上海大气冷凝水化学特性分析

2011年3月8日至4月11日期间利用新研制的大气冷凝水采样器收集了上海大气冷凝水样品.从冷凝水的化学组成及常见大气湿沉降的比较、冷凝水离子间的相关性、冷凝水离子浓度随时间变化等方面,分析了上海大气冷凝水的化学特性.结果表明,上海大气冷凝水pH值介于6.1~7.2,加权均值为6.5,多呈弱酸性;NH4+和SO42-是含量最高的2种离子,浓度分别为139.7μeq/L和125.7μeq/L,SO42-是主要致酸离子;NO2-含量为9.9μeq/L,比NO3-(9.5μeq/L)略高,且所有冷凝水样品中NO2-检出率为100%;4种低分子量有机酸MSA-(6.0μeq/L)、CH3COO-(5.9μeq/L)、C2O42-(3.9μeq/L)和HCOO-(3.7μeq/L)占阴离子总量的8.5%,含量远高于上海雨水;Ca2+(19.2μeq/L,4.0%)、Mg2+(4.9μeq/L,1.0%)含量比同期雾水低2~3个数量级;冷凝水离子浓度随时间变化较大,这与光化学反应、春季逆温等有关.     

中国南海大气降水化学特征

利用中国科学院南海海洋研究所"实验3"号船南海海洋断面科学考察2012年夏季航次进行大气降水采样,测定样品pH值和主要阴阳离子浓度,结合TrajStat软件模拟后向气团轨迹,分析南海夏季大气降水离子化学特征及来源.结果表明,夏季降水pH平均值为6.3,最小值为5.6.阴阳离子浓度顺序均分别表现为Cl->SO2-4>NO-3和Na+>Mg2+>Ca2+>K+,Cl-和Na+是主要的阴离子和阳离子,浓度平均值分别为2 637.5μeq·L-1和2 095.5μeq·L-1,表现出了海洋性大气降水的特征.7种离子间均表现出良好的线性相关关系,相关系数在0.9以上,说明它们可能具有统一来源;NO-3与其他离子的相关系数相对较低,可能NO-3具有相对复杂的来源;Ca2+和K+还可能跟南海珊瑚环境有关.本研究的6个站位后向轨迹显示,水汽气团来源于正南或西南方向,未经过大陆上空,因此本研究中南海夏季大气降水的离子来源受人为影响可以忽略.     

基于降水化学的北京城乡大气污染物差异探析

降雨化学成份的变化间接反映大气污染特征,是研究大气环境及沉降物影响的重要途径.本文比较了2013与2014年雨季北京市区到郊县延庆4个样点上降雨成份的时空差异,并结合PMF模型分析了各主要离子的可能来源.结果表明,4个样点降雨pH中值分别为6.52、6.57、6.60、6.52,从市区到远郊略有增加.各离子浓度都是春秋季高,夏季低.降雨中各离子的雨量加权平均浓度(VWM)表现为:Ca~(2+)、NH_4~+、SO_4~(2-)较高,分别在100~400μeq·L~(-1)、100~350μeq·L~(-1)、150~500μeq·L~(-1)之间,Mg~(2+)、Na~+和NO_3~-分别在0~150μeq·L~(-1)、0~250μeq·L~(-1)、0~150μeq·L~(-1)之间,K~+和Cl~-较低,分别在0~45μeq·L~(-1)、0~90μeq·L~(-1)之间.NH_4~+、Mg~(2+)的VWM从市区到郊区递减,K~+、SO_4~(2-)-S、Na~+、NO_3~呈近郊区略有增大,远郊区全部减小的趋势.SO_4~(2-)是主要的致酸离子,Ca~(2+)、NH_4~+和Mg~(2+)对雨水中酸根离子的中和因子平均值分别为0.5、0.4和0.1.市区BNU点SO_4~(2-)-S(以S计)与Ca~(2+)的沉降量分别为55.66 kg·hm~(-2)·a~(-1)和24.10 kg·hm~(-2)·a~(-1),在远郊YQ点为26.03 kg·hm~(-2)·a~(-1)和10.84kg·hm~(-2)·a~(-1).NH_4~+-N与NO_3~-N的沉降量在4点的变化范围为7.27~14.05 kg·hm~(-2)·a~(-1)及2.50~5.07 kg·hm~(-2)·a~(-1).Mg~(2+)和Cl~-从市区到远郊分别在1.32~4.48 kg·hm~(-2)·a~(-1)及3.67~6.10 kg·hm~(-2)·a~(-1)之间变化.所有离子以湿沉降为主,沉降量与相应的降雨量变化较为一致.根据PMF模拟结果,4点的地面扬尘和建筑源污染均较高,市中心尾气污染最严重,近市区二次源污染严重,近郊区氮污染严重,远郊区受养殖场、垃圾源等的NH_3排放影响较大.     

