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561.
京津唐地区地震灾害区域宏观脆弱性变化研究   总被引:4,自引:0,他引:4  
研究灾害脆弱性的变化有助于深入理解灾害及灾害风险的形成机制。在重新审视承灾体系统灾害脆弱性的分析层次和描述角度之后,深化了对地震灾害区域宏观脆弱性的影响因素和描述指标的再认识,完善了以主成分分析为核心技术的分析该类脆弱性时空变化的数理方法。以此为基础,以1985、1995、2000和2004年为代表时期,对京津唐地区20多年来的地震灾害区域宏观脆弱性的变化做了进一步的分析和总结。主要结论是:研究区地震灾害区域宏观脆弱性20多年来的时空变化可分解为少数几种脆弱性模式的变化;1985年以来,该类脆弱性的空间分异格局整体稳定;但是,各地自身脆弱与否的程度20多年来的变化却很显著——各大中城市市区的脆弱程度显著增强,其他地区整体减弱,且变化幅度前者显著大于后者;研究区地震灾害区域宏观脆弱性的时空变化主要受该地区的人口和经济特别是工商业经济的增长、城市化发展和产业结构的调整等3方面因素所驱动。  相似文献   
562.
对鄱阳湖沉积物中16种多环芳烃(PAHs)含量、时空分布及影响因素进行了研究,并对湖体不同区域的PAHs进行定量源解析.PAHs在沉积物中广泛存在,所有点位表层沉积物中ω (∑16PAHs)范围为203~2 318 μg·kg-1,其中湖体表层沉积物中PAHs含量高于入湖河流表层沉积物中PAHs含量.鄱阳湖PAHs环数比例大小依次排列为:4环>5环>6环>3环>2环,4环PAHs组成占主导地位,其含量占∑16PAHs的比例高达86.11%.2~3环以及部分4环PAHs包括Flua和Pyr更容易受到SOM的影响,4~6环PAHs更容易受到ORP及重金属等环境因子的影响.在空间分布上,∑16PAHs的较高含量位于湖体邻近都昌县与鄱阳县区域,此区域地形相对封闭,与周围区域水流交换量小,不利于污染物的迁移、转化及降解.在时间分布上,PAHs含量水平的变化与江西省GDP的发展呈现出高度一致性,经济发展和人类活动影响可能是导致PAHs含量水平不断增加的主要原因.鄱阳湖表层沉积物PAHs的主要来源包括石油污染及石油、煤炭和生物质燃烧源,不同区域PAHs来源存在一定的空间差异.本研究可为鄱阳湖表层沉积物中PAHs污染情况提供参考,对鄱阳湖生态环境保护和治理具有重要意义.  相似文献   
563.
王相男  张喆  刘方青 《环境科学》2024,45(3):1315-1327
针对天山北坡城市群开展PM2.5浓度时空分布特征和影响因素分析,对区域经济建设和环境保护具有积极的意义.通过地理加权回归(GWR)模型,利用MCD19A2气溶胶产品结合气象因子,反演得到天山北坡城市群2015~2021年3~11月的PM2.5浓度时空分布,继而实现变化趋势和影响因素分析.结果如下:①研究区PM2.5浓度高值主要分布在天山北麓和古尔班通古特沙漠之间的绿洲城市群地带,呈现“四周低,中间高”和“西低东高”的空间分布特征,2015~2021年研究区的ρ(PM2.5)年均值为16.98 μg·m-3,高值主要聚集在乌鲁木齐市市区部分,并向昌吉市和阜康市延伸递减;ρ(PM2.5)月均值分布规律与年均一致,但存在季节差异,表现为:秋季(20.32 μg·m-3)>春季(18.25 μg·m-3)>夏季(12.47 μg·m-3),春季和冬季聚集现象会更明显;②研究区PM2.5浓度年均值在2015~2021年呈现下降趋势,3~10月均值同样表现为下降趋势,仅11月表现为略有升高;从PM2.5浓度变化趋势空间分布分析,下降集中在主要城市市区部分,尤其是乌鲁木齐市市区部分及其周边地区减少幅度最大,变化最为剧烈;③研究区气温、气压与PM2.5浓度呈现正相关效应,而相对湿度,风速,大气边界层高度,降水量与PM2.5浓度呈现负相关效应;各因子影响程度从高向低排列为:大气边界层高度>相对湿度>气压>气温>风速>降水量.  相似文献   
564.
