陇中黄土高原垂直感热平流输送对LAS和EC观测感热通量差异的影响

利用"黄土高原陆面过程试验研究(LOPEX)"2010年6月定西站的陆面过程综合观测资料,以造成大孔径闪烁仪(LAS)和涡动相关仪(EC)测量感热通量的差异为切入点,从中尺度垂直感热平流输送过程入手,将垂直感热平流输送的贡献作为地表有效能量的一部分引入EC直接观测的感热通量,对比引入前后LAS和EC测量感热通量的差异大小.结果表明:黄土高原定西观测站近地层大气垂直方向主要表现为向上运动,峰值达到0.074 m·s^-1,为垂直感热平流输送提供了必要的动力条件.尤其该地区处在半干旱区,地表受太阳辐射加热比较显著,近地层温度梯度最大可达0.39 K·m^-1,为产生垂直感热平流提供了能量基础.加入垂直感热平流输送的贡献后,EC地表能量不闭合度的日均值由直接观测的0.30缩小到0.24.修正后,LAS和EC测量的感热通量拟合的线性趋势系数由直接观测时的1.258缩小到1.186,两者差异得以缩小.     

保定市大气颗粒物中含碳组分粒径分布

北京-天津-河北地区工业城市保定大气颗粒物(Particulate matter,PM)污染严重,保定大气颗粒物尤其是细粒子和超细粒子污染严重,其中含碳组分具有重大贡献,PM1.1、PM2.1和PM2.1-9.0中含碳气溶胶总量(total carbonaceous aerosols,TCA)分别占到(49±20)%、(45±19)%和(19±7)%。PM9.0中的含碳气溶胶主要富集在PM2.1乃至PM1.1中。颗粒物浓度谱分布及含碳气溶胶富集量呈显著季节变化,由于采暖过程秋冬季各粒径段有机碳(organic carbon,OC)和元素碳(elemental carbon,EC)的浓度均增加,秋、冬季节细颗粒物中OC浓度可高达44.0±38.3、78.5±30.2μg m-3,EC浓度分别为3.5±1.6、8.5±6.8μg m-3。各个季节OC和EC在总悬浮颗粒物(total suspended particulate,TSP)中的几何平均直径(geometric mean diameter,GMD)均集中在较小粒径段。粗颗粒物中OC的GMD在春夏季较高,秋季减少,而冬季最低。而粗颗粒物中EC的GMD则是冬季最高,夏季最低。保定0.4μm的颗粒物中OC/EC比值4个季节的水平较为稳定,春、夏、秋、冬季OC/EC比值分别为5.2、3.5、4.1和5.4,来源主要为交通和燃煤。其余几个粒径段的颗粒物的来源更为复杂,其来源主要为燃煤、木材和生物质。     

Groundwater mineralisation processes in Mediterranean semi‐arid systems (Cap‐Bon,North east of Tunisia): hydrogeological and geochemical approaches

The groundwater of the Korba plain represents major water resources in Tunisia. The Plio‐Quaternary unconfined aquifer of the Cap‐Bon (north‐east Tunisia) is subject to the intensive agricultural activities and high groundwater pumping rates due to the increasing of the groundwater extraction. The degradation of the groundwater quality is characterized by the salinization phenomena. Groundwater were sampled and analysed for physic‐chemical parameters: Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl^‐, SO₄^2‐, HCO₃^‐, NO₃^‐, pH, electrical conductivity (EC), and the temperature (T°). The hydrochemical analysis is coupled with the calculation of the saturation indexes (SI gypsum, SI halite, SI calcite and SI dolomite), ionic derivation and with the ion correlations compared to chloride concentrations: Na⁺/ Cl^‐, Ca²⁺/ Cl^‐ and Mg²⁺/ Cl^‐ ratios. Seawater fractions in the groundwater were calculated using the chloride concentration. Those processes can be used as indicators of seawater intrusion progression. EC methods were also conducted to obtain new informations on the spatial scales and dynamics of the fresh water–seawater interface of coastal groundwater exchange. The mixing zone between freshwater and saltwater was clearly observed from the EC profile in the investigated area where a strong increase in EC with depth was observed, corresponding to the freshwater and saltwater interface. Results of hydrochemical study revealed the presence of direct cation exchange linked to seawater intrusion and dissolution processes associated with cations exchange. These results, together with EC investigation, indicated that the groundwater is affected by seawater intrusion and is still major actor as a source of salinization of the groundwater in Korba coastal plain. Further isotopic and hydrological investigations will be necessary to identify and more understood the underlying mechanisms. Copyright © 2012 John Wiley & Sons, Ltd.     

Characteristics of carbonaceous aerosol in a two-week campaign at Ny-Alesund

The concentrations of organic carbon (OC) and elemental carbon (EC)in total suspended particle (TSP) were investigated at Ny-(A)lesund, Svalbard in a two-week campaign. The levels of OC and EC are 0.86 ±0.27 μgm-3 (mean±standard deviation) and 0. 19±0.10 μgm-3 , respectively. Back trajectory analysis of air masses arriving at Ny-(A)lesund reveals that long-range transport of polluted air play insignificant role in OC and EC levels, to which the potential influence of the local contamination were ascribed. The average OC/EC ratio is 5.41,suggesting the presence of the secondary organic aerosols. The estimated secondary organic carbon (SOC) in TSP is 0.59 μg/m3 , accounting for 64% of the total organic carbon.     

