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351.
Alan M. Jones Roy M. Harrison 《Atmospheric environment (Oxford, England : 1994)》2006,40(40):7733-7741
Proposals from the European Commission have raised the possibility that Member States may be able to subtract the concentrations of natural components of airborne particulate matter from measured concentrations when evaluating compliance with EU Limit Values. By applying the pragmatic mass closure model [Harrison et al., 2003. A pragmatic mass closure model for airborne particulate matter at urban background and roadside sites. Atmospheric Environment 37, 4927–4933] to chemical composition data for PM10, it has been possible to estimate the concentrations of natural sea salt, strongly bound water and secondary organic carbon (which is assumed wholly biogenic) to the measured mass of PM10. Because of the difficulty in distinguishing between natural and anthropogenic crustal dusts, the contribution of natural windblown dust and soil has not been accounted for. When the natural components are estimated for two urban and one rural site in the UK, the long-term mean PM10 concentration is reduced by between 5.2 and 7.3 μg m−3. The number of exceedences of the 50 μg m−3 24-h limit value falls dramatically from 54 to 21 (from a total of 291 days) at an urban street canyon site, 7 to 3 (n=292 days) at an urban background site and from 8 to 0 (n=241 days) at a rural site when using gravimetric PM10 concentrations. The calculations have also been performed using PM10 concentrations measured by TEOM increased by a factor of 1.3 as recommended by the European Commission as an interim means of estimating gravimetric equivalency, and the number of exceedences of the 24-h limit value fell from 92 to 47 (from a total of 291 days) at the urban street canyon site, from 11 to 3 (n=292 days) at the urban background site and from 6 to 3 (n=241) at the rural site. Clearly, therefore, application of this proposed measure would make a very major difference to the likelihood of compliance or otherwise with the 24-h limit value for PM10. 相似文献
352.
353.
通过实时在线监测了2018年11月27日~2019年1月15日北京市城区PM2.5、水溶性无机离子(Na+、NH4+、K+、Mg2+、Ca2+、F-、Cl-、NO2-、NO3-、SO42-、PO43-)、碳质组分(有机碳OC、元素碳EC)的质量浓度以及气态污染物浓度和气象要素,收集整理了近20年北京市冬季PM2.5、主要离子组分以及碳质组分浓度,分析研究了1999~2018年北京市冬季PM2.5、离子、碳质组分的变化特征,重点探讨了监测期间清洁日与两个典型重污染事件PM2.5及其组分的演变特征.结果表明:研究期间PM2.5浓度为53.5μg/m3,达到近20年北京市冬季较低值,且大气主要污染源由煤烟型污染源转变为燃煤型与机动车尾气复合型污染源.监测期间,湿度高、微弱的西南风导致重污染产生,清洁日、污染事件I与污染事件II PM2.5平均浓度分别为32.5,138.9,146.8μg/m3且不同时段PM2.5日变化趋势存在差异.各离子浓度变化为:NO3- > NH4+ > SO42- > Cl- > K+ > Ca2+ > Na+ > PO43- > F- > NO2-~Mg2+,总水溶性离子浓度为24.6μg/m3占PM2.5总浓度的46.0%,其中SNA浓度占总离子浓度的83.7%,是离子中最主要的组分.碳质组分浓度达到近二十年北京市冬季最低值,变化为:一次有机碳POC > EC > 二次有机碳SOC,OC与EC相关系数达到0.99,一次燃烧源对污染过程有较大贡献.NH4+在清洁日与污染II中富集,主要以(NH4)2SO4、NH4NO3和NH4Cl形式存在,在污染I中较少,仅以(NH4)2SO4和NH4NO3存在.在污染I和II期间,SO42-的形成昼夜均受相对湿度与NH3影响;NO3-的形成白天受O3与NH3的影响,夜间受相对湿度和NH3的影响. 相似文献
354.
塔里木盆地北缘绿洲4种土地利用方式土壤有机碳组分分布特征及其与土壤环境因子的关系 总被引:3,自引:0,他引:3
为明确干旱区土壤有机碳各组分分布状况,进而合理地开发与利用,解决土地利用效率低下问题,以塔里木盆地北缘盐碱地、天然林、沙地、30 a棉田这4种不同土地利用方式土壤为研究对象,分析不同土地利用方式土壤有机碳、微生物量碳、可溶性有机碳、易氧化有机碳的分布状况,结合冗余分析探索其与土壤环境因子的关系.结果表明,SOC在天然林表现出最高值(1.92 g·kg~(-1)),在沙地随土层增加而增加,在其他土地利用类型整体呈现下降趋势;MBC在天然林表现出最高水平,且随土层深度增加而降低,在其他土地利用类型无明显变化趋势.DOC含量最高值和最低值分别出现在天然林和30 a棉田的80~100 cm层(分别为143.23 mg·kg~(-1)和30.00 mg·kg~(-1)),在天然林中随土层深度增加而增加,在盐碱地中随土层深度增加而降低且不同土层含量均表现出显著差异(P0.05).EOC含量在不同土地利用类型和不同土层中未表现出明显规律.将各有机碳组分进行敏感性分析得出:MBC对不同土层最为敏感,DOC对土地利用变化最为敏感.通过冗余分析得出各有机碳组分与土壤含水量、全氮、p H呈正相关关系,与土壤容重、电导率呈负相关关系.土壤环境因子对各碳组分含量的重要性排序为:土壤容重含水量电导率土壤氮p H,即容重和含水量为影响干旱区有机碳组分的主要因子. 相似文献
355.
