积雪变化导致格陵兰盖高度变化

地面冰盖对气候变化的反应可能会对未来的海平面变化产生重大的影响。近年来格陵兰南部的卫星调查显示 ,较大高度的冰盖总体高度变化甚小 ,但空间变化很大。当然仅仅依靠卫星数据难以测定是什么地球物理过程引起了这种高度变化以及近年的变化速率是否超过了正常变化速率。我们利用雪粒密度增大的物理模型和根据高海拔１２个冰心再造的年雪堆积记录 ,获取了１９７８～１９８８年格陵兰南部冰盖高度的变化。该堆积导致的高度变化模式与同期卫星测量的冰盖高度变化十分吻合 ,因此１９７８～１９８８年观测的变化可以归因于积雪的变化。对更长的…     

Polycyclic aromatic hydrocarbons in bivalves from the San Francisco estuary: Spatial distributions, temporal trends, and sources (1993-2001)

Bivalve tissue samples were examined over a range of spatial and temporal scales (1993-2001) to determine PAH distributions, trends, and possible sources. Mussels (Mytilus californianus), oysters (Crassostrea gigas), and clams (Corbicula fluminea) were deployed for three months in the estuary at stations remote from known point source discharges. The range of summation operatorPAH detected in bivalves was oysters 184-6899 microg/kg dry wt (mean 678 microg/kg dry wt), mussels 21-1093 microg/kg dry wt (mean 175 microg/kg dry wt), and clams 78-720 microg/kg dry wt (mean 323 microg/kg dry wt). Linear regression analysis showed no statistically significant (p>0.05) temporal trends in clam and mussel summation operatorPAH at any of the deployment stations or estuary segments. On the other hand, a statistically significant (p<0.05) decreasing trend was found in summation operatorPAH in oysters at the Petaluma River station, and in the North Estuary segment. PAH isomer pair ratios applied as diagnostic indicators suggested that the bioaccumulated PAH were derived primarily from petroleum combustion, with lesser amounts derived from biomass and coal combustion, and unburned petroleum.     

Nutrient dynamics at the sediment-water interface in a Mediterranean lagoon (Thau, France): influence of biodeposition by shellfish farming activities

The Thau Lagoon, a French Mediterranean shallow lagoon, is a site where extensive shellfish farming occurs. The aim of the present work is to evaluate the role of this activity on nutrient exchange at the sediment-water interface in relation to organic matter (OM) sedimentation and degradation. Two stations inside (C5) and outside (C4) of the shellfish farming areas were sampled at three seasons. Porewater chemistry surveys and calculated diffusive fluxes were used to evaluate the trophic status of the Thau lagoon. Quantitative (Particulate Organic Carbon) as well as qualitative OM (Hydrogen Index, Carbohydrates) analyses were performed on sediments to assess OM characteristics. Results emphasized that surficial sediments at C5 are always more enriched in OM. Porewater nutrient concentrations are 10-20 times higher at C5 than at C4. In June 2003, the porewater profiles exhibit a sharp gradient at the bottom waters, indicating a hypereutrophic status, leading to an anoxic crisis.     

乌鲁木齐地区一次强沙尘天气过程分析

利用环境监测资料、常规气象资料、高低空环流形势数据和卫星遥感图像资料,对2004年4月19日造成乌鲁木齐地区强沙尘天气的天气背景进行了系统的分析。结果表明,此次天气过程在北疆沿天山88°E一带产生了严重风沙灾害。乌鲁木齐市可吸入颗粒物浓度从沙尘天气前的0.79mg/m3猛增到沙尘天气发生时的10.0mg/m3,API指数为500,属于重度污染。沙尘天气发生前后,乌鲁木齐市温度、气压、风速以及能见度发生了显著的变化。其中,风速>17m/s的大风持续时间较长,能见度降到了很低的水平,乌鲁木齐以外的地区能见度甚至降到了强沙尘暴能见度级别;由卫星云图、高低空环流形势分析和物理量分析可以得出,造成2004年4月19日强沙尘天气的主要原因是冷锋过境。锋前的抬升作用和高低空散度场的配置是沙尘天气的启发因素,而持续时间较强的锋后西北风是产生此次强沙尘天气的主要动力。     

Isotopic analyses of nitrogenous compounds from the Murchison meteorite: ammonia, amines, amino acids, and polar hydrocarbons

