城市大气总悬浮颗粒物与城市热岛

城市大气总悬浮颗粒物是造成全球大部分城市空气污染严重的原因之一,世界各国对之已进行过很多的研究。大量的研究显示,总悬浮颗粒物的污染非常严重,是影响城市空气质量的首要污染物。总悬浮颗粒物的源以人为来源为主,其汇则以湿沉降为主。总悬浮颗粒物对城市气候的影响主要通过2种方式:一种是通过散射或吸收太阳辐射直接影响气候;另一种是以云凝结核的形式改变云的光学特性和云的分布而间接影响气候。但是总悬浮颗粒物与城市热岛相互关系的研究目前还未受到应有的关注,总悬浮颗粒物与城市热岛的相互作用尚未有定论,总悬浮颗粒物既有促进城市热岛形成,也有促进城市冷岛形成的研究报道。文章认为可从如下3个方面探讨总悬浮颗粒物与城市热岛的相互关系:(1)总悬浮颗粒物在城市热岛中的贡献;(2)总悬浮颗粒物影响城市热岛的作用机理;(3)总悬浮颗粒物与城市植被和城市热岛的相互关系及植被对总悬浮颗粒物的净化、对城市热岛的缓解。研究总悬浮颗粒物与城市热岛的相互关系为制定科学合理的城市大气总悬浮颗粒物污染防治措施,有效缓解现代城市热岛难题提供理论依据。     

Persistence of Forest Birds in the Costa Rican Agricultural Countryside

Abstract:  Understanding the persistence mechanisms of tropical forest species in human-dominated landscapes is a fundamental challenge of tropical ecology and conservation. Many species, including more than half of Costa Rica's native land birds, use mostly deforested agricultural countryside, but how they do so is poorly known. Do they commute regularly to forest or can some species survive in this human-dominated landscape year-round? Using radiotelemetry, we detailed the habitat use, movement, foraging, and nesting patterns of three bird species, Catharus aurantiirostris , Tangara icterocephala , and Turdus assimilis , by obtaining 8101 locations from 156 individuals. We chose forest birds that varied in their vulnerability to deforestation and were representative of the species found both in forest and human-dominated landscapes. Our study species did not commute from extensive forest; rather, they fed and bred in the agricultural countryside. Nevertheless, T. icterocephala and T. assimilis , which are more habitat sensitive, were highly dependent on the remaining trees. Although trees constituted only 11% of land cover, these birds spent 69% to 85% of their time in them. Breeding success of C. aurantiirostris and T. icterocephala in deforested habitats was not different than in forest remnants, where T. assimilis experienced reduced breeding success. Although this suggests an ecological trap for T. assimilis , higher fledgling survival in forest remnants may make up for lower productivity. Tropical countryside has high potential conservation value, which can be enhanced with even modest increases in tree cover. Our findings have applicability to many human-dominated tropical areas that have the potential to conserve substantial biodiversity if appropriate restoration measures are taken.     

深部孤岛工作面区段煤柱冲击地压的试验研究

以冲击启动理论为基础,结合覆岩空间结构思想,采用相似模拟试验方法,研究了孤岛工作面上覆岩层空间结构特点及采动围岩应力场的分布、变化规律,进一步探讨了孤岛工作面区段煤柱冲击地压发生机理。结果表明,两侧充分开采的孤岛工作面上覆岩层呈"C"型覆岩空间结构,工作面承受上部岩层及两侧采空区上覆岩层转移过来的部分岩层重量,在工作面两侧形成应力集中区域,导致采动围岩应力场达到极限平衡状态,该集中应力可视为采动围岩近场极限平衡系统的静载荷。孤岛工作面开采过程中"C"型覆岩空间结构逐渐演化形成"W"型空间结构,极限平衡系统静载荷发生转移和改变,最终由上下区段煤柱全部承担上覆岩层重量,系统载荷增至最大,处于临界失稳状态。"W"型覆岩空间结构大面积失稳,为系统提供了外动载荷,系统在动载荷的扰动下突破平衡极限,从而发生区段煤柱冲击。最后,基于孤岛工作面应力分布规律确定了区段煤柱的合理尺寸。     

Threats to Avifauna on Oceanic Islands

Abstract:  Results of the study by Blackburn et al. (2004 a ) of avifauna on oceanic islands suggest that distance from the mainland and time since European colonization have major influences on species extinctions and that island area is a significant but secondary contributing factor. After augmenting the data of the study on geographical properties for some of the islands they examined, we used a causal analysis approach with structural equation modeling to reexamine their conclusions. In our model geographical properties of islands, such as island area and isolation, were considered constraints on biological factors, such as the number of introduced mammalian predators and existing number of avifauna, that can directly or indirectly influence extinction. Of the variables we tested, island area had the greatest total influence on the threat of extinction due to its direct and indirect effects on the size of island avifauna. Larger islands had both a greater number of threatened bird species and more avifauna, increasing the number of species that could become threatened with extinction. Island isolation also had a significant, positive, and direct effect on threats to island avifauna because islands farther from the mainland had fewer current extant avifauna. Time since European colonization had a significant negative, but relatively weaker, influence on threats compared with the traditional biogeographic factors of island area and distance to the mainland. We also tested the hypothesis that the amount of threat is proportionally lower on islands that have had more extinctions (i.e., there is a "filter effect"). Because the proportion of bird extinctions potentially explained only 2.3% of the variation in the proportion of threatened species on islands, our results did not support this hypothesis. Causal modeling provided a powerful tool for examining threat of extinction patterns of known and hypothesized pathways of influence.     

