基于小波变换的兰州市近十年空气污染指数变化

对兰州市近10年逐日空气污染指数的时间序列采用一维连续Morlet小波进行小波变换分析,研究了该市大气污染时间序列的多尺度变化特征、主周期和影响因素.结果表明:兰州市近10年空气污染指数在不同时问尺度上具有不同的"高一低"交替演化规律,且以300 d左右的变化为主周期,100 d左右的变化为次周期;受地形条件的影响,大...     

中国空气污染指数变化特征及影响因素分析

以2001～2010年我国42个城市逐日空气污染指数、主要污染因子、空气质量级别和空气质量状况资料为基础,分析了近10 a我国空气质量的变化特征.结果表明,我国城市大气受燃煤影响较为严重,可吸入颗粒物为主要污染因子,空气质量状况以优、良和轻微污染居多;空气质量季节变化明显,冬季空气污染最严重,夏季最轻;从年际变化看,空气质量表现出逐年好转趋势;城市大气环境质量在区域上存在显著差异,表现为由南到北、从沿海到内陆逐渐变差的趋势.对空气污染影响因素的分析表明,局地污染和西北地区沙尘传输造成的自然降尘是我国城市空气质量的主要污染源;气象要素对大气污染物有制约关系,空气污染指数与降水量、风速、逆温线性相关;地形的空间差异影响着气象条件的分布,进而对空气质量的空间变化产生影响;人类活动对城市空气质量也存在一定的影响,且具有双重作用.     

黄河上游段吸收性气溶胶指数（AAI）时空演化特征及潜在源区分析

为揭示黄河流域上游段吸收性气溶胶指数(Absorbing Aerosol Index,AAI)的时空演化特征、主要影响因子及污染严重的包头市污染物潜在来源.本文利用OMI OMAERUV L2气溶胶数据集,研究了2005—2020年黄河流域上游段的AAI时空分布,利用熵权TOPSIS法分析主要影响因子,同时借助后向轨迹模型(HYSPLIT)对污染严重城市的污染物进行聚类分析,追踪其潜在来源.结果显示：(1)从时间上看,2005—2009年黄河流域上游段AAI呈下降趋势,2009年AAI降到最小值;2009—2016年AAI波动上升,2016年达到最大值,随后由于国家颁布了一系列保护环境的政策使AAI下降.从空间上看,AAI在黄河上游流域的北部即内蒙古的包头、鄂尔多斯偏高,而在流域的南部大概在四川省内较低.(2)小波分析发现,季节变化方面,黄河上游AAI正负位相交替出现,月均值季节变化明显,且呈现冬>春>秋>夏的特征.夏季雨水的冲刷和扩散条件使得AAI全境低值;冬季污染物排放增加,局部为高压控制区,污染物难以扩散,AAI大范围出现高值.(3)熵权TOPSIS法表明,黄河...     

渭南市区冬春季PM2.5和PM10时间分布特征及与气象因素的关系

为研究渭南市区2014?—?2016年的冬春季雾霾天气的特点,选取覆盖渭南市区的4个监测站点,分析渭南市区PM_(10)和PM_(2.5)污染时间分布特征;同时选取日平均气温、相对湿度、风等气象因素,用线性回归分析法分析各个气象因素同大气中PM_(10)和PM_(2.5)的相互关系。研究发现:三年来冬季PM_(10)和PM_(2.5)的日变化的峰值主要出现在12月—?次年1月;春季PM_(10)和PM_(2.5)的逐日变化的峰值主要出现在3月;日内的周期变化趋势呈多次波动。渭南市区冬春PM_(10)和PM_(2.5)的质量浓度与风速、气温呈负相关,与相对湿度呈正相关,为雾霾的形成创造了条件,在冬季温度较高的情况下以及相对湿度较大的情况下应加强防范。在冬季12月—?次年1月和春季3月应注意雾霾的防范和治理,燃煤企业要安装脱硫脱硝装置,居民日常生活中尽量减少生物燃料的燃烧,同时政府应根据污染物排放量征税,用制度保护环境。     

重庆市空气污染持续过程特征及其气象成因分析

利用空气质量日报数据分析了重庆市主城区空气质量的总体概况以及持续空气污染过程的特征,并着重探讨了2005年11月29日至12月31日期间的空气污染指数API变化及其与主要气象条件的相关关系.结果显示,一年中主城区出现连续3 d以上空气污染指数API超过100的持续污染过程10次,累计污染超标日为61 d,占全年总超标天数的61.6%;持续污染过程的气象条件往往有着共同的特点,即平均风速小,无降水或降水稀少,大气层结稳定,混合层高度较低.     

