全站仪固定样地测树原理及精度分析

本文提出应用全站仪在森林固定样地中测树 ,全站仪与PC—E5 0 0袖珍计算机或PDA连接 ,可自动测量每一棵树的树高、胸径或任一直径、树心三维坐标、冠幅等。其测量树高的精度可达 1 / 1 4 0 0 ,测量直径的精度可达 1 / 2 0 0 ,树心平面坐标定位精度可达 1 5mm ,冠幅测量可达 1 / 1 30 0 0精度 ,均高于测树的需要精度。特别重复实验了任意高处直径的测量 ,与轮尺测量的结果最大差 2 1mm ,最小差 1 6mm。     

Poly-aromatic hydrocarbon (PAH) inputs from the Rhône River to the Mediterranean Sea in relation with the hydrological cycle: impact of floods

The concentrations of dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) were monitored in waters of the Rhône River (France) every fortnight for a full calendar year, from June 1994 to May 1995. All flood events occurring over the course of the experiment were sampled at higher frequency to better quantify the impact of these extreme hydrological episodes on the annual export of PAHs to the Mediterranean Sea. This time-series indicates that more than 90% of the annual load of particulate PAHs is transported during flood episodes, with 77% discharged during the course of only one extreme flood event occurring in November 1994. During these intense events, riverine particles are depleted in PAHs while at low river discharge particles are PAH-enriched. Dissolved PAHs were less variable and less abundant than adsorbed PAHs, consistently with the low solubility of these compounds.     

森林资源清查中树高、材积误差分析

在森林资源清查中,树高、胸径测量是最重要的部分之一,其测量误差不仅使树高、胸径本身数据精度降低,更影响着材积,乃至蓄积量。本文就树高测量误差的来源、树高和材积误差传播展开讨论,并提出减小误差的建议。     

Bioaccumulation and enantiomeric profiling of organochlorine pesticides and persistent organic pollutants in the killer whale (Orcinus orca) from British and Irish waters

Concentrations and enantiomeric profiles for a range of organochlorine compounds are reported in blubber samples from a number of individual killer whales (Orcinus orca) from British and Irish waters. Elevated contaminant levels and enriched isotopic ratios were determined in one individual whale sampled in the Scottish Western Isles compared to the others suggesting marine mammal based dietary influences. The potential application of isotopic ratios to model contaminant uptake, enantioselective enrichment and accumulation is demonstrated. Data are presented which provide information on enantioselective enrichment factors (EFs) for o,p'-DDT, alpha-HCH and toxaphene congeners CHB26 and CHB 50. This dataset further improves the current database on reported levels of a number of contaminants and provides additional background information on potential metabolic processes in killer whales from British and Irish waters.     

Polycyclic musks in green-lipped mussels (Perna viridis) from Hong Kong

Six polycyclic musk compounds [Cashmeran (DPMI), Celestolide (ADBI), Phantolide (AHMI), Traseolide (ATII), Tonalide (AHTN), and Galaxolide (HHCB)] were analysed in marine green-lipped mussels (Perna viridis) from Hong Kong. ADBI, HHCB and AHTN were detected in almost all samples, while AHMI, ATII and DPMI were not detected. Concentrations of ADBI, HHCB and AHTN in mussels ranged from below detection limit-0.0743 (mean: 0.0246), 0.247-6.08 (mean: 1.15) and 0.0591-0.738 (mean: 0.190)mg/kg lipid weight, respectively. Mussels from two sampling sites in central Victoria Harbour contained the highest total polycyclic musk levels, suggesting that these waters are heavily influenced by domestic sewage. Concentrations of HHCB and AHTN detected in the mussel samples were the second highest and the highest levels, respectively, compared to global concentrations. A preliminary risk assessment indicated that HHCB and AHTN in mussels pose little or no threat to the health of shellfish consumers. Nevertheless, more comprehensive studies are required to further assess the ecological and human health risks associated with polycyclic musks.     