The combined volatile bases (ammonia, aliphatic amines, and possibly other bases), ammonia, amino acids, and polar hydrocarbons were prepared from the Murchison meteorite for isotopic analyses. The volatile bases were obtained by cryogenic transfer after acid-hydrolysis of a hot-water extract and analyzed by combined gas chromatography-mass spectrometry of pentafluoropropionyl derivatives. The aliphatic amines present in this preparation comprise a mixture that includes both primary and secondary isomers through C5 at a total concentration of > or = 100 nmoles g-1. As commonly observed for meteoritic organic compounds, almost all isomers through C5 are present, and the concentrations within homologous series decrease with increasing chain length. Ammonia was chromatographically separated from the other volatile bases and found at a concentration of 1.1-1.3 micromoles g-1 meteorite. The ammonia analyzed includes contributions from ammonium salts and the hydrolysis of extractable organic compounds, e.g., carboxamides. Stable isotope analyses showed the volatile bases to be substantially enriched in the heavier isotopes, relative to comparable terrestrial compounds delta D < or = +1221%; delta 13C = +22%; delta 15N = +93%). Ammonia, per se, was found to have a somewhat lower delta 15N value (+69%) than the total volatile bases; consequently, a higher delta 15N (>93%) can be inferred for the other bases, which include the amines. Solvent-extractable polar hydrocarbons obtained separately were found to be enriched in 15N (delta 15N = +104%). Total amino acids, prepared from a hydrolyzed hot-water extract by cation exchange chromatography, gave a delta 15N of +94%, a value in good agreement with that obtained previously. Nitrogen isotopic data are also given for amino acid fractions separated chromatographically. The delta 15N values of the Murchison soluble organic compounds analyzed to date fall within a rather narrow range (delta 15N = +94 +/- 8%), an observation consistent with their formation, or formation of their precursors, by interstellar chemistry.     

交通发展区位测度的理论与方法

交通建设所引致的区位条件改善对促进各类生产要素集聚和地方经济发展,重塑区域空间结构具有重要作用,因此,交通区位的测度一直是地理学的核心议题之一。随着交通网络的不断发展与完善以及新技术、新模式、新因素和新业态的出现,地方传统区位条件被重构,个人出行理念和模式发生了一系列变化。① 交通区位的测度逐渐从依托空间位置和交通设施发展水平的传统地理区位扩展到依托网络连通性、可靠性与出行便捷性的“流空间”新区位;② 研究对象从关注不同地方的区位特征扩展到关注群体出行规律和个体行为差异的微观区位选择;③ 研究内容从交通设施网络的可达性扩展到基于“门到门”的全链条出行服务;④ 大数据挖掘技术和GIS-T技术的发展也使得交通区位的测度朝着更加精确化和精准化的方向迈进。     

枢纽机场的航班波体系结构及其喂给航线的空间格局研究

基于航班波的概念,提出了航班波识别的技术流程和喂给航线的研究方法,并对全国十大枢纽机场的航班波体系进行了研究与甄别。在此基础上,进一步分析了拥有明显航班波体系的枢纽机场的喂给航线空间格局演化。研究发现：① 北京首都、上海浦东、广州白云和昆明长水机场拥有较为明显的航班波体系;成都双流、深圳宝安、西安咸阳机场的航班波体系尚不清晰。②首位航空公司拥有足够的航班数量是机场构建航班波的必要但非充分条件,时刻资源的优化配置更为关键。③北京首都、上海浦东和广州白云三大枢纽机场的国际喂给航线和国内喂给航线在空间上存在显著的差异,且总体上与地理临近性无关,更多地与首位航空公司的航线网络扩张相关。     

国土空间规划：基础设施与公共服务设施单幅总图的研制

基础设施的建设与布局是在遵循自然系统格局的基础上,由人类活动所引致的物质环境再建构和空间秩序再安排,是构建和引领区域空间结构的重要支撑体系,因此一直是区域发展类规划的重要组成部分。结合省级空间规划试点工作,提出符合空间规划目标的基础设施与公共服务设施编制方案与技术流程,强调专项规划与“三区三线”、空间布局总图的关系,并以福建省为例,设计了基础设施与公共服务设施单幅总图的编制技术流程,以期为其他地区空间规划的编制提供借鉴意义。