我国大气环境中汞污染现状

综述了最近几十年中国大气汞的排放、分布、传输和沉降方面的研究.中国人为源每年汞排放量为世界最高,达到500~700t左右,超过全球人为排放量的25%~30%,并以每年4.2%的速度增加.通过已有观测和模型估算,中国来自自然地表过程(包括裸露地、地表水和森林土壤等)的汞排放量与人为源汞排放量相当,不容忽视.中国城市、农村和偏远地区大气汞浓度分布和变化范围很大,城市地区的总气态汞(TGM)浓度是北美和欧洲地区相似城市类型TGM的1.5~5倍左右;中国城市颗粒态汞(PHg)浓度比北美和欧洲地区高出2个数量级;中国沿海地区和偏远的背景区TGM、PHg和活性汞(RGM)低于中国内地城市地区,但是也明显高于背景值和北美和欧洲地区.相应地,高含量的大气汞浓度导致大量的大气汞沉降到地表,城市地区和背景区大气汞沉降分别比北美地区高出1~2个数量级和1~2倍.     

基于CALPUFF大气扩散模式空气环境总量控制对策研究

本文基于CALPUFF大气扩散模式与MM5气象模拟技术,深入开发、解析污染源普查数据,通过对主要污染物源解析和环境质量实测数据拟合,分析区域污染源排放对空气环境质量的影响,研究各类污染源总量控制多种方案,最终提出与环境容量相适应的总量分配方案和相关控制对策,并为包头市中心城区环境质量达标制定控制方案,为科学利用区域大气环境容量提供技术支持。     

Chlorophyll-bleaching by atmospheric pollutants and sunlight

The Science of Nature -     

戈壁荒漠上大气稳定度分类方法探讨和大气湍流变化特征

为了研究戈壁荒漠上大气扩散规律和边界层结构。根据气象铁塔常规气象观测和湍流观测的结果,分析戈壁荒漠大气边界层温度梯度和湍流变化的一些特征。分析结果表明,同其它下垫面相比温度梯度日变化大,与风速的关系较为奇特。采用通常P─T分类标准直接应用该地区作大气稳定度分类,与实际情况有较大误差,须经适当修改后才能使用。湍流统计量的日夜变化强,表明戈壁荒漠下垫面的热力作用对湍流混合的助长和抑制。这些特征为进一步分析戈壁荒漠上大气边界层结构和大气扩散研究提供了依据。     

大气中有机硫酸酯研究进展

介绍了国内外大气环境中有机硫酸酯（OSs）的研究现状,分别简述了OSs的理化特征及影响因素、不同分析方法及对应特征、OSs的分类、来源及形成机制、OSs在大气中的转化及归趋等内容,并对目前常见的OSs分子式和结构式以及三种典型的形成机制进行了归纳总结.聚焦目前OSs研究的前沿领域,探讨了目前OSs研究中有待解决的热点问题,并对未来的研究工作提出建议与展望.     

北京大气沉降样品中的PCBs

采集了4个北京大气沉降样品,包括3个总沉降与1个湿沉降样品.利用高分辨率气质联用仪(HRGC-HRMS),参照国际标准方法分析测定了其中的多氯联苯(PCBs)含量.总沉降样品的PCBs含量水平为4.47～7.08ng·g-1(平均为5.52ng·g-1)和TEQ为0.55～5.43 pg·g-1(平均为2.27 pg·g-1).湿沉降样品含量水平为15.02 ng·g-1,其TEQ为2.87 pg·g-1.首钢样品的TEQ远高于其它3个样品.根据我国大气降尘数据,粗略估计北京PCBs大气沉降通量平均值为67.9 ng·m-2·m-1和TEQ平均通量为27.9 pg·m-2·m-1.首钢样品中,IUPAC编号为77的类二(噁)英PCBs含量异常高,但TEQ仍以编号为126的PCBs所占比例最高.随着取代氯原子数的增加,同族体的含量逐渐降低.     

大气过氧自由基测量研究进展

过氧自由基是大气中重要的氧化剂 ,其浓度的测定对于深入理解大气化学过程具有重要意义。本文总结了二十多年的研究成果 ,论述了大气过氧自由基测量的研究进展 ,介绍了带基体分离的电子自旋共振技术、远红外及毫米波发射光谱技术、激光诱导荧光技术以及化学放大法等常用测量方法及测量结果 ,并展望其未来的发展。     

大气中痕量烯烃的观测与分析

采用两步深冷冻浓缩自动进样系统,配以气相色谱/质谱联机对北京大气中的烯烃进行了连续观测.结果表明,北京市大气中浓度最高的烯烃为C4烯烃,2000年日平均浓度为3.5×10^-9±3.0×10^-9(V/V).2h平均浓度的日变化在春、夏、秋、冬4季各有特点,但基本上呈双峰型模态,峰值分别出现在上午和傍晚;在季节变化中,1、10月份大气中C4烯烃的浓度最高,为6.0×10-9±1.2×10^-9(V/V),3、9月份最低,为0.31×10^-9±0.13×10^-9(V/V).     

