似文献   

Key natural analogue input required to build a safety case for direct disposal of spent nuclear fuel in Japan     

Ian G. McKinley  Hideki Kawamura  Susie M. L. Hardie  Elizaveta Klein  Tara M. Beattie 《Swiss Journal of Geoscience》2015,108(1):147-154

  相似文献