北京地区近35年大气污染扩散条件变化

本文使用NCEP(National Center for Environmental Prediction)再分析月平均数据(2.5°×2.5°)、1980~2015年北京地区(54511站点)的探空数据及温、压、湿、风、降水数据,分析了近35年来北京地区大气污染扩散条件的变化.主要结论有:1980~2015年,大气不断增温,1990年以后逆温明显,大气较为稳定,冷空气到达北京上空后对下层的影响减弱,3级以上偏北风频率减少,近地层辐合.同时,2000年以后中高层下沉运动位置不断下压,低层上升运动加强,低层上升运动被限制在边界层以内,这样会导致垂直扩散条件转差.1980~1989年大气容量指数较为稳定,1990~1999年大气容量指数出现波动,而2000~2015年大气容量指数呈现明显减小的趋势.总体来看,近35年大气自身的容纳能力呈现一个平缓的下降趋势.1980~1989年春季和冬季大气容量指数较大,1990~1999年春季和夏季大气容量指数较大,但是2000年以后,无论哪个季节,大气自身的容纳能力都是在减弱的,季节性差异变小.边界层高度在这30多年来都是春季和夏季较高,秋季和冬季明显降低.     

气候变化对浙江省大气污染的影响

开展气候变化对大气污染影响的研究有利于加深对大气污染形成机理的认识.利用1996-2015年浙江省大气成分、气象观测资料,分析气候变化对大气污染的影响.结果表明,近20 a来浙江省呈年高压天气日数增多、年均气温升高、降水集中及年均净辐射、日照时数、风速、气温日较差和水汽蒸发量都下降的气候变化事实.气候变化引起大气污染扩散能力下降,1996-2015年杭州市和浙江省年均大气扩散指数分别下降了0.55和0.81,降幅分别达35.71%和42.69%.大气扩散指数与ρ（PM₁₀）、ρ（PM_2.5）及年霾日数之间呈显著负相关,当大气扩散指数增大时,大气颗粒物浓度和年霾日数均下降,反之亦然.杭州市大气扩散指数与ρ（PM₁₀）、ρ（PM_2.5）之间的相关系数分别为0.73和0.76.杭州市和浙江省大气扩散指数与年霾日数之间的相关系数分别达到0.77和0.78,T检验值则分别为28.88和30.81,说明由气候变化引起的大气扩散能力改变是影响大气污染的重要原因,但不同大气成分受气候变化的影响程度不同.影响ρ（PM₁₀）的关键气候要素是降水量、风速及相对湿度等,影响ρ（PM_2.5）的主要是辐射、气温,影响ρ（SO₂）的主要是气温,影响ρ（NO₂）及ρ（NO₃-）、ρ（NH₄+）的主要是辐射.总体来说,浙江省近20 a的气候变化事实可能有利于促进ρ（PM₁₀）、ρ（PM_2.5）、ρ（NO₂）及ρ（O₃）等上升,促进ρ（SO₂）、ρ（NO₃-）、ρ（SO₄2-）、ρ（NH₄+）等下降.      

云南省大气污染扩散输送特征研究

通过分析各种野外探测资料和常规气象资料,全面讨论了影响云南省大气扩散输送能力的各种特征量的变化和特点,并试图说明高原山区的特殊地形及局地小气候条件对这些特征量的影响,认为云南全省大气扩散输送具有以下特征：大气稳定度以中性类居多,频率占50％以上;风速廓线指数值比平原地区大得多,也比一般山区的大;大气混合层高度春冬季较大,夏秋季较小,下午较大,凌晨较小;滇东和滇西北扩散参数较大,滇南较小;辐射雾出现频繁是一种影响当地大气扩散输送的天气现象。     

天津地区海风对大气污染物浓度的影响

采用污染物浓度监测数据、气象数据和大气化学模式WRF-CHEM分析天津地区海风对大气污染物浓度的影响.结果表明:天津地区东部沿海的空气质量优于西部内陆及城市中心.在天津地区污染天气高发的秋冬季,海风对污染物浓度起到了稀释作用,所以海风有利于天津地区大气污染的缓解,并且对城郊污染物浓度的影响相对较大,弱气压场形势下有海风存在相对于无海风时PM_(2.5)、PM_10和O3的日均浓度减幅分别为14.4μg/m~3,22.9μg/m~3和8.9μg/m~3.2015年1月4日海风过程的实例分析表明海风锋可将沿海的部分大气污染物输送至所经过的内陆地区,所以处于海风锋前的地区污染物浓度存在短暂的小幅上升,移至海风锋后部后污染物浓度呈下降趋势,市区的PM_(2.5)小时浓度由342μg/m~3上升为399μg/m~3,而后再呈下降趋势,降至160μg/m~3左右.海风有利于天津地区大气污染物的扩散,既将污染物向海风的下游方向输送,又增强了污染物的垂直扩散能力.此次过程影响范围较广,使得天津地区的大气污染得到了缓解,但并没有使大气污染物消散.     

