Soil discrimination using diffuse reflectance Vis–NIR spectroscopy in a local toposequence     

José Francirlei Oliveira  Michel Brossard  Pedro Rodolfo Siqueira Vendrame  Stanislas Mayi III  Edemar Joaquim Corazza  Robélio Leandro Marchão  Maria de Fátima Guimarães 《Comptes Rendus Geoscience》2013,345(11-12):446-453

Vis–NIR spectroscopy is nowadays presented as a possible routine method for soil sample analysis. However, there is still no consensus on which is the best multivariate statistical method to use. We propose to use principal component analysis to complete the spectral data treatment. The soil samples came from a pedological cover made up of red–yellow Latosols: 88 samples of 11 soil profiles on four toposequences were collected; clay, organic matter, silica, iron, aluminum and titanium total contents were determined; the contents of goethite, hematite, gibbsite, and kaolinite were calculated. Diffuse reflectance Vis–NIR spectroscopy at wavelengths from 400 to 2400 nm combined with principal component analysis (PCA) was sufficiently sensitive to discriminate different Latosols. Wavelengths of 700 nm and 2200 to 2300 nm were influenced by content ratios of organic matter and iron oxides (700 nm), and kaolinite and gibbsite absorption (2200 and 2300 nm). The spectral responses were affected not only by the content of these constituents, but also by the composition of the minerals, so that the same class of Latosol may have different or similar spectral responses. The role of microaggregation is discussed.  相似文献   

长江流域悬浮物磁性特征及其物源指示意义     

罗超  郑妍  郑洪波  王平  何梦颖  吴卫华 《第四纪研究》2013,33(4)

通过分析长江干流及主要支流表层悬浮物的环境磁学参数特征(类型、含量及粒度)及其空间变化,探讨环境磁学对河流物源示踪的意义.结果表明,长江悬浮物磁性矿物特征以磁铁矿为主,含有少量赤铁矿及针铁矿.上游不完整反铁磁性矿物含量高于中下游,反映四川盆地广泛分布的紫红色砂页岩的影响.受攀枝花钒钛磁铁矿影响,干流磁性矿物含量上游高于中下游,表现为在攀枝花处迅速增加,向下游逐渐降低并在经过三峡后显著降低,说明三峡大坝对上游磁性矿物有明显的拦截作用.支流中雅砻江、汉江及湘江较高的磁性矿物含量分别受控于流域出露的源岩及工农业等人为影响.长江悬浮物xfd％大于5％,表明样品中含有超顺磁颗粒.受流域地势及气候影响,磁性颗粒的粒径从上游至下游逐渐变细.长江悬浮物磁性特征能够在一定程度上反映物源特征,但长江地质条件复杂,气候类型空间变异大,且流域人为影响较大(三峡大坝等),使得利用磁性矿物特征示踪物源受到限制.  相似文献   

干燥箱烘焙加热法测定土壤有机质的方法改进          下载免费PDF全文

和振云  段九存  张旺强  祝建国 《甘肃地质》2013,22(3):77-81

对土壤有机质的测定方法从消煮方式、消煮温度、消煮时间、干扰因子的去除等方面进行了改进和探讨。用土壤国家标准物质GBW07406、GBW07427、GBW07428、GBW07430和自制二级土壤参考标准物质GRD40-13验证改进后的方法,测定值与标准值吻合。对GBW07402、GBW07424各进行12次测定,相对标准偏差(RSD,n=12)分别为:2.02%;0.73%。本法的氧化校正系数=1.00,且准确度高、重现性好、无污染、操作简便,已成功应用于诸多土壤样品分析中,结果完全能达到测试质量要求,适用于测定有机质含量在15%以下的土壤样品。  相似文献   

东濮凹陷古沉积环境及其对有机质丰度的影响     

鹿坤 《地质与勘探》2013,49(3):589-594

东濮凹陷南北古沉积环境、有机质丰度差别巨大,运用有机地球化学和微量元素等多种方法对东濮凹陷沙河街组古沉积环境及其对烃源岩有机质丰度的影响进行了研究,结果表明:东濮北部为典型的咸水、还原环境;南部为淡水-微咸水、弱氧化环境。古沉积环境对有机质丰度起决定性作用:古盐度越高,还原性越强,有机质丰度越高。在此基础上,对北部盐岩发育区有机质富集的原因进行了分析:水生生物来源和闭塞强还原环境是有机质富集的主要原因。  相似文献   

