青藏高原东缘黑碳气溶胶变化特征及其来源

黑碳(BC)作为最重要的吸收性气溶胶,可影响青藏高原地区的辐射、云和地表积雪等,进而影响全球季风环流及降水.本研究于2017年7月5日至9月5日在青藏高原东缘理塘县使用黑碳仪AE-33测量了BC浓度数据,结合黑碳仪模型、PSCF和CWT潜在来源模型,分析了BC的污染特征、潜在来源及其影响区域.结果表明,理塘ρ(BC)为0.4～4 699.8 ng·m^-3,平均值为816.4ng·m^-3,占PM_2.5的质量分数为5.96%.理塘ρ(BC_液态燃料)和ρ(BC_固态燃料)的平均值分别为486.1ng·m^-3和398.5ng·m^-3,BC_液态燃料的贡献率C为0.51.ρ(BC)主要分布在0～2 000 ng·m^-3,可占总观测期间的92.5%. BC、BC_液态燃料和BC_固态燃料的日变化为双峰型分布,峰值分别出现在08:00和20:00,早高峰主要与交通源和含...     

华北平原南部农村地区黑碳气溶胶浓度及来源

华北平原南部地区是当前我国大气污染的严重区域之一.作为连接南北方大气污染传输的关键区域,其大气环境研究相对薄弱.在华北平原南部某农村点位利用AE-33型黑碳仪,对2018年2～8月的黑碳（BC）气溶胶进行连续监测,采用光度计模型解析了黑碳来源.观测期间ρ（BC）的平均值为（3.51±2.29）μg·m^-3,冬季、春季和夏季的ρ（BC）平均值分别为（8.21±3.26）、（3.49±1.69）和（2.37±0.71）μg·m^-3.BC的季节性变化由气象因素和排放源的季节性变化共同导致.ρ（BC）日变化在08:00[（4.66±3.24）μg·m^-3]和20:00[（4.25±6.73）μg·m^-3]出现峰值,与居民做饭时间一致;在14:00[（2.44±3.33）μg·m^-3]出现谷值,与边界层高度较高有关.气溶胶波长吸收指数（AAE）在1.08～1.66之间,冬季、春季和夏季的AAE平均为1.41±0.08、 1.28±0.10和1.20±0.06,表明该区域的BC来源以化石燃...     

2008～2018年武汉市BC气溶胶时间演变特征及其来源分析

黑碳(BC)作为最重要的吸收性气溶胶,其辐射强迫显著地改变大气边界层结构和近地面大气污染物的累积。基于2008～2018年武汉市BC和气象要素的观测数据,结合CWT潜在来源模型,分析了BC的时间演变特征和潜在来源分布。结果表明武汉BC平均质量浓度为6 926.4±4 090.6 ng/m³,?ngstr9m指数(AAE)和液体燃料源对BC贡献占比(P)的平均值分别为0.98±0.44和76.6%,BC主要来自液体燃料的燃烧。2014～2017年BC质量浓度呈现显著的下降趋势,液体燃料对BC的贡献逐年增加。BC的季节分布为冬季(8 537.3 ng/m³)>春季(7 513.2 ng/m³)>秋季(6 820.2 ng/m³)>夏季(6 161.9 ng/m³),BC_liquid占比为秋季(80.0%)>冬季(77.3%)>春季(76.2%)>夏季(72.9%)。不同季节BC日变化特征不同。四个季节BC日变化在2008～2...     