卢荡  魏伟  王继平  闫彭  刘婷  周俊菊  颉斌斌 《环境科学》2024,45(6):3352-3362
基于温度-植被-降水的综合干旱指数(TVPDI)、地表径流、植被净初级生产力和粮食产量等数据,利用数据空间化方法、Slope趋势分析及Pearson相关分析等方法,探究了黄河流域从2001~2020年这20年间干旱时空变化特征以及对水资源、粮食资源和植被资源的影响,试图探究干旱与关键资源之间的相互影响.结果表明:①黄河流域干旱空间分布由东南向西北呈阶梯状加重,全流域有60.6 %的区域处于干旱状态;从变化看全流域干旱整体上呈逐年下降趋势,有94 %的区域由干旱逐渐向湿润转变,从春季到冬季干旱呈现先减轻后加重的趋势.②从流域重要资源的时空变化看,起关键作用的地表径流量有53 %的区域呈现增加趋势,且主要分布在流域西南地区;表征植被资源的植被净初级生产力(NPP)及表征粮食资源的粮食产量亦呈增长趋势.③干旱与3类资源呈现显著的空间关联度,干旱程度越高对地表径流量、植被生产力和粮食产量产生的影响越显著,但近年来变湿的地区,其重要资源并未显著增加,这说明干旱对3类重要资源的影响具有时间滞后性,且其滞后性在空间分布上具有显著差异性和地域分异规律.研究对于黄河流域农业生产和抗旱减灾、生态保育具有重要理论意义.  相似文献   
565.
A two-year study on temporal variations in the ground water heterotrophic bacterial cell sizes of free living bacteria(FLB)and particle bound bacteria(PBB)from the agricultural,domestic and industrial areas was carried out from Februar y2005 to January 2007.The overall mean cell length of FLB and PBB was similar in all the ground water studied.However,the season wise grouped data revealed significant seasonal changes in cell length of FLB and PBB,as smaller bacteria were noticed during rainy season in the ground water in agricultural area in both the years,and only in the second year of study in domestic and industrial areas.Generally,it was noticed that there were summer maximum and rainy minimum values of the cell length of PBB in the ground water in agricultural,domestic and industrial areas in the second year of study.The Pearson's correlations showed the presence of 8(in agricultural area),5(in domestic)and 3(in industrial) significant correlations with environmental(Physico-chemical)parameters,respectively.The regression analysis revealed that as much as 12%of variation in the mean length of FL Bwas due to NO3( )in agricultural area and 9%due to total solids( )indomestic area.However,the 8% variation in bacterial cell size of FLB was due to Mg( )in industrial area.Whereas,13%variation in mean length of PBB was due to S04( )in agncultural area and 10%due to total anions of strong acid(TASA)( )in domestic area.Furthermore,10% of variation Was due to PO4( )in industrial area.Thus,the statistical analysis revealed that several environmental variables were potentially responsible for some of the temporal variations in aquatic heterotrophic bacterial cell size,suggesting probably the stressed environment in these ecosystems.  相似文献   
566.
Competition among mammalian siblings for scarce resources can be severe. Whereas research to date has focused on competition for the mother’s milk, the young of many (particularly altricial) species might also be expected to compete for thermally favorable positions within the nest, den, or litter huddle. We investigated this in newborn pups of the European rabbit Oryctolagus cuniculus, a species in which the altricial young are not brooded by the mother, and in which competition for milk is severe. In eight unculled litters (N = 86 pups) of a domestic chinchilla strain, we calculated huddling indexes for individual pups on postnatal days 2–5 as a measure of the degree of insulation they received from littermates. Pups maintained almost constant physical contact with the litter huddle. They performed brief but frequent rooting and climbing behaviors, which usually improved their huddling index, interspersed with longer periods of quiescence during which their huddling index declined. As expected, we found a significant positive relation between pups’ mean huddling index and body temperature. Unexpectedly, however, we did not find a relation between huddling index and pups’ birth weight, survival, milk intake, or efficiency of converting milk to body mass. We conclude that rather than competing for thermally advantageous positions within the huddle newborn rabbits share out thermally advantageous positions as they move in a continual dynamic flow through it. Thus, in newborn rabbits, competition for the mother’s milk exists alongside mutual “cooperative” benefits of littermate presence. This contribution is part of the special issue “Sibling competition and cooperation in mammals” (guest editors: Robyn Hudson and Fritz Trillmich).  相似文献   
567.
