紫外极光图像极光卵提取方法及其评估

有效确定极光卵边界对于研究太阳风-磁层能量耦合过程是非常重要的.本文提出一种新的星载紫外极光图像极光卵边界的提取方法.该方法利用一种基于模糊局部信息C均值聚类方法,对紫外极光图像进行分割,并根据极光卵的环状特性,提取较完整的极光卵极向/赤道向边界.结合DMSP卫星沉降粒子观测数据,分别构建了极向边界和赤道向边界数据库,...     

赣南茶区生态地球化学环境

初步评价了赣南地区茶树生长的总体生态环境景观条件,着重进行了13个典型茶园的岩-土-茶地球化学调查,研究了茶园基岩、土壤元素地球化学特征,根据土壤有机质、营养元素全量和有效量评价了茶园的营养状况,为茶园生产管理、施肥提供了科学依据。通过与龙井茶元素含量的对比,评价了本区茶叶质量,探讨了茶叶内在品质与地质、地球化学背景的关系。     

南极中山站DPS-4电离层测高仪的中层夏季回波统计分析

The vertical temperature profiles of snow and sea ice have been measured in the Arctic during the 2nd Chinese National Arctic Research Expedition in 2003(CHINARE2003).The high-resolution temperature profile in snow is solved by one-dimensional heat transfer equation.The effective heat diffusivity,internal heat sources are identified.The internal heat source refers to the penetrated solar radiation which usually warms the lower part of the snow layer in summer.By temperature gradient analysis,the zero level can be clarified quantitatively as the boundary of the dry and wet snow.According to the in situ time series of vertical temperature profile,the time series of water content in snow is obtained based on an evaluation method of snow water content associated with the snow and ice physical parameters.The relationship of snow water content and snow temperature and temporal-spatial distribution of snow water content are presented     

改性桑树叶吸附材料对废水中Cd(Ⅱ)的吸附性能研究

桑树叶富含植物多酚和黄酮类化合物,表面存在着大量羟基、羧基功能基团,在一定条件下通过络合作用或静电作用能与重金属离子发生吸附作用。但由于生物质中普遍存在着可溶性单宁,直接使用生物质吸附废水中的镉,去除效果不够理想。本文以生物质桑树叶为原料,经沸水蒸煮去除小分子和稀磷酸酸化改性,提高桑树叶的吸附容量,制备成活性吸附材料去除废水中的Cd(Ⅱ)。吸附条件实验表明:在p H=4.0时改性桑树叶对Cd(Ⅱ)的吸附效果最佳,当Cd(Ⅱ)初始浓度为150 mg/L,改性桑树叶的添加量为6 g/L时吸附率可达96.58%。化学改性桑树叶对Cd(Ⅱ)的吸附过程符合准二阶动力学方程,Langmuir等温吸附模型能更好地描述改性桑树叶的吸附行为,Cd(Ⅱ)最大吸附量为30.58 mg/g,与前人报道的吸附量显著提高。本项研究的改性桑树叶吸附材料价廉易得,为废水中镉的处理提供了一个新的方法。     

Variability in the structure of epiphytic assemblages of the Mediterranean seagrass Posidonia oceanica in relation to depth

The aim of the present study was to evaluate whether the variability in the structure of the epiphytic assemblages of leaves and rhizomes of the Mediterranean seagrass Posidonia oceanica differed between depths at a large spatial scale. A hierarchical sampling design was used to compare epiphytic assemblages at two different depths (10 and 20 m) in terms of both species composition and abundance and patterns of spatial variability in the Tuscan Archipelago (North Western Mediterranean Sea, Italy). Results showed significant differences in the structure of assemblages on rhizomes and leaves at different depths. These differences were related to species composition and abundance; differences were not significant for total biomass, total percentage cover and percentage cover of animals and algae. Whereas the higher variability was observed among shoots in all the studied systems, patterns of spatial variability at the other spatial scales investigated differed between the two studied depths. Moreover, in the present study, analogous patterns between depths resulted for both the assemblages of leaves and rhizomes, suggesting that factors that change with depth can be responsible for the spatial variability of both the assemblages (leaves and rhizomes), and operate regardless of the microclimatic conditions and the structure of assemblages.     

