小体积液液萃取气相色谱-质谱法测定地下水中的克百威与3-羟基克百威

克百威和3-羟基克百威是一对典型的农药母体及其代谢产物,由于其水溶性高、毒性大,可通过地表水或地下水进行长距离迁移,对人类健康和环境安全造成危害.以往通常采用液相萃取或固相萃取的方式提取样品中的克百威和3-羟基克百威,但这些方法操作繁琐、耗时较长,不利于室内模拟实验中多组样品的检测.为实现克百威与3-羟基克百威在地下水...     

Exploring the applications of 3D proximity analysis in a 3D digital cadastre

Increasing population in urban areas and limitations of suitable lands for developing houses and urban infrastructure have led to the vertical development in cities. However, these developments are managed by a cadastral system which is mainly two-dimensional and cannot efficiently represent Rights, Restrictions, and Responsibilities (RRRs) in complex scenarios. In fact, a three-dimensional cadastre is required for efficiently registering and representing RRRs. In this paper, a 3D proximity analysis was proposed and implemented to determine RRRs and associated easement rights in non-topology-based data structures. This method can be used to investigate the surrounding spaces of a subject apartment unit or storage in a high-rise. The performance of the developed method was evaluated in a large complex high-rise in Tehran, Iran. The results confirmed that the proposed method can correctly identify the neighbor spaces in complex scenarios.     

"99.6"梅雨锋暴雨模拟资料的诊断分析

利用非静力中尺度模式MM5V3的模拟资料对"99.6"梅雨锋暴雨过程进行了对流动量输送(CMT)和视热源视水汽汇分析。CMT诊断分析表明,水平动量残差在切变低涡发展的不同阶段的作用是不同的,在中尺度低涡发生初期对流层低层动量残差X主要是加速西南气流的北上;在对流层中层动量残差在槽后加速冷空气南下,在槽前加速西南暖湿气流北上,非常有利于东亚大槽的发展。在低涡切变线强烈发展时,850hPa的X方向与发生阶段相反,此时西南气流受到了强烈的减速作用,同时500hPa东亚大槽的前部和后部出现了减速气流的动量残差,槽后冷空气和槽前的暖湿气流都已经受到减速作用,此后低涡切变线逐渐衰减。低涡切变线发展到最强的阶段,强X矢量几乎总是与强烈上升运动区相对应,能量转换E的水平分布表明,大尺度系统与中尺度系统之间的能量转换非常复杂,并不是简单的能量串级过程,但能量主要是从大尺度向次网格尺度转换。200hPa动能转换E的带状分布非常清楚,E的正负大值中心分布在高空急流的2侧,表明高空急流在能量转换的过程中起到非常重要的作用。视热源和视水汽汇的诊断分析显示,强凝结潜热的释放与低涡的发展相伴随,但视热源只与β中尺度系统有明显的对应关系,视水汽汇有和视热源非常相似的分布特征。     

北斗三号全球导航卫星系统全球广播电离层延迟修正模型(BDGIM)应用性能评估

2020年6月23日,我国北斗三号全球导航卫星系统正式完成星座全球组网.北斗三号全球导航卫星系统采用新一代全球广播电离层延迟修正模型(BDGIM),为用户提供电离层延迟改正服务.本文利用高精度全球电离层格网(GIM)以及实测BDS/GPS数据提供的电离层TEC作为参考,从延迟改正精度及北斗单频伪距单点定位应用、模型系数...     

The phase difference effects on 3-D structure of wave pressure acting on a composite breakwater

In designing the coastal structures, the accurate estimation of the wave forces on them is of great importance. In this paper, the influences of the phase difference on wave pressure acting on a composite breakwater installed in the three-dimensional (3-D) wave field are studied numerically. We extend the earlier model [Hur, D.S., Mizutani, N., 2003. Coastal Engineering 47, 329–345] to simulate 3-D wave fields by introducing 3-D Navier–Stokes solver with the Smagorinsky's sub-grid scale (SGS) model. For the validation of the model, the wave field around a 3-D asymmetrical structure installed on a submerged breakwater, in which the complex wave deformations generate, is simulated, and the numerical solutions are compared to the experimental data reported by Hur, Mizutani, Kim [2004. Coastal Engineering (51, 407–420)]. The model is then adopted to investigate 3-D characteristics of wave pressure and force on a caisson of composite breakwater, and the numerical solutions were discussed with respect to the phase difference between harbor and seaward sides induced by the transmitted wave through the rubble mound or the diffraction. The numerical results reveal that wave forces acting on the composite breakwater are significantly different at each cross-section under influence of wave diffraction that is important parameter on 3-D wave interaction with coastal structures.     

