一种大气CO2源汇反演模式方法的建立及应用

在一个二维全球大气化学传输模式的基础上,通过对模式的修改和调整,建立了一个简单二维扩散、传输模式,用于CO2源汇的反演研究.在验证了模式的有效性之后,将其应用于大气CO2源汇分布的研究.大气CO2的源主要集中在赤道地区和北半球中高纬度地区.其中,海洋和陆地生态系统(热带雨林的破坏)是赤道地区的主要碳源;北半球中高纬度的陆地生态系统是重要的碳汇,而南半球中纬度地区则表现为CO2的弱汇.对El Nino年(1982年)和其他年份的碳源汇分布情况作了比较,两者之间存在显著的差异,由于化石燃料燃烧排放并无明显波动,因此认为碳通量的年际变化是由于El Nino事件对陆地和海洋碳循环产生影响而造成的.     

中国1961-2000年月平均气温空间插值方法与空间分布

利用地理信息系统软件ARC/INFO,在考虑海拔高度对气温影响和没有考虑海拔高度对气温影响的两种情况下,分别运用样条插值法、普通克立格法和逆距离权重法对中国623个气象站1961—2000年40 a的逐月平均气温进行了空间插值,并利用交叉检验方法对插值精度进行了评估,结果表明:考虑了海拔高度影响的3种插值方法的精度都有比较明显的提高,对于普通克立格法,平均绝对误差(MAE)从1.44℃降到0.82℃,均方根误差(RMSE)从2.31℃降到1.28℃;对于逆距离权重法,MAE从1.52℃降到0.88℃,RMSE从2.38℃降到1.34℃;对于样条插值法,MAE从1.54℃降到0.87℃,RMSE从2.49℃降到1.35℃。在6种插值方法中,考虑了海拔高度影响的普通克立格法是最优空间插值方法。     

Double Allee Effects and Extinction in the Island Fox

Abstract:  An Allee effect (AE) occurs in populations when individuals suffer a decrease in fitness at low densities. If a fitness component is reduced (component AE), per capita population growth rates may decline as a consequence (demographic AE) and extinction risk is increased. The island fox ( Urocyon littoralis ) is endemic to six of the eight California Channel Islands. Population crashes have coincided with an increase in predation by Golden Eagles ( Aquila chrysaetos ). We propose that AEs could render fox populations more sensitive and may be a likely explanation for their sharp decline. We analyzed demographic data collected between 1988 and 2000 to test whether fox density (1) influences survival and reproductive rates; (2) interacts with eagle presence and affects fox fitness parameters; and (3) influences per capita fox population trends. A double component AE simultaneously influenced survival (of adults and pups) and proportion of breeding adult females. The adult survival AE was driven by predation by eagles. These component AEs led to a demographic AE. Multiple-component AEs, a predation-driven AE, and the simultaneous occurrence of both component and demographic AEs in a mammal are all previously unreported processes. Populations below 7 foxes/km² could have suboptimal population growth rates due to the demographic AE, and AEs may have contributed to the dramatic declines in three fox populations. Because fox densities in critically endangered populations are well below this level, removing Golden Eagles appears necessary to prevent a predation-driven AE. Conservationists should also be aware of AEs when planning the release of captive foxes. More generally, our findings highlight the danger of overlooking AEs in the conservation of populations of rare or threatened species.     

SIMULTANEOUS EQUATION SYSTEMS: A CONSISTENT ESTIMATOR FOR UNKNOWN PARAMETERS IN CONFINED AQUIFERS1

ABSTRACT: This paper presents criteria for establishing the identification status of the inverse problem for confined aquifer flow. Three linear estimation methods (ordinary least squares, two-stage least squares, and three-stage least squares) and one nonlinear method (maximum likelihood) are used to estimate the matrices of parameters embedded in the partial differential equation characterizing confined flow. Computational experience indicates several advantages of maximum likelihood over the linear methods.     

Climate change decision-support and the tolerable windows approach

The Tolerable Windows Approach (TWA) to Integrated Assessments (IA) of global warming is based on external normative specifications of tolerable sets of climate impacts as well as proposed emission quotas and policy instruments for implementation. In a subsequent step, the complete set of admissible climate protection strategies which are compatible with these normative inputs is determined by scientific analysis. In doing so, minimum requirements concerning global and national greenhouse gas emission paths can be determined. In this paper we present the basic methodological elements of TWA, discuss its relation to more conventional approaches to IA like cost–benefit analyses, and present some preliminary results obtained by a reduced-form climate model.     

