哈尔滨市供暖期PM2.5组分特征及来源解析

在哈尔滨市2014年1—3月的供暖期间对城区、郊区及周边农村地区的室内外PM_2.5样品进行了同时采集,分析了样品中碳质组分、水溶性离子及无机元素后,通过颗粒物热力学模型计算了颗粒物原位酸度,并通过基于标记的正矩阵分解（PMF）模型对室内外颗粒物的来源进行了表征.计算结果表明,3个地点室外PM_2.5原位酸度均低于室内,且室内外颗粒物原位酸度均为市区最高.PMF结果表明,哈尔滨市区、郊区及农村地区二次源对室外PM_2.5的贡献均排第3位.交通源对市区及郊区的贡献在16%~20%,对于农村地区则是最弱的影响因素.生物质燃烧是农村地区室内外PM_2.5的首要来源;燃煤和工业排放则是市区室内外PM_2.5的主要来源;工业排放是郊区室外PM_2.5的首要来源,与郊区的石化及金属工业有密切联系.因此,为提升哈尔滨市供暖期的空气质量,在进行农村散煤与生物质燃烧治理,推进农村地区清洁能源利用的同时,应多措并举注重城市交通状况改善和促进燃煤锅炉与工业超低排放技术的升级改造,促进区域协同治理.     

广州城区秋季大气PM_(2.5)中主要水溶性无机离子分析

分别在广州市中心城区高楼顶(距地50m)和交通干线路边(距地1.2m),于2006年秋季连续一周采集了大气PM2.5样品,对比分析了SO42-、NO3-、Cl-、F-、Na+、NH4+、Ca2+、K+、Mg2+等9种水溶性无机离子含量。结果表明,楼顶相对充分混合大气中PM2.5的质量浓度范围59.5～129.5μg/m3,均值为83.7μg/m3;交通干线路边大气PM2.5的质量浓度范围为108.4～132.2μg/m3,均值为121.1μg/m3。9种离子总浓度平均达到50.9(楼顶)和44.1(路边)μg/m3,占PM2.5质量浓度的60.8%(楼顶)和36.4%(路边)。SO42-和NO3-为水溶性无机离子主要组成,其占PM2.5质量浓度的比例均是楼顶高于路边,显示二次气溶胶对楼顶充分混合大气中PM2.5有较大贡献,而路边样品中一次来源贡献相对较大。计算表明采样期间海盐对广州大气PM2.5中的水溶性组分贡献较小。NH4+当量浓度远小于SO42-和NO3-的当量浓度,中和度远1,反映PM2.5酸性较强,且楼项PM2.5粒子酸性高于路边样品。     

高锰酸盐指数（酸性法）的条件性

高锰酸盐指数是一个相对的条件性指标,其测定结果与溶液的酸度、高锰酸盐的浓度、加热温度和时间等有关。因此,测定时必须严格遵守操作规定,使其结果具有可比性。     

Reinvestigation of the Henry’s law constant for hydrogen peroxide with temperature and acidity variation

Hydrogen peroxide is not only an important oxidant in itself;it also serves as both sink and temporary reservoir for other important oxidants including HOx(OH and HO2) radicals and O3 in the atmosphere.Its partitioning between gas and aqueous phases in the atmosphere,usually described by its Henry's law constant(KH),significantly influences its role in atmospheric processes.Large discrepancies between the KH values reported in previous work,however,have created uncertainty for atmospheric modelers.Based on our newly developed online instrumentation,we have re-determined the temperature and acidity dependence of KH for hydrogen peroxide at an air pressure of(0.960 ± 0.013) atm(1 atm = 1.01325 × 105 Pa).The results indicated that the temperature dependence of KH for hydrogen peroxide fits to the Van't Hoff equation form,expressed as lnKH = a/T-b,and a =-ΔH/R,where KH is in M/atm(M is mol/L),T is in degrees Kelvin,R is the ideal gas constant,and ΔH is the standard heat of solution.For acidity dependence,results demonstrated that the KH value of hydrogen peroxide appeared to have no obvious dependence on decreasing pH level(from pH 7 to pH 1).Combining the dependence of both temperature and acidity,the obtained a and b were 7024 ± 138 and 11.97 ± 0.48,respectively,ΔH was(58.40 ± 1.15) kJ/(K·mol),and the uncertainties represent σ.Our determined KH values for hydrogen peroxide will therefore be of great use in atmospheric models.     

模拟酸雨对不同土层酸度和K+淋失规律的影响

在江西表土施用KCl肥料后,用室内模拟酸雨的土柱实验,研究酸雨对不同土层酸度及K⁺淋失的影响.其结果表明,不同土层淋出液pH值的变化先下降后上升,但起始pH值存在明显差异,pH2.5酸雨在A层和AB层淋溶的中后期又下降;淋出液电导变化有一个峰值,其出现在淋溶的起始阶段,表明土壤中养分迅速向下迁移.K+的淋失与降雨的酸度有关,pH2.5酸雨会加速K⁺在土体内向下迁移,在A层土壤中K⁺的释放可分为2个阶段:快速释放过程和中速释放过程;至于pH4.5酸雨淋溶下,K⁺淋失分为快速释放过程和慢速释放过程.     

