相关分析和主成份分析在有机酸来源分析中的应用

源解析是大气中低分子有机酸研究的重要内容。收集了贵阳市和尚重镇2006年5月至2007年4月降水样品,测定其中有机酸和主要的无机离子。结果表明,大气降水有机酸存在显著相关关系,说明两地区均存在有机酸的共同来源。运用不同来源示踪剂发现,尚重镇低分子有机酸来源比较单一,主要是受植物或土壤的直接和间接释放作用的影响;贵阳市低分子有机酸的来源相对复杂,尤其是人为活动和大气光化学反应都可能是大气有机酸的重要来源。主成分分析把贵阳市和尚重镇大气降水中主要离子大致分为3类,尚重镇SO42-、NO3-、HCOOH、CH3COOH和(COOH)2是第一主成份,反映了农业活动、土壤释放和生物质燃烧可能是这类污染物的重要来源,贵阳市降水中CH3COOH、HCOOH和(COOH)2具有较高的因子负荷,为第三主成份占方差总和的19.68%。     

Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer

Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor (MOUDI). The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), and combined with a fractional Brownian motion (fBm) processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m3 (dC/dlogdp) existed in the dominant mode (180–320 nm). A relatively high proportion of these aggregates appeared in PM1, accentuating the relevance regarding adverse health e ects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coe cients (H) of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641–1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%–50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.     

LCA法在韩国环境标志产品评价中的应用研究

中国在大力发展和推广环境标志产品的同时,对环境标志产品的系统评价工作却显得薄弱,仍主要停留在能源消耗、污染物排放、废弃回收等单一因素或简单组合方式,缺乏客观性、全面性。因此借鉴国外有关先进经验,尽快建立系统的环境标志产品评价体系是很有必要的。韩国环境标志产品LCA评价的最大优点是将复杂、专业的数据转变为易于国民理解的简单形式,而有利于环境标志产品的宣传与发展。文章以LCA法在评价韩国环境标志产品中的应用为实例,系统说明其评价过程,并探讨其优势和不足,为中国相关工作的开展提供可借鉴的经验。     

液相色谱稳定特征峰比值鉴别模拟渤海溢油

考察室外自然风化对原油液相色谱稳定特征峰分布的影响,提出基于溢油液相色谱稳定特征峰比值结合聚类分析和"t-检验"分析进行模拟溢油鉴别.结果表明,液相色谱稳定特征峰比值结合聚类分析可以初步推测模拟溢油样品来源,进一步采用特征峰比值和"t-检验"分析可以实现模拟溢油样与可疑原油样品的成功判别.     

孕期低剂量镉暴露对不同性别胎鼠肝脏发育的影响及其分子调控机制的研究

为探究镉对胎儿肝脏发育的毒性作用.拟选用15只性成熟的8周龄的雌性C57BL/6小鼠,与雄鼠交配见栓后,于妊娠第7.5 d(Embryonic 7.5,E7.5)时,随机分为3组(每组5只),分别通过饮用水暴露法饲喂0、20和40 mg·L^-1的氯化镉溶液,并于E14.5 d时收集各组小鼠的胎儿肝脏等组织.通过Ki67和TUNEL染色方法探究镉对不同性别胎鼠肝脏的增殖功能和凋亡功能的影响,并通过PCR芯片筛查和实时定量PCR方法检测镉处理组的雌性和雄性胎鼠肝脏中与细胞增殖和凋亡功能相关基因的表达变化.此外,我们还将通过石墨炉火焰原子吸收技术对镉处理组的雌性和雄性胎鼠的镉含量进行检测.结果显示:孕期低剂量镉暴露对胎儿体重、胎肝重量和肝脏指数均无显著性影响.在本实验条件下,镉对胎鼠肝脏的凋亡功能无显著性影响,但对增殖功能具有抑制作用,且该抑制作用具有雌性依赖性的特征.镉特异性诱导雌性胎鼠肝脏中NF1等多个细胞增殖功能相关基因以及TGF-β1信号通路分子的表达失衡;但对雄性胎鼠肝脏中相关基因的表达水平无显著性影响.镉在雌性胎儿组织中的积累量显著高于雄性胎儿组织.综上所述,孕期低剂量镉暴露特异性抑制雌性胎儿肝脏的细胞增殖功能,并诱导雌性胎儿肝脏中NF1等多个增殖功能相关基因以及TGF-β1信号通路分子的表达失衡,该性别依赖性的抑制作用可能与镉在雌性胎儿中相对较高的积累量相关.     

