Effects of Different Dietary Lipid Contents on Growth and Lipase Activity ofEriocheir sinensis Larvae     

ZHENG Debin  PAN Luqing  FANG Bo 《青岛海洋大学学报(英文版)》2011,(1):55-60

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Effect of grazing on soil-water content in semiarid rangelands of southeast Idaho     

K.T. Weber  B.S. Gokhale 《Journal of Arid Environments》2011,75(5):464-470

Although numerous factors influence soil-water content, it is considered a key indicator of rangeland health. This paper investigates the effect of grazing on soil-water content using three treatments within the same soil association. The treatments, simulated holistic planned grazing (SHPG), rest-rotation (RESTROT), and total rest (TREST) applied stocking rates of 36, 6, and 0 animal days/hectare respectively. Soil-water content was measured continuously from 2006 to 2008 using 36 capacitance sensors. Statistical analyses revealed differences in percent volumetric-water content (%VWC) and in all treatments, the SHPG pasture had the highest %VWC. Mixed procedures models indicate strong environmental and treatment effects as explanatory variables for the observed difference in %VWC. Although results of vegetation cover analyses indicated no difference in percent shrub cover in the two production pastures (SHPG and RESTROT), percent litter cover differed in the latter years of this study. It was concluded that in addition to a variety of other factors, management decisions (grazing and rest) can have substantial influence upon soil-water content and that soil-water content can vary substantially as a result of animal impact and the duration of grazing.  相似文献   

溶质类型与矿化度对土壤水分扩散率的影响   总被引：3，自引：0，他引：3  

郭全恩  王益权  马忠明  车宗贤  南丽丽  徐世文  刘延东 《干旱区地理》2011,34(1):86-90

以甘肃省秦安县果园石灰性土壤为研究对象,采用水平土柱入渗法,探讨了不同矿化度下(lg/L、3g/L、5g/L、10g/L)的三种钠盐(Nacl、Na2SO4和Na2CO3)对石灰性土壤水分扩散率的影响.结果表明:在水盐复合迁移体系中盐分与水分迁移具有不同步性,影响不同步性的因子与盐分类型有很大关系.NaCl对水分移动速...  相似文献   

黑河流域荒漠区土壤水分对降水脉动响应   总被引：16，自引：5，他引：11  

刘冰  赵文智  常学向  李守波 《中国沙漠》2011,30(3):716-722

 利用气象站资料,对黑河流域荒漠区降水特征及其土壤水分对降水脉动响应进行了系统研究。结果表明,荒漠区降水属于降水脉动事件,降水前后土壤水分特征存在显著差异,且随土层增加差异逐渐变小。土壤水分在降水量、土壤深度和降水前后的差异极显著,交互效应也极显著(P<0.0001),表明荒漠区土壤水分对降水脉动具有显著的响应现象。土壤水分的降水脉动响应表现为降水后土壤含水量激增,在蒸散作用下缓慢减小。降水前后土壤含水量的时间序列变异规律均能较好地拟合成变异函数的理论模型。降水前后土壤含水量随机变异均小于结构性变异,反映出荒漠区土壤水分在时间尺度上具有较强的自相关性格局。降水使土壤水分空间结构差异呈现下降趋势,在时间序列上异质性降低。  相似文献   

Herbaceous layer development during spring does not deplete soil nitrogen in the Portuguese montado     

D.O. Otieno  H. MirzaeiM.Z. Hussain  Y.L. LiM.W.T. Schmidt  M. Wartinger  E. Jung  N. RibeiroJ.S. Pereira  J. Tenhunen 《Journal of Arid Environments》2011,75(3):231-238

Nitrogen (N) content in the soil and in the herbaceous biomass were monitored during spring of 2004-2006 to determine how the herbaceous layer development influences soil N availability in the montado ecosystem of southern Portugal. Highest (246.6 ± 52.7 g m⁻²) and lowest (123.2 ± 89.5 g m⁻²) peak biomass occurred in 2006 and 2005 respectively. Total soil N within the top 20 cm soil profile ranged between 0.2 ± 0.1% in February and 0.41 ± 0.2% in May, while available soil N was lowest (5 ± 2 μg g⁻¹soil) in February but increased three-to-five fold in March and was >17.5 μg g⁻¹soil at senescence in May. Significant (p < 0.001) increase in total N in the aboveground pool occurred between February and May. There was however, no decay in soil N content. Instead, the herbaceous vegetation enhanced soil N input and N retention in the ecosystem. Most of the herbaceous plants were annuals with large reserves of organic N at senescence, which returned to the soil as detritus. The herbaceous vegetation is a critical component of the montado that contributes to N recharge and cycling within the ecosystem.  相似文献   

