西安西南郊“夏防期”大气VOCs污染特征及来源解析

于2021年8月1日—9月30日开展“夏防期”西安西南郊大气挥发性有机物（VOCs）污染监测,累计监测到不同大气VOCs组分70种. 基于监测结果梳理分析西安西南郊大气VOCs污染分布特征及进行臭氧生成潜势（OFP）评估,并运用PMF模型解析VOCs主要来源.结果表明：①监测期间西安西南郊平均TVOCs浓度为181.89 μg·m^-3,工业园区污染物浓度（189.32 μg·m^-3）整体略高于城区（164.96 μg·m^-3）,以甲醛和 乙醛为主的醛酮类物质占比最高（88.10%）,醛酮类物质浓度下午时段高于上午时段.②OFP评估结果表明,醛酮类物质对西安西南郊臭氧生成贡献较大,其中,甲醛、乙醛和丙醛是对该区域近地面O₃生成贡献最大的3种物质.③PMF源解析结果显示,西安西南郊大气VOCs主要来源依次为移动源、油气挥发源、溶剂涂料源、工业过程源,其中,以工业企业生产排放为主的溶剂涂料源与工业过程源均指向工业园区,表明当前西安西南郊大气VOCs来源以机动车尾气排放和工业园区企业生产排放为主.     

2007年春节期间北京大气颗粒物中多环芳烃的污染特征

利用大流量颗粒物采样器分昼夜采集了2007年春节前后大气气溶胶中PM₁₀和PM_2.5样品，并采用气相色谱-质谱技术对PM_2.5样品中的多环芳烃进行了检测.春节期间大气颗粒物中PM₁₀和PM_2.5夜间平均质量浓度为232 μg·m^-3和132 μg·m^-3,分别高于白天的PM₁₀(194 μg·m^-3)和PM_2.5(107 μg·m^-3)；除夕后颗粒物日平均质量浓度为252.3 μg·m^-3 (PM₁₀)和123.8 μg·m^-3 (PM_2.5)，分别高于除夕前的166.7 μg·m^-3(PM₁₀)和106.8 μg·m^-3(PM_2.5)；同时夜间PM_2.5中多17种多环芳烃(PAHs)的总浓度都高于相应白天的总浓度，且除夕前多环芳烃日均总浓度为95.9 ng·m^-3，高于除夕后的58.9 ng·m^-3.结果表明，除了受一定的气象条件的影响外，大量燃放烟花爆竹会对大气颗粒物浓度有影响，但对大气中的多环芳烃影响不大，而春节期间工业及交通污染排放的减少削减了排放到大气中的PAHs.根据荧蒽/芘等比值指标判别北京PAHs主要以燃煤为主、交通为次的混合局地源污染.     

列车车厢内醛酮化合物的污染状况

建立了室内及公共场所空气中10种醛酮(甲醛、乙醛、丙烯醛、丙酮、丙醛、丁烯醛、丁醛、苯甲醛、环己酮、戊醛)的采集、前处理及分析方法,采样效率为92%～100%,回收率为91%～104%,检测限为0.26 ng/m³～0.82 ng/m³.调查评价了6辆列车车厢空气中醛酮的污染状况.结果表明,列车车厢空气中醛酮的总浓度为0.1591 mg/m³～0.2828 mg/m³,平均浓度为0.2330 mg/m³,其中甲醛、乙醛、丙酮的平均浓度分别为0.0922 mg/m³、0.0499 mg/m³、0.0580 mg/m³,占总平均浓度的42.6%、21.4%、24.9%.初步确定列车车厢空气中的醛酮化合物来自木制品和抽烟的混合源.乘客的醛酮吸入量约为0.043 mg/h～0.076 mg/h.     

