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821.
无机气溶胶是天津冬季霾天出现的主要成分,研究挑选了2020年1月污染天中两个典型的高浓度无机气溶胶(SIA)过程(CASE1和CASE2),利用观测数据和耦合了在线污染物来源追踪方法的大气化学传输模式NAQPMS综合探究了气象要素、区域输送和化学过程的影响.两个过程的ρ(SIA)均值分别为76.8 μg·m-3和66.0 μg·m-3,硝酸盐浓度高于硫酸盐和铵盐,均为硝酸盐为主导的污染过程.气象条件影响了无机气溶胶的生成,CASE1过程ρ(SIA)>80 μg·m-3对应的温度和相对湿度区间分别是[-6℃,0℃]、[2℃,4℃]和[50%,60%]、[80%,100%];CASE2过程对应的温度和相对湿度区间分别是[2℃,4℃]和[60%,70%].外来源对CASE1和CASE2过程SIA的平均贡献率为62.3%和22.1%,分别为区域传输主导和局地生成主导过程.CASE1本地排放对硝酸盐和硫酸盐的贡献分别为16.2 μg·m-3和8.2 μg·m-3,均高于外来源的贡献(31.7 μg·m-3和8.8 μg·m-3);CASE2过程本地排放对硝酸盐和硫酸盐的贡献分别为29.3 μg·m-3和25.1 μg·m-3,而外来源的贡献为8.1 μg·m-3和9.4 μg·m-3.这表明CASE1本地生成和外来源输送贡献造成硝酸盐高于硫酸盐浓度,而CASE2仅本地源造成硝酸盐浓度高于硫酸盐.两个污染过程气相氧化反应是无机气溶胶生成的首要来源,贡献率分别为48.9%和57.8%;非均相反应也是重要过程,对SIA的贡献率分别为48.1%和42.2%;液相反应的影响小. 相似文献
822.
在2006年北京加强观测期间,以颗粒物-液体转换采集系统(PILS)测量的气溶胶各可溶性离子组分的质量浓度、颗粒物分级采样器(MOUDI)测量的各可溶性离子组分及有机碳(OC)、碳黑(EC)的分级质量谱分布为基础,对离子组分的可能存在形态进行判断,计算了化学组分质量浓度及各化学物种的粒径数谱浓度;利用Mie模型及各化学物种的密度、折射率、吸湿粒径增长因子等参数计算得到外混、内混的粒子群在干燥状态、不同相对湿度下的散射系数,最终计算得到不同化学组分外混、内混状态下的散射吸湿增长因子;将模型模拟的气溶胶散射吸湿增长因子与观测得到的该因子进行对比,发现模拟值与观测值能够在一定误差范围内吻合,实现了该因子的闭合实验. 相似文献
823.
A two-year study on temporal variations in the ground water heterotrophic bacterial cell sizes of free living bacteria(FLB)and particle bound bacteria(PBB)from the agricultural,domestic and industrial areas was carried out from Februar y2005 to January 2007.The overall mean cell length of FLB and PBB was similar in all the ground water studied.However,the season wise grouped data revealed significant seasonal changes in cell length of FLB and PBB,as smaller bacteria were noticed during rainy season in the ground water in agricultural area in both the years,and only in the second year of study in domestic and industrial areas.Generally,it was noticed that there were summer maximum and rainy minimum values of the cell length of PBB in the ground water in agricultural,domestic and industrial areas in the second year of study.The Pearson's correlations showed the presence of 8(in agricultural area),5(in domestic)and 3(in industrial) significant correlations with environmental(Physico-chemical)parameters,respectively.The regression analysis revealed that as much as 12%of variation in the mean length of FL Bwas due to NO3( )in agricultural area and 9%due to total solids( )indomestic area.However,the 8% variation in bacterial cell size of FLB was due to Mg( )in industrial area.Whereas,13%variation in mean length of PBB was due to S04( )in agncultural area and 10%due to total anions of strong acid(TASA)( )in domestic area.Furthermore,10% of variation Was due to PO4( )in industrial area.Thus,the statistical analysis revealed that several environmental variables were potentially responsible for some of the temporal variations in aquatic heterotrophic bacterial cell size,suggesting probably the stressed environment in these ecosystems. 相似文献
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采用2016年大气多参数站监测数据,分析连云港市大气中ρ(黑碳气溶胶)的小时及月度变化规律,结果表明,观测期间,黑碳气溶胶与NO_2、CO、PM_(10)、PM_(2.5)显著相关,与风速、能见度等呈负相关;黑碳气溶胶年均值为2.10μg/m~3,日变化呈明显双峰型,峰值出现在08:00和21:00左右;从季节看,ρ(黑碳气溶胶)冬春季高、夏秋季低;在不利气象条件时,ρ(黑碳气溶胶)有所增高,通过模型分析化石燃料燃烧产生的黑碳占比增大,说明在不利气象条件时,化石燃料燃烧产生的黑碳是影响ρ(黑碳气溶胶)及ρ(颗粒物)上升的主要因素。 相似文献
828.
Quantitative relationship between visibility and mass concentration of PM2.5 in Beijing 总被引:4,自引:0,他引:4
WANG Jing-li ZHANG Yuan-hang SHAO Min LIU Xu-lin ZENG Li-min CHENG Cong-lan XU Xiao-feng 《环境科学学报(英文版)》2006,18(3):475-481
The pollution of particulate matter less than 2.5μm (PM2.5) is a serious environmental problem in Beijing. The annual average concentration of PM2.5 in 2001 from seasonal monitor results was more than 6 times that of the U,S, national ambient air quality standards proposed by U.S. EPA. The major contributors to mass of PM2.5 were organics, crustal elements and sulfate. The chemical composition of PM2.5 varied largely with season, but was similar at different monitor stations in the same season. The fine particles (PM2.5) cause atmospheric visibility deterioration through light extinction, The mass concentrations of PM2.5 were anti-correlated to the visibility, the best fits between atmospheric visibility and the mass concentrations of PM2.5 were somehow different: power in spring, exponential in summer, logarithmic in autumn, power or exponential in winter. As in each season the meteorological parameters such as air temperature and relative humidity change from day to day, probably the reason of above correlations between PM2.5 and visibility obtained at different seasons come from the differences in chemical compositions of PM2.5. 相似文献
829.
HAO Li-qing WANG Zhen-y FANG Li ZHANG Wei-jun WANG Wei LI Cheng-xiang SHENG Liu-si 《环境科学学报(英文版)》2006,18(5):903-909
Photooxidation reaction of toluene in smog chamber systems was initiated by the UV radiation of tolucne/CH5ONO/NOx mixtures. The products of the photooxidation reaction of toluene and its subsequent reactions were analyzed directly utilizing Fourier transform infrared spectrometer (FTIR). Detailed assignments to FTIR spectrum of gas-phase products were given. The information of some important functional groups in the products, such as, carbonyl groups (C-O), hydroxyl groups (-OH), carboxylic acid (- COOH), C-C bonding, N O bonding and C-H bonding (C H), was got from this analysis. These results were compared to those analyzed by aerosol time of flight mass spectrometer (ATOFMS). It was found that there are some differcnccs between FTIR analysis of gas-phase products and that of particle-phase, for example, the products with carbonyl groups, which were connected to unsaturated chemical bonds, was relatively higher in the gas phase, while kctoncs, aldehydes, carboxylic acid and organonitrates were the dominant functional groups in the aerosol-phase reaction products. The possible reaction pathways of some important products in the gas phase were also discussed. 相似文献
830.