Late Quaternary vegetation changes around Lake Rutundu,Mount Kenya,East Africa: evidence from grass cuticles,pollen and stable carbon isotopes

Woody, subalpine shrubs and grasses currently surround Lake Rutundu, Mount Kenya. Multiple proxies, including carbon isotopes, pollen and grass cuticles, from a 755‐cm‐long core were used to reconstruct the vegetation over the past 38 300 calendar years. Stable carbon‐isotope ratios of total organic carbon and terrestrial biomarkers from the lake sediments imply that the proportion of terrestrial plants using the C₄ photosynthetic pathway was greater during the Late Pleistocene than in the Holocene. Pollen data show that grasses were a major constituent of the vegetation throughout the Late Pleistocene and Holocene. The proportion of grass pollen relative to the pollen from other plants was greatest at the last glacial maximum (LGM). Grass cuticles confirm evidence that C₄ grass taxa were present at the LGM and that the majority followed the cold‐tolerant NADP‐MEC₄ subpathway. Copyright © 2003 John Wiley & Sons, Ltd.     

The importance of oxygen isotope provenance in relation to solute content of bulk meltwaters at Imersuaq Glacier,West Greenland

Stable oxygen isotope analysis and measurement of several dissolved cations and anions of bulk meltwater samples have provided information about the hydrochemical environment of the glacial hydrological system at Imersuaq Glacier, an outlet tongue from the Greenland ice‐sheet, West Greenland. The samples were collected at frequent intervals during the period 20–28 July 2000 in a small (<20 L s^?1) englacial meltwater outlet at the glacier margin. The results document the following findings: (i) a marked diurnal variation of δ¹⁸O is related to the composition of oxygen isotope provenances, mainly near‐marginal local superimposed ice and basal up‐sheared ice further up‐glacier; (ii) a relationship is seen between all base cations (Na⁺, K⁺, Ca²⁺, Mg²⁺), SO₄^2? and δ¹⁸O, indicating that solute acquisition is provided by solid–solution contact with the up‐sheared ice—as the relationship with Cl^? is weak the influence of seasalt‐derived solutes is small in the area; (iii) when the melt rate is high, two diurnal maxima of δ¹⁸O values and solute concentrations are measured, and it is suggested that a snow meltwater component is responsible for the second maximum of δ¹⁸O—a short residence time leads to a delayed decrease in ion concentrations. Copyright © 2003 John Wiley & Sons, Ltd.     

北京市基础测绘技术规程的探讨

分析了规程与现行相关法律、法规和标准的关系,探讨了北京市基础测绘技术规程的内容,介绍了其创新点和应用情况。通过分析介绍,该地方标准统一了北京市基础测绘的技术标准,规范了基础测绘成果,有利于实现测绘信息资源的共享和有效利用。     

中国北方两种现代草地动物牙齿珐琅质δ~(13)C值与植被类型的关系初探

在简单了解研究区的植被、气候状况的基础上 ,分析了内蒙古锡林郭勒和青海海北两种典型草地食草动物牙齿的δ1 3C值 ,测定了采样点表土有机质的δ1 3C值。锡林郭勒的表土有机质碳同位素组成略分散 ,且与植被和微环境密切相关。海北的表层土壤有机质碳同位素组成比较集中。两地的碳同位素组成都偏轻 ,是植被中C4植物含量少的反映。两地放牧动物的珐琅质δ1 3C值分别比当地植物偏重 12 .9‰和 13.5‰ ,或 14 .1‰和 14 .7‰。火灾等高温过程对动物牙齿的碳同位素组成可能没有显著影响     

震级加权四指标Blade算法及在地震带识别中的应用

Blade算法的产生是根据地震点的分布寻找地震断层，其优势在于能从较稀疏的点分布中找出线型条带模式，但不足的是完全不考虑地震的震级屑性。针对Blade算法的几个不足之处逐步改进，提出了震级加权四指标Blade算法。算法主要的改进体现在：①引入以震级为变量的权重函数，体现了高震级地震的控制作用，通过模拟与实例比较了三种权重函数的效果；②改进原方法中所挑出的Blade中心必须有地震点，引入四指标评价体系代替原方法的二指标评价体系，同时还根据指标值将挑选出的线型条带修正到更淮确的位置。将原算法与改进算法应用于华北地区4级以上的地震数据集以按寻地震带，结果表明，震级加权四指标Blade算法较Blade算法有显改进，取得了较好的应用效果。     

Treatment of Malting Wastewater in a Granular Sludge Sequencing Batch Reactor (SBR)

Aerobic granular sludge was successfully cultivated in a sequencing batch reactor (SBR) treating wastewater from the malting process with a high content of particulate organic matter. At an organic loading rate of 3.2 kg/(m³ d) COD_total and an influent particle concentration of 0.95 g/L MLSS an average removal of 50% in COD_total and 80% in COD_dissolved could be achieved. A comparison of granular and flocculent sludge grown under the same operating conditions showed no significant difference in removal efficiency although granules exhibited a higher metabolic activity in terms of specific oxygen uptake rate (r_{O2, X}). Two distinct mechanisms of particle removal were observed for granular sludge: during initial granule formation, particles were incorporated into the biofilm matrix. For mature granules, a high level of protozoa growth on the granule surface accounted for the ability to remove particulate COD. Combined evaluation of the development in MLSS content and sludge bed settling rate (i.e., mean derivative of the normalized sludge volume) was found to be an adequate method for monitoring the characteristic settling properties of a granulizing sludge bed. By means of this method, a distinct substrate gradient out of several operating conditions was concluded to have the biggest impact on the formation of aerobic granular sludge.     