基于反演模型的焦炉无组织苯并[a]芘排放因子研究

由于焦炉无组织苯并[a]芘排放因子难以测量,导致了焦炉苯并[a]芘大气污染研究存在一定的不确定性.针对上述问题,本研究根据1999年~2003年上海某焦化厂的产量、空气质量监测等数据,建立了基于AERMOD(AMS/EPA REGULATORY MODEL)模型反演苯并[a]芘排放因子的方法.结果显示,企业周边3个监测点年平均浓度结果分别为0.033,0.0024,0.0031μg/m³,均超过了2012年颁布的环境空气质量标准,通过AERMOD模型反演得到该焦化厂苯并[a]芘平均排放因子为14.71mg/t焦煤, 苯并[a]芘预测浓度超标面积125km²,超标区域主要集中在焦化厂周围,超标焦炉苯并[a]芘防护距离为6300m.     

焦化场地内外土壤重金属空间分布及驱动因子差异分析

焦化场地作为典型的工业污染场地,其特征污染物重金属严重危害人体健康,研究其场地内外污染物的空间分布及驱动因子,对于后续的采样设计、风险评估、污染防控等工作具有重要指导意义.本研究基于反距离加权法分析某在产焦化厂内部及外部的重金属As、Cd、Cr、Cu、Hg、Ni、Pb和Zn的空间分布,并利用地理探测器分析焦化厂内部及外部的重金属空间分布驱动因子差异.结果表明,该焦化厂内部及周边除As、Ni和Zn外,其余重金属的超背景值率均在50%以上,且内外部重金属变异系数超过30%,空间分布连续性较差.其中内部平均变异程度为：Hg > Cd > As > Cu > Zn > Cr > Pb > Ni,外部平均变异程度为：Hg > Cu > Cd > As > Zn > Pb > Cr > Ni.根据分异及因子探测结果,理化性质因子中对焦化厂内部及外部重金属空间分布贡献最大的均为土壤全氮、有机质和有效中微量元素含量;距离污染源因子中对内部重金属空间分布贡献最大的为粗苯、冷鼓工段,对外部重金属空间分布贡献最大的为焦炉熄焦工段,并且污染源及土壤理化性质的交互因子对内部重金属空间分布的贡献度略高于外部.根据结果可知,决定焦化厂内部及外部的重金属空间分布的理化性质驱动因子较为一致,其主要基于土壤养分元素对重金属有效性的影响.而决定焦化厂内外部重金属分布的污染源存在差异,内部重金属分布主要受到焦化产品精制工艺中排放含重金属废气及废水等的驱动,外部重金属分布主要受到炼焦制气工艺中排放废气沉降的驱动.     

吉林省东部山区干旱时空特征

基于吉林省东部山区13个气象站点1958—2009年逐月降水量数据,采用标准化降水指数(SPI)作为干旱评价因子,对吉林省东部山区干旱程度及时空特征进行分析。在时间上,吉林省东部山区干旱具有持续性的特点,干旱出现的频率在增加。在空间上,发生轻旱的空间分布面积最广,安图县、和龙市、延吉市、龙井市、图们市、梅河口市、通化县和集安市的东南部这些地区轻旱、中旱、重旱的程度均较为严重。     

逆流湍动床短程硝化反应器的运行性能及基质抑制动力学模型

采用模拟含氨废水和逆流湍动床(inverse turbulent bed.ITB)反应器研究了短程硝化工艺的运行性能及基质抑制动力学模型.结果表明,采用"预挂膜"和"快速排泥"的联合挂膜方法,以及"低浓度,高负荷"的启动策略,可在20 d将ITB短程硝化反应器NH4+-N负荷升至0.59 kg·(m3·d)-1,实现快...     

基于差分进化-NM单纯形法的危化品泄漏源定位*

为确定危化品泄漏源的强度和位置,提出1种基于DE-NM算法的危化品泄漏源定位方法,以监测浓度与扩散模型计算浓度的误差作为优化目标,在差分进化过程中每隔一定代数执行单纯形法,使得二者误差最小的源强和位置即为最优定位结果。研究结果表明:DE-NM算法能够快速有效地反算出泄漏源的强度和位置,满足应急响应的要求;同时,能够避免DE算法的过早收敛,以及NM算法对初值敏感的问题,有效降低单一算法对定位结果精度造成的不利影响。