The slowly pulsating sdB star EC 21324−1346

We present results from a two-week, single-site photometric campaign on the slowly pulsating sdB star, EC 21324−1346. Nine frequencies are detected between about 333 and 125 μHz (periods between 3000 and 8000 s) with amplitudes ranging from 0.003 to 0.001 mag; large for this class of star. Comparison with sparser, earlier data indicates that some of these oscillations are persistent, though at least one shows clear evidence of substantial amplitude variation.     

A European digital accelerometric database:statistical analysis of engineering parameters of small to moderate magnitude events

During the NERIES Project, an accelerometric database containing European digital information was developed. Besides event and station metadata, ground motion parameters, computed in a homogeneous manner, were assembled:PGA, PGV, AI, TD, CAV, HI and PSV(f,5%)(19,961 components, 2629 events, 547 stations). Merging small and moderate magnitude events produced a unique database capable of providing important information such as:(i) Correlations between several ground motion parameters follow analogous trends as in previous worldwide datasets, with slight corrections.(ii) Although PGA attenuations with distance show great uncertainties, four recent GMPEs recommended for Europe fit quite well the central 50% data interval for the distance range 10 R 200 km; outside these distances, they do not fit.(iii) Soil amplification ratios indicate that weak motion(low magnitudes and larger distances) shows larger amplification than strong motion(short distances and large magnitudes) as represented in UBC97 for the USA, but not in EC8 for Europe.(iv) Average spectral shapes are smaller than in the EC8.(v) Differences in amplification factors for PGA, PGV and HI for EC8 soil classes B and C, and differences in spectral shapes for these soil classes, indicate that EC8, Type 2 S-coefficient should be frequency dependent, as in UBC97.     

Stream typology and lake outlets — a perspective towards validation and assessment from northern Germany (Schleswig-Holstein)

The objective of this paper is twofold: 1) to validate the German stream typology for Schleswig-Holstein, and 2) to develop an assessment system for lake outlets. The German stream typology, based on a top-down analysis of geomorphological variables, was validated using biotic data of streams in Schleswig-Holstein, northern Germany. A null model analysis was conducted to test for differences between seven stream types (sand streams and rivers, gravel streams and rivers, partly-mineralic streams, limnic marsh streams, and lake outlets). The dataset compiled for the statistical analysis comprised 28 streams, 65 different sampling sites, 428 samples, and 296 taxa. The analysis confirmed all stream type except partly-mineralic streams, which showed faunal overlap with all types except gravel streams. Gravel streams were the most distinctive stream type. Lake outlets were shown to be a unique type, having a distinct macroinvertebrate fauna. Furthermore it was shown, that the species composition differed between lentic and lotic outlets. Canonical correspondence analysis of 19 investigated lake outlets revealed that characteristics of the lakes had only a minor effect on macroinvertebrate community structure.

The developed assessment system of lake outlets was based on the habitat association of 132 macroinvertebrate taxa. Taxa were allotted to five categories of lake outlet preferences depending on the results from ordinations, frequency tables and abundance distributions. A qualitative and a quantitative lake outlet index (LTI) were tested with independent data sets. The quantitative LTI_quan proved to be more robust and only slightly affected by seasonal changes in the macroinvertebrate community composition. Assessments of lake outlets based on macroinvertebrates should be conducted in spring and autumn to reduce the risk of misclassifications, in particular, for boundary cases rated between good and moderate quality classes.     

The Seismic Shear Demand in Ductile Cantilever Wall Systems and the EC8 Provisions

The seismic shear provisions of EC8 for ductile reinforced concrete walls, serving as the lateral load resisting system in multistorey building structures are re-examined. Two aspects are considered (1) single walls, or a system comprising a number of equal-length walls, (2) a resisting system comprising walls of different lengths. It is demonstrated, in light of recent parametric studies, that the EC8 provisions for walls in the medium- and high-ductility classes (DC-M and DC-H, respectively) are both in need of revision. Possible revisions of requirements and a design procedure for a wall system are presented.     

多环芳烃对海洋浮游植物的生物毒性研究

采用静态实验方法研究了4种（多环）芳烃对6种海洋浮游植物的生物急性毒性效应,并应用对数模型计算了其EC～（50）值。结果表明,根据对数模型计算的EC～（50）值与定义作图法所得结果较为一致,但在低浓度PAHs对浮游植物有促进作用时,其具有准确和合理的优点。其中甲苯、萘、2-甲基萘、菲的72h-EC～（50）分别为34.1～114mg/L,3.9～7.3mg/L,169～3.03mg/L,0.6～1.92mg/L。4种芳烃对6种浮游植物的生物急性毒性顺序为:小新月菱形藻>甲藻>三角褐指藻>中肋骨条藻>小球藻>亚心形扁藻。此外,4种芳烃的72h-EC～（50）与其相应的Kow值有较好的log-log相关性。     

神经智能信息处理系统的研究现状及其在水文水资源中的应用展望

从神经网络(NN),模糊系统(FS)和进化算法(EC)三者相结合的角度,介绍了神经智能信息处理系统的研究现状,讨论了该系统在水文水资源中的应用,并对其应用发展趋势进行了预测。