Temporal stability of soil water content as affected by climate and soil hydraulic properties: a simulation study   总被引：1，自引：0，他引：1       下载免费PDF全文

Gonzalo Martínez  Yakov A. Pachepsky  Harry Vereecken 《水文研究》2014,28(4):1899-1915

Temporal stability of soil water content (TS SWC) is an often‐observed phenomenon, which characterization finds multiple applications. Climate and variability in soil properties are usually mentioned as factors of TS SWC, but their effects are far from clear. The objective of this work was to use SWC modeling to evaluate the effects of climate and soil hydraulic properties on the TS of soil water at different measurement schedules. We selected four representative climates found in USA and simulated the multiyear SWC dynamics for sandy loam, loam, and silty clay loam soils, all having the lognormal spatial distribution of the saturated hydraulic conductivity. The CLIMGEN and the HYDRUS6 codes were used to generate weather patterns and to simulate SWC, respectively. Four different methods were applied to select the representative location (RL). The low probability of having the same variability of mean relative differences of soil water under different climates was found in most of the cases. The probability that the variance of mean relative differences depended on sampling frequency was generally higher than 91% for the three soils. The interannual difference in mean relative differences variation from short and intensive summer campaigns was highly probable for all climates and soils. The RLs changed as climate and measurement scheduling changed, and they were less pronounced for coarse‐textured soils. The RL selection methods based solely on bias provided more consistency as compared with other methods. The TS appears to be the result of the interplay between climate, soil properties, and survey protocols. One implication of this factor interaction effect on TS SWC is that a simulation study can be useful to decide on the feasibility of including a search for TS‐based RLs for a specific site. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Estimation of Generic Subslab Attenuation Factors for Vapor Intrusion Investigations     

Roger Brewer  Josh Nagashima  Mark Rigby  Martin Schmidt  Harry O'Neill 《Ground Water Monitoring & Remediation》2014,34(4):79-92

Generic indoor air:subslab soil gas attenuation factors (SSAFs) are important for rapid screening of potential vapor intrusion risks in buildings that overlie soil and groundwater contaminated with volatile chemicals. Insufficiently conservative SSAFs can allow high‐risk sites to be prematurely excluded from further investigation. Excessively conservative SSAFs can lead to costly, time‐consuming, and often inconclusive actions at an inordinate number of low‐risk sites. This paper reviews two of the most commonly used approaches to develop SSAFs: (1) comparison of paired, indoor air and subslab soil gas data in empirical databases and (2) comparison of estimated subslab vapor entry rates and indoor air exchange rates (IAERs). Potential error associated with databases includes interference from indoor and outdoor sources, reliance on data from basements, and seasonal variability. Heterogeneity in subsurface vapor plumes combined with uncertainty regarding vapor entry points calls into question the representativeness of limited subslab data and diminishes the technical defensibility of SSAFs extracted from databases. The use of reasonably conservative vapor entry rates and IAERs offers a more technically defensible approach for the development of generic SSAF values for screening. Consideration of seasonal variability in building leakage rates, air exchange rates, and interpolated vapor entry rates allows for the development of generic SSAFs at both local and regional scales. Limitations include applicability of the default IAERs and vapor entry rates to site‐specific vapor intrusion investigations and uncertainty regarding applicability of generic SSAFs to assess potential short‐term (e.g., intraday) variability of impacts to indoor air.  相似文献   

Book review     

Harry M. Parker 《Mathematical Geology》1988,20(7):899-903

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The two-body problem with radiation pressure in a rotating reference frame     

Harry Dankowicz 《Celestial Mechanics and Dynamical Astronomy》1995,61(3):287-313

We study a perturbed Newtonian two-body problem, in which the perturbation is due to a force field of constant magnitude but rotating direction. By considering this system as a perturbation of the non-rotating case a Melnikov-type analysis allows us to show the existence of horseshoes in the level sets of the Hamiltonian and the subsequent sensitive dependence on initial conditions and non-integrability. We discuss the consequences of these results for a particular planar restricted three-body problem.Supported by a grant from the Royal Swedish Academy of Sciences and AFOSR NM 91-0329.  相似文献   

Announcement Internatioal Society for Diatom Research and Nederlands-Vlaamse Kring van Diatomisten     

Gaston Mialaret  Gilbert Landsheere  Dieter Mahr  Marcel Postic  A. Harry Passow  et al. 《Journal of Paleolimnology》1991,6(2):171-172

Announcement Internatioal Society for Diatom Research and Nederlands-Vlaamse Kring van Diatomisten  相似文献   

The fine structure of the Saturnian ring system     

Harry L. F. Houpis  D. A. Mendis 《Earth, Moon, and Planets》1983,29(1):39-46

A dust disc within a planetary magnetosphere constitutes a novel type of dust-ring current. Such an azimuthal current carrying dust disc is subject to the dusty plasma analog of the well known finite-resistivity ‘tearing’ mode instability in regular plasma current sheets, at long wavelengths. It is proposed that the presently observed fine ringlet structure of the Saturnian ring system is a relic of this process operating at cosmogonic times and breaking up the initial proto-ring (which may be regarded as an admixture of fine dust and plasma) into an ensemble of thin ringlets. It is shown that this instability developes at a rate that is many orders of magnitude faster than any other known instability, when the disc thickness reaches a value that is comparable to its present observed value.  相似文献   

Source contributions to Devonian granite magmatism near the Laurentian border, New Hampshire and Western Maine, USA     

Paul B. Tomascak  Michael Brown  Gary S. Solar  Harry J. Becker  Tracey L. Centorbi  Jinmei Tian 《Lithos》2005,80(1-4):75-99