通过GC-MS分析,研究了气化温度和气料比S/B(水蒸气与污泥的质量比)对污泥气化焦油中芳香烃、含氮化合物、含氧化合物和含硫化合物分布特征的影响变化规律.结果表明:污泥气化焦油中芳香烃的化学组分主要为菲类、萘类、芴类和联苯类化合物,其中S/B值1.1、1.5和1.9时菲类和萘类化合物的产率在850℃均达到最大值,S/B值1.5和1.9时芴类产率随气化温度的升高而呈先升高后降低,而800℃时联苯类产率则随S/B值的增加而呈先升高后降低,其最高产率为1.284g/kg.含氮化合物以吲哚类化合物为主,其产率在S/B值为1.5和1.9时均随气化温度的升高而呈降低趋势;含氧化合物中主要为酚类化合物,其产率在750℃时随S/B值的升高而升高,其最高产率3.103g/kg;含硫化合物主要为4,4'-双(四氢噻喃),且仅在850℃、S/B值为1.9气化条件下检出产率为0.263g/kg的萘并[1,2-b]噻吩. 相似文献
356.
This paper considers the use of meiofauna (benthic metazoa 45 to 500 m in size) as biological indicators for monitoring marine environmental health. To date, this abundant and ubiquitous group of invertebrates has been largely neglected in applied sampling programmes; instead, emphasis has been placed upon more conspicuous biological components such as seagrass, macrofauna and epiphytes. In an attempt to redress this balance, this paper sets out three objectives: (1) to explain the reasons for selecting biological response indicators from across the whole spectrum of phylogenetic organisation, (2) to summarise those aspects of meiofaunal life-history and demography that render this group suitable for monitoring anthropogenic pollution and disturbance, (3) to suggest how to optimise the inclusion of meiofauna in monitoring programmes so that they provide maximum information for management purposes. To achieve these objectives the environmental impact assessment framework of Ward and Jacoby (1992) is adopted as a matrix into which the relevant components of meiofaunal ecology are fitted. Using this matrix, meiofauna are shown to have advantages that include their sessile habit, high species diversity, short generation time, direct benthic development and ubiquitous distribution. Disadvantages include their small size, high level of spatial and temporal variability, the potential cost of sample processing and the limited taxonomic literature accessible to non-specialist workers. The paper concludes with a discussion of sampling strategies and methods of analysis that may be used to efficiently incorporate meiofauna as biological response indices into environmental monitoring. Emphasis is placed on cost-effective techniques such as taxonomic minimalism. 相似文献
357.
Relationships of Human Disturbance, Bird Communities, and Plant Communities Along the Land-Water Interface of a Large Reservoir 总被引:1,自引:0,他引:1
We examined the relationships of humanactivity, bird communities, and plant communities along theland-water interface of Lake Texoma, a large human-madereservoir on the Texas-Oklahoma border. Measurements ofhuman activity, plant surveys, and bird surveys wereperformed at 40 paired transects, one with humandisturbance, the other undisturbed. Both principalcomponents and correspondence analyses of bird-survey dataseparated disturbed sites from paired undisturbed sites, andtypical disturbance-tolerant species from those lesstolerant of human activity. Compared to undisturbed sites,disturbed sites tended to have more individual birds persurvey, pavement, and mowed lawns, and less canopy,vegetation volume, and vegetation vertical diversity. Aprincipal components analysis of quantitative disturbancemeasurements revealed that most bird and plant measures werehighly correlated with the first disturbance component. However, the correlation between birds and human activitywas much stronger than that between birds and plants, orbetween plants and disturbance. Our data suggest that bird-species composition is regulated more by human activity thanby plant-community composition. Also, in this system, birdcommunities are a better choice than plant communities toindex the effect of human disturbance. To maintain regionaldiversity of both birds and plants, undisturbed areas shouldbe maintained around reservoirs. 相似文献
358.
359.
由于因子分析法对解决多指标问题具有良好的适用性,可用于资源与环境可持续发展的综合评价,因此利用江苏省近年来的数据进行了实证分析,并提出了对策和措施以进一步推进江苏省资源与环境的可持续发展. 相似文献
360.