基于MODIS数据黄海绿潮覆盖面积精细化提取

针对MODIS数据绿潮提取存在大量混合像元导致绿潮覆盖面积偏大这一问题,基于3 m分辨率的机载SAR高分影像,结合归一化植被指数(NDVI),对MODIS研究区中大于NDVI阈值的像元进行混合像元分解得到绿潮的"覆盖面积";获取的准同步3 m机载SAR提取的绿潮面积为"真实值",然后建立二者之间的关系模型,并选取不同的样本区域对该模型进行了验证。实验结果表明:NDVI等传统算法所提取的绿潮覆盖面积约为"真实值"的2.68倍;基于混合像元分解的方法所提取的绿潮面积较"真实值"偏小,约为"真值"的0.56倍;与传统的NDVI等多波段比值法相比,该精细化模型方法提取的绿潮覆盖面积更接近于"真实值",与"真实值"误差仅为6.7%。     

Re-planning the layout of an inner city park by planting species with a low allergological impact

Summary The current situation of parkland in Turin metropolitan area is described. Recently (1979–81) a large area (18 hectars) was turned into a Park named Colonnetti. A project of total re-organisation of the area is proposed.In particular, from the botanical point of view, we suggest the use of non allergenic plants to reduce the allergenic airborne pollen concentration.The multidisciplinary exchange of information among experts such as physicians, botanists, local authorities and the people in charge of the public green areas, may play an important role and contribute to the improvement of the overall situation of airborne pollens in the city atmosphere.     

陕西中部黄土高原地区空气花粉组成及其与气候因子的关系——以洛川县下黑木沟村为例

空气花粉研究是现代孢粉学、植被变迁与预测的重要内容之一.陕西省黄土高原地区洛川县2007-2009连续2a的空气花粉分析表明:空气花粉组成与区域植被分布特征和植物花期一致.与2007—2008年相比,2008-2009年的花粉总通量及蒿属花粉通量明显增加,但木本植物花粉通量降低,这主要与2008-2009年降水明显偏少密切相关.2007-2008年降雨量高于500 mm,花粉组合中乔木花粉百分比高于30％,表现出森林植被特点;2008-2009年降雨量少于450 mm,花粉组合中草本花粉高于80％,乔木花粉低于10％,更多表现出草原植被特点.但从植被观测来看并没有明显的变化,表明花粉组合较植被对气候变化更为敏感.主要花粉类型与气候因子的相关分析表明:气候因子影响空气花粉的组成及数量.栎属、松属、蔷薇科花粉数量主要受春季温度影响,温度越高花粉数量越多;其他季节花粉数量主要受相对湿度影响,湿度越低,花粉数量越大.榆属花粉数量主要与冬季温度有关,温度越高,花粉数量越高.杨属只受春季温度影响,春季温度越低,花粉数量越多.胡颓子科花粉含量主要受春季相对湿度、风速影响,相对湿度越低,风速越大,花粉数量越多.绝大多数草本花粉数量均主要受春、冬季相对湿度及风速影响,相对湿度越低,风速越大,花粉数量越高;此外,禾本科花粉数量还受春季温度影响,温度越高,花粉数量越多;菊科花粉数量在夏秋季节还受温度、湿度和风速的共同影响,温度越低,湿度越低,风速越大,花粉数量越多.这些结果表明,黄土高原中部地区的空气花粉特征能反映区域植被组成,且对气候变化非常敏感,对认识和预测当地气候变化与植被动态等具有重要意义.     

利用机载激光雷达技术估测东北林区典型针叶林的蓄积量

为了推广激光雷达技术在森林蓄积量估测计量方面的应用,本研究以东北林区云冷杉林、落叶松林、红松林和樟子松林4种典型针叶林为对象,基于机载激光雷达获取的点云数据提取特征变量,结合800块地面样地数据,采用逐步回归方法和偏最小二乘方法,建立4种针叶林的蓄积量模型.结果 表明:偏最小二乘法建立的模型精度优于逐步回归方法(ΔR2...     