北京市表层土壤中PAHs含量特征及来源分析     

黄勇  王安婷  袁国礼  李欢  黄丹 《岩矿测试》2022,(1):54-65

土壤,作为城市中最重要的环境介质,承担了较高多环芳烃(PAHs)的环境负荷,开展土壤PAHs分布特征及来源分析研究,可以为污染风险防控、环保政策制定提供支撑.为研究北京市不同功能区土壤环境中PAHs的含量、组成及来源,本文在北京市主城区进行了大范围采样,同时针对工业区、农业种植区、水源保护区及居民区等不同功能区进行了分...  相似文献   

平顶山矿区原生结构煤和构造煤孔渗实验对比          下载免费PDF全文

郭德勇  李春娇  张友谊 《地球科学》2014,39(11):1500-1506

为了研究构造煤孔渗变化特性, 利用平顶山矿区原生结构煤和构造煤, 进行了不同围压、温度、湿度和煤体结构类型等条件下孔隙度及渗透率的实验测定, 对煤层孔渗特性在不同条件下的变化趋势进行了分析.结果表明: 围压、温度、湿度和煤体结构类型4种因素对煤的孔隙度和渗透率均有较大影响, 当温度和围压同时作用时, 围压的作用效果大于温度的作用效果.并用Origin软件对部分实验数据进行了数据拟合, 得出原生结构煤和构造煤的渗透率-孔隙度函数关系.   相似文献   

A laboratory study on the undrained strength of a silty sand from Central Western Taiwan   总被引：2，自引：0，他引：2  

Yao-Tao Huang  An-Bin Huang  Yu-Chen Kuo  Ming-Dou Tsai 《Soil Dynamics and Earthquake Engineering》2004,24(9-10):733

The sand deposit in Central Western Taiwan typically contained significant amounts of fines. The assessment of liquefaction potential using the simplified procedure often involved adjustment in field test results to account for the effects of fines. The available fines content (FC) adjustment methods are highly empirical and may lead to very different conclusions. The need and/or level of FC adjustment should be justified based on cyclic behavior of sand and its relationship with fines. This study made an attempt to provide that reference information for a silty sand commonly found in Central Western Taiwan. A series of isotropic consolidation, undrained monotonic and cyclic triaxial tests were conducted on reconstituted Mai Liao Sand (MLS) with various FCs and densities. Concurrent shear wave velocities were measured using bender elements in some of the cyclic triaxial tests. This paper describes the geological background, the laboratory tests and their implications in the assessment of liquefaction potential for MLS.  相似文献   

建平膨润土的提纯工艺探索及其表征   总被引：1，自引：0，他引：1  

林涛  任建晓  殷学风  李雪  李杰 《岩石矿物学杂志》2013,32(3):401-404

采用湿法工艺对辽宁低品位钙基膨润土进行提纯,研究了分散剂的类型以及用量、液固比、离心时间、离心速度以及膨润土温度对蒙脱石含量的影响,并通过x-射线衍射对原土及提纯土的结构进行了表征.结果表明,建平膨润土最佳提纯条件为:分散剂用量0.5％、最佳液固比12、离心时间9 min、离心速度2 500 r/min、膨润土温度60℃.最佳条件下蒙脱石含量可以提高到92％以上.  相似文献   

矿渣微细粉掺量对水泥水化产物的影响     

肖万  马鸿文 《岩石矿物学杂志》2013,32(6):882-888

利用X射线衍射、TG-DSC综合热分析以及环境扫描电子显微分析技术等,研究了矿渣微细粉对水泥水化产物钙矾石、Ca(OH)₂、CSH凝胶等的影响规律。研究结果表明,在水化早期,矿渣微细粉即参与水泥水化进程,显著影响水泥水化产物钙矾石、Ca(OH)₂和CSH凝胶等的生成速度和生成量及微观形貌,并且随着其掺量增大及水化时间延长,矿渣微细粉参与水泥水化反应程度逐渐提高。  相似文献