Growth and feeding habits of invasive Pseudorasbora parva in the Chabalang Wetland(Lhasa,China) and its trophic impacts on native fish

In recent years, fish invasion has become one of the main reasons for the decline of native fish stocks. Pseudorasbora parva is considered one of the major invasive species worldwide. The present study investigated the fish resources of the Chabalang Wetland (Lhasa, Tibet) during diff erent seasons in 2009 and 2013. Four hundred and twelve individuals were subsampled to estimate age, growth, and feeding habit of P . parva . Furthermore, food relationships between P . parva and the native Schizothoracinae fish were also examined. The results revealed a significant shift in species composition and community structure characterized by the disappearance of native fish and outbreak of non-native fish. The percentage of nonnative P . parva in the fish collections significantly increased from 33.64% in 2009 to 64.08% in 2013. The standard length (SL) ranged from 22.00 to 78.71 mm, and their age was 1–5 a. The von Bertalanff y function was used to model the observed length-at-age data as L t =112.19(1–e^-0.1495 ( t +0.8012)) for females and as L t =123.12 (1–e^-0.1500 ( t +0.7132)) for males. The results indicated that P . parva in Tibet has lower growth and mortality rates compared with that from the native ranges. Ninety-seven prey taxa belonging to 9 prey categories were identified in the gut of 38 P . parva . P . parva can be considered a generalized and opportunistic predator, competing with the native fish, especially Schizothorax o’connori , Schizopygopsis younghusbandi younghusbandi , and Ptychobarbus dipogon , for Bacillariophyta and Chironomid larvae. This is an important reason for the decline in native fish population.     

Decadal variations of the North Pacific Tropical Water at 137°E

The decadal variations of the North Pacifi c Tropical Water (NPTW) at 137°E in the western North Pacific Ocean are investigated based on the repeated hydrographic observations along with two global gridded ocean products. The results indicate that the maximum salinity of NPTW experiences signifi cant quasi-decadal variations, having maxima around 1979, 1987, 1995, 2004, and 2012, while minima around 1974, 1983, 1991, 1999, and 2008 during the period of interest. The NPTW area also shows similar quasidecadal variation, expanding/shrinking as its maximum salinity increases/decreases at the 137°E section. These variations are induced mainly by changes in the mixed layer salinity in the source region and largescale circulation in the northwestern tropical Pacific Ocean, both of which are related to the Pacific Decadal Oscillation. The underlying processes at work are further confi rmed through conducting the subsurface salinity budget analysis. Besides, short-term processes are also at work through nonlinear interactions, especially after 2000.     

风云三号C星微波成像仪升降轨偏差问题分析及订正

风云三号(FY-3)的微波成像仪(MWRI)能够全天候获取全球大气水汽含量、云雨参数及海面温度等的空间分布,并可为数值天气预报提供初始场信息进而提高天气预报的准确性。但FY-3C MWRI O-B(O是卫星观测亮温,B是数值天气预报模式模拟亮温)偏差结果存在较大升降轨差异,严重制约了遥感信息的正确提取以及在数值天气预报模式中的业务同化应用。本文通过分析定标方程各参数:定标黑体物理温度、热反射镜背瓣亮温、热反射镜物理温度、冷空反射镜物理温度、接收通道温度、黑体观测计数值、冷空观测计数值、定标斜率、定标截距,并对定标方程各项进行敏感性分析,找出了引起MWRI升降轨偏差的主要原因是热反射镜的发射率异常增大引起的。经过不断调整MWRI的热反射镜发射率,使升轨O-B与降轨O-B的概率分布逐渐重合,初步估算了热反射镜发射率。本文的订正方法可指导未来仪器的发展,并为直接同化MWRI辐射数据提供了条件。     

网络三维技术下的时空可视化分析

随着数据获取技术的快速发展,海量时空数据的来源越来越广。然而受限于数据的认知能力,人们无法高效地从海量时空数据中获取有用信息。利用人的视觉带宽,进行数据可视化分析,可以大大增强对数据的认知能力,提高数据分析效率,从而更快地对时空进行感知,制定决策。时空立方体作为一种三维的时空数据可视化方法,可以直观地展示时空数据的动态特质、周期性规律以及分布状况,对于辅助决策具有重要意义。本文利用WebGL技术,实现了Web端时空立方体的快速生成;并基于中国铁路运输开展实验,对全国铁路运输时空数据进行可视化分析,验证了网络时空可视化分析的实用性。     