煤系有机质多阶段成气的分子碳同位素表征及其对高过成熟干酪根生气潜力评价的启示     

孙永革  杨中威  Bernhard CRAMER 《地球化学》2013,42(2)

采用开放体系在线程序升温裂解-色谱-碳同位素比值质谱技术(PY/GC-IRMS)考察了煤系有机质热演化过程中甲烷瞬时生成速率与碳同位素组成特征,提出煤系有机质不同热演化进程甲烷生成的四个阶段:生油窗阶段、主生气阶段、晚期生气阶段(芳环侧链断裂)、开环-缩聚作用阶段.以一级反应动力学为基础,采用高斯分布算法,计算了各阶段甲烷产出的动力学参数.研究结果对煤成气资源量的正确评价,特别是近年来有机质高演化阶段成气潜力的评价具有重要指示意义.  相似文献   

郑州市气象因子对大气颗粒物浓度的影响研究          下载免费PDF全文

马格  田国行  李永华 《气象与环境科学》2018,41(3):31-40

基于2015、2016年河南省环境监测中心站获取的郑州市9个监测点颗粒物浓度和逐日气象数据,对气象因素和颗粒物浓度相关性进行了研究。结果表明:郑州市大气颗粒物浓度受季节影响较强,总体呈现冬季高、夏季低的趋势。降水量与大气颗粒物浓度呈现明显的负相关。相对湿度的增高不利于PM_(2. 5)浓度的降低,而PM_(10)的浓度则随着相对湿度的增高有所降低。春夏秋三季的主要风向为东北偏东,当春季风为东南风和西风时,颗粒物浓度最低;当夏季风为东北偏东风时,颗粒物浓度最低;秋季吹东北风时,颗粒物浓度最低。冬季吹西北风(郑州冬季盛行风向)时,大气颗粒物质量浓度最低。  相似文献   

Light Relative Efficiency Factors for ions in BGO and Al2O3 at 20 mK     

《Astroparticle Physics》2013

Dark matter direct search experiments with scintillators need an accurate knowledge of Light Relative Efficiency Factors (REF) between electron and nuclear recoils to estimate the energy of the recoiling nuclei from the scintillation signal (if the light signal is used with this purpose) or to implement an effective background rejection based on the comparison of the scintillation with ionization or heat signals (if the light signal is used for particle discrimination). The Light REF between α and γ particles is required in some nuclear physics applications of scintillators like rare α decay searches, internal radiopurity assessment and some double beta decay searches. Two scintillating bolometers of BGO and Al₂O₃ were operated at 20 mK and exposed to fast neutrons, gamma rays, α particles and heavy nuclei. We measured their Light REF between γ and α particles and between electron and neutron induced nuclear recoils as a function of the deposited energy. We also measured the Light REF for O and Np ions in BGO. Results obtained for the different Light REFs were unsuccessfully compared with calculations based on a simple semi-empirical approach (with only one fitting parameter) proposed by Tretyak.  相似文献   

Ionization efficiency study for low energy nuclear recoils in germanium     

《Astroparticle Physics》2013

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Reliability of sediment rating curves for a deciduous forest watershed in Iran     

Seyed Hamidreza Sadeghi 《水文科学杂志》2013,58(5):821-831

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Application of the honey-bees mating programming (HBMP) algorithm to sediment concentration modelling     

Hassan Ebrahimi  Ebrahim Jabbari  Mostafa Ghasemi 《水文科学杂志》2013,58(10):1853-1864

Abstract

The honey-bees mating programming (HBMP) algorithm is introduced as a novel tool for predicting suspended sediment concentration for the Mad River catchment near Arcata, USA. The paper also applies gene expression programming (GEP) as a comparison and shows that these two approaches can the produce transparent, nonlinear relationships between the independent and dependent variables. Some modifications have been made to the HBMP algorithm to improve its capability and efficiency. The results achieved from this method and GEP are compared with two different sediment rating curves based on regression techniques. The findings show that the results from both the HBMP and GEP methods are promising and outperform the results obtained from the sediment rating curves.