施用尿素和硫酸铵对红壤硝化和酸化作用的影响

通过室内恒温培养试验,研究施用CO(NH2)2和(NH4)2SO4对初始pH值分别为5.14、4.77和4.34的红壤酸化速率和硝化速率的影响。结果表明,施用CO(NH2)2显著增加了3种红壤的硝化速率,从而显著加速土壤酸化。培养结束时,3种红壤pH值较培养过程中最高值分别下降2.14、1.23和0.56。施用(NH4)2SO4抑制了初始pH<5.0的2种红壤的硝化作用,从而显著降低这2种红壤的硝化速率和酸化速率,但显著增加了初始pH>5.0红壤的硝化速率,对其酸化速率则未见显著影响。3种红壤的酸化速率与硝化速率间存在显著线性相关关系。硝化作用是导致农田红壤pH值下降的主要原因之一,但不同氮肥对红壤硝化速率和酸化速率的影响不同。     

中国长三角背景点冬季大气棕碳污染特征及来源解析

为探究长三角城市群背景点大气棕碳（brown carbon,BrC）的污染特征及来源,本研究采集并分析了长三角城市群下风向地区上海崇明岛2018年12月~2019年1月大气PM_2.5样品的化学组成及光学特性.结果表明,甲醇萃取的棕碳在波长365 nm处的吸光系数（absorption coefficients,Abs_365,M）平均为（5.39±3.33）M^-1·m^-1,是水萃取棕碳的1.3倍,且二者均随pH值的增大而显著增加,显示大气颗粒物酸度较弱时有利于棕碳光吸收.冬季Abs₃₆₅和单位质量吸光效率（mass absorption efficiency,MAE₃₆₅）均呈现出夜高昼低的变化趋势,且夜间Abs₃₆₅与左旋葡聚糖呈强线性相关（R²=0.72）,说明生物质燃烧排放大量的吸光性物质是导致夜间Abs₃₆₅较高的一个重要原因.冬季硝基芳香族化合物（nitro-aromatic compounds,NACs）和多环芳烃（polycyclic aromatic hydrocarbons,PAHs）平均浓度分别为（1.5±1.1）ng·m^-3和（8.3±4.7）ng·m^-3,作为棕碳重要的发色基团,二者在365 nm波长处对BrC的吸光贡献分别为0.1%和0.067%.正交矩阵源解析（positive matrix factorization,PMF）分析表明,生物质和化石燃料等燃烧源的直接排放是冬季崇明岛棕碳的主要来源,贡献达56%,其次是二次生成棕碳,占比为24%,而道路扬尘源仅占6%.     

基于集对分析的降水酸度及水质相似预测模型研究

应用集对分析法刻画历史样本之间的相似性,用多个最相似的历史样本的加权平均值作为当前样本预测值,建立了基于集对分析的降水酸度及水质相似预测模型(SFM-SPA),并运用该模型进行了降水酸度及水质预测的实例验证。结果表明,在主要影响因子选择适当、历史样本的代表性和相似性较好等限定条件下,利用模型进行环境预测是可行的,它较直观、计算简便,为环境污染预测提供了新的途径。     

阴离子表面活性剂测量因素的探讨

针对亚甲蓝分光光度法测定阴离子表面活性剂较难处理的乳化现象,采用破乳剂－异丙醇消除,方法回收率良好,准确度为95％－105％。     

Volcanic sulphate and arctic dust plumes over the North Atlantic Ocean

High time resolution aerosol mass spectrometry measurements were conducted during a field campaign at Mace Head Research Station, Ireland, in June 2007. Observations on one particular day of the campaign clearly indicated advection of aerosol from volcanoes and desert plains in Iceland which could be traced with NOAA Hysplit air mass back trajectories and satellite images. In conjunction with this event, elevated levels of sulphate and light absorbing particles were encountered at Mace Head. While sulphate concentration was continuously increasing, nitrate levels remained low indicating no significant contribution from anthropogenic pollutants. Sulphate concentration increased about 3.8 μg m⁻³ in comparison with the background conditions. Corresponding sulphur flux from volcanic emissions was estimated to about 0.3 TgS yr⁻¹, suggesting that a large amount of sulphur released from Icelandic volcanoes may be distributed over distances larger than 1000 km. Overall, our results corroborate that transport of volcanogenic sulphate and dust particles can significantly change the chemical composition, size distribution, and optical properties of aerosol over the North Atlantic Ocean and should be considered accordingly by regional climate models.