Theory predicts that frequent dyadic association should promote cooperation through kin selection or social tolerance. Here we test the hypothesis that sex differences in the strength and stability of association preferences among free-ranging chimpanzees conform to sex differences in cooperative behavior. Using long-term data from the Kanyawara chimpanzee (Pan troglodytes schweinfurthii) community (Kibale National Park, Uganda), we calculated indices of intra-sexual dyadic association over a 10-year period. We found that (1) male–male dyads had significantly stronger association indices than female–female dyads, (2) the pattern of association preferences in both sexes changed little over the entire study period, and (3) when comparing periods with different alpha males, changes in association strength were more frequent among males. These results demonstrate that both the strength and stability of association patterns are important components of social relationships. Male chimpanzees, which are characterized by frequent cooperation, had association preferences that were both strong and stable, suggesting that forming long-term bonds is an important dominance strategy. However, the fact that male association patterns were sensitive to upheaval in the male dominance hierarchy suggests that males also take advantage of a changing social climate when choosing association partners. By contrast, the overall strength of female associations was relatively weak. Female association preferences were equally stable as males’; however, this reflected a dyad’s tendency to be found in the same party rather than to associate closely within that party. Therefore, in this community, female association patterns appear to be more a consequence of individual ranging behavior rather than a correlate of cooperation.  相似文献   
568.
Quantification of the forest water flux provides valuable information for the understanding of forest ecosystem functioning. As such, throughfall (and stemflow to a lesser extent) has been frequently measured. Although throughfall collection may seem relatively simple, the requirements to obtain reliable estimates are often underestimated. This review addresses the criteria to take into account when working out the sampling procedure, from the selection of equipment to implementation in the field. Sound sampling of the forest water flux is difficult due to its high spatial and temporal variation. The high costs entailed by the ideal sampling design often prohibit its implementation. Different procedures are available, some of which are compromises between the aim of the study (monitoring or experimental study, short or long term objectives, absolute or relative estimates, quality of the assessment to be achieved) and the available means.  相似文献   
569.
This study seeks to advance our understanding of the leadership consequences that may ensue when supervisors and their teams have similar versus differing orientations toward the past. Integrating a leader–team fit perspective with functional leadership theory, we cast incongruence between supervisor and team past temporal focus as a key antecedent of supervisors' active (i.e., task-oriented and relationship-oriented) and passive (i.e., laissez-faire) leadership behaviors toward the team. We tested our hypotheses in a team-level study that included a field sample of 84 supervisors and their teams using polynomial regression and response surface analyses. Results illustrated that supervisors demonstrated more task-oriented and relationship-oriented leadership when supervisors' and their team's past temporal focus were incongruent rather than aligned. Furthermore, in situations of supervisor–team congruence, supervisors engaged in less task-oriented and relationship-oriented leadership and more laissez-faire leadership with higher (rather than lower) levels of supervisor and team past temporal focus. In sum, these findings support a complex (mis)fit model such that supervisors' attention to the past may hinder their productive leadership behaviors in some team contexts but not in others. Hence, this research advances a novel, multiple-stakeholder perspective on the role of both supervisors' and their team's past temporal focus for important leadership behaviors.  相似文献   
570.
Despite the rapid growth of organizational research on subjective time, the extant literature is fragmented due to a lack of conceptual clarification and integration of temporal constructs. To address this fragmentation, we synthesize temporal research from both organizational behavior and adjacent disciplines (i.e., strategy, entrepreneurship, and organizational theory) and introduce a framework that allocates temporal constructs according to their basic conceptual nature (trait–state) and level of analysis (individual–collective). We employed the Linguistic Inquiry and Word Count text analysis to determine the trait–state property of the constructs and a coding method to determine their level of analysis. This framework categorizes four generic types of subjective time: individual temporal disposition, individual temporal state, collective temporal state, and collective temporal disposition. We clarify the conceptualizations of the temporal constructs belonging to each of the four archetypes of subjective time and review their key findings in the organizational literature. Based on this integrative framework, we identify critical knowledge gaps in the current state of research and chart a future agenda with specific suggestions.  相似文献   
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