沿淮麦区大气无机态氮质量浓度的观测研究

2010年6月6日至6月16日,运用采样器TH-110B和TH-150C收集了地处沿淮麦区3个观测点的气体（NH3和NO2）和气溶胶样品,初步探讨了小麦收获期大气气态氮和颗粒态氮质量浓度的特征。结果表明：气态氮质量浓度以NO2最高,其时均质量浓度和日均质量浓度分别为0.57～0.64 mg.m-3和0.29～0.63 mg·m-3,且均超标（0.24和0.12 mg·m-3）;颗粒态氮质量浓度以NH4＋-N最高（4.12～78.28μg·m-3）,占总氮的47.00%～71.19%。此外,农业活动如收割,可增加大气气溶胶及无机态氮的质量浓度。     

一种气溶胶测量仪器标定系统的设计及性能评估

对气溶胶测量仪器进行准确标定是保证大气环境及污染源颗粒物测量数据质量的重要前提.本研究搭建了一套多分散在线标定气溶胶测量仪器的系统,该系统采用超声气溶胶发生装置产生多分散颗粒物,并用空气动力学粒径谱仪对颗粒物粒径分布进行测量.评测结果表明该系统干燥腔室内气溶胶稳定、均匀,且符合对数正态分布.以采样器为例,已有研究多使用单分散离线标定方法对采样器切割性能进行标定,该方法操作繁琐、实验周期长.利用多分散在线标定系统对PM_(2.5)和PM_(10)双级虚拟撞击采样器进行标定,并与单分散离线标定方法进行了对比,两套系统的标定结果呈现较好的一致性,但多分散在线方法大大缩短了标定实验周期.     

北京市秋季大气气溶胶质量浓度谱分布特征的观测研究

为了研究不同天气形势和气象要素对不同粒径段的大气气溶胶质量浓度谱分布的影响,2010年秋季在北京市采用空气动力学粒径仪对0.5 ～20 μm的大气颗粒物进行了为期2个月的连续观测.结果表明,在不同天气形势和气团运动下,质量浓度谱分布差异明显.受到西北气流影响,在质量浓度较小的清洁天气,谱分布主要集中在粗粒径段(清洁天气).当天气以静稳为主,颗粒物质量浓度值中等偏高时,粗细粒径气溶胶分布中出现谱值相近的高峰(中等浑浊天气).在受到西南气流主要影响的高质量浓度的观测日中,细粒径气溶胶在谱分布中占主要地位(高浑浊天气).在相同气团影响的天气下,昼夜间质量浓度谱分布的谱型变化趋势一致.清洁天气保持了粗粒径段的单峰分布,中等浑浊和高浑浊天气呈双峰分布.清洁天气细粒径段谱值受光化学反应影响在日间略高于夜间.中等浑浊天气中质量浓度的谱值在夜间受相对湿度和温度变化影响有显著增加.高浑浊天气下,昼夜温湿差别小,谱分布未出现明显变化.     

大气中挥发性有机物(VOCs)对二次有机气溶胶(SOA)生成贡献的参数化估算

大气中二次有机气溶胶(SOA)是PM25中的重要组成部分,挥发性有机物(VOCs)的光化学氧化是其主要来源之一.从VOCs转化生成SOA的过程非常复杂,参数化方法是一种相对简化的估算方式,可以用于区分不同VOCs物种对SOA生成的贡献.本文介绍了基于二产物和基于挥发性分级两种常用的参数化估算方法,并总结分析文献报道的SOA估算结果.文章中也指出现在的参数化估算还存在一些问题,如何准确量化VOCs向SOA的转化过程将是大气化学未来的重要研究工作.     

一种纳米气溶胶发生系统的设计及性能测试

气溶胶发生系统是校准大气颗粒物测量仪器、研究纳米颗粒物特性和开展烟雾箱模拟实验的必备仪器之一.针对现有气溶胶发生仪器稳定性差和不利于外场监测等缺点,本研究设计了一款新型纳米气溶胶发生系统(包括气溶胶发生器和扩散干燥管),并通过搭建实验系统对该仪器的工作性能进行了测试.在性能测试中使用氯化钠(NaCl)-水溶液和癸二酸二辛酯(DOS)-异丙醇溶液分别产生固态NaCl和液态DOS气溶胶,利用扫描电迁移率粒径谱仪测试生成气溶胶的粒径分布.测试结果表明,通过调节溶液浓度(0.01～0.50 g·L-1)和载气流量(1.64～3.67 L·min-1),生成不同大小(几何平均粒径:25～51nm)和不同数浓度(106～107个·cm-3)的气溶胶.对仪器稳定性能测试发现,在3 h的测试时间里生成的气溶胶几何平均粒径变化小于6%,数浓度变化小于12%.     

Effect of humic acids and sunlight on the cytotoxicity of engineered zinc oxide and titanium dioxide nanoparticles to a river bacterial assemblage