大气气溶胶干沉降研究进展

从干沉降速度定义出发,综述了过去几十年来国内外在气溶胶干沉降实验技术和理论方面的主要进展.气溶胶粒子从大气向地表沉降的过程决定于颗粒物的粒径、密度和空气粘性系数,同时受空气动力学阻力、粘滞层阻力和表面收集阻力的影响,这些阻力分别与大气层温度、风速、相对湿度等微气象条件密切相关.获取干沉降速度的方法主要有示踪法、梯度法和涡流相关法等.风速的三维瞬时量、动能、摩擦速度、温度和涡旋扩散系数可由超声风速温度仪测定.由于气溶胶具有很宽的粒径谱分布,通常使用几台仪器（如串联式多级采样器、空气动力学粒径谱分布仪和扫描电迁移率颗粒物粒径谱仪）进行联合测量.干沉降参数化方案中,基于斯托克斯定律的物理模型着重于平衡重力、浮力和阻力的作用,半经验方案则进一步考虑了大气湍流、分子运动以及表面捕获机制包括布朗扩散、碰撞、截留、反弹、热泳和扩散泳.然而,参数化方案预测结果在某些粒径段与外场测量数据仍存在显著差异.结合目前干沉降研究存在的问题,对今后气溶胶干沉降的研究方向和技术方法进行了展望.     

大气环境腐蚀性因素的相关性

通过相关性数据处理和模糊聚类分析,发现影响大气环境腐蚀性的21种环境因素在相关系数大于0.54的情况下,可明显地聚为5类在此基础上,进一步通过对逐个因素的分类能力的特征评价,选取大气环境腐蚀性的主要因素（RH＞80％时数,SO₂沉积速度,水溶性尘降,Cl^－沉积速度,NO₂浓度）,进而在特征空间中进行镀锌层样本的大气环境腐蚀性预测和考评,为今后实现我国大气环境腐蚀性等级评判提供依据．     

林地大气氮沉降的观测研究

2004年11月～2005年10月,以小叶栎林地为研究对象,研究了大气沉降氮通量及其3种物理形态(气态、颗粒态、雨水)4种氮化物(NH₃,NH₄⁺-N,NO₃^--N,NO₂)的相对贡献.结果表明,大气氮沉降总量为82.8kg/(hm²·a),其中干沉降占67%;NH3-N是氮沉降的主要贡献者,占干沉降的82%,占总氮沉降量的56%;还原态的氮化物(NH₃,NH₄⁺-N)占总氮沉降量65%.     

The changing winds of atmospheric environment policy

Atmospheric environmental policies have changed considerably over the last several decades. Clearly the relative importance of the various issues has changed over half a century, for example from smoke, sulphur dioxide and photochemical smog being the top priorities to greenhouse gases being the major priority.The traditional policy instrument to control emissions to the atmosphere has been command and control regulation. In many countries this was successful in reducing emissions from point sources, the first generation issues, and to a lesser extent, emissions from mobile and area sources, the second generation issues, although challenges remain in many jurisdictions. However once the simpler, easier, cheaper and obvious targets had been at least partially controlled this form of regulation became less effective. It has been complemented by other instruments including economic instruments, self-regulation, voluntarism and information instruments to address more complex issues including climate change, a third generation issue.Policy approaches to atmospheric environmental issues have become more complex. Policies that directly focus on atmospheric issues have been partially replaced by more integrated approaches that consider multimedia (water, land, etc.) and sustainability issues.Pressures from stakeholders for inclusion, greater transparency and better communication have grown and non-government stakeholders have become increasingly important participants in governance.The scale of the issues has evolved from a local to national, regional and global scales. Consequently the approaches to atmospheric environmental policy have also been amended. The international dimensions of atmospheric issues have grown in prominence and challenge governance and politics with pressures for international cooperation and harmonisation of policies. This is reducing the policy flexibility of national governments.Partially in response to these changes, to manage environmental risks and protect their brands, leaders in the corporate sector have generally found it beneficial to increase responsibility and accountability, including establishing corporate environmental policies, environmental management systems, risk management, sustainability reporting and other measures.This analysis clearly identifies that these changes are inter-related. Acting together they have transformed the way that atmospheric issues are governed in the last several decades in developed countries. Together they have led to governments in many developed countries vacating leadership roles and becoming increasingly managers of the policy process. As the leadership role of governments has been partially eroded, governments are more reliant on persuasion and diplomacy in their relations with stakeholders. As a consequence, governance arrangements have become more complex, multilevel and polycentric.     

