Carbon dioxide partial pressure and carbon fluxes of air-water interface in Taihu Lake, China

1 INTRODUCTION Carbon dioxide (CO2) is principal greenhouse gas. Its air-water exchange is important in terrestrial ecosystems for climate change (Frankignoulle et al., 1998; Schimel et al., 2001). The direction of CO2 gas movement depends on the CO2 concentration gradient between air and surface water. The amount of CO2 exchange is related to the gas exchange coefficient, k. All lakes, with their small area but large atmospheric CO2 flux are important to under-stand the CO2 fluxes …     

对流层高、低空急流的耦合和强对流风暴发展的关系

一、引言对流层高、低空急流的相互作用对于对流性风暴系统的发展很重要,这个概念是由福布什和米勒(Fawbush和Miller;1953,1954)提出来的。他们指出:伴随对流层中空强西风的冷、干平流和低空暖、湿舌迅速北伸,是深厚对流发展的有利条件。并且指出风向强烈顺转很可能增强对流,这样对流层中空的风向与低空湿舌轴线之间的夹角很大。彼得森(Petterssen,1956)和牛顿(Newton,1967)指出风随高度的顺转及其造成的高、低空急流轴线交叉点上温度和湿度差动平流与对流不稳定发展的关系。最大的对流不稳定发生在高、低空急流轴线趋于正交和平流强度最大的时候。关于对流层急流在强对流风暴发展中的作用,     

北京冬春季节大气气溶胶化学成份的研究

1980年3月6日至20日,利用美国佛罗里达州立大学自制的条式连续采样仪,在北京北郊大气物理所气象塔观测场取得连续两周的大气气溶胶样品。用PIXE方法分析,得到了该样品中 Ca、Fe、Al、Si、K、Cl、S、Ti、Mn、Zn、Sr、pb等微量元素的相对浓度。 本文分析了北京冬春季节大气气溶胶化学元素的浓度分布特征以及浓度变化与气象条件的关系。并与其他地区的观测结果作了比较。     

中国玛珥湖的时空分布与地质特征

自新生代以来 ,在亚洲东部大陆边缘的裂谷系和青藏高原内部及周边地区 ,火山活动频繁发生 ,形成大量火山和火山岩 ,在一些火山区还发育有大小不等、形态不一的玛珥湖 ,其中有的积水 ,有的干枯 ,它们集中分布于雷琼、东北、青藏高原等地区 ,跨越了热带、亚热带、温带和高寒地带。从中新世的山东山旺盆地 ,早更新世东北龙岗地区的龙湾 ,到雷琼地区中晚更新世的田洋、湖光岩等 ,几乎各个时代、各种类型的玛珥和玛珥湖都有 ,玛珥湖中的沉积物从几十米到一二百米厚度不等 ,记录了不同地区、不同时段气候环境演变的历史 ,对全球变化研究有着重要意义。     

南半球气流的气候特征

依据几十年的船舶和陆基观测资料而得到的网格点上的平均地面地转风,来估算南半球月平均地面流线。在南半球已确认有4个年气流源地。在南半球冬季的7个月期间,澳大利亚是第5个气流源地区域。北半球的气流流到南半球(夏季)的热带辐合带处。在平均年份中,南半球空气来自上述4个年气流源地的占46％,太平洋贡献最大(20％),其次是印度洋(12％)、大西洋(9％)和南极洲(5％)。最常见的汇流带有4条。     

夏季110°E附近的低空越赤道气流与西北太平洋台风活动

在西北太平洋赤道地区夏季有一支源自南半球的气流.这支位于110°E 附近的大尺度季风气流是过去研究中所提到的源自澳洲的越赤道气流与中国低空急流.低空越赤道气流的强度变化与台风的发生发展有联系.     

