植物样品中无机元素分析的样品前处理方法和测定技术   总被引：11，自引：5，他引：6  

刘亚轩  李晓静  白金峰  马娜  张勤 《岩矿测试》2013,32(5):681-693

植物样品中无机元素的分析测定在环境地球化学和生物地球化学的研究中起着重要作用。植物样品中元素含量一般较低,须选用科学合理的前处理技术和灵敏度高、精密度好、检出限低的测定方法。本文针对植物样品前处理方法和无机元素分析测定技术的研究进展、优势与不足进行评述。前处理方法主要根据样品和待测元素的性质进行选择:干法灰化所用试剂少、空白值低,但组织致密型的样品不易灰化完全、高温下易造成元素挥发损失;湿法消解样品消解较为完全,但试剂消耗大、空白值高、操作繁琐;微波消解可以防止部分易挥发元素损失,用酸量少、消解速度快,但称样量相对较小,不适于需要大称样量的样品分析。几乎所有针对元素分析的仪器分析技术都可以用于植物样品分析,主要根据仪器适用的元素、必要的干扰校正以及基体改进等方面进行选择:电感耦合等离子体质谱法可同时测定植物样品中40种以上的元素,高分辨质谱的检出限可达fg/mL;电感耦合等离子体发射光谱法适用于某些植物样品中含量较高的P、K、Na等元素的测定;原子吸收光谱法可分析元素达70余种,是普及程度最高的仪器分析技术之一;原子荧光光谱法与氢化物发生技术的联用,在元素含量较低的植物样品分析中技术优势更加明显;新兴的激光诱导击穿光谱技术已被应用于植物样品分析,无需复杂的样品前处理,操作简单快速,可实现原位、在线、实时、多元素同时检测;其他选择性强、灵敏度高的分析技术,满足了一些特定元素不能用常规分析技术测定的需求。当前主流分析技术的样品前处理方法都存在着缺陷,固体进样技术将成为植物样品分析领域的发展方向之一。  相似文献   

Assessment of physical vulnerability to agricultural drought in China   总被引：1，自引：0，他引：1  

Zhiqiang Wang  Fei He  Weihua Fang  Yongfeng Liao 《Natural Hazards》2013,67(2):645-657

Food security has drawn great attention from both researchers and practitioners in recent years. Global warming and its resultant extreme drought events have become a great challenge to crop production and food price stability. This study aimed to establish a preliminary theoretical methodology and an operational approach for assessing the physical vulnerability of two wheat varieties (“Yongliang #4” and “Wenmai #6”) to agricultural drought using Environmental Policy Integrated Climate model (EPIC). Drought hazard index was set up based on output variables of the EPIC water stress (WS), including the magnitude and duration of WS during the crop-growing period. The physical vulnerability curves of two wheat varieties to drought were calculated by the simulated drought hazard indexes and loss ratios. And the curve’s effect on drought disaster risk was defined as A, B and C sections, respectively. Our analysis results showed that (a) physical vulnerability curves varied between two wheat varieties, which were determined by genetic parameters of crops; (b) compared with spring wheat “Yongliang 4#” winter wheat “Wenmai 6#” was less vulnerable to drought under the same drought hazard intensity scenario; (c) the wheat physical vulnerability curve to drought hazard displayed a S shape, suggesting a drought intensity–dependent magnifying or reducing effect of the physical vulnerability on drought disasters; (d) the reducing effect was mainly in the low-value area of vulnerability curve, whereas the magnifying effect was in the middle-value area, and the farming-pastoral zone and the Qinling Mountain–Huaihe River zone formed important spatial division belts.  相似文献   

Correlation between land-use change and greenhouse gas emissions in urban areas   总被引：1，自引：1，他引：0  

C.-H. Liao  C.-L. Chang  C.-Y. Su  P.-T. Chiueh 《International Journal of Environmental Science and Technology》2013,10(6):1275-1286