Wood-based building materials and atmospheric carbon emissions

This study investigates the global impact of wood as a building material by considering emissions of carbon dioxide to the atmosphere. Wood is compared with other materials in terms of stored carbon and emissions of carbon dioxide from fossil fuel energy used in manufacturing. An analysis of typical forms of building construction shows that wood buildings require much lower process energy and result in lower carbon emissions than buildings of other materials such as brick, aluminium, steel and concrete. If a shift is made towards greater use of wood in buildings, the low fossil fuel requirement for manufacturing wood compared with other materials is much more significant in the long term than the carbon stored in the wood building products.As a corollary, a shift from wood to non-wood materials would result in an increase in energy requirements and carbon emissions.The results presented in this paper show that a 17% increase in wood usage in the New Zealand building industry could result in a 20% reduction in carbon emissions from the manufacture of all building materials, being a reduction of about 1.5% of New Zealand’s total emissions. The reduction in emissions is mainly a result of using wood in place of brick and aluminium, and to a lesser extent steel and concrete, all of which require much more process energy than wood. There would be a corresponding decrease of about 1.5% in total national fossil fuel consumption. These figures have implications for the global forestry and building industries. Any increases in wood use must be accompanied by corresponding increases in areas of forest being managed for long term sustained yield production.     

湛江:创新思路力促减排出实效

近年来,湛江市的环境保护工作取得了卓越的成就,根据城市综合整治定量考核结果显示,"十五"以来湛江市的环境质量一直居于全国47个环保重点城市的前列.     

大气红外辐射超高光谱探测仪临边探测—污染气体的反演精度和光谱通道评估

利用RFM模式,模拟计算了在研仪器—大气红外辐射超高光谱探测仪的临边探测模式下大气污染气体体积混合比的权重函数.结合仪器的可探测亮温阈值（0.3 K）,利用权重函数线性化方法,计算并分析了6种大气状态下,气体混合比廓线在不同反演精度条件下可获得的光谱通道数随切点高度的变化,并给出了可用光谱通道在不同切点高度的位置.结果表明,随着相对反演精度的降低,可用光谱通道数量增加,除热带大气外,其它5种大气在10%臭氧反演精度和5%甲烷反演精度条件下有足够的通道,可用于反演4.6 km以上的混合比廓线.CO在15%反演精度条件下,6种大气均能获得反演6.9 km以上廓线的光谱通道.近地面切点高度反演比较困难,很难获得较高的反演精度.可用光谱通道位置与气体吸收线位置特别是峰值区域一致,也与气体模拟亮温高值区一致.     

四川盆地大气NO2特征研究

利用臭氧观测仪(OMI)卫星遥感反演的NO2柱密度数据,分析了2004年以来四川盆地对流层NO2柱密度和总NO2柱密度的时空特征.结果表明,对流层NO2柱密度和总NO2柱密度呈逐渐上升的趋势,年平均增长率分别约为5.14%和3.42%,而且对流层NO2柱密度的变化特征和总NO2柱密度的相似(r =0.91).春、夏季对流层NO2柱密度和总NO2柱密度明显大于秋、冬季,对流层NO2柱密度与总NO2柱密度比率的最小值和最大值分别出现在6月和12月,分别为0.51和0.66,比率的变化特征呈现了人为排放影响的特征.在重庆市、成都市等经济较为发达的城市地区出现NO2柱密度高值中心,对流层NO2柱密度更为明显,多年平均值分别达10.52′1015和8.92′1015 molec/cm2.对流层NO2柱密度和总NO2柱密度的变化呈现强的正相关,大部分地区的相关系数>0.95(比率>0.5),特别是在成都市和重庆市等经济较为发达的城市地区,相关系数接近1,比率达到0.8以上,突出了人为排放NO2的作用.     

Buoyancy and turbulence-driven atmospheric circulation over urban areas

In the buoyancy and turbulence-driven atmospheric circulations (BTDAC) that occur over urban areas where the approach means wind speeds are very low (less than turbulent fluctuations and typically < 3 m/sec), the surface temperatures are significantly higher than those in the external rural areas, and the atmosphere above the mixing layer is stably stratified. In this paper, the mechanisms of BTDAC formation are studied through laboratory experiments and modelling, with additional low-level inflow from external rural areas and a divergent outflow in the opposite direction in the upper part of the mixed layer. Strong turbulent plumes in the central region mix the flow between lower and higher levels up to the inversion height. There are shear-driven turbulent eddies and weaker buoyant plumes around the periphery of the urban area. As the approach flow is very weak, the recirculating streamlines within the dome restrict the ventilation, and the dispersion of pollution emitted from sources below the inversion height leading to a rise in the mean concentration. Low-level air entrained from rural areas can, however, improve ventilation and lower this concentration. This trend can also be improved if the recirculating structure of the BTDAC flow pattern over urban areas breaks down as a result of the surface temperature distribution not being symmetrical, or as the approach wind speed increases to a level comparable with the mean velocity of circulation, or (except near the equator) the urban area is large enough that the Coriolis acceleration is significant.     

On the influence of sand-wind on atmospheric environment

The authors seek, through tests on simulated sand samples in a wind tunnel and analysis of minerals combination and trace elements, to discover the environmental implications of flying-up, falling-down and concentration variation as a function of natural wind speed and direction, distance of movement, range and extent of influence on the atmospheric environment, of micro-granular components on the ground surface in the Keerqin desert area in northwest Liaoning Province of China.