九龙江流域大气氮湿沉降研究

通过2004～2005年对位于我国东南沿海的九龙江流域及周边共17个站点的实地观测,运用GIS技术定量揭示了大气氮湿沉降强度和时空分布特征,并利用氮稳定同位素分析雨水硝态氮的主要来源.结果表明,①17个站点雨水总氮平均浓度为(2.20±1.69)～(3.26±1.37) mg·L-1(以N计,下同),铵态氮、硝态氮和有机氮分别占39%、25%和36%;②雨水氮浓度随降雨强度的增大呈降低趋势,旱季浓度明显大于雨季,降水对大气具有清洗作用;③低δ15N值表明雨水硝态氮主要来源于汽车尾气排放、化石燃料燃烧和化肥施用;④九龙江流域大气氮湿沉降量平均9.9 kg·hm-2,春夏2季约占全年的91%,大气氮湿沉降占沉降总量的66%,揭示了该地区1∶2的大气氮干湿沉降结构.大气氮湿沉降时空差异与降雨量和氮的排放直接相关.     

湛江东海岛海雾雾水化学特征的对比分析

利用2010年和2011年在广东省湛江市东海岛海雾外场观测试验中获得的雾水样本和雾滴谱资料,对南海沿岸海雾化学特性进行研究.结果表明:2010年雾水的p H和电导率(EC)平均值分别为5.20和1884μS·cm-1,2011年的p H和EC平均值分别为3.34和505μS·cm-1.2011年雾水酸性变强的原因主要考虑到酸性物质比重增加.海洋源离子Cl-和Na+的离子浓度很高;SO_2-4和NO-3具有同源性,人为污染的贡献明显.2010和2011年总离子浓度(TIC)的平均值分别为38260μeq·L~(-1)和5600μeq·L~(-1),而实际大气中离子负荷量相差不大,主要是由于2011年观测地点海拔高度的升高会降低湍流因子的影响,减少粒径较大雾滴的沉降,从而促使液态水含量增加,在大气中污染物质浓度变化不大的情况下,离子浓度下降.     

戴云山国家级自然保护区大气氮沉降特点

利用干湿沉降采集器,持续观测戴云山国家级自然保护区内大气氮素干、湿沉降,调查当地大气氮沉降的种类和沉降通量.结果表明,2015-03-27~2015-10-09观测期间,戴云山自然保护区大气氮干、湿沉降量分别为2.30 kg·hm~(-2)和14.79kg·hm~(-2),以湿沉降形式为主(87%).干沉降中可溶性有机氮的沉降量为1.21 kg·hm~(-2),占干沉降通量的53%;无机氮以硝态氮为主(0.71 kg·hm~(-2)),铵态氮相对较低(0.37 kg·hm~(-2)).湿沉降中无机氮和可溶性有机氮沉降量分别为9.41 kg·hm~(-2)和5.38 kg·hm~(-2),其中无机氮以铵态氮为主(6.07 kg·hm~(-2)).大气氮湿沉降量和当地降雨量显著正相关,降雨量越大,对应的湿沉降氮量也越大.戴云山国家级自然保护区大气氮素沉降量较高,可能会对当地生态环境产生较大的影响.     

