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1.
Assessing uncertainty in best management practice effectiveness under future climate scenarios 
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下载免费PDF全文 Uncertainty of best management practice (BMP) performance in future climates is an important consideration for water resources managers. The objective of this study was to quantify the level of uncertainty in performance of seven agricultural BMPs due to climate change in reducing sediment, total nitrogen, and total phosphorus loads. The Soil and Water Assessment Tool coupled with mid‐21st century climate data from the Community Climate System Model were used to develop climate change scenarios for the Tuttle Creek Lake Watershed of Kansas and Nebraska. Uncertainty level of each BMP was determined using Latin Hypercube Sampling, a constrained Monte Carlo sampling technique. Samples were taken from distributions of several variables (monthly precipitation, temperature, CO2, and BMP implementation parameters). Cumulative distribution functions were constructed for each BMP, pollutant, and climate scenario combination. Results demonstrated that BMP performance uncertainty is amplified in the extreme climate scenario. Among BMPs, native grass replacement generally had higher uncertainty level but also had the greatest reductions. This study highlights the importance of incorporating uncertainty analysis into mitigation strategies aiming to reduce negative impacts of climate change on water resources. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
2.
Shyh-Lung?HwangEmail author Pouyan?Shen Hao-Tsu?Chu Tzen-Fu?Yui Juhn?G.?Liou Nikolay?V.?Sobolev Ru-Yuan?Zhang Vladislav?S.?Shatsky Anton?A.?Zayachkovsky 《Contributions to Mineralogy and Petrology》2004,148(3):380-389
Kokchetavite, a new polymorph of K-feldspar (KAlSi3O8), has been identified as micrometer-size inclusions in clinopyroxene and garnet in a garnet-pyroxene rock from the Kokchetav ultrahigh-pressure terrane, Kazakhstan. Kokchetavite has a hexagonal structure with a =5.27(1) Å, c=7.82(1) Å, V=188.09 Å3, Z=1, and is found to be associated with phengite + /-cristobalite (or quartz) + siliceous glass ± phlogopite/titanite/calcite/zircon, occurring as multi-phase inclusions in clinopyroxene and garnet. It is concluded that kokchetavite could not be an exsolution phase in host minerals. Instead, it might be metastably precipitated from an infiltrated K-rich melt during rock exhumation. Alternatively, although less likely, kokchetavite might be derived from dehydration of K-cymrite, which, in turn, was formed at high pressures. In either case, kokchetavite is a metastable polymorph of K-feldspar. 相似文献
3.
Shyh‐Lung Hwang Pouyan Shen Hao‐Tsu Chu Tzen‐Fu Yui Yoshiyuki Iizuka Hans‐Peter Schertl 《Journal of Metamorphic Geology》2019,37(8):1079-1098
Metamorphic garnet commonly contains needle‐like rutile inclusions as well as equant rutile inclusions that surround quartz inclusions and range in size from submicrometer to nanometer. Although the origin of these equant rutile inclusions, that is, exsolution or non‐exsolution, has important implications for petrological and tectonic processes, the crystallographic characteristics of these inclusions have rarely been studied because of the small sizes and analytical difficulties involved. Here, we report the crystallographic characteristics pertinent to the genetic origin of minute equant rutile inclusions in cloudy, nearly spherically shaped garnet domains with Ti‐depleted compositions surrounding quartz inclusions in ultrahigh‐pressure garnet from several diamondiferous Erzgebirge quartzofeldspathic gneissic rock samples. TEM analyses show that the equant rutile crystals in cloudy garnet domains are partially bounded by the low‐energy {100}rt ± {110}rt ± {101}rt facets and have rather random crystallographic orientation relationships (CORs) with the garnet host, with preferential alignment of low‐energy lattice planes, for example, {100}rt//{112}grt, for some rutile crystals. Although the rather random CORs are unlikely to be attributed to solid‐state exsolution subjected to the stringent topotactic garnet lattice constraints, the characteristic subhedral {100}rt ± {110}rt ± {101}rt crystal forms of rutile can be rationalized by a metasomatic dissolution‐reprecipitation mechanism via a fluid phase. In this scenario, the quartz+fluid inclusions in garnet were first subjected to decompression microcracking during rock exhumation, followed by dissolution of Ti‐bearing garnet matrix at the crack tips or along the crack surfaces and subsequent reprecipitation of rutile, apatite, gahnite, akdalaite, and Ti‐depleted garnet. The rapid coalescence between rutile and garnet crystals in fluid or direct attachment of rutile crystals onto the dissolving crack surfaces would then yield the rather random CORs as reported here. These results, along with previous work on rutile needles, indicate rather diverse genesis of rutile inclusions in various crystal forms, thus shedding light on the controversial exsolution origin for other inclusion suite/microstructure in minerals. 相似文献
4.
