铜藻(Sargassum horneri)在营养限制胁迫后对NH₄-N的超补偿吸收研究     

李大鹏  马增岭  李慧  丁刚  辛美丽  吴海一  郭文 《海洋与湖沼》2018,49(4):904-909

以经济马尾藻铜藻(Sargassum horneri)为研究材料,研究了其在营养限制胁迫后对NH_4-N的超补偿吸收情况。实验分营养限制和恢复营养两个阶段进行,每个阶段均设置饥饿处理组、饱和处理组和正常对照组。铜藻在低营养限制胁迫(饥饿)下培养10天后,恢复营养盐培养3天,分别采用次溴酸盐氧化法和锌镉还原法测定培养液中的NH_4-N和NO_3-N的浓度。本文研究发现,饥饿处理组中铜藻吸收氨氮的速率远高于正常对照组和饱和处理组,在恢复培养第一天时,饥饿处理组对NH_4-N的吸收速率最高为14.94μmol/(g·h),与正常对照组及饱和处理组间差异显著。在恢复培养的后两天,三个处理组中铜藻对NH_4-N的吸收速率差异慢慢变小,直至最后几乎相同。三组对NO_3-N没有表现出较高的吸收,最高仅为6.15μmol/(g·h),结果表明:氮源包括NH_4-N和NO_3-N时,铜藻优先选择吸收NH_4-N。实验后称重测定生长速率:对照组、饥饿处理组和饱和组生长率(SGR)分别为8.48%、8.86%、8.01%,ANOVA方差分析表明,三者存在显著差异(P=0.0320.05),从而证实了铜藻也存在超补偿生长的现象。  相似文献   

Assessment of alternative adsorption models and global sensitivity analysis to characterize hexavalent chromium loss from soil to surface runoff          下载免费PDF全文

Chuan‐An Xia  Juxiu Tong  Bill X. Hu  Xiujie Wu  Alberto Guadagnini 《水文研究》2018,32(20):3140-3157

We investigate our ability to assess transfer of hexavalent chromium, Cr(VI), from the soil to surface runoff by considering the effect of coupling diverse adsorption models with a two‐layer solute transfer model. Our analyses are grounded on a set of two experiments associated with soils characterized by diverse particle size distributions. Our study is motivated by the observation that Cr(VI) is receiving much attention for the assessment of environmental risks due to its high solubility, mobility, and toxicological significance. Adsorption of Cr(VI) is considered to be at equilibrium in the mixing layer under our experimental conditions. Four adsorption models, that is, the Langmuir, Freundlich, Temkin, and linear models, constitute our set of alternative (competing) mathematical formulations. Experimental results reveal that the soil samples characterized by the finest grain sizes are associated with the highest release of Cr(VI) to runoff. We compare the relative abilities of the four models to interpret experimental results through maximum likelihood model calibration and four model identification criteria (i.e., the Akaike information criteria [AIC and AIC_C] and the Bayesian and Kashyap information criteria). Our study results enable us to rank the tested models on the basis of a set of posterior weights assigned to each of them. A classical variance‐based global sensitivity analysis is then performed to assess the relative importance of the uncertain parameters associated with each of the models considered, within subregions of the parameter space. In this context, the modelling strategy resulting from coupling the Langmuir isotherm with a two‐layer solute transfer model is then evaluated as the most skilful for the overall interpretation of both sets of experiments. Our results document that (a) the depth of the mixing layer is the most influential factor for all models tested, with the exception of the Freundlich isotherm, and (b) the total sensitivity of the adsorption parameters varies in time, with a trend to increase as time progresses for all of the models. These results suggest that adsorption has a significant effect on the uncertainty associated with the release of Cr(VI) from the soil to the surface runoff component.  相似文献   

自然资源一体化政务服务系统及数据融合建设——以南京为例     

陈波  崔蓓  丁鑫 《测绘通报》2020,(12):75-78

自然资源部制定的信息化建设总体方案中，要求构建“互联网+自然资源政务服务”应用体系，实现“服务事项标准统一、整体联动、业务协同，自然资源政务服务和共享开放能力全面提高”。一体化政务服务系统作为政务服务应用体系的重点建设内容，也是落实自然资源管理“两统一”职责的重要支撑，如何整合各类数据资源、发挥系统作用，成为亟待研究的问题。本文在分析自然资源业务管理需求后，提出了一体化政务服务系统及数据融合的建设思路。  相似文献   

利用超快速精密星历约束的北斗卫星实时精密定轨     

范磊  施闯  李敏 《大地测量与地球动力学》2018,38(9):937-942

以广播星历为起算轨道的北斗卫星实时滤波精密定轨往往需要较长收敛时间，针对此，提出利用超快速精密星历约束的实时精密定轨方法。通过MGEX跟踪网全球分布的51个测站连续7 d的实测数据，利用平方根信息滤波对北斗卫星实时精密轨道进行确定，并以3 d解事后轨道作为参考，评估北斗卫星实时滤波轨道精度。结果表明，利用广播星历作起算轨道时，北斗实时滤波轨道平均需要经过15 h收敛才能达到稳定，而新方法在这段时间内轨道变化较为平稳，未出现明显的收敛现象，并且7 d时间内GEO卫星在切向、法向和径向上RMS分别优于2.5 m、20 cm和30 cm，IGSO和MEO卫星在3个方向上分别优于30 cm、15 cm和10 cm。
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基于高斯两步移动搜寻法的村镇避难场所可达性研究     