Kinetics and Equilibrium Sorption Studies of 4-Nitrophenol on pyrolyzed and activated oil shale residue

Sorption of the organic pollutant 4-nitrophenol (4-NP) by pyrolyzed and activated Jordanian oil-shale was studied. Pyrolyzed oil shale was prepared using a fluidized bed reactor at 520 °C in the presence of nitrogen. Physical activation was carried out by treating the pyrolyzed oil shale with CO₂ at 830 °C, while chemical activation was achieved by using KOH and ZnCl₂ as impregnating agents. Batch kinetics and isotherm studies were conducted to evaluate the sorption process. Effects of contact time, initial sorbate concentration, sorbent concentration, temperature, pH and inorganic salts (NaCl and KCl) on the sorption process by the different sorbents were considered. Chemically activated oil shale, pretreated with ZnCl₂, gave the highest uptake of 4-NP. The isotherm experimental data fit reasonably well to Langmuir, Freundlich and Redlich-Paterson models. Three kinetic models, namely the Morris-Weber, Lagergren, and Pseudo-Second-Order model (PSOM), were applied to represent the experimental results for both pyrolyzed and ZnCl₂-oil shale sorbents.     

从FY-4A卫星遥感数据和GFS资料估算全天空状况下的地表长波辐射通量

本文介绍一种利用FY-4A成像仪遥感数据和全球预报系统(GFS)资料估算全天空地表长波辐射通量的反演方法。该方法通过辐射传输模拟和统计回归计算建立云天地表下行长波辐射通量的反演模式,并基于GFS资料处理云覆盖地区的地表上、下行长波辐射通量。这种全天空状况下两种通量的反演结合了FY-4A晴空地表长波辐射业务产品和本文反演模式处理的云天地表上、下行长波辐射通量。2018年9月1日的处理结果与Aqua/CERES同类产品相对比,精度为:RMSE=20.52 W·m^-2,R=0.9481,Bias=3.3 W·m^-2(夜间地表下行辐射通量对比);RMSE=25.58 W·m^-2,R=0.9096,Bias=5.4 W·m^-2(白天地表下行辐射通量对比);RMSE=10.97 W·m^-2,R=0.9762,Bias=-3.3 W·m^-2(夜间地表上行辐射通量对比);RMSE=19.97 W·m^-2,R=0.9283,Bias=5.0 W·m^-2(白天地表上行辐射通量对比)。这些结果表明本文发展的方法能够反演出精度较好的云天上下行长波辐射通量资料,为今后利用FY-4后续星处理生成全天空状况下的地表长波辐射通量产品奠定了理论基础。     

高时空分辨率三维风场在强对流天气临近预报中的融合应用研究

以业务应用为目标,开展高时、空分辨率三维风场在强对流天气临近预报中的融合应用研究。运用北京快速更新多尺度分析和预报系统集成子系统（RMAPS-IN,Rapid-refresh Multi-scale Analysis and Prediction System-Integration）,对雷达四维变分分析系统（VDRAS）30 min临近预报的高时、空分辨率三维风场作为数据源与自动气象站风场观测进行快速融合处理。结果表明,以VDRAS临近预报风场取代数值模式预报场作为融合初猜场后形成的分析结果对于风场有明显的改善:（1）长时间序列客观检验结果表明,地面10 m高风场U/V分量绝对误差分别为0.05和0.06 m/s。实时融合对未来预报的影响随着预报时效的延长,U/V分量的绝对误差不断增大。（2）对于11个强对流个例,地面10 m高风场风速均方根误差降低0.3 m/s,风向均方根误差降低13°;边界层三维风场,风速均方根误差降低0.8 m/s,风向均方根误差降低10°。平原站点融合以后风速、风向预报效果有较大改善,山区站点融合以后改善相对较小。（3）通过对2017年7月20日暴雨和7月7日雷暴大风个例的详细分析,发现融合基于雷达资料四维变分同化获得的高分辨率临近预报风场对各对流系统中的中尺度结构特征给出了更加细致准确的描述。      

区域大气环境应急响应数值预报系统

介绍了针对国内有毒气体泄漏等突发性大气中污染物扩散问题建立的区域精细大气环境应急响应数值预报业务系统。该系统基于污染扩散模式HYSPLIT_4,利用中尺度模式WRF为其提供气象场,对污染扩散的路径和浓度以及地面沉降进行计算,系统后端开发了基于GIS的产品制作平台对模式产品进行叠加地理信息的处理。为实现快速应急响应的功能,模式业务系统始终处于热准备状态,并可在接到指令后迅速完成产品制作。文中给出一个大气环境应急响应演习应用实例,显示该模式系统对影响范围较大的有毒气体泄漏事件应急响应工作具备一定的指导意义和应用前景。