Microbial Fe(III) Reduction in Acidic Mining Lake Sediments after Addition of an Organic Substrate and Lime

To elucidate the role of Fe(III) reduction in mining lake sediments amended with organic substrates, we performed a large (10 m diameter) enclosure experiment in which sediments were amended with Carbokalk, a waste product from sugar industry containing organic carbon and lime. Fe(III) reduction rates were determined monthly by measuring the accumulation of Fe(II) in the sediments in the field. Fe(III) reduction rates were also determined by incubating sediment samples with synthetic Fe(III) oxyhydroxide under in situ temperature in the laboratory. Sulfate reduction was selectively inhibited in the Fe(III) reduction experiments by addition of sodium molybdate. Sulfate reduction was measured by accumulation of reduced inorganic sulfides in the field and by ³⁵S radiotracer using a core injection technique. Sediment incubation and determination of sulfate reduction rates with radiotracer showed that sulfate reduction and direct microbial Fe(III) reduction occured simultaneously in the upper centimeters of the sediments and that both processes contributed to alkalinity generation. However, Fe(III) reduction was the initial process and rates were at least 3.5 fold higher than sulfate reduction rates. The results indicate that the presence of suitable anions for Fe(II) precipitation as carbonate or sulfide is needed in order to prevent loss of potential alkalinity by Fe(II) diffusion and reoxidation in the water column.     

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.     

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.     

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.     

浙江省地质灾害现状及防治措施

概述了浙江省地质灾害的发生背景及灾害现状;从行政管理与技术治理两方面提出了地质灾害防治措施。     

西藏浪卡子至洛扎公路沿线的地质灾害

西藏浪卡子至洛扎公路是西藏山南地区环线公路的西段，全长120km，集交通、外交、军事于一体。由于公路位于高寒、新构造运动强烈的地区，特殊的地质背景、气候因素和地理环境，为该地区地质灾害的发生孕育了良好的条件。公路沿线的地质灾害主要有泥石流、滑坡、坍岸等，各类地质灾害影响公路总长7248m，其中泥石流42条，滑坡1处，坍岸12处。各类地质灾害对公路的建设和运营构成了极大的危害，针对各类地质灾害发育的特点。结合当地的环境和公路的等级要求，提出了切实有效的治理措施。     

噪声背景值对噪声监测结果的影响

环境背景噪声对边界噪声监测结果有没有影响,有多大的影响,本文就此作了一些探讨,就背景噪声对监测结果修正提出了一些看法。笔者认为：测量值与背景的差值超过１０分贝时,可以忽略背景值对测量结果的影响;测量值与背景值差值在３－１０分贝时,根据公式Ｌ测＝１０Ｌｇ「１０＾０．１Ｌ实际＋１０＾０．１Ｌ背」计算出经背景值修正后的实际值Ｌ实际;当测量值与背景值的差值小于３分贝时,应重新选时间测定。     

渝东南典型地质高背景区土壤重金属来源解析及污染评价

为了解渝东南典型地质高背景区土壤重金属的污染特点,解析其污染来源并针对性地提出风险管控建议,在重庆市酉阳县北部兴隆镇和木叶乡共采集土壤表层样品(0～20 cm)211件,分析了表层土壤8种重金属(As、 Cd、 Cr、 Cu、 Hg、 Ni、 Pb和Zn)的含量及土壤pH值,采用数理统计、污染负荷指数、潜在生态风险指数、相关性分析和正定矩阵因子分解(PMF)模型等技术,研究了表层土壤重金属的含量及空间分布特征,并开展了污染评价和重金属的来源解析.结果表明,表层土壤重金属平均含量均超过重庆市土壤背景值,呈现出不同程度的富集情况,其中Cd超《土壤环境质量农用地土壤污染风险管控标准》(GB 15618-2018)中筛选值的比例高达83.41%,超管制值的比例为7.58%,潜在风险较高.污染负荷指数法评价结果显示研究区整体呈轻微污染,潜在生态风险指数评价结果显示研究区整体生态风险较高,其中重金属Hg、 Cd和As的贡献率分别为50.27%、 28.63%和11.70%.PMF结果显示研究区土壤中重金属的来源主要3种,即自然母质源、农业源和工业活动及交通排放的混合源,所占比例分别为40.49%、...     

基于地球化学基线的土壤重金属污染风险评价

在实地采样分析的基础上,采用标准化方法确定浑河冲洪积平原表层土壤中Cu、Pb、Zn、Ni、Cr、As、Cd这七种重金属的地球化学基线,分别以土壤环境背景值和地球化学基线为参比值,结合müller地积累指数法和Hkanson潜在生态风险指数法对污染现状和潜在生态风险进行评价。结果表明:其中Pb和As污染较为严重,七种重金属均具有不同程度的潜在生态风险,Cd是具有相对较高潜在生态风险的污染因子,45%采样点土壤多种重金属的潜在生态风险达到中等。