但文羽  肖映辉  胡周灵  詹庆明 《地球信息科学学报》2018,20(10):1412-1421

避难场所可达性是指避难场所与受灾居民之间的通达性,即灾害发生时,避难人员通过避难疏散通道到达避难场所的难易程度,是评价避难场所布局合理性的重要指标。本研究结合高斯两步移动搜寻法和网络分析法,从供需双向出发对村镇地区避难场所进行可达性分析。2种方法的结合,既充分考虑了需求点与设施点的相互作用,又充分考虑了设施点的吸引力随距离的衰减关系,并基于实际道路,以步行疏散时间作为搜索半径,降低了传统研究中因忽略供需间相互作用及实际距离而引起的可达性结果的误差。最后,以神农架松柏镇区为例,验证该方法的实际应用价值。结果表明,该方法能够有效测定村镇地区避难场所的空间可达性,同时,基于GIS软件可以直观地揭示研究区域内避难场所可达性空间分布差异。该方法可为制定科学的村镇防灾减灾规划提供方法支持。  相似文献   

Properties of geogrid-reinforced marine slope due to the groundwater level changes     

Ramin Vali  Jie Li  Gholamreza Shams  Pieter van Gelder 《Marine Georesources & Geotechnology》2018,36(6):735-748

Evaluation of slope stability, especially in the absence of a proper bed such as marine soils, is one of the most important issues in geotechnical engineering. Using geogrid layers to enhance the strength and stability of embankments is regarded as a commendable stabilization method. On the other hand, groundwater level erratically fluctuates in coastal areas. Therefore, the aim of this research is to study the effects of groundwater level changes on stability of a geogrid-reinforced slope on loose marine soils in Qeshm Island, Iran. At first, geotechnical properties of the site were obtained by comprehensive series of geotechnical laboratory and in situ tests. Then, by simultaneous changes of groundwater level and several parameters such as embankment slope, loading, geogrid length, geogrid number, and tensile strength of geogrid, different characteristics such as embankment safety factor (SF), vertical and horizontal displacements at embankment top and embankment base were studied. It was observed that groundwater level had significant effects on behavior of the embankment. For most of the observations, by decreasing the groundwater level, the displacements decreased and consequently safety factor increased. Increasing the length, number, and tensile strength of geogrid led to the reduction of displacements and an increase in the safety factor.  相似文献   

基于圆柱多段拟合的隧道中轴线提取方法研究     

荆海峰  李广云  王力  杨文锋 《大地测量与地球动力学》2018,38(2):211-215

提出基于圆柱多段拟合的隧道中轴线提取方法。首先对隧道点云数据进行预处理，并将点云按隧道走向分成不同区段；然后对各区段依据轴线与表面点云法线垂直关系，提取精度较低的中轴线；最后对各区段利用圆柱多段拟合，提取精度较高的中轴线。实验表明，隧道中轴线的提取在一定的采样区间具有较高的稳定性，对直线和弯曲的圆形隧道有良好的适用性，算法可靠，精度较高。  相似文献   

基于GIS的石家庄市雾霾分析     

苏亚聪  史娟  徐爽 《北京测绘》2020,(2):233-237

为了得出雾霾气象成因机制、影响因素和时空分布特征,以石家庄市区与郊县为研究区域,将2013年9月至2016年12月石家庄市各市区、郊县的PM2.5历史监测数据中的有效数据进行了数据分析处理得到雾霾浓度数据,还有温度、降水、风速、地形和人口密度等数据,运用GIS分析的方法,模拟绘制石家庄雾霾的时空分布图、雾霾与各影响因子的专题对比图,得到雾霾形成机制的因子、雾霾的时空分布规律、雾霾季节变化特征、雾霾与地形间的关系等;运用数据分析软件OriginPro8.SR3分析雾霾浓度与风速数据、降雨数据、温度数据间的相关性。  相似文献   

基于LiDAR的农田地形环境三维重建方法     

郎朗  冯晓蓉  刘浪 《测绘通报》2020,(2):55-60

为克服传统农田土地平整测量方法耗时费力的特点，提出采用LiDAR技术对农田地形进行重建的探索性研究。通过HDL-32E型激光雷达等搭建了系统的硬件平台，应用C++语言编写了系统数据的采集程序；在此基础上对激光雷达所采集数据进行了标定，研究了农田地形重建系统中不同坐标系的转换方法；同时基于最小值去噪法设计了更适用于农田地形点云去噪的均值限差去噪法。通过对比在农田起伏较大区域不同坡度范围内RTK与激光雷达所测单元个数，对系统精度进行了评价；最后实现了车载农田地形重建系统的界面显示、应用与精度评估。结果表明，在10°~15°、25°~30°大坡度范围内激光雷达所获农田地形更为丰富，精度更高。该方法重建的农田地形模型点云数据和原始农田地形点云数据投影面积逼近度可达93%，验证了本文研究方法应用于农田地形环境重建的可行性，同时为今后的土地精细平整工作提供了理论参考与依据。  相似文献   

资源三号和天绘一号卫星影像无控联合平差精度分析     

郑义  张宏伟  杜晓  张俊辉  周琦  林尚纬  陈利军 《测绘通报》2020,(7):10

近年来国产卫星传感器类型日益丰富，使用自主可控的国产卫星影像进行生产和研究的需求越来越大，多源国产卫星影像联合平差的精度分析显得尤为重要。本文针对在立体测图生产中，资源三号卫星影像在时相较旧、噪声较大、云覆盖和摄影漏洞等特殊困难的条件下，利用天绘一号卫星影像进行补漏生产的情况，最终分析并验证了两者无控联合平差的可行性和成果精度。  相似文献