61～50kaBP亚洲季风百年尺度气候振荡的黔西南石笋记录

12个U/Th年龄测试结果显示,黔西南普安县雾露洞长度分别为667mm和830mm的两支石笋覆盖了61～50kaBP时段。据两支石笋999个δ18O数据建立了平均分辨率达15年的亚洲夏季风强度变化序列。雾露洞δ18O记录揭示了4个振幅达1.7‰的千年尺度季风增强事件,对应于格陵兰冰心DO17—DO14事件。在总体特征上,该记录峰谷振荡特征及振幅与贵州董歌洞、南京葫芦洞记录一致,进一步证实亚洲季风区大气降水同位素组成变化在大范围空间内具有一致性。在百年尺度上,亚洲季风区石笋δ18O清晰记录了MIS3早期6个DO亚旋回事件,而且在更短时间尺度上具有类似高纬气温振荡特征。这种低纬季风系统与北高纬气候变化的耦合关系表明,大气环流快速重组和传输可能是连接高低纬DO旋回及亚旋回气候变化的主要纽带。     

Comparison of ecophysiological characteristics between introduced and indigenous mangrove species in China

Due to its rapid growth, the introduced mangrove species Sonneratia apetala from Bangladesh has been widely used in mangrove restoration in southeastern China since 1985. As an indigenous mangrove species in Hainan, China, Sonneratia caseolaris was also planted in Guangdong Province for afforestation purposes. Both species have developed well in their new habitats, but their ecophysiological differences with the native mangrove species have not been studied. In this study, leaf gas exchange, water and nitrogen use efficiencies of two Sonneratia species were compared with those of selected native mangrove species (Avicennia marina, Aegiceras corniculatum, Kandelia candel, and Excoecaria agallocha) in Hainan and Shenzhen. The introduced S. apetala maintained lower carbon assimilation rate (A) and photosynthetic nitrogen use efficiency (PNUE) than the indigenous S. caseolaris. In Shenzhen, the two introduced Sonneratia had comparable photosynthetic rates and water use efficiency (WUE) with the native mangrove species, except that PNUE in S. caseolaris was significantly higher than in the native mangrove species. The two Sonneratia species showed significant overlap in PNUE and long-term WUE. Photosynthetic parameters derived from leaf photosynthetic light–response curves and A–C_i curves also suggested lower carbon assimilation capacities for the introduced Sonneratia than for the native mangrove species in both study sites. The lower light compensation point (LCP) of two introduced Sonneratia in both study sites also indicated a better adaptation to a low light regime than the native mangrove species. The results of photosynthetic capacities indicated that the introduced mangrove species have little competitive advantage over local native mangrove species in their respective new habitats.     

Isotopic,trace element and nutrient characterization of coastal waters from Ubatuba inner shelf area,south-eastern Brazil

Stable isotopes, tritium, radium isotopes, radon, trace elements and nutrients data were collected during two sampling campaigns in the Ubatuba coastal area (south-eastern Brazil) with the aim of investigating submarine groundwater discharge (SGD) in the region. The isotopic composition (δD, δ¹⁸O, ³H) of submarine waters was characterised by significant variability and heavy isotope enrichment. The stable isotopes and tritium data showed good separation of groundwater and seawater groups. The contribution of groundwater in submarine waters varied from a few % to 17%. Spatial distribution of ²²²Rn activity concentration in surface seawater revealed changes between 50 and 200 Bq m⁻³ which were in opposite relationship with observed salinities. Time series measurements of ²²²Rn activity concentration in Flamengo Bay (from 1 to 5 kBq m⁻³), obtained by in situ underwater gamma-spectrometry showed a negative correlation between the ²²²Rn activity concentration and tide/salinity. This may be caused by sea level changes as tide effects induce variations of hydraulic gradients, which increase ²²²Rn concentration during lower sea level, and opposite, during high tides where the ²²²Rn activity concentration is smaller. The estimated SGD fluxes varied during 22–26 November between 8 and 40 cm d⁻¹, with an average value of 21 cm d⁻¹ (the unit is cm³/cm² per day). The radium isotopes and nutrient data showed scattered distributions with offshore distance and salinity, which implies that in a complex coast with many small bays and islands, the area has been influenced by local currents and groundwater–seawater mixing. SGD in the Ubatuba area is fed by coastal contaminated groundwater and re-circulated seawater (with small admixtures of groundwater), which claims for potential environmental concern with implications on the management of freshwater resources in the region.     

A comparison of economic performance in the fisheries sector: A short- and long-term perspective

Indicators of the economic performance of fishing vessels are frequently computed in various countries. In this paper, we use different types of information to assess capital value and the economic performance of fishing vessels. On the one hand, field surveys provide technical and financial information on the main components of fishing capital. On the other hand, book values are given in bookkeeping databases. We use both sources of information on fishing capital are used for the same set of vessels, namely the commercial fishing fleet of the French region of Brittany. Based on these two sources, measures of economic performance can be produced for the short term using gross surplus; and for the long term including the cost of capital. The measures of performance obtained are presented and the differences between them are then discussed.     

3-甲基胆蒽对斑马鱼组织病理效应的初步研究

分别用25、50、100、200和400μg/L的3-甲基胆蒽(3-MC)对斑马鱼进行水浴染毒,于第7天和第14天采集各染毒组和对照组活鱼的肝、鳃、心、肠和肾,进行病理组织学检查。结果发现,一定剂量的3-MC能导致肝细胞变性,胞浆内出现脂肪滴,严重时肝细胞坏死解体,界限模糊;心肌细胞萎缩坏死;肠粘膜上皮细胞纹状缘不整齐,有的脱落;鳃丝结构异常,鳃小片表面粗糙,上皮细胞不完整;肾小管上皮细胞肿胀,细胞界限不清,管腔内均质红染。供试斑马鱼的病理组织变化与3-MC的作用剂量和作用时间存在一定的关系。