This study measures the reaction rate of dolomite and aragonite (calcite) into Mg-calcite at 800, 850, and 900°C and 1.6 GPa. The dry synthetic dolomite-aragonite aggregate transformed very rapidly into dolomite-calcite polycrystalline aggregate while Mg-calcites formed at a relatively slow rate, becoming progressively richer in Mg with run time. We modeled the reaction progress semi-empirically by the first-order rate law. The temperature dependence of the overall transport rate of MgCO3 into calcite can be described by the kinetic parameters (E?=?231.7 kJ/mol and A o ?=?22.69 h?1). Extrapolation using the Arrhenius equation to the conditions during exhumation of UHPM rocks indicates that the reaction of dolomite with aragonite into Mg-saturated calcite can be completed as the P-T path enters the Mg-calcite stability field in a geologically short time period (<1 Ky). On the other hand, the extrapolation of the rate to prograde metamorphic conditions reveals that the Mg-calcite formed from dolomitic marble in the absence of metamorphic fluid may not reach Mg-saturation until temperatures corresponding to high-grade metamorphism (e.g., >340°C and >10 My). SEM-EDS analysis of individual calcite grains shows compositional gradients of Mg in the calcite grains. The Mg-Ca inter-diffusion coefficient at 850°C is around 1.68?×?10?14 m2/sec if diffusion is the major control of the reaction. The calculated closure temperatures for Ca-Mg inter-diffusion as a function of cooling rate and grain size reveal that Ca/Mg resetting in calcite in a dry polycrystalline carbonate aggregate (with grain size around 1 mm) may not occur at temperatures below 480°C at a geological cooling rate around 10°C/My, unless other processes, such as short-circuit interdiffusion along grain boundaries and dislocations, are involved. 相似文献
5.
A kinematic hardening based model for unsaturated soils considering different hydraulic conditions 下载免费PDF全文
下载免费PDF全文 At present, several of the existing elastoplastic constitutive models are adapted for describing the stress–strain behavior of unsaturated soils. However, most of them present certain limitations in this field. These limitations can be related to the basic model and/or added unsaturated state variables and formulations. In this regard, inability to model the hydro‐mechanical behavior in constant water (CW) conditions is an example of these limitations. In this paper, an advanced version of CJS model is selected for adaptation to the unsaturated states. Adaptation to unsaturated states is achieved in the framework of effective stress approach. Effective stress equation and unsaturated state variables are selected based on the recent research existing in the literature. The developed model is capable of describing the complex behavior of unsaturated soil in the CW condition in addition to predicting the behavior at failure and post–failure, nonlinear elastoplastic behavior at low levels of stress and strain (by selecting a very small elastic domain), as well as wetting and collapse behaviors. In order to validate the model, results of triaxial tests in CD and CW conditions are used. The validation results indicate the good capability of the proposed model. Behavior of the unsaturated soils during wetting is an important issue. For this reason, the model is also evaluated based on the results of wetting and collapse triaxial tests. A comparison between the tests and simulation results shows that the model is able to predict the soil behavior under the wetting path. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
6.
Shyh-Lung Hwang Tzen-Fu Yui Hao-Tsu Chu Pouyan Shen Ru-Yuan Zhang Juhn G. Liou 《Contributions to Mineralogy and Petrology》2011,161(6):901-920
Optical microscopy, secondary electron microscopy and analytical electron microscopy were used to characterize crystallographic
orientation relationships between oriented mineral inclusions and clinopyroxene (Cpx) host from the Hujialing garnet clinopyroxenite
within the Sulu ultrahigh-pressure (UHP) terrane, eastern China. One garnet clinopyroxenite sample (2HJ-2C) and one megacrystic
garnet-bearing garnet clinopyroxenite (RZ-11D) were studied. Porphyroblastic clinopyroxene from sample 2HJ-2C contains oriented
inclusions of ilmenite (Ilm), spinel (Spl), magnetite and garnet, whereas clinopyroxene inclusions within megacrystic garnet
from sample RZ-11D contain oriented inclusions of ilmenite and amphibole. Specific crystallographic relationships were observed
between ilmenite/spinel plates and host clinopyroxene in sample 2HJ-2C and between ilmenite plates and host clinopyroxene
in sample RZ-11D, i.e. [1[`1]00 1\bar{1}00 ]Ilm//[0[`1]0 0\bar{1}0 ]Cpx (0001)Ilm//(100)Cpx; and [110]Spl//[0[`1]0 0\bar{1}0 ]Cpx ([`1]11 \bar{1}11 )Spl//(100)Cpx. These inclusions are suggested to be primary precipitates via solid-state exsolutions. Most of the needle-like magnetite/spinel
inclusions generally occur at the rims or along fractures of clinopyroxene within sample 2HJ-2C. Despite the epitaxial relation
with host clinopyroxene, these magnetite/spinel needles would have resulted from fluid/melt infiltrations. Non-epitaxial garnet
lamellae in clinopyroxene of sample 2HJ-2C were formed via fluid infiltration-deposition primarily along (010) and subordinately
along (100) partings. Epitaxial amphibole plates (with a thickness <1 μm) and lamellae (with a thickness = 1–10 μm) in host
clinopyroxene of sample RZ-11D were probably results of hydration processes, although amphibole plates could otherwise be
interpreted as exsolution products. Temporal relations between mineral inclusions in each sample can be established, and a
semi-quantitative P–T path for this garnet clinopyroxenite body was derived accordingly. The present results show that the
Hujialing garnet clinopyroxenite may not have subducted to mantle depths as deep as 250 km during UHP metamorphism as suggested
by previous studies. This study demonstrates that the crystallographic and temporal/spatial relationships between aligned
inclusions and host minerals are essential to a correct genetic interpretation of metamorphic rocks. 相似文献
7.