近10年中国主要城市空气API及与气象因子相关性分析

据2000年6月-2012年6月中国47个主要城市的空气污染指数(API)逐日监测数据,分析中国近年空气质量,并分析其与气温、露点、降水、风及温度露点差(T-T d)等气象要素的相关性。通过分析发现:我国空气污染西北重、东南低;空气质量变化呈现明显的季节变化,冬季最高,春季较高且变化幅度大,夏秋季节相对较低;主要污染物以可吸入颗粒物(PM10)为主;广西地区化学污染突出。随着污染治理工作的开展,近年API值呈下降趋势,由2001年的年均82.75下降至2011年的66.1。分析API与气象要素的相关性,发现降水对空气污染的净化作用明显;风在沿海地区能稀释空气污染,而在西北内陆这一作用不明显;API与气温、露点均呈负相关;而与二者之差所表征的空气干燥程度呈较高的正相关。     

2015～2021年京津冀及周边地区PM2.5和臭氧复合污染时空特征分析

为了解京津冀及周边地区“2+26”城市PM_2.5和O₃复合污染时空分布特征,利用ArcGIS和SPSS软件对2015～2021年京津冀及周边地区“2+26”城市空气质量数据和气象数据进行关联性分析.结果表明：(1) 2015～2021年PM_2.5污染持续减缓,污染集中在区域中南部;O₃污染呈波动上升趋势,空间分布呈现“西南低,东北高”的格局.季节变化来看,PM_2.5浓度主要为：冬季>春季≈秋季>夏季,O₃-8h浓度为：夏季>春季>秋季>冬季.(2)“2+26”城市PM_2.5超标天数持续下降,O₃超标天数波动上升,复合污染日下降趋势显著;PM_2.5和O₃污染在夏季呈强正相关,相关系数最高达0.52,冬季呈强负相关.(3)对比典型城市臭氧污染时期与复合污染时期气象条件,复合污染发生的温度区间集中在23.7～26.5℃、湿度48%～65%和S～S...     

陕西省冬春季PM2.5时空分布特征研究

根据陕西省2016年12月至2017年5月PM_2.5质量浓度逐小时数据，利用ArcGIS分析陕西省PM_2.5污染时空变化格局，并分析造成南北差异的原因，再利用小波分析手段探讨各市PM_2.5污染时间序列周期和突变特性。结果表明：（1）陕西省冬季PM_2.5污染重，春季污染轻，并表现出"关中高，南北低"的特征，秦岭南北经济发展差异和供暖差异是控制陕西省PM_2.5污染空间格局的主要原因；（2）冬季和春季单日PM_2.5浓度变化趋势基本一致，为"双峰双谷型"，日最低值出现在16∶00~18∶00；（3）Morlet小波分析结果显示，陕西省PM_2.5日均变化序列存在多时间尺度特征。陕北城市PM_2.5污染第1主周期为40 d，关中城市和陕南商洛市有40 d和65 d两个共同周期，安康市和汉中市共同周期为20 d和80 d；（4）陕西省PM_2.5突变事件冬季频繁而春季较少，多发生在1月和2月，春季1次大范围的沙尘天气，造成了陕西省5月5日8个城市PM_2.5污染浓度剧增。     

石河子-昌吉地区地下水水质时空变化及污染源解析

为了探明新疆石河子-昌吉地区地下水水质时空变化并解析污染源,综合运用基于香农熵的贝叶斯水质评价模型、 Spearman秩相关系数、主成分分析和绝对主成分得分-多元线性回归受体模型(APCS-MLR)等方法,对23眼原位井2016～2021年逐年地下水水质数据进行分析.结果表明：(1)研究区多年地下水水质状况总体较好,潜水水质类别以Ⅰ类和Ⅱ类为主,承压水主要为Ⅰ类.(2)从时间看,2016年和2017年分别为潜水和承压水水质变化的关键时间节点,Ⅳ类和Ⅴ类水仅出现在节点之前,之后在Ⅰ～Ⅲ类水范围内波动.(3)从空间看,潜水水质优劣排序为：石河子市≈呼图壁县>玛纳斯县>昌吉市;承压水为：石河子市≈昌吉市>呼图壁县>玛纳斯县.(4)研究区多年地下水水质类别和主要水质指标在时空变化上基本对应,且异质性较强.(5)潜水水质主要受到溶滤作用(67.30%)、溶滤-迁移作用(10.89%)和农业-生活污染(9.44%)的影响,溶滤-富集作用(52.08%)、农业-生活污染(16.06%)和碱性环境的离子交换作用(12.64%)对承压水水质影响较大.尽管研究区多年水质状况整体呈改...     

典型西南工业城市春冬季PM2.5来源与潜在源区分析——以柳州市为例

为了揭示柳州城区春冬季PM_2.5的来源及其潜在源区分布和贡献,利用2018年24h自动监测数据和气象数据对柳州市大气污染物浓度变化特征进行了分析,并且使用后向轨迹模型(HYSPLIT)对春冬季柳州市PM_2.5逐日72h气流后向轨迹和前向轨迹进行聚类分析,同时结合潜在源贡献因子分析法(WPSCF)和轨迹浓度权重法(WCWT)对其潜在源区和浓度贡献进行了分析.结果显示,(1)在研究期内,不利的主导风向和工业区布局导致研究区PM_2.5在春冬季污染较严重,且工业源和交通源是其主要本地来源;(2)春冬季PM_2.5高值主要来源于西北和东南方向,其中,西北向PM_2.5主要来源于本地排放,且浓度在空间上呈现西高东低的趋势;(3)春季后向轨迹PM_2.5浓度整体大于冬季,春冬季中对柳州市PM_2.5影响最大轨迹均来自东部的短距离输送,而来自西北的气流轨迹输对PM_2.5贡献最低.春冬季柳州市大气PM_2.5通过气流传...     

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.     

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.     

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.     

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.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

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

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.