甘肃省农田水分平衡及其时空分布规律

采用农田水量平衡模型,以县域为基本单元,对甘肃省1961～2001年10种作物逐月天然状态下农田水分平衡时空分布规律进行了研究。结果表明:天然状态下,甘肃省多年平均农田需水量为121.06×10⁸m3;亏水量为43.28×10⁸m3;盈水量为0.62×10⁸m3,降水不能满足作物生长需求。在25%、50%、75%三种降水保证率下,作物的亏水总量分为35.99×10⁸m3、42.93×10⁸m3、49.85×10⁸m3,盈水量分别为0.61×10⁸m3、0.11×10⁸m3、0.00×10⁸m3。农田水分亏缺是甘肃省农田水分平衡的主要特征。对大多数作物而言,亏水量集中于夏季,10种作物夏季亏水总量占全年亏水总量的60.2%。全生育期棉花水分盈亏的稳定性最强,水量盈亏变异系数为6.9%,麻类最差,变异系数高达43.6%。全省天然状态下,农田亏水量由东南向西北、高山向河谷递增,农田盈水量由东南向西北递减,农田水分满足率与农田水分盈亏波动性具有从东南向西北递减的趋势。     

稻田生态系统服务及其经济价值评估方法探讨

稻田生态系统是一种特殊的生态系统,它为各种生物提供了生存环境,也为人类提供了各种产品和服务,在亚洲季风区国家和地区,它更是人们生活、生产的物质基础和基本条件。文章概述了生态系统服务的概念和类型,阐述了稻田生态系统服务的重要性及其内涵,提出了稻田生态系统服务的经济价值评估方法,展望了下一步深入研究的问题。     

Mitigation of methane emission from an old unlined landfill in Klintholm,Denmark using a passive biocover system

Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system was designed based on a conceptual model of the gas emission patterns established through an initial baseline study. The study included construction of gas collection trenches along the slopes of the landfill where the majority of the methane emissions occurred. Local compost materials were tested as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux chamber based emission measurements and logging of compost temperatures) proved that the biocover system had an average mitigation efficiency of approximately 80%. The study showed that the system also had a high efficiency during winter periods with temperatures below freezing. An economic analysis indicated that the mitigation costs of the biocover system were competitive to other existing greenhouse gas mitigation options.     

建筑施工现场安全检查问题剖析及对策

结合建筑施工现场安全生产检查现状,分析现有安全生产检查过程中存在的主要问题,这些问题导致安全检查成本过高,效率低下,检查流于形式,建筑施工企业在安全生产检查上缺乏主动性。在此基础上提出通过政府调整安全管理组织体系,采用"少检查,大处罚"的方式,结合计分制度,加强群众舆论监督,充分调动企业内部的积极性,逐步把安全生产检查转变成企业主导行为,从而提高建筑施工现场安全管理水平。     

Monitoring and targeting the sanitation poor: A multidimensional approach

Water, sanitation and hygiene (WaSH) are at the core of sustainable development. As we embark on a new round of global goals, namely the Sustainable Development Goals, a top priority is to address a coherent framework for monitoring these services. In the coming years, the sector will witness the development of a variety of multidimensional monitoring measures, albeit from different perspectives. This paper reviews the relevant literature and discusses the adequacy and applicability of one approach that is increasingly adopted for multidimensional poverty measurement at the household level, the Alkire‐Foster methodology. Drawing on this method, we identify and combine a set of direct household‐related water and sanitation deprivations that batter a person at the same time. This new multidimensional measure is useful for gaining a better understanding of the context in which WaSH services are delivered. It captures both the incidence and intensity of WaSH poverty, and provides a new tool to support monitoring and reporting. For illustrative purposes, one small town in Mozambique is selected as the initial case study.     

基于CVM的荆州市稻田生态系统的景观休闲旅游价值评价

采用条件价值评估法（Contingent Valuation Method,CVM）调查了荆州市居民对稻田生态系统景观休闲旅游功能的认知程度和支付意愿,对受访者的社会经济特征与支付意愿进行了相关性分析,并对荆州市稻田景观休闲旅游功能的价值进行了货币化评估。结果表明,居民对稻田景观休闲旅游功能的认知程度很低,对其十分了解的仅占3.5%,并且更侧重于旅游这一目的,达到61.1%。同时,78.7%的受访者认为稻田景观休闲旅游是赋有乡愁情感的。对影响受访者支付意愿的诸多因素进行相关性分析显示,稻田景观休闲旅游功能的支付意愿与受访者的文化程度（P=0.000）和月收入（P=0.004）呈极显著正相关。运用Logistic回归分析得出,文化程度对支付意愿的敏感性较大。按人均支付意愿计算,荆州市稻田生态系统景观休闲旅游的总价值约为4.43亿元     

