城市扩张过程对土壤重金属积累影响的定量分离

定量提取人为活动对土壤重金属积累的影响是进行土壤污染模拟的基础。本文研究了1949年来宜兴城区的扩张过程及在其影响下土壤中Cd、Cu、Pb和Zn等重金属的积累过程。利用变量分离法提取了重金属含量中的人为影响分量和自然背景分量,并估算了城市扩张影响下的积累通量。研究结果发现随着宜兴城区扩张快速,土壤中的重金属元素含量随着城市建设年限的增长而升高。变量分离法较成功的解释了重金属元素积累的影响因素,Cd、Cu、Pb和Zn的人为影响分量的均值分别占各实测含量均值的16.6%、18.4%、33.22%和2.7%。空间分布上4种重金属元素的趋势分量沿城市扩张方向均表现出明显的递减趋势,而自然背景分量无明显的空间变化趋势,主要受土壤理化性质的影响。最后,进一步推算了土壤重金属元素输入通量空间变化方程,这可为进一步模拟城市化背景下重金属积累提供有效的参数。     

柽柳对盐碱土养分与盐分的影响及其区化特征

为了研究柽柳对盐碱土的生物改良作用及其有效作用范围,通过大田对比试验,以盐碱荒地为对照,分析了柽柳对土壤养分、全盐及盐分离子的影响及其区化特征。结果表明,柽柳能够提高盐碱地土壤养分,降低pH值、全盐及盐分离子含量。与对照相比,表层0—20cm土壤有机质增加了30.5%,碱解氮增加了48.9%,速效磷增加了51.4%;底层20—50cm土壤3者分别增加了78.8%,21.3%,25.0%;表层土壤pH值降低0.3个单位,但是底层20—50cm土壤pH值增加了0.4个单位;表层和底层脱盐率分别达到86.4%和88.2%,碱化度分别降低了75.4%和53.8%;柽柳对土壤盐分离子表现出选择吸收性,Na+和Cl-降幅高于Ca2+,Mg2+,K+,SO24-。柽柳在深度0—25cm,距离树干0—15cm范围内,形成"低盐、低pH值、高有机质"的优化区域。确定合理的柽柳配置方案,充分发挥其生物和非生物功能,是土壤理化性质向良性循环方向发展的关键。     

基于连续灰分区间定标模型的生物炭金属含量LIBS检测

为实现应用激光诱导击穿光谱(LIBS)技术准确检测农业生物炭中主要金属元素含量,并提高检测灵敏度,提出采用高温处理法去除水分、固定碳和有机基体效应的影响。首先获取灰分质量分数在28%～42%范围内具有代表性的66个农业生物炭样品,并选用不同灰分区间间距(14%、7%、3. 5%和2%)对样品集进行划分。当间距设为7%时,样品集的灰分区间被划分为28%～35%(38个样品)和35%～42%(28个样品),对应的高温处理前后各元素含量平均决定系数均大于0. 96。理论上表明,可以利用高温处理后样品光谱信息,并结合原始样品化学信息,构建农业生物炭中主要金属元素含量的连续灰分区间定标模型。通过比较原始样品和高温处理后样品数据集所构建模型的效果,得出高温处理后样品偏最小二乘回归(PLSR)模型的交互验证相对标准偏差明显较低,其预测集的成对T检验显示,LIBS和电感耦合等离子体质谱(ICP-MS)测定结果无显著性差异。结果表明,高温处理结合连续灰分区间定标模型能够实现农业生物炭中主要金属元素的LIBS同步精确定量分析。     

近45a山西冬季0cm地温时空分布及气候分区

利用1965—2009年山西省59个气象站冬季逐月0 cm地温资料,应用多种统计方法,对近45 a山西冬季0 cm地温时空分布及其次区域特征进行研究。结果表明:(1)近45 a来,山西区域冬季平均0 cm地温为显著升温趋势,升温幅度达0.52℃/10 a;从其年代际变化看,20世纪60年代中期到70年代初略呈下降趋势,70年代中期以后呈现明显上升趋势,并在1993年发生突变,进入温度偏高期。从各站点看,全省大部分地区冬季0 cm地温升温趋势显著。(2)山西冬季0 cm地温的空间分布主要表现为全省一致偏高或偏低,其次是北部和南部盆地偏高、南部山区偏低或相反的分布。(3)山西冬季0 cm地温可分为北部、西南部、东南部3个气候区;近45 a来,各区均为显著升温趋势,东南部、西南部、北部分别在1989,1993,1994年发生突变,突变后各区进入0 cm地温偏高期。     