张家界森林大气中醛酮类化合物浓度变化特征

为探究中亚热带森林大气中醛酮类化合物浓度变化特征,于2014年8月—2015年1月在张家界森林公园采用 EPA TO-11A方法对张家界森林大气中醛酮类化合物质量浓度进行了监测.结果表明:张家界森林大气中主要的醛酮类化合物为甲醛、乙醛、丙酮、丙醛和MACR(甲基丙烯醛),质量浓度分别为4.32、0.95、3.01、0.48和0.51 μg/m3.大气中ρ(甲醛)、 ρ(乙醛)和ρ(MACR)的季节变化特征很明显,夏季和秋季醛酮类化合物质量浓度较高,冬季醛酮类化合物质量浓度较低.此外,醛酮类化合物质量浓度日变化显著,除了10月、12月受人为因素影响较大外,其余月份醛酮质量浓度最大值通常出现在13:00—15:00.张家界森林大气中C1/C2(ρ(甲醛)/ρ(乙醛))为5.72,比城市地区(C1/C2为1左右)高,但比偏远森林地区(C1/C2为10左右)低.ρ(甲醛)与ρ(乙醛)、 ρ(MACR)均呈正相关且达到显著水平,而ρ(丙酮)与ρ(甲醛)、 ρ(乙醛)与ρ(MACR)的相关性差.与文献报道的加拿大Ontario、墨西哥Langmuir等地区对比,张家界森林大气中醛酮类化合物质量浓度较高,但明显低于北京、上海等城市地区.研究显示,张家界森林大气中甲醛、乙醛和MACR主要来自森林地区植物排放的VOCs光氧化生成,丙酮除了来自植物排放的有机物光氧化分解外,还有其他人为源,进一步说明了张家界森林大气中醛酮类化合物浓度变化主要受光化学反应等自然影响,但人为因素的影响也不容忽略.      

长三角北部沿海城市2018年大气VOCs分布特征

于2018年4—9月在连云港市不同功能区进行了VOCs苏玛罐采样,分析了57种PAMS物种和15种醛酮化合物.结果表明,工业区VOCs浓度最高（54.51 μg·m^-3）,其次是城区（52.59 μg·m^-3）,郊区浓度最低（43.98 μg·m^-3）.不同功能区的VOCs组分占比类似,都为醛酮（39.29%~45.94%） > 烷烃（27.61%~33.15%） > 芳香烃（15.99%~20.25%） > 烯烃（6.49%~7.39%） > 乙炔（0.55%~0.85%）.连云港市PAMS组分浓度与我国其他城市相比明显处于较低水平,季节变化趋势在连云港市城区和郊区基本一致,各组分浓度水平则是城区和工业区较为接近,明显高于郊区.醛酮类化合物中含量最高的为丙酮和2-丁酮,与我国其他城市和乡村地区相比也处在较高水平,季节变化趋势在连云港市所有功能区均呈现春季最高,秋季最低,夏季居中的情况.采用MIR系数计算VOCs的臭氧生成潜势（OFP）,不同功能区对臭氧生成贡献最大的都是芳香烃（39.18%~46.63%）,醛酮（23.90%~29.89%）其次.OFP排名前十物种表明,在连云港市控制正己烷、甲苯、二甲苯、三甲苯等芳香烃和丙酮、2-丁酮,可以有效控制O₃生成.甲苯/苯比值在2左右表明连云港市交通源对大气VOCs贡献显著,由异戊烷/TVOCs比值可知城区和郊区汽油挥发源贡献明显大于工业区,甲醛/乙醛比值在1左右表明连云港市不同功能区大气都符合城市地区的特征,从苯/甲苯与二甲苯/苯比值散点图发现连云港市大气老化特征明显.     

天津冬季两个典型污染过程高浓度无机气溶胶成因及来源分析

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.     

北京大气PM10中水溶性氯盐的观测研究

氯盐是大气气溶胶中重要水溶性无机盐,对2004年全年北京大气可吸入颗粒中氯盐的变化进行了监测,结果表明北京大气中可溶性氯盐的年均值在(3.1±1.7)μg·m^-3,采暖期平均浓度为(4.6±2.1)μg·m^-3,非采暖期平均浓度为(2.6±1.6)μg·m^-3.最低值出现在5月,为(1.3±0.8)μg·m^-3;最高值出现在12月,为(5.8±5.3)μg·m^-3.日变化在秋冬季多为白天浓度低,晚上浓度高,夏春季多呈现上午高,下午低的特征;季节变化呈现秋冬季高,春夏季低的特点.     