基于场理论的沪苏浙皖地区旅游空间差异研究

区域旅游供给场是一种重要的旅游场类型,场叠加、场结构与场核的作用效应是区域旅游供给场研究的核心内容。在对区域旅游供给场相关概念进行定义与空间解析的基础上,以游客密度作为旅游场强变量,运用GIS技术对由沪苏浙皖这一区域的空间差异进行了模拟和分析,研究结果表明:(1)随着旅游业的发展,区域旅游场的场域分异更为显著,但游客密度的集中程度在下降;(2)区域旅游场内存在较明显的"三阶梯"等级结构特征,且在考察末期,第一阶梯和第二阶梯场域范围不断扩大,尤以第二阶梯的扩大最为明显;(3)由场核向外围随着距离的增加,旅游场强呈现出显著的衰减特征,各次级场域的场核间也存在明显的场强波动地带;(4)区域旅游场极化、扩散作用并存,上海这一区域型场核在极化作用的同时在东西方向上对区域旅游场的扩散作用明显,但其扩散作用强度仍有待提高。     

基于高分辨率在线测量的轻型汽油车含氧挥发性有机物排放模型构建

机动车排放的含氧挥发性有机物(OVOCs)具有较高的大气反应活性,但在线测量识别其高分辨率排放特征的研究仍处于起步阶段,缺乏计算和预测OVOCs排放特征的模型工具.本研究利用质子转移反应飞行时间质谱仪(PTR-TOF-MS)与离子/分子反应质谱仪(IMR-MS),在简易瞬态测试工况下对轻型汽油车排放甲醛、丙酮和乙醇等8种OVOCs组分进行了在线测量.结果表明,OVOCs组分受工况变化影响显著,国Ⅰ～国Ⅴ车辆排放过程中OVOCs排放峰值相对于怠速阶段的增幅分别为183％、105％、56％、92％和244％,同时随着排放标准从国Ⅰ升级到国Ⅴ,含量较高且作为特征组分的甲醛、丙酮和甲醇排放量的降幅分别为90.9％、93.3％和93.7％,但乙醇排放相对稳定.国Ⅰ～国V排放标准下轻型汽油车8种OVOCs总量排放因子分别为12.5、10.2、5.4、4.2和1.6 mg-km-1,总体减排幅度87％.本研究发现OVOCs排放率与比功率(VSP),排放因子与修正碳燃烧效率(MCE)密切相关,将不同排放标准车辆的VSP与排放率和MCE与基于里程的排放因子(EFs)进行拟合,分别建立了一阶线性函数关系.提出了修正碳燃烧损失率(MCL)这一概念,并得到简化的MCL与排放因子的正比例函数关系,从而阐明了OVOCs排放因子的决定性因素.基于VSP和MCL建立的OVOCs排放模型可以计算和预测轻型汽油车在不同热运行状态下的排放率和排放因子,从而为准确评估OVOCs排放贡献和建立排放源清单提供有效工具.     

运用盐充法测量双壳贝类的壳腔体积

以长牡蛎（Crassostreagigas）和紫贻贝（Mytilusedulis）为例,研究了以食盐为填充物（盐充法）测量贝类壳腔体积的测量方法,并运用“水容法”进行验证。对两种贝类的测量结果表明,两种方法测得的壳腔容积结果相近,均无显著性差异（P〉0．05）。但运用盐充法测量牡蛎壳腔体积是水容法效率的8．4倍,测量贻贝壳腔体积的效率是水容法的6．2倍。由此可见,运用盐充法测量双壳类的壳腔体积具有操作简便和高效的特点,可广泛应用于贝类生理、生态和环境科学等领域的研究中。     

Numerical analysis of keyhole geometry and temperature profiles in plasma arc welding

In keyhole plasma arc welding (PAW), the formation of the keyhole involves complicated thermo-physical mechanism. The shape and dimensions of the keyhole directly determine the heat deposition along the thickness direction of the test plates, the penetration depth and the weld bead quality. Based on analysis of the forces acting on the weld pool, a keyhole model is established according to the force-balance condition on the keyhole wall. The shape and dimensions of quasi-steady state keyhole are numerically predicted. The keyhole shape and size are used to calibrate some distribution parameters of the combined volumetric heat source which takes into consideration the geometrical feature of welds with larger ratio of penetration depth to width and volumetric distribution characteristic of the plasma heat intensity along the plate thickness direction. The temperature fields on stainless steel plates are numerically simulated. The calculated fusion line at the transverse cross-section of PAW welds are compared with the experimental measurements. It is found that the predicted results are in agreement with the experimental data.