南极绿藻中类菌胞素氨基酸对UV-B胁迫的响应

南极上空臭氧层的破坏导致了紫外辐射日益增强,高强度的UV-B辐射会造成细胞中DNA的损伤,影响蛋白质、脂类和色素的代谢过程。生长在南极的绿藻具有一系列防御机制以应对增强的UV-B辐射,其中类菌胞素氨基酸(Mycosporine-like amino acids, MAAs)是一类重要的紫外防御物质。为探究类菌胞素氨基酸对UV-B辐射的响应,本文以南极冰藻(Chlamydomonassp.ICE-L)、针丝藻(Raphidonema nivale Lagerheim, NIES-2290)和胶球藻(Coccomyxa subellipsoidea E.Acton, NIES-2166)三种生活在南极的绿藻为材料,采用UV-B辐射胁迫(强度0.35 W/m~2,短时处理3 h),并通过液相色谱-质谱联用法检测类菌胞素氨基酸的种类和含量的变化。Mycosporine-glycine为三种南极绿藻中共有的MAAs,在UV-B辐射胁迫下三种南极绿藻中Mycosporine-glycine含量变化不尽相同,表明不同的南极绿藻中MAAs对UV-B辐射的响应各有其特性。首次在绿藻(南极冰藻和胶球藻)中检测到Gadusol。Gadusol作为MAAs的合成前体,它的合成积累使得生活在海冰环境的南极冰藻和胶球藻具有良好的抗UV-B辐射能力。其中南极冰藻抗紫外能力最强,这可能得益于不同MAAs间的动态转化,含量升高的Palythine及Usujirene/Palythene可能对南极冰藻的紫外屏蔽起着至关重要的作用。     

东南亚近岸海区浮游植物光合色素和群落组成—印度尼西亚贯穿流和吉兰丹河口区的比较研究

Water samples were collected in order to study the spatial variation of photosynthetic pigments and phytoplankton community composition in the Lembeh Strait(Indonesia) and the Kelantan River Estuary(Malaysia)during July and August 2016, respectively. Phytoplankton photosynthetic pigments were detected using high performance liquid chromatography combining with the CHEMTAX software to confirm the Chl a biomass and community composition. The Chl a concentration was low at surface in the Lembeh Strait, which it was 0.580–0.682 μg/L, with the average(0.620±0.039) μg/L. Nevertheless, the Chl a concentration fluctuated violently at surface in the Kelantan River Estuary, in which the biomass was 0.299–3.988 μg/L, with the average(0.922±0.992) μg/L. The biomass at bottom water was higher than at surface in the Kelantan River Estuary, in which the Chl a concentration was 0.704–2.352 μg/L, with the average(1.493±0.571) μg/L. Chl b, zeaxanthin and fucoxanthin were three most abundant pigments in the Lembeh Strait. As a consequence, phytoplankton community composition was different in the two study areas. In the Lembeh Strait, prasinophytes(26.48%±0.83%) and Synechococcus(25.73%±4.13%) occupied ～50% of the Chl a biomass, followed by diatoms(20.49%±2.34%) and haptophytes T8(15.13%±2.42%). At surface water in the Kelantan River Estuary, diatoms(58.53%±18.44%)dominated more than half of the phytoplankton biomass, followed by Synechococcus(27.27%±14.84%) and prasinophytes(7.00%±4.39%). It showed the similar status at the bottom water in the Kelantan River Estuary,where diatoms, Synechococcus and prasinophytes contributed 64.89%±15.29%, 16.23%±9.98% and 8.91%±2.62%,respectively. The different phytoplankton community composition between the two regions implied that the bottom up control affected the phytoplankton biomass in the Lembeh Strait where the oligotrophic water derived from the West Pacific Ocean. The terrigenous nutrients supplied the diatoms growing, and pico-phytoplankton was grazed through top down control in the Kelantan River Estuary.     

户外风测量设备检测方法研究

进行户外风测量设备的检测是保证安全生产与获得准确的气象观测数据的前提。通过测量标准对户外风测量设备的测量数据进行实时比测,规定检测环境条件、检测项目、检测方法,剔除异常值,以减小数据采集不同步造成的不确定度分量,得到户外风测量设备的检测结果。对检测结果的不确定度进行分析评定,对户外风测量设备的性能进行评价。     