Radiogenic isotope data (initial Nd, Pb) and elemental concentrations for the Mooselookmeguntic igneous complex, a suite of mainly granitic intrusions in New Hampshire and western Maine, are used to evaluate petrogenesis and crustal variations across a mid-Paleozoic suture zone. The complex comprises an areally subordinate monzodiorite suite [377±2 Ma; ε_Nd (at 370 Ma)=−2.7 to −0.7; initial ²⁰⁷Pb/²⁰⁴Pb=15.56–15.58] and an areally dominant granite [370±2 Ma; ε_Nd (at 370 Ma)=−7.0 to −0.6; initial ²⁰⁷Pb/²⁰⁴Pb=15.55–15.63]. The granite contains meter-scale enclaves of monzodiorite, petrographically similar to but older than that of the rest of the complex [389±2 Ma; ε_Nd (at 370 Ma)=−2.6 to +0.3; initial ²⁰⁷Pb/²⁰⁴Pb 15.58, with one exception]. Other granite complexes in western Maine and New Hampshire are 30 Ma older than the Mooselookmeguntic igneous complex granite, but possess similar isotopic signatures.

Derivation of the monzodioritic rocks of the Mooselookmeguntic igneous complex most likely occurred by melting of Bronson Hill belt crust of mafic to intermediate composition. The Mooselookmeguntic igneous complex granites show limited correlation of isotopic variations with elemental concentrations, precluding any significant presence of mafic source components. Given overlap of initial Nd and Pb isotopic compositions with data for Central Maine belt metasedimentary rocks, the isotopic heterogeneity of the granites may have been produced by melting of rocks in this crustal package or through a mixture of metasedimentary rocks with magmas derived from Bronson Hill belt crust.

New data from other granites in western Maine include Pb isotope data for the Phillips pluton, which permit a previous interpretation that leucogranites were derived from melting heterogeneous metasedimentary rocks of the Central Maine belt, but suggest that granodiorites were extracted from sources more similar to Bronson Hill belt crust. Data for the Redington pluton are best satisfied by generation from sources in either the Bronson Hill belt or Laurentian basement. Based on these data, we infer that Bronson Hill belt crust was more extensive beneath the Central Maine belt than previously recognized and that mafic melts from the mantle were not important to genesis of Devonian granite magma.  相似文献   

High resolution mapping and classification of oyster habitats in nearshore Louisiana using sidescan sonar     

Yvonne C. Allen  Charles A. Wilson  Harry H. Roberts  John Supan 《Estuaries and Coasts》2005,28(3):435-446

Sidescan sonar holds great promise as a tool to quantitatively depict the distribution and extent of benthic habitats in Louisiana’s turbid estuaries. In this study, we describe an effective protocol for acoustic sampling in this environment. We also compared three methods of classification in detail: mean-based thresholding, supervised, and unsupervised techniques to classify sidescan imagery into categories of mud and shell. Classification results were compared to ground truth results using quadrat and dredge sampling. Supervised classification gave the best overall result (kappa=75%) when compared to quadrat results. Classification accuracy was less robust when compared to all dredge samples (kappa=21–56%), but increased greatly (90–100%) when only dredge samples taken from acoustically homogeneous areas were considered. Sidescan sonar when combined with ground truth sampling at an appropriate scale can be effectively used to establish an accurate substrate base map for both research applications and shellfish management. The sidescan imagery presented here also provides, for the first time, a detailed presentation of oyster habitat patchiness and scale in a productive oyster growing area.  相似文献   

Evidence from coleopteran assemblages for a short but intense cold interlude during the latter part of the MIS11 Interglacial from Quinton, West Midlands, UK     

G. Russell Coope  Harry K. Kenward 《Quaternary Science Reviews》2007,26(25-28):3276-3285

A sequence of fossiliferous organic sediments spanning the whole of an interglacial has been investigated from Quinton, near Birmingham, United Kingdom This interglacial can be correlated on palynological grounds with the Hoxnian Interglacial of England; equivalent to the Holsteinian Interglacial of central Europe and to Marine Isotope Stage 11. A pollen diagram and coleopteran spectrum were obtained from the same series of samples. By using the mutual climatic range method on the coleopteran assemblages, it has been possible to quantify the thermal climatic conditions at this time. They show clear evidence for a sudden and intense climatic oscillation during the late temperate stage of the interglacial—named the Quinton Cold Interlude. At this time mean temperatures of the warmest month (July) declined suddenly by at least 5 °C and mean temperatures of the coldest months (January and February) by more than 10 °C. Subsequently cool-temperate conditions returned. The pollen diagram through this interval shows little or no response to this climatic event. It is too early yet to generalise about the regional significance of the Quinton Cold Interlude but a similar climatic oscillation also occurs towards the closing stage of the MIS11 Interglacial at Hoxne, Norfolk, UK, suggesting that the cold interlude was at least regional in extent. A short climatic oscillation of similar intensity has also been interpreted from coleopteran evidence towards the end of the MIS13 Interglacial at Waverley Wood Farm Pit, Warwickshire, UK, indicating that such events may characterise the later stages of other interglacials. These severe climatic oscillations towards the end of interglacials may have relevance to our understanding of the closing phase of the present interglacial.  相似文献   

An interlaboratory comparison of source rock data     

Harry Dembicki 《Geochimica et cosmochimica acta》1984,48(12):2641-2649

Organic matter in eight rock samples has been analyzed by nineteen laboratories and the results show that source rock data from any one laboratory cannot be directly compared to data from any other laboratory. A high degree of variability exists among the data reported by the nineteen participating laboratories, most of which can be explained by differences in the sample preparation steps and analytical procedures used in these laboratories. Differences also exist in the definition of basic units of measurement being reported. In order to make the data more comparable, standard rock samples and analytical methods should be developed and used by all laboratories. Until then, extreme caution must be used when comparing source rock data from different laboratories.  相似文献