雷州半岛滨海湿地表层沉积物中重金属含量分布与生态风险评价   总被引：1，自引：0，他引：1       下载免费PDF全文

甘华阳  林进清  梁开  利锋  段志鹏 《热带海洋学报》2014,33(3):79-87

采用多元统计方法分析了雷州半岛滨海湿地表层沉积物中重金属的含量、相关性、空间分布特征和来源,并对其生态风险进行了评价。研究区表层沉积物中的Cu、Zn、Pb、Cr、As、Cd和Hg的含量平均值分别为10.29±7.80、47.06±28.47、24.74±10.78、41.70±26.25、7.98±4.73、0.042±0.029和0.020±0.027μg·g-1。Cu、Zn和Cr以及Pb、Cd和Hg为2个强正相关群,第一个群中的重金属元素以自然来源为主,第二个群则兼有人为输入和自然2个来源。重金属含量的高值区主要分布在流沙港、湛江港西部、海安港和雷州湾西部海域。对照美国海洋与大气管理局(NOAA)的生物效应标准,研究区绝大部分海域内的表层沉积物中除As含量在约50%的站位的值在"效应范围低"(effect range low)和"效应范围中等"(effect range median)阈值之间,对底栖生物会偶尔发生负面效应外,其他重金属基本不发生负面效应。重金属总体为低污染程度和低潜在生态风险。应重视人类活动较强的区域如湛江港西部、流沙港、海安港等海区的重金属污染,以避免持续累积至能对生物造成危害的水平。  相似文献   

短时强降水特征统计及临近预警   总被引：9，自引：3，他引：6  

段鹤  夏文梅  苏晓力  王秀英  刘建平 《气象》2014,40(10):1194-1206

利用多普勒天气雷达、探空和逐小时降水量资料,对2010 2012年,滇西南普洱、西双版纳537次短时强降水天气过程进行统计分析,建立三种短时强降水概念模型,分别是:低质心弱辐合型短时强降水、低质心辐合型短时强降水、高质心短时强降水。对比分析了不同类型短时强降水的强度特征、移速特征、生命期特征、垂直风切变特征等,探讨了辐合作用与强降水维持时间的关系、辐合切变量与雨强的关系、D_(VIL)与降水量的关系。并得出预警方法:满足如下条件时,出现短时强降水的可能较大:(1)低质心强降水中,回波无倾斜特征,强度以40~45 dBz为主,强度从低层到高层维持或缓慢减弱,大部分回波的H_((40dBz))≥H_0,且0℃层高度上40 dBz的回波的累计长度/回波移速≥0.67 h(辐合切变量≥2.2 m·s~(-1)时,累计长度/回波移速≥0.50 h),预报提前时间30~40 min。(2)高质心强降水中,强回波边缘存在宽≥3 km、强度为40~45 dBz的回波,且0℃层高度上40 dBz的回波的累计长度/回波移速≥0.47 h,预报提前时间28 min左右。此外,对短时强降水成因进行了探讨。  相似文献   

Uncertainties in Quantitatively Estimating the Atmospheric Heat Source over the Tibetan Plateau          下载免费PDF全文

DUAN An-Min  WANG Mei-Rong  XIAO Zhi-Xiang 《大气和海洋科学快报》2014,(1)

As a huge,intense,and elevated atmospheric heat source(AHS) approaching the mid-troposphere in spring and summer,the Tibetan Plateau(TP) thermal forcing is perceived as an important factor contributing to the formation and variation of the Asian summer monsoon.Despite numerous studies devoted to determine the strength and change of the thermal forcing of the TP on the basis of various data sources and methods,uncertainties remain in quantitative estimation of the AHS and will persist for the following reasons:(1) Routine meteorological stations cover only limited regions and show remarkable spatial inhomogeneity with most distributed in the central and eastern plateau.Moreover,all of these stations are situated at an altitude below 5000 m.Thus,the large area above that elevation is not included in the data.(2) Direct observations on heat fluxes do not exist at most stations,and the sensible heat flux(SHF) is calculated by the bulk formula,in which the drag coefficient for heat is often treated as an empirical constant without considering atmospheric stability and thermal roughness length.(3) Radiation flux derived by satellite remote sensing shows a large discrepancy in the algorithm in data inversion and complex terrain.(4) In reanalysis data,besides the rare observational records employed for data assimilation,model bias in physical processes induces visible errors in producing the diabatic heating fields.  相似文献   