基于CMAQ模式的中国大气BaP迁移转化模拟研究

在空气质量模式CMAQ中增加了对大气中苯并[a]芘(BaP)传输、转化和沉降过程的模拟,新增了BaP气相/颗粒相间分配模式(K_OA吸收模式)以及BaP化学转换,并采用该模型模拟了2014年1、4、7、10月四个季节代表月中国大气中BaP的浓度以及干湿沉降通量的空间分布特征.模拟结果与部分地区的实测数据进行了初步对比验证,结果显示BaP浓度的模拟值和测量值的量级基本一致,其比值基本在1~2个量级范围内,表明模拟结果处于可接受的范围.基于模型结果,还探讨了BaP浓度与沉降季节变化特征与人为源排放的紧密联系,说明湿沉降是BaP最主要的沉降途径.BaP沉降的空间分布与其排放源和浓度具有密切的联系,并且具有长距离输送的特征等.     

2010年中国大气氮沉降特征分析

利用区域空气质量模式Models-3/CMAQ对我国2010年的氮沉降特征进行了模拟分析.结果表明,2010年我国氮沉降总量约为7.6′ 103Gg,化学组成上以NHx-N(包括NH3、NH4+中的氮)沉降为主,平均占到2/3以上.夏季氮沉降量最高,冬季最低.干沉降为氮沉降的主要途径(约占62%),主要为气态含氮污染物的贡献,湿沉降的氮则主要来自颗粒态的铵盐和硝酸盐.我国氮沉降的空间分布具有东高西低、地区间差异显著的特征,高沉降通量区域主要集中在华北平原、四川盆地、华中的中南部、两广以及东北部分地区.加强对氨排放的管理和控制,同时重视东部沿海的发达地区的氮氧化物排放,对减少氮沉降具有重要意义.     

南京夏秋季节大气干沉降水溶性离子特征及来源分析

本研究利用采集的2014年7~10月南京地区84个有效干沉降样品,探讨了南京夏秋季节大气干沉降中水溶性离子的化学组成及其来源.结果表明南京夏秋季干沉降样品平均p H为6.2,干沉降偏中性.Ca~(2+)和NH~+_4是主要的阳离子,日均浓度分别为115.7μeq·L~(-1)和31.2μeq·L~(-1),分别占阳离子总量的68.3%和18.6%.阴离子以SO~(2-)_4、Cl~-和NO~(2-)_3为主,日均浓度为30.4、20.7和18.7μeq·L~(-1),共占总阴离子的89.2%.干沉降浓度变化受温度湿度等气象条件和污染气团输送共同作用的影响,其中本地气团对干沉降污染的影响较大,干沉降污染具有局地性.南京夏秋季节固定源(燃煤)对大气干沉降水溶性离子的贡献大于移动排放源(机动车),8月因举办青奥会而采取的环境管控措施对固定源的影响大于移动源.主要离子来源分析表明NO~-_3和SO~(2-)_4大部分源自于人为排放,Cl~-主要为海洋输入,K~+和Mg~(2+)主要来自陆相输入.     

沈阳市降水化学成分及来源分析

沈阳市2007年降水样品化学组分研究表明,该区降水pH值在4.89～8.02之间,雨量加权平均值为6.89,与杭州等南方地区相比,沈阳降水中离子浓度比较高,但降水的酸化程度和酸化频率却不高,表明沈阳市整体上降水没有呈现酸化,主要是碱性离子的中和作用.SO24-和Cl-是主要的阴离子,雨量加权平均值为330.00μeq·L-1和85.05μeq·L-1,分别占阴离子总量的60.32%和15.55%;Ca2+和NH4+是主要的阳离子,雨量加权平均值为291.17μeq·L-1和175.13μeq·L-1,分别占阳离子总量的49.51%和29.78%.季节变化特征研究表明离子浓度变化呈现秋冬高,春夏低的状态.NF计算结果表明NH4+和Ca2+具有较强的中和能力,而Mg2+和K+的中和能力比较小,相较于NH4+和Ca2+几乎可以忽略不计.利用富集系数法计算表明,SO24-和NO3-主要来源于人为输入,Cl-主要为海洋输入,NH4+和K+主要来源于土壤和人为活动的输入.     

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.     

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.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.