南京北郊黑碳气溶胶分布特征及来源

黑碳(black carbon, BC)是含碳物质燃烧排放所产生的大气颗粒物(particulate matter, PM)中一种重要组分,其对辐射效应表现为对太阳辐射的吸收和散射,影响着地气系统的能量交换.本研究于2019年1～5月在南京北郊利用黑碳仪AE33(aethalometer,magee)测量了黑碳气溶胶浓度数据,对其日夜变化和季节变化进行分析,并筛选出污染天与清洁天,对其特征和来源进行分析.结果显示采样期间黑炭气溶胶的平均浓度为(3.8±2.3)μg·m^-3,冬季浓度为春季的1.3倍.BC浓度呈现明显的日变化,BC高值出现在日间交通高峰时间段,受到交通排放的影响较大.?ngstr?m指数α冬春整体差异不大,春季为1.32冬季为1.30,此结果也指出BC排放源以机动车排放为主.此外,针对采样期间污染天与清洁天的BC来源特征进行分析,发现污染天机动车排放源占比为68%～87%,清洁天为72%～86%,清洁天来源小幅波动但均以机动车排放源为主,污染天相对而言存在一定的机动车源减少生物质和煤炭燃烧源增加的情况,取决于污染时段的排放情况,利用BC/CO(0.0...     

南京市黑碳气溶胶时间演变特征及其主要影响因素

为了研究南京市黑碳(black carbon,BC)气溶胶的时间演变特征及其主要影响因素,使用多波长Aethalometer(AE-33)每个季节选取典型月份观测了BC质量浓度,结合大气污染物数据、气象要素和边界层探测数据,分析了BC的季节变化、日变化、周末效应和来源特征.结果表明,南京的BC浓度具有明显的季节变化,春季[(3 351±919) ng·m^-3]>冬季[(3 234±2102) ng·m^-3]>秋季[(3 064±967) ng·m^-3]>夏季[(2 632±1 705) ng·m^-3]. 4个季节BC日变化均为双峰型分布,峰值分别位于06:00～08:00和21:00～23:00. BC不同季节的早晚高峰分布特征不同.早高峰春季BC浓度最高,晚高峰冬季浓度最高.冬季早高峰出现时间要比其他季节滞后2 h,而夏季晚高峰时间反而比其他季节提前2 h.风速对BC日变化季节分布差异的影响远大于相对湿度(relative humidity,RH).逆温层结对大气污染物浓度的影响...     

南京市溧水区大气挥发性有机物污染特征及来源解析

为了解南京市溧水区大气挥发性有机物(VOCs)的组分、来源及其对臭氧的贡献,2021年对区域内VOCs开展了为期1 a的走航监测,进行数据分析.结果表明,溧水区ρ(TVOC)年均值为223.45μg·m^-3,其中ρ(烷烃)为49.45μg·m^-3(占比22.13%),ρ[含氧(氮)VOCs]为50.63μg·m^-3(占比22.66%),ρ(卤代烃)为64.73μg·m^-3(占比28.95%),ρ(芳香烃)为35.46μg·m^-3(占比15.87%),ρ(烯烃)为18.26μg·m^-3(占比8.19%),其他为4.9μg·m^-3(占比2.2%).夏季的ρ(TVOC)平均值较高,为263.75μg·m^-3,冬季较低,为187.2μg·m^-3,春季为246.11μg·m^-3,秋季为204.77μg·m^-3.日均TVOC浓度,在09:00～10:00和14...     

天津市典型市区隧道机动车黑碳污染排放特征与健康风险评价

在天津五经路隧道开展机动车排放的黑碳(Black carbon,BC)浓度特征及其对人群健康影响研究,对机动车排放BC的浓度水平与变化特征进行分析,同时计算获得汽油车和柴油车的BC排放因子,并通过美国环保局(US EPA)的健康风险评价模型对BC的健康风险进行评价.结果表明,隧道入口和出口处BC质量浓度均值分别为(2.21±0.74)和(4.02±1.56)μg·m^-3.隧道内BC累计质量浓度在凌晨、早高峰和晚高峰3个时间段上存在极大值点,说明交通道路BC浓度变化与车辆类型和车流量变化密切相关.隧道中机动车BC综合排放因子为(2.62±0.60) mg·km^-1·辆^-1,基于多元线性回归方法计算获得隧道内汽油车和柴油车的BC排放因子分别为(1.51±0.24)和(56.9±15.2) mg·km^-1·辆^-1.健康风险评价结果表明,对于儿童和成人,隧道进口与出口处BC的非致癌风险指数均小于1,非致癌风险在安全范围之内.但BC对成人和儿童的致癌风险均超过EPA推荐的可接受风险阈值(...     