大气污染物扩散影响因素及影响程度探究

影响大气污染物扩散的因素很多,一般包括大气稳定度、垂直和水平温度梯度、低空风场引起的平流动力输送、地面粗糙度、湍流运动、雨雾等。这些因素都不同程度地影响大气污染物的扩散,以一定的传输和扩散规律决定大气污染水平的高低,并由此使各局部区域污染程度各不相同。     

基于APEI的2013—2018年福建省大气污染评价

为了在区(县、市)级尺度上准确衡量福建省大气污染情况,构建大气污染评价APEI指数。基于高分辨率大气污染数据集和夜间灯光数据,分析2013—2018年福建省78个县市大气污染程度时空变化特征及其影响因素的时空异质性。结果表明：1)福建省中心偏北县市大气污染程度小,东部沿海县市大气污染严重。近6年福建省78.21%的县市大气污染程度减弱;2)全省东部沿海区域空气污染严重,主要表现在NO₂和PM₁₀这2种大气污染物,均超过全省平均水平;3)从大气污染物时序变化趋势看,PM_2.5和PM₁₀变化相似,自2014年起逐年下降,到2018年分别下降约23.15%和12.21%,SO₂和NO₂分别下降明显。O₃呈U形变化,而CO则呈倒U形变化;4)全省6种大气污染物均呈现较明显的季节性波动特征;5)采用时空加权回归(STWR)模型分析夜间灯光对APEI影响的时空异质性,发现2014—2018年负向影响区域持续扩大;全省34个县市5年回归系数均为正值...     

近地面大气污染模拟模型的建立与应用研究

针对以往把整个混合层作为大气扩散研究对象的问题,研究了近地面大气污染带概念,建立了大气污染模拟模型。又考虑到目前大气污染模型仅注重研究铅直面上的二维扩散变化,而较少研究平面二维扩散问题,运用有限差分方法建立了近地面大气污染带的平面二维数值模型。通过应用证实,该大气污染模拟模型能够真实反映近地面大气中污染物的扩散趋势及空间分布特征,对城市大气环境污染预测和防治具有实际意义。     

太原市大气扩散示踪试验

太原市位于山西中部,东、西两山夹峙,汾河南北中贯,地形北部较高,南部开放,西部有一缺口,是一个封闭不完全的盆地。风速较小,1971—1980年平均风速为2.5m/s,静风频率为24％。在无系统天气过境时,近地层气象十分复杂,城南和城北、河东和河西的地面风往往不同。 近年来,太原市大气污染日趋严重,我们于1985年10—11月在太原地区进行了大气扩散示踪试验,以期能对该地区大气污染物的输送和扩散有所了解。     

山东省不同下垫面大气扩散参数的对比分析

利用在山东各地进行的多次建设项目大气环境影响评价中的大气扩散试验结果,对不同垫面的大气扩散参数做对比分析,讨论下垫面的变化对大气扩散参数的影响以及大气扩散能力与大气污染物浓度分布的关系,试验均采用平衡法进行。结果表明：不同地形下的大气扩散参数有明显差异。与国际扩散参数值相比,山区比平原高０．５－１级,平原地区与国标基本一致,工业区模向扩散参数与国标基本相当,垂直扩散参数１个级别以上;沿海地区横向扩     

天津大气扩散条件对污染物垂直分布的影响研究

利用2017~2019年夏、冬季天津市大气污染物监测和气象观测数据,基于天津气象铁塔垂直观测,针对大气垂直扩散条件对PM_2.5和O₃的影响进行研究.结果显示:近地面PM_2.5浓度随高度的升高而下降,O₃浓度则随高度的升高而上升,受大气垂直扩散条件的季节和日变化影响,冬季,地面与120m PM_2.5质量浓度相关明显,与200m PM_2.5质量浓度无明显相关.夏季,120m和200m PM_2.5质量浓度相关系数为0.72,午后通常出现120m和200m PM_2.5质量浓度高于地面的情况.夏季,不同高度O₃浓度差异小于冬季,地面与120m高度O₃浓度接近.以大气稳定度、逆温强度和气温递减率作为大气垂直扩散指标,对地面PM_2.5和O₃垂直分布具有指示作用.冬季,TKE与PM_2.5质量浓度相关系数为到-0.65,夏季,TKE与ΔPM_2.5相关系数为-0.39.夏、冬季TKE与地面O₃浓度的相关系数分别为0.46和0.53,与ΔO₃的相关系数分别为0.73和0.70.弱下沉运动对地面O₃浓度影响较强,40m高度垂直运动速度与地面O₃浓度的相关系数在冬、夏季分别为-0.54和-0.61.对冬季典型PM_2.5重污染过程的分析发现,雾霾的生消维持和PM_2.5浓度的变化与大气稳定度、气温垂直递减率和TKE的变化有直接关系.对夏季典型O3污染过程的分析发现,近地面的O₃污染的形成与有利光化学反应的气象条件密切相关,同时,垂直向下输送和有利垂直扩散条件对O₃污染的形成和爆发影响明显.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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