Urban areas are the main sources of greenhouse gas (GHG) emissions. Previous studies have identified the effectiveness of better urban design on mitigating climate change and land-use patterns in cities as important factors in reducing GHG by local governments. However, studies documenting the link between land-use and GHG emissions are scant. Therefore, this study explores the driving forces of land-use change and GHG emission increments in urban areas and investigates their correlations. The study area, Xinzhuang, is a satellite city of Taipei that has rapidly urbanized in the past few decades. Twenty-one potential variables were selected to determine the driving forces of land-use change and GHG emission increments by binomial logistic regression based on the investigation data of national land use in 1996 and 2007. The correlation of land-use change and GHG increments was examined by Spearman rank-order analysis. Results of logistic regression analysis identified that population and its increasing density rate are main driving forces on both land-use change and GHG increments. The Spearman rank correlation matrix indicates that fluctuating urbanization level is significantly correlated with the increase of total GHG emissions, the emissions of residence, commerce, and transportation sectors in neighborhoods; and the emissions of residence and transportation sectors seem closely connected to current urbanization level. The findings suggest that relationships among land-use, urbanization, and GHG emissions in urban areas vary greatly according to residence and transportation characteristics. Land-based mitigation may provide the most viable mechanism for reducing GHG emissions through residence and transportation sectors.  相似文献   

新疆库鲁克塔格阔克塔格西碱性岩年代学、岩石地球化学特征及其地质意义     

郭瑞清  秦切  张晓帆  孙宝生  郭寅 《吉林大学学报(地球科学版)》2013,(2):457-468

阔克塔格西碱性岩体出露于库鲁克塔格地块东段,兴地断裂南0.5km,呈椭圆状岩株产出,出露面积约17.5km2。岩体北部和西北部侵入于古元古界兴地塔格群中亚群大理岩、片岩及片麻岩之中,南部和东南部分别侵入于中元古代黑云母石英正长岩和黑云母角闪二长岩中。岩体从边部至中心可分为霓石钠长岩、霓石角闪正长岩和角闪正长岩3个岩相带。岩体边部内接触带形成ERR-Nb-Ta-Zr中型矿床。岩体锆石U-Pb年龄(LA-ICP-MS方法)为(224±2)Ma。岩石主要矿物为微斜长石和条纹长石,暗色矿物主要为钠铁闪石,具有碱性岩典型的富碱、低硅的特点。此外,富集轻稀土元素,负Eu异常,富集Nb、Ta、Th及Hf等高场强元素,亏损Sr、P及Ti不相容元素。Hf同位素特征显示岩浆源于富集岩石圈地幔。地球动力学背景属造山后的板内演化阶段。  相似文献   

利用特色叠前深度偏移技术消除崎岖海底影响——以珠江口盆地番禺—流花地区应用为例     

刘道理  汪瑞良  秦成岗  全志臻  刘杰  徐乐意  张忠涛  屈亮  高鹏  徐徽  邢贞贞 《海相油气地质》2013,(1):67-70

叠前深度偏移技术可有效地进行复杂构造成像,针对不同的地质条件,需要应用不同的处理技术。针对陆架坡折带崎岖海底造成的地震成像差、构造畸变等问题,选择使用了如下叠前深度偏移技术:通过海平面叠前深度偏移技术得到精确的海底成像;通过约束速度反演、加入断层控制建立初始速度模型;采用百分比扫描速度分析对速度模型进行迭代修改,进而快速得到较为收敛的速度体;在此基础上再采用Kirchhoff积分法进行偏移。在珠江口盆地番禺—流花地区应用上述技术,基本消除了崎岖海底对下伏地层的影响,改善了断层和地层成像,并落实了该地区的构造圈闭。  相似文献   

Carbon cycle in the epikarst systems and its ecological effects in South China   总被引：2，自引：0，他引：2  

Zhongcheng Jiang  Yanqing Lian  Xiaoqun Qin 《Environmental Earth Sciences》2013,68(1):151-158

The carbon cycle in a global sense is the biogeochemical process by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the earth. For epikarst systems, it is the exchange of carbon among the atmosphere, water, and carbonate rocks. Southern China is located in the subtropical zone; its warm and humid weather creates favorable conditions for the dynamic physical, chemical, and ecological processes of the carbon cycle. This paper presents the mechanisms and characteristics of the carbon cycle in the epikarst systems in south China. The CO₂ concentration in soils has clear seasonal variations, and its peak correlates well with the warm and rainy months. Stable carbon isotope analysis shows that a majority of the carbon in this cycle is from soils. The flow rate and flow velocity in an epikarst system and the composition of carbonate rocks control the carbon fluxes. It was estimated that the karst areas in south China contribute to about half of the total carbon sink by the carbonate system in China. By enhancing the movement of elements and dissolution of more chemical components, the active carbon cycle in the epikarst system helps to expand plant species. It also creates favorable environments for the calciphilic plants and biomass accumulation in the region. The findings from this study should help in better understanding of the carbon cycle in karst systems in south China, an essential component for the best management practices in combating rock desertification and in the ongoing study of the total carbon sink by the karst flow systems in China.  相似文献   

