应用遥感与地理信息系统评价公路地质背景的方法

在公路的预设计阶段 ,需要快速、廉价的公路地质背景信息 ,遥感与GIS技术正能满足这种要求。本文认为利用遥感与GIS评价公路地质背景应包括地理因素、地质条件、水文地质与工程地质等因素 ,空间评价应从公路分段评价、重点工程评价、地质灾害分布三方面进行。本文介绍了应用这种方法对贵州省镇兴公路关岭至兴仁段的地质背景评价     

我国土壤中稀土元素背景值特征

本文报道了中国土壤15个稀土元素的背景含量、共生组合关系及稀土元素的分异系数和分布模式,讨论了41种土类,35个省市行政区域土壤稀土元素背景含量的差异及其原因.     

Perfluorocarbon background concentrations in Europe

Five studies of the background level of several perfluorocarbon compounds in Europe are here presented together with measurements from the European Tracer Experiment (ETEX). The tracers used during the two ETEX tracer releases were the perfluorocarbons (PFCs); perfluoromethylcyclohexane (C₇F₁₄, PMCH) and perfluoromethylcyclopentane (C₆F₁₂, PMCP). Their background concentrations were detected by using both passive and active sampling techniques, to define the spatial and temporal variation of the PFCs over Europe. Also the background variations of four isomers of the PFC compound perfluorodimethylcyclohexane (C₈F₁₆, PDCH) were studied. The results were compared to other PFC tracer studies in the U.S.A. and Europe. The mean and median values of the measured PFCs were found to vary slightly and randomly in space and time. They were found to be higher and to have a larger standard deviation than the measurements from the American studies. The background concentrations were still found to be low and stable enough for PFCs to be highly suitable for use in tracer studies. The following concentrations were found: PMCP; 4.6±0.3 fl ℓ^-1, PMCH: 4.6±0.8 fl ℓ^-1, ocPDCH: 0.96±0.33 fl ℓ^-1, mtPDCH: 9.3±0.8 fl ℓ^-1, mcPDCH: 8.8±0.8 fl ℓ^-1, ptPDCH: 6.1±0.8 fl ℓ^-1. A study of the correlation between the measured PFC compounds showed a significant correlation between most of the compounds, which indicate that there are no major PFC sources in Europe.     

Monitoring Of Vehicles Derived Particulates Using Magnetic Properties Of Leaves

Biomonitoring of vehicle-derived particulates is conducted by taking magnetic measurements of roadside tree leaves. Remanent magnetization (IRM_{300 mT}) of more than 400 Delbergia sissoo leaves was determined and IRM_{300 mT} normalized for the leaf area. The normalized 2-D magnetization as shown by results is dominantly controlled by the tree's distance to the road. The spatial and temporal variations of vehicle-derived particulates were mapped using magnetic analysis. 2D-magnetizations values were higher for leaves collected adjacent to major road sections than for those from village road suggesting vehicle emissions, rather than resuspended road dust, as the major cause of magnetic particles of roadside tree leaves. Vehicles derived particulates are responsible for tree leaf magnetism, and the leaf magnetizations values fall significantly from high values proximal to the roadside to lower values at the distal side. This suggests the ability of trees to reduce particulates concentrations in the atmosphere. The rainfall produces a net decrease in the leaf magnetic dust loadings.     

Air Quality in Norwich, UK Multi-Scale Modelling to Assess the Significance of City, County and Regional Pollution Sources

Norwich is the eastern most city in the United Kingdom. Despite a population of only 100,000 and very little local industry, studies have shown that the city experiences levels of nitrogen dioxide, ozone, particulates and sulphur dioxide exceeding the UK Air Quality Standards. Because of Norwich's situation within a large, predominantly rural area a large non-resident workforce is one factor that contributes to large, often very congested traffic flows. The city's location close to the European mainland also exposes it to polluted airmasses transported from the continent, especially in the case of particulates and ozone. In order to assess the relative contributions of local and regional sources, data from rural and urban monitoring sites are to be used in conjunction with ADMS-Urban and the UK Meteorological Office's NAME model.     

厂界噪声背景值修正问题的讨论

在实际计算中 ,按照国家标准 (GB1 2 3 4 9-90 )扣除背景噪声值常常会与待测声源的实际声级值产生较大的误差。利用对噪声源的实际测量数据 ,探讨这种误差产生的原因及结果 ,并建议今后采用计算结果列表查找或者直接用公式计算的方法扣除背景噪声 ,以消除因数据处理不当而产生的误差。     

核算间接冷却水污染当量数的研讨

针对间接冷却水的特点和核算其污染当量数过程中存在的问题 ,阐述了间接冷却水的界定、水源水的采样监测技术、本底值的扣除以及超标排放的判别等环节的技术要求和注意事项 ,并就与之密切相关的几个问题展开了讨论 ,为核算间接冷却水的污染当量数提供了一定的参考依据。建议增加水温排放指标 ,以切实控制间接冷却水造成的主要污染——热污染     

石墨炉原子吸收法测定海水中Pb——以0.1NHNO3抗坏血酸-NaI作基体改进剂

研究了以0.1N HNO3抗坏血酸-NaI作基体改进剂测定海水中Pb的方法,讨论并确定了测定的最佳条件.结果表明在仪器最佳条件下,以0.1N HNO3抗坏血酸-NaI作基体改进剂可有效消除海水基体干扰,检出限为1.2μg/L,实际样品相对标准偏差小于4%,加标回收率为95%～104%.     

武汉20世纪90年代暴雨异常的物理环境变化背景探讨

根据武汉1951－2000年50年暴雨日数资料，应用Mann-Kendall统计方法对暴雨邓列进行年限突变检验。揭示出武汉暴雨在1979年发生突变，20世纪80年代后暴雨出现频数明显上升，强度增大，90年代达到最大，同时指出武汉20世纪90年代暴雨日数和暴雨量异常的显著特征，着重从西太平洋副热带高压，阻塞高压，太平洋海温等重要物理环境因子的突变出发，探讨造成20世纪90年代武汉暴雨异常的物理变化背景，结果表明，在武汉暴雨异常多的90年代与暴雨异常少的70年代，所对应的大气，海洋环境背景显著不同，90年代北半球500hPa月平均高度场是处于几十年中正异常最大的阶段，西太平洋副热带高压持续偏南，偏强，西伸脊点偏西，东亚中高纬度环流异常，维持稳定的阻塞高压形势，赤道东太平洋海温（SST）出现最大正距平，为近50年来的异常增温时期，厄尔尼诺（ENSO）事件发生频繁。     

Nitrogen interception in floodwater of rice field in Taihu region of China

A field experiment located in Taihu Lake Basin of China was conducted,by application of urea or a mixture of urea with manure, to elucidate the interception of nitrogen(N)export in a typical rice field through"zero-drainage water management"combined with sound irrigation,rainfall forecasting and field drying,N concentrations in floodwater rapidly declined before the first event of field drying after three split fertilizations,and subsequently tended to retum to the background level.Before the first field drying,total particulate nitrogen(TPN)was the predominant N form in floodwater of plots with no N input,dissolved inorganic nitrogen(DIN)on plots that received urea only,and dissolved organic nitrogen(DON)on plots treated with the mixture of urea and manure.Thereafter TPN became the major form.No N export was found from the rice field,but total nitrogen(TN)of 15.8 kg/hm~2 was remained,mainly due to soil N sorption.The results recommended the zero-drainage water management for full-scale areas for minimizing N export.