Uncertainties in Quantitatively Estimating the Atmospheric Heat Source over the Tibetan Plateau简   总被引：1，自引：0，他引：1       下载免费PDF全文

DUAN An-Min  WANG Mei-Rong  XIAO Zhi-Xiang 《大气和海洋科学快报》2014,(1):28-33

As a huge,intense,and elevated atmospheric heat source（AHS） approaching the mid-troposphere in spring and summer,the Tibetan Plateau（TP） thermal forcing is perceived as an important factor contributing to the formation and variation of the Asian summer monsoon.Despite numerous studies devoted to determine the strength and change of the thermal forcing of the TP on the basis of various data sources and methods,uncertainties remain in quantitative estimation of the AHS and will persist for the following reasons：（1） Routine meteorological stations cover only limited regions and show remarkable spatial inhomogeneity with most distributed in the central and eastern plateau.Moreover,all of these stations are situated at an altitude below 5000 m.Thus,the large area above that elevation is not included in the data.（2） Direct observations on heat fluxes do not exist at most stations,and the sensible heat flux（SHF） is calculated by the bulk formula,in which the drag coefficient for heat is often treated as an empirical constant without considering atmospheric stability and thermal roughness length.（3） Radiation flux derived by satellite remote sensing shows a large discrepancy in the algorithm in data inversion and complex terrain.（4） In reanalysis data,besides the rare observational records employed for data assimilation,model bias in physical processes induces visible errors in producing the diabatic heating fields.  相似文献   

Time-Dependent Nonlinear Forcing Singular Vector-Type Tendency Error of the Zebiak-Cane Model          下载免费PDF全文

ZHAO Peng  DUAN Wan-Suo 《大气和海洋科学快报》2014,(5):395-399

Based on the Zebiak-Cane model, the timedependent nonlinear forcing singular vector （NFSV）-type tendency errors with components of 4 and 12 （denoted by NFSV-4 and NFSV-12） are calculated for predetermined El Nifio events and compared with the constant NFSV （denoted by NFSV-1） from their patterns and resultant prediction errors. Specifically, NFSV-1 has a zonal dipolar sea surface temperature anomaly （SSTA） pattern with negative anomalies in the equatorial eastern Pacific and positive anomalies in the equatorial central-western Pa- cific. Although the first few components in NFSV-4 and NFSV-12 present patterns similar to NFSV-1, they tend to extend their dipoles farther westward; meanwhile, the positive anomalies gradually cover much smaller regions with the lag times. In addition, the authors calculate the predic- tion errors caused by the three kinds of NFSVs, and the results indicate that the prediction error induced by NFSV-12 is the largest, followed by the NFSV-4. However, when compared with the prediction errors caused by random tendency errors, the NFSVs generate significantly larger prediction errors. It is therefore shown that the spatial structure of tendency errors is important for producing large prediction errors. Furthermore, in exploring the tendency errors that cause the largest prediction error for E1 Nifio events, the timedependent NFSV should be evaluated.  相似文献   

Simulation of Typhoon Muifa using a mesoscale coupled atmosphere–ocean model   总被引：2，自引：0，他引：2  

SUN Minghu  DUAN Yihong  ZHU Jianrong  WU Hui  ZHANG Jin  HUANG Wei 《海洋学报(英文版)》2014,33(11):123-133