沙尘暴对北京市空气细菌多样性特征的影响

亚洲沙尘暴携带着各类污染物质,严重影响下风向地区大气过程及生态系统和相关人群的健康。然而,沙尘天气对中国华北地区空气细菌群落及多样性特征影响的研究较少。以北京市为例,系统研究了沙尘暴对城市空气细菌多样性特征的影响。2015年4月,通过定点采样连续收集了一次沙尘暴及其前后4天的空气颗粒物样本,DNA提取、PCR扩增后进行16S rRNA基因高通量测序。共获得169122条高质量序列,生物信息学分析表明,北京市空气细菌物种多样性较高,沙尘暴不能引起细菌OTU数目的增加,但沙尘暴天气下细菌群落Pielou、Shannon和Simpson指数显著增加。菌群分类分析发现,北京市空气细菌由35个细菌门构成,其中变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)相对丰度最高,分别占总序列的32.76%、28.09%、25.46%和6.32%;芽单胞菌门(Gemmatimonadetes)和酸杆菌门(Acidobacteria)次之,分别占序列总数的2.11%和1.81%,其他细菌门的相对丰度均低于1%。沙尘暴天气下,变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、芽单胞菌门(Gemmatimonadetes)和酸杆菌门(Acidobacteria)显著升高(P<0.05),分别由31.67%、5.74%、1.82%、1.51%升高至41.46%、10.98%、4.48%和4.26%;而放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)显著降低(P <0.05),分别由28.84%、27.10%降低至22.13%和12.35%。冷杆菌属(Psychrobacter),纤维单胞菌属(Cellulomonas),不动杆菌属(Acinetobacter),假单胞菌属(Pseudomonas)和梭菌属(Clostridium)可能含有人类条件病原菌,其在沙尘暴天气中相对丰度下降,但绝对丰度会大幅增加。沙尘暴能降低人体免疫力,因此致病菌潜在健康风险可能显著增强。通过聚类分析和主成分分析发现,沙尘暴日与非沙尘暴日空气细菌群落差异较大,而沙尘暴前后群落结构差异较小。沙尘暴前后空气细菌群落α-多样性和β多样性均无显著差异,推测沙尘暴只能暂时影响空气细菌群落特征,不能显著改变其群落结构。本研究通过分析了沙尘暴侵袭下北京市空气细菌群落多样性特征及动态,为制定中国北方城市沙尘暴灾害预警措施和建立气传疾病的防控机制提供数据支持。     

雾霾空气中细菌特征及对健康的潜在影响

论文从群落结构、浓度变化及粒径分布的角度论述了雾霾天气对空气细菌特征的影响,并结合了雾霾天气相关疾病的发病率,综合评价了雾霾天气空气病原菌导致的人群潜在健康风险的变化,最后提出了以前研究存在的不足及未来的发展趋势。综合研究结果,雾霾天气对空气细菌群落结构、浓度变化及粒径分布的影响,研究人员在不同城市得出的研究结果不同,可能由样点的时空环境、气象因素、雾霾程度及采集、检验、鉴定空气细菌方法等多种因素的差异引起。雾霾空气中已发现病原细菌均为条件致病菌,在空气中含量很低,但雾霾天气下部分病原菌的相对丰度增加,致病力会显著增强。此外,高浓度的细颗粒物和化学污染物可损伤皮肤黏膜屏障,打破呼吸道和皮肤的微生态平衡,为病原菌侵入创造较好的机会。两者的协同作用,显著增加了雾霾天气空气中病原菌的健康风险。     

Studies on marine algae of the British Isles. 10. The genus Rhodymenia

Antarcticothamnion polysporum gen. et sp. nov. (Rhodophyceae: Ceramiaceae) is described from the South Shetland Is. and the Antarctic Peninsula. It differs from all previously described Ceramiaceae in vegetative structure: an indeterminate apex, which divides by alternating oblique septa, produces simple alternate-distichous determinate branches, while indeterminate branches are initiated on main axes in a verticillate arrangement. Reproductive structures are borne on modified indeterminate branch systems. Sporangia are polyhedrally divided. Spermatangia are formed in loose heads. Procarps are borne near the apex, but not always on the subapical cell, of a fertile branch. Two auxiliary cells may participate in the formation of a carposporophyte. A fusion cell is lacking and most cells of the gonimoblast develop into carposporangia, which are binucleate.

The suite of morphological characters exhibited by Antarcticothamnion sets this genus sufficiently apart from all previously described Ceramiaceae to warrant placement in its own tribe, Antarcticothamnieae trib. nov. It shares important features, however, with Callithamnieae, Compsothamnieae, and Ptiloteae.

Apical division is reviewed in the various tribes of Ceramiaceae. It is concluded that a pattern of alternating oblique septa is correlated with transitory or chronic structural imbalance resulting from a particular combination of timing and spatial sequence in the initiation and development of branches. The distribution of oblique apical division within Ceramiaceae is strongly correlated with features generally considered to be important at the level of tribe.