Summary. It has been reported that no stoichiometric FeO can be formed at temperatures above about 600°C regardless of pressure. The stoichiometry of Fe X O quenched from static high pressure and temperature experiments appears to decrease with increasing pressure in the range 100–300kbar. On the basis of these observations, we have re-interpreted the recent shock results on Fe0.94 O, and have found that the Hugoniot data can be reasonable interpreted by the same shift in stoichiometry as observed in the static high-pressure experiments instead of a first-order transformation as proposed. If oxygen is assumed to be the light component of the outer core, the outer core can be chemically homogeneous only if the stoichiometry of Fe X O decreases with increasing pressure. A constant stoichiometry would demand that the oxygen content decreases by a factor of 2 from the top to the bottom of the outer core. A chemically homogeneous outer core is consistent with a convecting outer core. 相似文献
8.
Regional analysis of wind climatic erosivity factor: a case study in fars province, southwest Iran 总被引：1，自引：0，他引：1
Wind erosion climatic erosivity is a measure of the climatic tendency to produce conditions conducive to wind erosion. This research develops a method to determine the regional climate’s tendency to cause wind erosion on the basis of a physically based climatic factor (CE) and linear moment analysis (L-moments) in Fars province, southwest Iran. CE is calculable from wind speed quantiles and other available meteorological data. The wind quantiles can be estimated by a frequency analysis of the available wind data. Wind speed data are often either not available or are of short record length, and thus, CE estimates from such data have large standard errors. In such a situation, data from several sites can be used to estimate wind speed quantiles at each site based on a regional frequency analysis. Monthly averages of maximum daily wind speed of 19 meteorological stations in Fars province were used for regional analysis. Based on L-moment analysis, two homogeneous regions were determined. Regional wind speed quantiles were calculated, and the results were used to calculate CE values for two 6-month wet and dry periods for each homogeneous region. Furthermore, CE values were estimated for each station in the study area using a Weibull distribution, and the results were compared with the regional-based CE values. It showed that CE values estimated using the regional-based approach have smaller sampling variance compared to those obtained from the Weibull method. The proposed method can be used to evaluate the regional risk of wind erosion in arid and semi-arid environments. 相似文献
9.
Local and mine scale exploration models for anomaly recognition within known ore fields are discussed. Traditional geochemical exploration methods are based on multivariate statistical analysis, metallometry, vertical geochemical zonality and criteria of natural field geochemical associations, which suffer several shortcomings, including lack of a geostatistical generalised approach for separating anomalies from background. These shortcomings make the interpretation process time consuming and costly. Fuzzy set theory, fuzzy logic and neural network techniques seem very well suited for typical mining geochemistry applications. The results, obtained from applying the proposed technique to a real scenario, reveals significant improvements, comparing the results obtained from applying multivariate statistical analysis. Computationally, the introduced technique makes possible, without exploration drilling, the distinction between blind mineralisation and zone of dispersed ore mineralisation. The methodology developed in this research study has been verified by testing it on various real-world mining geochemical projects. 相似文献
10.
Mohammady Majid Pourghasemi Hamid Reza Yousefi Saleh Dastres Emran Edalat Mohsen Pouyan Soheila Eskandari Saeedeh 《Natural Resources Research》2021,30(6):4861-4884
Natural Resources Research - Habitat suitability modeling and mapping are important aspects of long-term strategies for sustaining plant ecosystems. In this study, seven state-of-the-art machine... 相似文献