城市热岛的遥感研究

随着城市建设事业的发展以及人为热释放的增多，城市热岛效应呈现不断增强趋势。将遥感技术与常规城市热岛监测方法结合起来，才能深入进行城市热岛监测研究。通过回归分析建立一定模式，将遥感手段获得的辐射温度（亮温）转换为常规方法所用的空气温度（气温）是城市热岛遥感研究的主要思路和方法。以武汉市城市热岛分析为例，本文探讨了城市覆盖层与边界层的热岛形成因子，城市热岛效应直接或间接对城市其他气候要素产生多种影响，并对城市居民生产生活和健康带来有利和不利的因素。     

Using Gall Wasps on Oaks to Test Broad Ecological Concepts

Abstract:  Planning conservation of insect herbivores requires knowing what needs to be conserved and developing a set of predictor variables that aid management. We conducted a state-wide survey to examine the species richness of gall wasps (Hymenoptera: Cynipidae) on six oak species dominant in the threatened scrub-oak vegetation in peninsular Florida. Eighty-eight cynipid species were recorded; 23 were new species to Florida (a 35% increase), including 17 species new to science and 6 species newly recorded in the state. The cynipid species represented 68% of cynipids of Florida, on only 24% of oak species sampled. This fauna represents a hotspot of richness, justifying conservation initiatives in scrub-oak habitat and throughout the state. We derived predictor variables from general ecological concepts: (1) the theory of island biogeography that insect species richness increases as host plant geographic area increases and as local abundance increases, (2) the plant-architecture hypothesis that insect species richness increases with increased plant size, and (3) phytochemical patterns in leaves, including nutrients and digestibility reducers predicting suitability for insect herbivores. Concepts 1 and 2, developed for large scales and species numbers, were tested at smaller scales relevant to much conservation research and management. A stepwise multiple regression including all predictor variables accounted for 99% of the variance in cynipid species richness with three variables: foliar hemicellulose concentration (81%), host geographic area (16%), and tree height (2%). The trends were negative, however, and opposite to those predicted by concepts 1 and 2. Ecological theory was not applicable to discovery of predictors of cynipid species richness on six oak species. Thus, we promote caution in applying ecological theory to a narrow set of species without specific testing of how patterns conform to theoretical predictions.     

酒泉市城南热岛成因分析

根据遥感资料分析了酒泉市城市热岛的成因。指出建筑空间、污染物、水体都是影响城市热岛的主要因素。     

海峡西岸清洁岛屿秋季VOCs特征及来源解析

挥发性有机物（VOCs）是臭氧（O₃）和二次有机气溶胶（SOA）的重要前体物.为夯实国内海岛背景点VOCs监测,研究海峡西岸清洁岛屿平潭VOCs污染特征及来源,探索化学二次生成对清洁岛屿O₃的影响,于2018年秋季,对平潭大气VOCs进行了监测研究.结果表明,平潭2018年秋季VOCs浓度为1.94~52.12 μg·m^-3,平均值为15.54 μg·m^-3,烷烃占比最高（66.02%）,乙烷为浓度的最大物种,达到6.82 μg·m^-3.平潭秋季VOCs浓度日变化呈双峰型,表现出典型的人类活动相关性.经比较甲苯/苯（T/B）可知,平潭秋季VOCs来源主要是交通排放及燃料蒸发.利用正交矩阵分解（PMF）源解析发现,汽车尾气（72.8%）、船舶排放（12.4%）、生物质燃烧（8.7%）、工业排放和溶剂使用（3.5%）和燃料蒸发（2.6%）是平潭VOCs的五大来源.平潭秋季VOCs的O₃生成潜势（OFP）差异较大,其中,烯烃（62.6%） > 烷烃（24.7%） > 芳香烃（12.7%）.当平潭O₃属于VOCs控制型时,控制大气中烯烃的浓度可一定程度上防治平潭O₃的污染.     

景观格局类型对热岛效应的影响——以福州市中心城区为例

以“火炉”城市之一福州市为例,运用RS与GIS技术、半变异函数分析等方法,以2009年、2018年Landsat TM/OLI系列影像为数据源,从城市尺度分析了景观格局与城市热岛的关系,从景观格局特征尺度分析了景观格局类型对热岛效应的影响.结果表明：从2009年、2018年9个景观格局指数计算结果显示福州市中心城区景观格局破碎化程度增加;2009年与2018年的景观格局特征尺度分别为3600m,2500m,表明后者的景观格局更为丰富;虽然主城区的热岛效应得到了一定缓解,但城市热岛的范围逐渐扩大,八个新城分别成为了新的热岛中心;不同景观格局类型的热岛效应的严重情况依次为：纯人工本底格局 > 人工本底的散布格局 > 人工本底的指状、网络格局 > 自然本底的指状、网络格局 > 自然本底的散布格局 > 纯自然本底格局.研究以期通过细化景观格局研究尺度,为具有热岛降温作用的景观格局提出优化的方向.     

岛屿地形下的核电厂护岸防洪设计研究

对国内第一个岛屿地形下核电厂的护岸防洪设计进行了研究,提出直立式护岸结构方案以满足核电厂防洪和避让毗邻海岛的要求。在波浪数值模拟计算结果基础上,开展了波浪整体物理模型试验、波浪局部整体物理模型试验和波浪断面物理模型试验,对护岸的越浪量和结构稳定性进行了优化验证。研究结果表明,岛屿地形下,波浪破碎和波能集中导致护岸堤身坡脚处波高增大,须加高挡浪墙和优化挡浪墙结构型式;在相同的越浪量标准下,采用直立堤结构相对斜坡堤结构对应的护岸挡浪墙的高程须明显加高;利用部分海岛地形斜坡高地作为厂区护岸一部分时,原状海岛地形斜坡高地处的波浪爬高效应明显,须加高邻近护岸挡浪墙的高程。