利用组件GIS和构件技术建立林业GIS系统

随着计算机技术的进步,以林业GIS系统为代表的林业信息化进程得到前所未有的发展,但也存在着工程重复建设的问题,没有按统一的标准、规范和要求进行,特别是林业专业模型的实现一直进展缓慢.本文将软件复用的思想引入到林业GIS系统专业模型的构件设计与开发上,通过组件GIS技术与构件技术相结合的方法实现林业GIS系统功能的复用,...     

北京绿化隔离地区绿化而积监测及分析

为有效监督北京市绿化隔离地区的绿化进展情况,北京市测绘设计研究院实施了对绿化隔离地区2000～2003年现状绿地的钉桩.应用地理信息系统叠加(Overlay)技术,产生了不在绿化隔离地区内的绿化地块以及虽在绿化隔离地区内但与规划严重不符的绿地地块;对各区的规划绿地指标、实际绿地指标、不合格地块以及地块合格率进行统计.研究表明2000～2003年全市绿化隔离地区范围内新增绿化面积89 km2,基本完成了政府任务.政府应加强对绿化工作完成数量和质量尤其是质量的监管.各区完成绿地程度不同地存在与规划不一致的现象.     

应用三次样条法进行林地面积量算的研究

本文通过对各种面积量算方法的比较研究,提出了各种量算方法的优缺点和适应性。比较了仪器实测与图上量测林地面积精度之间的关系,得出图上量测林地面积因不可避免的存在系统误差而其精度要比仪器实测林地面积所得精度要低的结论。最后本文着重推导了利用三次样条法测定林地面积的数学原理,并对梯形公式法、辛普生法、等距三次样条法和三次样条法对于林地面积边界不规则曲线的拟合原理进行了分析比较,结合对中国科协北京绿化基地地块同精度的GPS测量试验结果运用上述四种方法量算面积的精度结果进行比较,可知三次样条法量算林地面积的精度最高,且该方法便于差分GPS(RTDGPS)作业。     

GPS RTK联合全站仪在唐山煤矿塌陷区测图中的应用与研究

GPS测量技术能够实时地提供测站点厘米级的3维坐标,速度快、精度高,但应用范围受天气、地域条件、卫星运行等环境因素限制[1]。全站仪是自动化程度很高的野外测量仪器,精度高、应用广,但受通视条件、测量距离等因素制约。本文根据在唐山煤矿塌陷区测量中的测量区域成带状分布、面积广、密集的防护林让卫星信号变弱的实际情况讨论了两者的有机结合,探索出GPS RTK与全站仪相配合进行塌陷区测量的作业方法,使用这两种仪器在实际测量中,提高了测图的工作效率、减少了外界的干扰、降低了作业人员的劳动强度,点位精度得到有效的保证,并对遇到的碎部点精度问题提出了RTK与全站仪相互检测的方法。在此基础上,研究将卫星接收机与全站仪集成,研制物理结构和数据处理一体化的低成本智能化仪器,解决在特种环境下定位效率低、精度低、可靠性差、干扰因子多的瓶颈技术问题,实现特种环境中高精度、低成本、实时定位与精准监测的功能。     

我国森林植被遥感调查及建库研究

我国森林植被的覆盖程度受到土壤、气候、海拔、人为等各种因素的互相影响,为了能够遵循＂适地适树＂原则而更加精确在不同地区栽种适宜的树种从而提高我国森林覆被率,利用遥感技术对全国森林植被及其所生长的条件进行调查是重中之重。本文以全国范围为研究区域,利用MODIS数据对土壤、植被及气候数据进行提取,引入梯形网格,对全国进行等经纬度的网格划分,利用ArcGIS,ENVI等软件绘出我国土壤类型、N、P元素及有机质含量、年降雨量、年最高温度及最低温度的温度等值线,再利用数据挖掘技术提取与森林植被覆盖率相关的影响因子得出我国现阶段森林植被覆盖图,计算出我国现有林地面积并对影响森林植被覆盖的因子进行数据库的录入。