Study on Vortex-Induced Motions of A New Type of Deep Draft Multi-Columns FDPSO

A numerical simulation and an experimental study on vortex-induced motion (VIM) of a new type of deep draft multi-columns floating drilling production, storage and offloading (FDPSO) are presented in this paper. The main dimension, the special variable cross-section column and the cabin arrangement of the octagonal pontoon are introduced based on the result. The numerical simulation is adapted to study the effects of current incidence angles and reduced velocities on this platform''s sway motion response. The 300 m water depth equivalent truncated mooring system is adopted for the model tests. The model tests are carried out to check the reliability of numerical simulation. The results consist of surge, sway and yaw motions, as well as motion trajectories. The maximum sway amplitudes for different types of offshore platform is also studied. The main results show that the peak frequencies of sway motion under different current incidence angles and reduced velocities vary around the natural frequency. The analysis result of flow field indicates that the change of distribution of vortex in vertical presents significant influences on the VIM of platform. The trend of sway amplitude ratio curve of this new type FDPSO differs from the other types of platform. Under 45° current incidence angle, the sway amplitude of this new type of FDPSO is much smaller than those of other types of offshore platform at 4.4 ≤ V_r ≤ 8.9. The typical ‘8’ shape trajectory does not appear in the platform''s motion trajectories.     

中国城市流动人口回流意愿的空间分异及影响因素

基于国家卫计委2016年流动人口动态监测数据（CMDS）,运用相关GIS空间统计工具探讨了中国279个地级及以上城市流动人口回流意愿空间分异问题,进而考察流动人口回流意愿的影响因素。研究发现：① 相比居留意愿及户籍迁移意愿,中国城市流动人口回流意愿偏低（6.17%）,其中,绝大多数流动人口（74.05%）的回流去向地是返回原居住地。城市规模、城市等级与流动人口回流意愿呈非对称“U型”格局。② 流动人口回流意愿总体上呈现出集聚分布模式,并具有显著的空间分异特征,长江三角洲、京津冀等城市群流动人口的回流意愿较高,成渝和哈长城市群流动人口回流意愿较低;东部地区流动人口回流意愿最高,东北地区的回流意愿最低;华南、中南和部分华东地区为回流意愿热点区,东北和华北地区为回流意愿的冷点区。③ 回流意愿受流动人口内部因素与流入地外部因素的共同影响,同时作为内部因素和外部因素的教育水平及经济发展变量对流动人口回流意愿的影响方向不同。④ 流动人口的家庭联系、社会网络、住房及经济因素是塑造流动人口空间格局的主要力量,流入地家庭规模及住房拥有率等对流动人口回流意愿产生抑制作用,非流入地家庭规模、流动次数、家庭收入支出比等对回流意愿产生促进作用。     

华南南华纪南沱冰期海洋环境的沉积地球化学记录——来自黔东部南华系南沱组白云岩碳氧同位素和微量元素的证据

新元古代"雪球地球"事件代表地球经历的极端气候条件,对其后的大气和海洋氧化、生物地球化学循环和真核生物的演化都产生了深远的影响。然而同冰期化学沉积岩的缺乏,严重制约了对冰期海洋环境的了解。笔者等在贵州松桃地区一钻孔岩芯南华系南沱组中采集到一套同冰期白云岩,为南沱冰期海洋环境研究提供了理想材料。岩芯中白云岩层位于南沱组下部,夹持于两套杂砾岩、粉砂质泥岩组合中间,厚度1.61 m。偏光显微镜和扫描电镜观察表明岩性为微晶白云岩。采用Delta V Advantage稳定同位素质谱仪分析白云岩的碳、氧同位素,测定结果为:δ~(18)O_(V-PDB)在-16.97‰～-8.37‰之间,δ~(13)C_(V-PDB)在-9.68‰～-8.42‰之间,与冰期前后碳同位素组成对比,δ~(13)C_(V-PDB)具显著低负值特征。电感耦合等离子体质谱仪(ICP-MS)微量元素分析结果表明:白云岩样品中铁、锰含量很高,铁含量的平均值约为92867×10~(-6),锰含量的平均值约为10644×10~(-6);Mn/Sr值较大,平均值约为26.89。综合碳、氧同位素的相关性及微量元素特征分析表明,南沱组同冰期白云岩碳同位素组成代表了原始的沉积记录。研究结果表明:①南沱组白云岩的出现反映了南沱冰期海洋中存在着开放的水体,这些开放水体为此时真核生物提供了重要的栖息场所。②南沱冰期海洋处于富铁缺氧的环境,白云岩中碳同位素低负值主要是甲烷厌氧氧化的结果。③同位素质量平衡计算表明,冰期海洋中较高比例的有机质埋藏和极其有限的大气-海洋气体交换导致了大气中氧浓度的升高。