南京城市交通甲烷排放特征

城市交通是CH_4等温室气体的重要排放源,而CH_4排放的观测研究是定量分析城市碳排放的基础.本项研究考虑城市交通的周变化和日变化特点,于2014年10月17日、18日、20日、23日每日5个时段在南京市主城区三条交通主干道上和2015年9月11日的早晚时段在南京长江隧道内,观测大气CH_4和CO_2浓度,分析交通CH_4排放特征及其影响因素.结果表明:1南京城区交通主干道的CH_4平均浓度均大于背景大气CH_4浓度.受交通车流量的影响,ΔCH_4浓度的空间差异显著.ΔCH_4浓度的日变化呈现倒"W"型,在交通早晚高峰时出现峰值.2由于隧道内"活塞风"的作用,长江隧道内的CH_4浓度从入口到出口逐渐增大,出入口浓度差在0.21×10-6~0.38×10-6(摩尔分数,下同)之间.3大气CH_4浓度与CO_2浓度之间线性相关.交通主干道上的ΔCH_4∶ΔCO_2值平均为0.009 1;隧道内的ΔCH_4∶ΔCO_2值仅为0.000 47~0.001 4.4影响南京城区道路大气ΔCH_4浓度和ΔCH_4∶ΔCO_2值的主要因素分别是车流量和天然气车占车流量的比例.     

广州市夏季室内外PM2.5中有机碳、元素碳的分布特征

2004年7～8月在广州市9个采样点的室内、室室外同步采集了PM2 5样品,采用热光反射碳分析仪分析得到OC、EC的质量浓度,对OC、EC污染水平、空间分布、室内室外质量浓度关系、0C/EC质量浓度关系及二次有机碳等特征进行了深入细致的分析研究.结果表明,OC室内、外平均质量浓度为17.3和19.9μg·m-3,EC室内、室外平均质量浓度为6.5和6.6μg·m-3,总碳气溶胶占PM25质量的50%以上;在不同类型采样点0C、EC质量浓度存在区别;室内环境中OC、EC质量浓度相关性显著,室外环境中0C、EC质量浓度相关性不显著;0C、EC质量浓度比ρ(OC)/ρ(EC)超过2;室内、室外PM2 5中二次有机碳质量浓度是7.6和10.0μg·m-3,占总有机碳的比率为43.8%、45.5%.     

Effects of Urbanization on the Distribution and Abundance of Amphibians and Invasive Species in Southern California Streams

Abstract:  Urbanization negatively affects natural ecosystems in many ways, and aquatic systems in particular. Urbanization is also cited as one of the potential contributors to recent dramatic declines in amphibian populations. From 2000 to 2002 we determined the distribution and abundance of native amphibians and exotic predators and characterized stream habitat and invertebrate communities in 35 streams in an urbanized landscape north of Los Angeles (U.S.A.). We measured watershed development as the percentage of area within each watershed occupied by urban land uses. Streams in more developed watersheds often had exotic crayfish ( Procambarus clarkii ) and fish, and had fewer native species such as California newts ( Taricha torosa ) and California treefrogs ( Hyla cadaverina ). These effects seemed particularly evident above 8% development, a result coincident with other urban stream studies that show negative impacts beginning at 10–15% urbanization. For Pacific treefrogs ( H. regilla ), the most widespread native amphibian, abundance was lower in the presence of exotic crayfish, although direct urbanization effects were not found. Benthic macroinvertebrate communities were also less diverse in urban streams, especially for sensitive species. Faunal community changes in urban streams may be related to changes in physical stream habitat, such as fewer pool and more run habitats and increased water depth and flow, leading to more permanent streams. Variation in stream permanence was particularly evident in 2002, a dry year when many natural streams were dry but urban streams were relatively unchanged. Urbanization has significantly altered stream habitat in this region and may enhance invasion by exotic species and negatively affect diversity and abundance of native amphibians.     

Cultural Erosion and Biodiversity: Canoe-Making Knowledge in Pohnpei, Micronesia

Abstract:  Erosion of traditional knowledge and practice is a serious and accelerating problem, but quantitative work on traditional knowledge loss and its importance to biodiversity conservation is lacking. We investigated traditional knowledge of canoe making, a skill heavily dependent on plant biodiversity, on Pohnpei, Federated States of Micronesia, through a survey of 180 island residents. Our results showed that there has been an intergenerational erosion of canoe-making skills. Given current trends, the present generation of Pohnpeians may be the last to retain any knowledge of this traditional craft. We also identified several correlates of knowledge loss—including Western educational level and occupation—that highlight potential avenues for skill conservation via governments, traditional leadership, and schools. These institutions could intervene to emphasize traditional knowledge, which would reinforce institutional contexts in which traditional knowledge and practice is valued. The heightened awareness of the value of biodiversity that is linked to traditional knowledge is key to biological conservation on Pohnpei and can help support local conservation programs.