The effect of a terrestrial humic acid (HA) and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles (ZnONPs) and titanium dioxide nanoparticles (TiO2NPs) to natural aquatic bacterial assemblages was measured with spread plate counting. The effect of HA (10 and 40 ppm) on the cytotoxicity of ZnONPs and TiO2NPs was tested factorially in the presence and absence of natural sunlight (light irradiation (LI)). The experiment was of full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS analytical software. The method of least squares means was used to separate the means or combinations of means. We determined the mechanism of toxicity via measurements of oxidative stress and metal ions. The toxicity of ZnONPs and TiO2NPs to natural aquatic bacterial assemblages appears to be concentration dependent. Moreover, the cytotoxicity of ZnONPs and TiO2NPs appeared to be affected by HA concentration, the presence of sunlight irradiation, and the dynamic multiple interactions among these factors. With respect to light versus darkness in the control group, the data indicate that bacterial viability was inhibited more in the light exposure than in the darkness exposure. The same was true in the HA treatment groups. With respect to terrestrial versus Suwanee River HA for a given nanoparticle, in light versus darkness, bacterial viability was more inhibited in the light treatment groups containing the terrestrial HA than in those containing Suwanee River HA. Differences in the extent of reactive oxygen species formation, adsorption/binding of ZnONPs/TiO2NPs by HA, and the levels of free metal ions were speculated to account for the observed cytotoxicity. TEM images indicate the attachment and binding of the tested nanoparticles to natural bacterial assemblages. Besides the individual parameter, significant effects on bacterial viability count were also observed in the following combined treatments: HA-ZnONPs, HA-LI, ZnONPs-LI, and HA-ZnONPs-LI. The main effects of all independent variables, plus interaction effects in all cases were significant with TiO2NPs.     

Biodegradation of organochlorine pesticide endosulfan by bacterial strain Alcaligenes faecalis JBW4

The recently discovered endosulfan-degrading bacterial strain Alcaligenesfaecalis JBW4 was isolated from activated sludge. This strain is able to use endosulfan as a carbon and energy source. The optimal conditions for the growth of strain JBW4 and for biodegradation by this strain were identified, and the metabolic products of endosulfan degradation were studied in detail. The maximum level of endosulfan biodegradation by strain JBW4 was obtained using broth at an initial pH of 7.0, an incubation temperature of 40℃ and an endosulfan concentration of I00 mg/L. The concentration of endosulfan was determined by gas chromatography. Strain JBW4 was able to degrade 87.5% of α-endosulfan and 83.9% of β-endosulfan within 5 days. These degradation rates are much higher than the previously reported bacterial strains. Endosulfan diol and endosulfan lactone were the major metabolites detected by gas chromatography-mass spectrometry; endosulfan sulfate, which is a persistent and toxic metabolite, was not detected. These results suggested that A. faecalis JBW4 degrades endosulfan via a non-oxidative pathway. The biodegradation of endosulfan by A. faecalis is reported for the first time. Additionally, the present study indicates that strain JBW4 may have potential for the biodegradation of endosulfan residues.     

Classification of multiple types of organic carbon composition in atmospheric particles by scanning transmission X-ray microscopy analysis

A scanning transmission X-ray microscope at the Lawrence Berkeley National Laboratory is used to measure organic functional group abundance and morphology of atmospheric aerosols. We present a summary of spectra, sizes, and shapes observed in 595 particles that were collected and analyzed between 2000 and 2006. These particles ranged between 0.1 and 12 μm and represent aerosols found in a large range of geographical areas, altitudes, and times. They include samples from seven different field campaigns: PELTI, ACE-ASIA, DYCOMS II, Princeton, MILAGRO (urban), MILAGRO (C-130), and INTEX-B. At least 14 different classes of organic particles show different types of spectroscopic signatures. Different particle types are found within the same region while the same particle types are also found in different geographical domains. Particles chemically resembling black carbon, humic-like aerosols, pine ultisol, and secondary or processed aerosol have been identified from functional group abundance and comparison of spectra with those published in the literature.     

济源冬季VOCs污染特征、来源和SOAP

重工业城市济源经常发生雾-霾污染事件.挥发性有机化合物（VOCs）是二次有机气溶胶（SOA）生成的前体物,SOA对细颗粒物(PM_2.5)贡献约15%～20%.于2019年12月1日至12月31日在济源进行PM_2.5、 O₃、 VOCs和其他微量气体在线监测,并分析VOCs污染特征、来源和SOA生成潜势（SOAP）.济源观测到φ（TVOC）平均值为（54.3±27.5）×10^-9.烷烃、卤代烃和炔烃是主要组分.运用正交矩阵因子分解模型（PMF）识别并分配VOCs来源.确定8个主要VOCs来源：液化石油气/天然气（LPG/NG）、聚氯乙烯（PVC）工业、机动车、焦化工业、溶剂使用、工业、工艺过程和油气挥发.二次有机气溶胶生成潜势分析发现芳香烃对SOAP的贡献最大,其中苯系物（BTEX）对SOAP贡献最大.     

人工诱导水库分层水体提前混合对细菌群落结构和代谢活性的影响

水库水体分层是导致底层水体厌氧,产生内源污染的重要原因,人工强制混合充氧可以使分层水体提前实现完全混合,当秋冬季气温低于混合水温时,停止混合充氧系统水体仍可自发地持续进行混合,极大地延长了底层水体及沉积物的好氧周期.上述阶段中,人工强制混合期底层水体温度逐渐升高直至完全混合,自然混合期混合水体温度持续下降,溶解氧保持在7.84～9.86 mg·L^-1.为研究人工诱导水体提前混合对水源菌群及有机污染物代谢的影响,以西安金盆水库为研究对象,在原位监测水质指标的基础上,采用高通量DNA测序技术和Biolog技术分析细菌群落组成及其代谢活性.结果表明,持续自然混合期金盆水库优势菌门为放线菌门（Actinobacteria）和变形菌门（Proteobacteria）,二者相对丰度之和占细菌群落的60.9%～66.2%.放线菌门（Actinobacteria）中的优势菌为CL500-29＿marine＿group（15.96%）,其次为hgcl＿clade（9.25%）.水库水体在完全混合初期,受温度和溶解氧升高影响,细菌活性相对较高,有机污染物指标高锰酸盐指数和溶解性有机碳...