Perfluorinated compounds in estuarine and coastal areas of north Bohai Sea, China

Perfluorinated compounds (PFCs) in water, sediment, soil, and biota collected from estuarine and coastal areas of the north Bohai Sea, China, were determined by use of HPLC-MS/MS. Significant concentrations of PFCs were found in water (mean: 18.4 ng/l) and biologic samples (fish: 265 ng/g dw), while concentrations of PFCs in soils and sediments were less. The predominately detected compound was perfluorooctanesulfonate (PFOS), with a maximum concentration of 30.9 ng/l in water and 791 ng/g dw in fish. Concentrations of PFCs were significantly greater in the Liaohe River system than other locations, which suggests point sources in this urbanized and industrialized region. PFOS concentrations in water and biota were both less than the reported threshold concentrations. Detection of PFCs at relatively great concentrations in various environmental matrices from this region suggested that further studies characterizing concentrations of PFCs, their sources and potential risk to both humans and wildlife are needed.     

Spatial and vertical distribution of organochlorine pesticides in sediments from Daya Bay, South China

The spatial and vertical distribution of organochlorine pesticides (OCPs) has been investigated in Daya Bay, China. The concentration of total OCPs in surface sediment range from 16.66 to 44.04ng/g dry weight with a mean concentration of 26.60ng/g. DDTs and HCHs were the predominant species. The ratios of (DDD+DDE)/DDT reflected a cocktail input pattern of fresh and weathered DDTs. The predominant alpha-HCH and the alpha/beta-HCH ratios indicated that the technical HCH contamination was mainly due to historical usage, although there was fresh input of lindane. The variation profiles of concentrations showed that OCPs were extensively applied between the late 1950s and early 1980s in China. A recent increasing trend in concentrations of DDTs and HCHs was found in both cores. The increasing ratios of (DDE+DDD)/DDT with corresponding decreases of DDE/DDT ratio implied that most of the DDTs deposited after their production ban were more likely "weathered" DDTs derived from soil residues.     

Species diversity and distribution for phytoplankton of the Pearl River estuary during rainy and dry seasons

Based on data collected at 31 stations and 1 continuous station in the Pearl River estuary during cruises of July 1999 (rainy season) and January 2001 (dry season), this study examined taxonomic composition, abundance, and spatial distribution of phytoplankton. Results indicated 130 species of phytoplankton in the samples from the rainy season, and 132 species in the dry season. Among them, in the rainy season, 82 species of diatom, 39 fresh-water and half-fresh-water species and 41 species of red tide organisms were found. Within these, there were 54 tropical and sub-tropical species, 47 cosmopolitan species and 17 temperate species. The abundance of phytoplankton in the rainy season was higher than that of the dry season, with an average of 6.3 x 10(5) cells x L(-1) and 1.4 x 10(5) cells x L(-1), respectively. Diversity index (H') and evenness (J) were 2.47 and 0.57 in the rainy season, and 2.01 and 0.54 in the dry season. The dominant phytoplankton species in the rainy season was Skeletonema costatum with an average of 2.8 x 10(5) cells x L(-1) and 45.0% of the total phytoplankton abundance. In the dry season, Eucampia zoodiacus became the key dominant species (5.9 x 10(4) cells x L(-1)) when it was 43.47% of the total phytoplankton abundance. Distribution of the dominant species varied with salinity of sea-water, and their amounts correlated negatively with nutrients and zooplankton.     

兰州盆地活断层的高分辨率浅层地震勘探技术

针对城市活断层浅层地震探测的一些技术问题,在兰州盆地的金城关断层和刘家堡断层沿线开展活断层浅层(50 m以内)地震勘探技术研究.主要采用纵波和横波多次覆盖共CMP点地震反射方法,获得了目标场地地震图像资料,尤其横波地震剖面更加清晰地反映出超浅层构造空间特征.以红艺村测线(HYC)和师范学校西测线(SFXX)为例,分析总结了数据采集、资料处理、剖面解释三方面浅层活断层地震探测的技术要点.结果可以为兰州市及类似复杂构造地区活断层地震调查提供技术参考.