中国东部秋季大气黑碳分布和来源的数值模拟

应用耦合黑碳源示踪方法的区域大气化学WRF-Chem模式,对中国东部秋季黑碳气溶胶(BC)分布特征进行研究.研究发现中国中东部BC浓度较高(>2μg/m³), BC高值区(>4μg/m³)分布在华北平原、长江三角洲、两湖及四川东部等地区.工业源、居民生活源、交通源是BC的主要排放源,其中工业源会造成近地层BC分布呈点状高值,地形及气象条件也是影响BC累积和传输的重要因素.BC浓度较高的京津冀BC以本地源贡献为主,在不同的风场及大气扩散条件下,外来源对京津冀BC贡献占比的变化较大.BC来源可分为两种情形:一是传输型:地面风速较大,外来源贡献占比达35.1%;二是静稳型:地面风速小,大气条件静稳,以本地贡献(80.1%)为主,来自京津冀周边省份(山东、河南、山西和陕西)的贡献较少(6.9%).本地源与外来源对京津冀BC贡献比呈相反的日变化特征,其中傍晚～早上,本地贡献占比维持在较高水平;午后本地贡献占比减小,外来输送明显增强.当京津冀地区受外来输送影响更大时,日变化特征更明显,外来贡献在午后占比可超过40%.     

黄石市大气PM2.5中碳氮组分的污染特征及来源解析

基于稳定同位素技术与正定矩阵因子分解(PMF)模型,探究黄石市城区大气PM_2.5中碳氮组分的污染特征和来源.结果表明,黄石市城区大气PM_2.5中总碳浓度[ρ(TC)]与总碳同位素组成(δ¹³C_TC)均呈冬高夏低的季节性变化特征,夏季分别为(4.4±1.2)μg·m^-3和(-26.3±0.5)‰,冬季分别为(9.9±3.5)μg·m^-3和(-25.5±0.5)‰;总氮浓度[ρ(TN)]在夏季[(9.1±9.1)μg·m^-3]明显低于冬季[(62.4±26.4)μg·m^-3],而总氮同位素组成(δ¹⁵N_TN)在夏季[(12.8±1.9)‰]较冬季[(2.9±4.0)‰]明显富集.除本地源贡献外,黄石市PM_2.5中碳氮组分主要受湖南北部近距离区域排放和西北方向远距离传输影响.贝叶斯混合模型(MixSIAR)与PMF模型解析出机动车排放源为PM_2...     

重庆典型城区冬季碳质气溶胶的污染特征及来源解析

于2021年1～2月在重庆典型城区万州区(WZ)、渝北区(YB)和双桥区(SQ)同步采集PM_2.5样品,分析冬季碳质气溶胶的污染特征、来源及潜在源区.结果表明,观测期间SQ的ρ(PM_2.5)、ρ(OC)和ρ(EC)均值分别为(72.6±33.3)、(18.2±8.2)和(4.4±1.7)μg·m^-3,高于WZ[(67.2±30.3)、(17.2±7.4)和(5.1±2.4)μg·m^-3]和YB[(63.4±25.7)、(15.4±6.3)和(4.2±1.9)μg·m^-3].与清洁日相比,WZ污染日EC浓度及其对总碳的贡献率均涨幅最大(103.0%和8.1%),但OC/EC值下降最明显(-10.5%),表明WZ污染日碳质气溶胶的一次排放明显增强.观测期间SQ和YB的ρ(SOC)均值分别为(7.7±4.8)μg·m^-3和(6.9±2.8)μg·m^-3,明显高于WZ[(4.5±1.9)μg·m^-3],表明二次转化对SQ...     

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.     

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.