Phylogenetic relationships within Ptiloteae, a tribe characterized inter alia by oblique apical division, are suggested from an analysis of branching patterns. The validity of Falklandiella as a genus distinct from Dasyptilon is emphasized. Gymnothamnion and Tokidaea are removed from Ptiloteae, but without being assigned to another tribe. Tanakaella is removed from Sphondylothamnieae to Compsothamnieae, while Mazoyerella is removed from Compsothamnieae to Spermothamnieae.

Spongoclonium orthocladum A. et E. S. Gepp is discussed as a possible species of Antarcticothamnion, while an undescribed alga from the South Orkney Is. is definitely indicated as a second species of the genus.     

Flying honey bees adsorb airborne viruses

Tethered honey bees (Apidea Apis melifera) coaxed to fly in a miniature wind tunnel for a specific time interval, adsorb a virus (i.e., bacteriophage MS2) aerosol at a linear rate of 1% of the aerosol concentration for every 6.73 pC of electrostatic charge on the bee.     

Development of a method to detect and quantify <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> conidia by quantitative PCR for environmental air samples

Exposure to Aspergillus fumigatus is linked with respiratory diseases such as asthma, invasive aspergillosis, hypersensitivity pneumonitis, and allergic bronchopulmonary aspergillosis. Molecular methods using quantitative PCR (qPCR) offer advantages over culture and optical methods for estimating human exposures to microbiological agents such as fungi. We describe an assay that uses lyticase to digest A. fumigatus conidia followed by TaqMan™ qPCR to quantify released DNA. This method will allow analysis of airborne A. fumigatus samples collected over extended time periods and provide a more representative assessment of chronic exposure. The method was optimized for environmental samples and incorporates: single tube sample preparation to reduce sample loss, maintain simplicity, and avoid contamination; hot start amplification to reduce non-specific primer/probe annealing; and uracil-N-glycosylase to prevent carryover contamination. An A. fumigatus internal standard was developed and used to detect PCR inhibitors potentially found in air samples. The assay detected fewer than 10 A. fumigatus conidia per qPCR reaction and quantified conidia over a 4−log₁₀ range with high linearity (R ² > 0.99) and low variability among replicate standards (CV=2.0%) in less than 4 h. The sensitivity and linearity of qPCR for conidia deposited on filters was equivalent to conidia calibration standards. A. fumigatus DNA from 8 isolates was consistently quantified using this method, while non-specific DNA from 14 common environmental fungi, including 6 other Aspergillus species, was not detected. This method provides a means of analyzing long term air samples collected on filters which may enable investigators to correlate airborne environmental A. fumigatus conidia concentrations with adverse health effects.     

Toward understanding the contribution of waterbodies to the methane emissions of a permafrost landscape on a regional scale—A case study from the Mackenzie Delta,Canada

Waterbodies in the arctic permafrost zone are considered a major source of the greenhouse gas methane (CH₄) in addition to CH₄ emissions from arctic wetlands. However, the spatio‐temporal variability of CH₄ fluxes from waterbodies complicates spatial extrapolation of CH₄ measurements from single waterbodies. Therefore, their contribution to the CH₄ budget of the arctic permafrost zone is not yet well understood. Using the example of two study areas of 1,000 km² each in the Mackenzie Delta, Canada, we approach this issue (i) by analyzing correlations on the landscape scale between numerous waterbodies and CH₄ fluxes and (ii) by analyzing the influence of the spatial resolution of CH₄ flux data on the detected relationships. A CH₄ flux map with a resolution of 100 m was derived from two aircraft eddy‐covariance campaigns in the summers of 2012 and 2013. We combined the CH₄ flux map with high spatial resolution (2.5 m) waterbody maps from the Permafrost Region Pond and Lake Database and classified the waterbody depth based on Sentinel‐1 SAR backscatter data. Subsequently, we reduced the resolution of the CH₄ flux map to analyze if different spatial resolutions of CH₄ flux data affected the detectability of relationships between waterbody coverage, number, depth, or size and the CH₄ flux. We did not find consistent correlations between waterbody characteristics and the CH₄ flux in the two study areas across the different resolutions. Our results indicate that waterbodies in permafrost landscapes, even if they seem to be emission hot spots on an individual basis or contain zones of above average emissions, do currently not necessarily translate into significant CH₄ emission hot spots on a regional scale, but their role might change in a warmer climate.