Extraction of organochlorine pesticides in sediments using soxhlet,ultrasonic and accelerated solvent extraction techniques

The application of soxhlet, ultrasonic and accelerated solvent extraction techniques to the analysis of six organochlorine pesticides (α-HCH, β-HCH, γ-HCH, o, p'-DDT, p,p'-DDT and p, p'-DDE) in Taihu Lake sediment samples is described. It was found that the limits of quantification ranged from 0.002μgg-1 to 0.004μgg-1, and the recoveries of organochlorine pesticides with the three extraction techniques were acceptable (>80.7%). With a mass selective detector, better results were obtained by accelerated solvent extraction using hexane-acetone (1:1) as compared with soxhlet and ultrasonic extraction. It was shown that the accelerated solvent extraction was the optimum technique for the analysis of organochlorine pesticides in sediments. The general features of the three extraction techniques are also presented.     

呼和浩特市一次局部降雪漏报的原因

对2008年3月22日呼和浩特北部武川县及市区降雪漏报的原因进行了分析,认为本次降雪出现在地面冷锋后部,冷高压的东部,是下沉逆温和锋面逆温共同作用的结果。造成预报失误的主要原因是:(1)从环流形势高低层的配置分析认为未来天气主要以降温和大风为主,因为低层湿度较小,预报时忽略了前期的降水作用。(2)各种数值预报产品也没有分析出降水预报。(3)呼和浩特北部特殊的地形对降水也起到了一定的作用。(4)对下沉逆温和锋面逆温在高压前部造成的降水认识不够。     

基于SVG的矢量WebGIS实现技术研究

SVG是一种基于XML的用来描述二维矢量图形和矢量/栅格混合图形的标记语言,虽然SVG不是为了面向地理空间数据发布而制定的标准,但它的许多特性都能被广泛地应用到WebGIS中,从而实现矢量WebGIS。由于SVG通过简单的文本语句描述矢量图像,所以SVG通常数据量很小,并且SVG支持GZIP压缩,所以基于SVG构建WebGIS能减轻网络传输负载,加快地图显示速度。SVG内置了对JavaScript的支持,且SVG可通过DOM解析映像成内存中的树型结构,所以客户层可通过JavaScript对DOM的操作实现对地图的缩放、漫游、查询、图层控制等交互操作。     

Altitude as environmental filtering influencing phylogenetic diversity and species richness of plants in tropical mountains

Elucidating how multiple factors affect biodiversity and plant community assembly is a central issue in ecology, especially in vulnerable ecosystems such as tropical mountains. These studies are more relevant in global warming scenarios that induce the upward displacement of plant species towards reduced habitats and hostile environments in tropical mountains. This study aimed to analyze how altitude affects taxonomic and phylogenetic diversity in plant communities of tropical mountains. Thus, w...     

基于WebGIS的网络化数据采集方法

随着计算机、GIS和数据库技术的不断发展,W ebGIS正在从简单的数据发布、查询工具向真正的网络化GIS发展,这其中包括数据的分布式存储、并行计算以及GIS功能的共享。本文就W ebGIS中GIS功能的共享以及基于B/S结构的网络化数据采集方式、方法作了讨论。     

灰色系统预测模型的修正研究——以芜湖市耕地为例

针对GM(1,1)模型预测的不足,对其进行修正得到修正模型,并利用芜湖市耕地变化进行实例验证和应用。结果表明:1)应用灰色预测的修正模型对耕地变化进行预测比直接应用灰色预测模型更精确;2)分段建模和建立灰色—马尔柯夫模型是从两个不同的角度对GM(1,1)模型进行修正,但两者可以相互结合,使预测结果更准确。3)建立灰色—马尔柯夫模型可以避免其他多种影响因素,更具科学性和实用性。     

温度与天气对IGS跟踪站联测的残差影响分析

针对一年中全球卫星导航系统(GNSS)服务(IGS)跟踪站联测残差影响较大等问题,总结平均温度变化、雨雪天气情况与IGS站联测残差的关系,判断影响IGS跟踪站联测残差的因素.适合我国境内及周边IGS站联测的基准站的稳定性检测,并使用标准化均方根误差平均值(NRMS)进行评价,在避免影响精度因素的情况下进行联测,提高精度.最后选取2018年CHAN站作为未知站点,对我国东北地区周边4个IGS站(BJFS、DAEJ、SHAO、ULAB)进行联测,利用GAMIT/GLOBK软件进行高精度基线处理,并选择2017年数据进行检核.实验结果表明平均温度变化与雨雪天气是影响IGS跟踪站联测残差的两项因素,平均温度与NRMS值呈负相关趋势,相关性大于60%.雨雪天气联测效果较差,较非雨雪天气NRMS值相差0.5mm左右,其中降雪天气联测精度最低,不建议雨雪天气进行联测任务.     

Zooneuston and zooplankton abundance and diversity in relation to spatial and nycthemeral variations in the Gulf of Aqaba and northern Red Sea

Zooplankton and zooneuston observations were made at seven stations(four from the Gulf of Aqaba and three from the northern Red Sea), during September and October 2016. The main objective of this study was to assess the variability of nycthemeral fauna in relation to the sampling methods using two different types of nets namely,WP2 net and Neuston net along the two study sites, i.e., the Gulf of Aqaba and the northern Red Sea. Zooplankton was sampled vertically using a standard WP2 net from a depth of 200 m to the surface, whereas zooneuston was made using a standard Neuston net from a depth of 0–10 cm of the water surface. Total zooplankton density was maximum during night time((617.83 ± 201.84) ind./m~3) at the Gulf of Aqaba and total zooneuston was maximum during night at the northern Red Sea((60.94±29.48) ind./m~3), respectively. The most abundant taxa were Copepoda, Gastropoda, Bivalva, Chaetognatha, Tunicata and Ostracoda. The abundance was almost 50% higher at night time at both the Gulf of Aqaba and the northern Red Sea. Overall, 30 taxa covering 10 phyla and 27 taxa covering 8 phyla were recorded in the Gulf of Aqaba and the northern Red Sea.     

昌黎生态监控区夏季大型底栖动物群落特征及其环境影响因子分析

选取2015年昌黎生态监控区夏季的大型底栖动物和环境因子的监测数据,基于ArcGIS 10.0、surfer 10和Canoco 4.5软件平台,采用Shannon-Weaver多样性指数(H′)、Pielou均匀度指数(J)和Margalef丰富度指数(d_(Ma))、典型对应分析法(CCA)等,对2015年夏季监控区大型底栖动物群落结构特征以及与环境因子的关系进行综合分析。结果表明:夏季监测到52种,其中豆形短眼蟹(Xenophthalmus pinnotheroides)、镜蛤(Dosinia corrugata)和栉孔扇贝(Chlamys farreri)等为优势种,平均丰度为99.36个/m~2,平均生物量为34.12 g/m~2;从丰度、生物量的物种组成上看,节肢动物甲壳类、软体动物和环节动物多毛类都是监控区的主要类群;监控区大型底栖动物群落生物多样性较差;大型底栖动物群落受多种因子共同作用影响,其中底质环境的粘土含量、粉砂土含量、砂土含量和硫化物以及水质参数中的盐度和硫酸盐等6种环境因子为影响该区域群落的主要环境因子。