青岛大气中HNO3、HNO2和NH3的浓度及其影响因素

硝酸(HNO₃)、亚硝酸(HNO₂)和氨气(NH₃)是大气中重要的含氮化合物,不仅影响大气的光化学氧化能力和酸碱性,还在大气氮沉降中有重要贡献.利用2012年5月4—13日在青岛采集的denuder大气样品,分析了其中HNO₃、HNO₂和NH₃的浓度.青岛大气中HNO₃、HNO₂和NH₃浓度分别为0.88~6.15 μg·m^-3、0.07~2.02 μg·m^-3和0.47~7.87 μg·m^-3,平均分别为2.06 μg·m^-3、0.92 μg·m^-3和3.03 μg·m^-3.大气中3种气体浓度的昼夜变化均无显著性差异.平行采集的样品分析结果显示:denuder涂层的差异对HNO₃和NH₃的观测结果影响较小,但对HNO₂的影响较大,且高温天气易于造成HNO₂更大的观测误差.青岛大气中HNO₃浓度与温度呈正相关、与湿度呈负相关关系,高温低湿天气时样品中HNO₃的浓度一般较高,而高湿或降雨天气时的浓度则较低.NH₃浓度与风向呈显著相关关系,主要受局地一次排放源的影响, NH₄NO₃和NH₄NO₂分解对青岛大气中NH₃的贡献小于23%.青岛大气样品中NH₃的浓度在阵雨时以受土壤释放的影响为主,浓度较高;而连续降雨时则以受湿清除作用的影响为主,浓度较低.     

沈阳市郊区环境空气中醛酮类化合物的污染特征与来源分析

为探究沈阳市郊区环境空气中醛酮类化合物的污染特征,于2017年8月24日—9月2日采用2,4-二硝基苯肼固相吸附/高效液相色谱方法对沈阳市郊区醛酮类化合物进行观测分析,利用美国环境保护局推荐的人体健康风险评价方法对部分有毒有害醛酮类化合物的人体健康风险进行了评价,并利用比值法对醛酮类化合物的来源进行了初步分析.结果表明:醛酮类化合物质量浓度日均值范围为23.16~38.38 μg/m3;质量浓度最高的4种醛酮类化合物依次是丙酮、甲醛、正丁醛和乙醛,其质量浓度日均值的平均值分别为8.71、5.90、5.48和2.95 μg/m3.对·OH消耗速率(L_OH)贡献较大的醛酮类化合物物种是正丁醛、甲醛和乙醛,臭氧生成潜势贡献(OFP)较大的醛酮类化合物物种是甲醛、正丁醛和乙醛,在研究区影响醛酮类化合物光化学反应活性的物种主要是甲醛、乙醛和正丁醛.研究区观测期间,环境空气中甲醛和乙醛的致癌性风险值分别为1.18×10-5和5.91×10-6,对暴露人群存在潜在的致癌风险;乙醛的非致癌风险值为0.05,对暴露人群不存在非致癌风险.在研究区的一次臭氧轻度污染过程期间,环境空气中的甲醛和乙醛受天然源排放的挥发性有机物二次转化的影响减弱,甲醛、乙醛和丙酮受到炼焦工业和机动车等人为源排放的影响增强,而正丁醛主要受当地精细化工产业排放的影响.研究显示,沈阳市应加大对炼焦工业、精细化工和机动车来源排放醛酮类化合物的管制,以降低环境空气中活性醛酮类化合物及有毒有害醛酮类化合物的浓度.      

西安市新装修室内空气中醛酮类化合物的污染特征及健康效应

室内空气质量与人体健康息息相关，为了解新装修室内大气中醛酮类化合物的污染特征及健康效应，实验对西安市三个不同装修材料及不同装修风格房间的大气环境开展研究。使用2,4-二硝基苯肼硅胶提取小柱（DNPH）进行采样，并采用高效液相色谱（high performance liquid chromatography，HPLC）对18种醛酮类物质进行检测，研究其污染水平及特征，并根据物质的光化学反应活性，计算其臭氧生成潜势（ozone formation potential，OPF），评估其对不同年龄段人群的非致癌和致癌健康效应。研究表明：（1）18种醛酮类物质在三个新装修房间空气样品中的总含量为79.9—194.4 μg·m⁻³，高于普通室内环境中的含量。且在供暖期含量显著增加，升高了23.9%—53.3%。其中丙酮、甲醛、乙醛、正壬醛是主要的污染物，其中丁酮在Room 2中显著高于其他两个房间。（2）甲醛和乙醛的光化学活性显著高于其他物质，因而对OPF贡献较大。丙酮虽然含量显著高于其他物质，但是由于光化学活性较低，对OPF贡献不显著。（3）乙醛超过了室内安全排放标准，且在Room 2和Room 3中的非致癌风险危险熵（hazard quotient，HQ）不容忽视。终身致癌风险评估（incremental lifetime cancer risks，ILCR）显示不同人群暴露甲醛的I_LCR均大于1×10⁻⁶，存在潜在健康风险。人群暴露乙醛的I_LCR值仅青少年和老年人在Room 1中低于1×10⁻⁶。由此可见新建住房室内空气中醛酮类物质的污染所产生的健康效应不能忽视。     

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.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.