关于高阶导数求法的探讨

针对利用莱布尼茨公式在求某些函数n阶导数时无法得出通项公式的问题,本文采用三角形公式及欧拉公式解决了指数函数与三角函数相乘的n阶求导问题,并给出相应的例子。     

论有限责任的实现及其法律适用界限

有限责任制度适用于公司、商业信托、合伙企业等各种商业组织形态。在这些企业中，有限责任通过构建商业组织和资产分割得到实现。组织化的重要功能在于通过建立公司或商业信托构建法律实体、促成资产分割并形成独立公司财产或独立信托财产从而实现商业组织所有人的有限责任。有限责任削弱了对债权人利益的保护，容易造成利益不均衡。在有限责任制度被滥用的情况下，应适用法人人格否认、实质合并规则等制度性措施予以纠正。同时，应谨慎对待有限责任在专业服务领域的适用，强调专家严格责任。     

Nutrient Dynamics in Orange Trees: The Effect of Soil Fertility

Lime-induced iron (Fe) chlorosis is a nutritional disorder common in calcareous soils, which may result from a low level of Fe available or adverse factors that inhibit Fe mobilization and uptake by plants. Organic-matter amendments can prevent or correct Fe chlorosis in plants but the effect of endogenous soil organic matter (SOM) on this disorder is not known. The main subject of this work was to investigate the consequence of two contrasting levels of soil fertility on the nutritional status of an orange grove [Citrus sinensis (L.) Osb. cv. Valencia Late]. The field experiment was conducted in a commercial citrus grove using mature trees distributed in two plots with different values of SOM, phosphorus (P), and potassium (K), but with the same level of active lime. The concentration of nitrogen (N), P, K, magnesium (Mg), calcium (Ca), Fe, copper (Cu), zinc (Zn), and manganese (Mn) in young and mature leaves and flowers was evaluated. The level of Mg and the Mg/Zn ratio in flowers from both plots, although significantly different, only indicated moderate Fe chlorosis, as predicted by a previously developed model, and was consistent with the amount of chlorophyll present in the leaves. However, nutrient partitioning between leaves of contrasting age was very different. Mature leaves from trees grown in the high-fertility plot (HF) had larger concentrations of N, P, and K but lower concentrations of Ca, Fe, and Mn than did those from the low-fertility plot (LF). Young leaves from the LF had more N, P, Mg, Cu, and Mn and less Ca and Fe than did those from the HF. Flower analysis, although useful to predict Fe chlorosis, failed to detect differences in the nutritional status of plants resulting from contrasting levels of soil fertility. Furthermore, endogenous SOM had only a marginal effect on Fe chlorosis.     

首都机场高速公路中央隔离带桧柏生长障碍因子研究

本研究采用定点调查的方法 ,连续 2年对隔离带桧柏生长状况进行的调查分类 ,与此同时还在不同长势地段进行的土壤剖面调查 ,土壤理化性状分析 ,以及病虫害调查等项工作 .结果表明 ,在绝大多数情况下 ,桧柏长势差的原因是由于不良的土壤物理性状造成的     

湿热灭菌和氯化汞灭菌对双液相体系中PAHs降解的影响

A two-liquid-phase(TLP) soil slurry system was employed to quantify the efficiencies of autoclaving and mercuric chloride sterilization in the dissipation of polycyclic aromatic hydrocarbons(PAHs).The fates of 11 PAHs(naphthalene,fluorene,phenanthrene,anthracene,fluoranthene,pyrene,benzo(a)anthracene,benzo(a)pyrene,benzo(b)fluoranthene,benzo(k)fluoranthene,dibenzo(a,h)anthracene) were recorded over 113 days of incubation.No microorganisms were detected in the HgCl 2-sterilized soil slurries during the whole incubation period,indicating very effective sterilization.However,about 2%-36% losses of PAHs were observed in the HgCl 2 sterilized slurry.In contrast to the HgCl 2-sterilized soil slurry,some microorganisms survived in the autoclaved soil slurries.Moreover,significant biodegradation of 6 PAHs(naphthalene,fluorene,phenanthrene,anthracene,fluoranthene and pyrene) was observed in the autoclaved soil slurries.This indicated that biodegradation results of PAHs in the soil slurries,calculated on basis of the autoclaved control,would be underestimated.It could be concluded that the sterilization efficiency and effectiveness of HgCl 2 on soil slurry was much higher than those of autoclaving at 121℃ for 45 min.     

基于簇中心动态迁移的一个聚类算法

基于动态簇中心迁移算法对K means算法进行改进,试验结果表明,该算法能够获得一个较好的初始划分,从而获得一个较好的聚类结果.