深圳福田几种红树植物繁殖体与不同发育阶段叶片热值研究

对深圳福田红树林区的秋茄 (Kandelia candel)、木榄 (Bruguiera gymnorrhiza)、桐花树 (Aegiceras corniculatum)、无瓣海桑 (Sonneratia apetala)、海漆 (Excoecaria agallocha)、银叶树 (Heritiera littoralis)不同发育阶段叶片以及秋茄、木榄、桐花树、无瓣海桑、海漆繁殖体的灰分含量和热值进行研究.结果表明( 1)不同发育阶段叶片的灰分含量变化趋势没有一定的规律性, 6种红树植物中老叶灰分含量均不是最低;植物繁殖体的灰分含量低于成熟叶;( 2)秋茄、无瓣海桑、木榄、桐花树繁殖体的干质量热值和去灰分热值基本上低于不同发育阶段叶片,而海漆繁殖体的干质量热值和去灰分热值高于不同发育阶段叶片;( 3) 6种红树植物不同发育阶段叶片的干质量热值与灰分含量具有极显著的线性负相关( P<0.01),不同发育阶段叶片和繁殖体的干质量热值与灰分含量具有显著线性负相关( P<0.05).     

运用切基线法测算卵形曲线要点解析

针对高等级公路复杂的卵形曲线测设与计算,将包含卵形曲线的整个平曲线分拆成非对称基本型和特殊非对称基本型两种典型线形组合,同时,运用切基线原理和选定的设计参数,详细解析第二圆曲线半径的推算过程和方法,并给出具体应用要点和算例。     

塔里木河流域中下游胡杨典型叶片光谱响应特征

光谱的研究是遥感模型构建的基础和前提。由于塔里木河两岸横向与纵向生态供水的差别,导致胡杨的生存环境有所差别。为了研究胡杨叶片是否对环境具有标识作用,选择中下游的5个实验点胡杨典型叶片作为研究对象,研究结果表明:①同一实验点不同树龄叶片在近红外和短波红外波段差异明显,而不同实验点不同树龄叶片光谱在波段1 270~1 290 nm和1 600 nm附近可以进行有效区分;而且随着距河道垂直向距离的增加"红边"呈"蓝移"趋势;②不同断面、不同实验点叶片在825 nm,1 270 nm和1 605 nm光谱差异较大,红边由中游到下游呈"蓝移"趋势;初变黄的叶片随着水分的流失光谱曲线在各波段有增大的趋势,当水分流失减速时,光谱曲线在400~1 000 nm之间时变化仍较明显。综上,胡杨叶片光谱具有可分性,对生存环境能够起到标识作用。     

Nutrient and caloric dynamics in Avicennia marina leaves at different developmental and decay stages in Zhangjiang River Estuary,China

Avicennia marina is a typical mangrove species in the subtropical coastlines of China. The main objective of this study was to assess nutrient and caloric dynamics in A. marina leaves at different developmental and decay stages. Decomposition studies using litter bags suggested that the time required for the loss of half of the initial dry weight (t₅₀) was 19 days. The extracts of A. marina leaves contained non-tannin phenolics and tannin phenolics (hydrolysable tannin), but no condensed tannin. Non-tannin phenolics and tannin phenolics contents did not differ significantly from each other at various developmental stages, but decreased rapidly during leaf decomposition. Avicennia marina leaves had high N levels, and both N and P concentrations decreased significantly during senescence. During decomposition, N concentration of the leaf litter increased gradually but the phosphorus concentration showed a decrease in the first week, and both N and P remained the same towards the end of the experiment. The gross caloric value (GCV) of mature leaves was significantly higher than those of young and senescent leaves, while ash-free caloric value (AFCV) did not change significantly during leaf development and senescence. During leaf decomposition, both GCV and AFCV increased gradually and remained the same at late stages. In subtropical Zhangjiang River Estuary, high N levels and lack of condensed tannins in A. marina leaves were responsible for the fast rate of decay. Non-tannin phenolics and tannin phenolics had no great effect on rate of decay. Nitrogen resorption during leaf senescence, and high litter decomposition followed by nitrogen immobilization are the important nutrient conservation strategy for A. marina.     

太阳活动低年南极中山站电离层F层的平均特性

根据１９９５-１９９７年３年中山站数字式电离层测高仪的数据,分析了中山站不同季 节Ｆ层的临频变化特点．中山站夏季主要受太阳光光化电离的影响,Ｆ层临频随地方时的变 化与中纬台站相似;两分季,极隙区软电子沉降的作用显著,Ｆ层临频随磁地方时而变化,有 较明显的磁中午现象．冬季,太阳全天处于地平线以下,中山站Ｆ层临频的变化主要受极隙 区软电子沉降和极区等离子体漂移的影响,其峰值变化处于碰中午和地方时中午之间．中山 站夏季全天都能观测到Ｆ层的存在;两分季Ｆ层在地方时子夜附近的出现率较少;冬季月份 在磁地方时午后和子夜Ｆ层出现率明显减少,这可能与南半球冬季的高纬槽和极洞有关．对 Ｆ层不均匀区的分析认为,中山站在ｔ_(ＬＴ)为１６：００左右处于极光带赤道侧,２０：００左右进入极盖 区。