Removal of 2,4-dichlorophenol and pentachlorophenol from aqueous media by electrochemical process     

Jui-Yuan Huang  Wing-Ping Liao  Siou-Mei Lai 《Environmental Earth Sciences》2013,68(8):2281-2288

Chlorophenols are persistent toxins in the natural environment. In this investigation, 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP) in aqueous media were degraded using an electrokinetic process (EK) and an electro-Fenton process (EF) using stainless steel and graphite as the anode and cathode, respectively. Chlorophenols were degraded via direct electrolysis at the surface of the electrode in the EK process. However, in the EF process, the degradation mechanism includes direct electrolysis and oxidation by hydroxyl radicals. The optimal conditions were a current density of 0.75 mA/cm² and an air flow of 0.7 l/min at pH 4. Under the optimal conditions, the 2,4-DCP and PCP removal rates in the EF process were 80.18 and 64.03 %, respectively. The mineralization efficiencies of 2,4-DCP and PCP were 78.23 and 75.77 %, respectively. The results of dechlorination reveal that almost all of the chlorines were released, but some were retained in the intermediates. The dechlorination efficiency revealed that the EF and EK4 processes two chlorines from 2,4-DCP. They released four or five chlorines and four chlorines from PCP, respectively. The kinetic results provide evidence of pseudo-first degradation. The rate constant (k _cp) declined as pH_i was increased from 4 to 10. The k _cp values reveal that the pH is an important factor that affects the degradation efficiency in the electrochemical process.  相似文献   

超深地下连续墙施工中几个问题的探讨          下载免费PDF全文

马勤  王芳 《探矿工程》2013,40(11):68-71

结合武汉某地下连续墙工程,探讨了超深嵌岩地下连续墙施工过程中出现的因三轴搅拌桩施工造成成槽困难的问题,以及超深地下连续墙接头管安装和起拔问题,并提出了相应的解决措施。实践证明,这些措施是有效的,可以为武汉地区的类似工程提供参考。  相似文献   

沉积盆地深层地下卤水资源量评价之若干探讨   总被引：1，自引：0，他引：1  

周训  姜长龙  韩佳君  唐丽伟  曹琴  李婷 《地球学报》2013,34(5):610-616

沉积盆地深层地下卤水(包括富钾卤水)处于深埋封闭和无补给状态; 卤水具有很高的测压水头, 天然条件下处于停滞状态, 不同储卤构造之间无水力联系; 具有多个平行叠置的储卤层, 不同储卤层之间无水力联系; 储卤层空隙性和渗透性差, 卤水主要富集于背斜、裂隙带和断层裂隙带; 卤水水化学和物理特性在短期内比较稳定; 卤水储存资源量较大, 在开采条件下卤水资源逐渐减少趋于衰竭。本文在分析总结沉积盆地深层地下卤水资源量评价的现状和卤水特征的基础上, 讨论和阐明深层地下卤水资源评价中的若干问题, 包括深层卤水资源量的类型和评价方法的选取、储卤层计算范围和边界的概化处理、渗透性分区和卤水密度影响的处理、测压水头的换算、钻井预测水头降深的确定等, 目的在于提高深层地下卤水资源量评价计算的精度。  相似文献   

一个直接用观测资料计算大范围散度、涡度和垂直速度的方案   总被引：1，自引：1，他引：1  

廖洞贤  王两铭  王超  张光智  张建春 《气象学报》1980,38(4):309-320

提出了一个直接用观测资料,便于用电子计算机计算大范围散度、涡度和垂直速度的方案。还提出了计算某些物理量的梯度、平流和通量的方法。对于在垂直方向不均匀分层的计算,垂直边界条件个数和连续方程不协调的问题,以及在地形起伏的山地如何计算垂直速度等问题,也作了初步讨论。最后,用一次华南大范围降水的例子进行了计算,结果和预报员经验还比较一致。  相似文献