A mesoscale coupled atmosphere–ocean model has been developed based on the GRAPES(Global and Regional Assimilation and Prediction System) regional typhoon model(GRAPES_TYM) and ECOM-si(estuary, coast and ocean model(semi-implicit)). Coupling between the typhoon and ocean models was conducted by exchanging wind stress, heat, moisture fluxes, and sea surface temperatures(SSTs) using the coupler OASIS3.0. Numerical prediction experiments were run with and without coupling for the case of Typhoon Muifa in the western North Pacific. To investigate the impact of using more accurate SST information on the simulation of the track and the intensity of Typhoon Muifa, experiments were also conducted using increased SST resolution in the initial condition field of the control test. The results indicate that increasing SST resolution in the initial condition field somewhat improved the intensity forecast, and use of the coupled model improved the intensity forecast significantly, with mean absolute errors in maximum wind speed within 48 and 72 h reduced by 32% and 20%, respectively. Use of the coupled model also resulted in less pronounced over-prediction of the intensity of Typhoon Muifa by the GRAPES_TYM. Moreover, the effects of using the coupled model on the intensity varied throughout the different stages of the development of Muifa owing to changes in the oceanic mixed layer depth. The coupled model had pronounced effects during the later stage of Muifa but had no obvious effects during the earlier stage. The SSTs predicted by the coupled model decreased by about 5–6°C at most after the typhoon passed, in agreement with satellite data. Furthermore, based on analysis on the sea surface heat flux, wet static energy of the boundary layer, atmospheric temperature, and precipitation forecasted by the coupled model and the control test, the simulation results of this coupled atmosphere–ocean model can be considered to reasonably reflect the primary mechanisms underlying the interactions between tropical cyclones and oceans.  相似文献   

长江中下游成矿带抛刀岭大型斑岩型金矿特征及找矿前景   总被引：2，自引：0，他引：2  

段留安  杨晓勇  汪方跃 《地球科学与环境学报》2014,(1):161-170

抛刀岭金矿位于长江中下游成矿带安庆—池州矿集区,累计金金属量大于22t,为池州地区首例大型金矿床。该矿床金矿体主要产在英安玢岩中,基本不伴生其他有益金属元素,为独立金矿床。通过详细的矿床地质特征描述,结合已有斑岩型金矿的成矿模式,同时利用以往对该含矿岩体U-Pb锆石定年及相关地球化学研究,综合分析认为该矿为产在早白垩纪岛弧背景下的贫铜斑岩型金矿床,同时局部矿段在成矿过程中还经历了热液叠加作用。矿体产出严格受NE向构造-岩浆岩带控制,含矿岩体出露面积小于1.0km2,属于典型的小岩体成大矿。运用"相似类比"、"矿床谱系"、"趋势外推"、"综合信息评价"等原则,指出该矿具有特大型金矿的潜质;同时,受同一NE向构造控制的乌石、白虎山及自来山等同期岩浆岩发育地区,具有与抛刀岭金矿类似的成矿条件,是未来工作的重点靶区;发育于上述同期岩浆岩之间的志留纪地层中的破碎带蚀变岩、与斑岩型矿床配套产出的低温热液多金属硫化物型矿床等,都将是外围工作的重点研究地区。  相似文献   

基于GPU的SIFT特征点快速匹配     

柯涛  田一涵  段延松 《测绘与空间地理信息》2014,(12)

影像匹配是计算机视觉及数字摄影测量的核心问题,基于特征的SIFT匹配算法由于其较强的匹配能力和良好的健壮性成为研究的热点.但SIFT算子的多量性及提取特征点维度较高的特点,直接影响了匹配速度.因此,本文利用GPU强大的并行处理能力,就SIFT特征点匹配在GPU上的设计与实现进行了详细的介绍,并通过对比实验说明利用GPU对SIFT特征点进行匹配所带来的优势.  相似文献   

基于ArcGIS的土地利用现状图缩编方法研究   总被引：1，自引：0，他引：1  

毕强  崔利  段建刚  杨清臣 《测绘通报》2011,(3):78-81

从ArcGIS的制图综合功能出发,结合相关的制图综合理论,提出基于ArcGIS平台的人机交互式缩编技术方法,并对其中关键过程的处理技巧进行阐述.  相似文献   

城市基础空间数据建库中一些质量控制方法探讨——以广州市规划局1∶10000城市地图数据建库为例     

段新民 《测绘与空间地理信息》2011,34(5):113-116

城市基础空间数据库是城市GIS的核心,而数据质量的高低又是数据库建设成功与否的关键。本文在分析城市空间数据的基本特征、数据的特点以及空间数据库中存在的误差来源基础上,结合广州市1∶10 000城市地图数据建库,详细论述了城市基础空间数据建库中进行质量控制的内容及方法。  相似文献