金属表面涂装行业VOCs排放特征及排放系数

对比了浙江省2014和2018年金属表面涂装企业的有机废气排放及治理情况,分析了该行业涂料及稀释剂的使用、主要污染因子,测算了溶剂型、水性涂料的挥发性有机物（VOCs）产生系数和排放系数.结果表明：2018年VOCs治理水平明显高于2014年,水性涂料使用企业比例由18%上升至36%,纯溶剂型企业由82%下降至64%;金属表面涂装行业的主要排放污染物为二甲苯、丁醇、乙酸乙酯、乙酸丁酯、甲苯、丙二醇、乙苯、苯乙烯等8种有机物.溶剂型和水性涂料的VOCs产生系数分别为0.72和0.31kg/kg;溶剂型和水性涂料2014年VOCs排放系数为0.64和0.29kg/kg,2018年为0.48和0.21kg/kg.     

离子液体吸收废印刷线路板热拆解过程中挥发性有机物——基于COSMO-RS模型

模拟废印刷线路板（WPCB）的热拆解过程,分析热拆解过程中的挥发性有机物（VOCs）组分;利用真实溶剂似导体屏蔽（COSMO-RS）模型对浓度较高的污染物进行量子力学模拟,研究离子液体（ILs）组成单元对目标污染物溶解度的影响差异,分析溶解过程中主导分子间作用力类型,确定优选吸收剂;测定不同溶剂进行溶解性,验证模型适用性.结果表明：①乙酸乙酯和环戊酮是浓度较高的VOCs组分,在240和250℃时浓度分别为43.1,153mg/m³和105,252mg/m³,质量百分比总和分别为76.3%和67.3%.②高表面屏蔽电荷密度分布峰、长烷基链阴阳离子和亲电基团的存在可提高乙酸乙酯和环戊酮在ILs中的溶解度.双三氟甲磺酰基亚胺盐（NTf₂^-）类ILs是一类优良吸收剂.静电力和范德华力对溶解过程起主导作用.③COSMO-RS模型可定性和半定量用于预测乙酸乙酯和环戊酮的溶解度.     

高原高寒污水处理系统的微生物群落特征

为研究高原高寒污水处理系统活性污泥的微生物群落结构及多样性,以拉萨、云南、四川的3座高原污水厂作为实验组,同时以重庆2座非高原污水厂作为对照,采用PCR-DGGE技术对比分析了高原与非高原污水厂的微生物特性.研究表明：高原污水厂样品与非高原样品在聚类中展现出了较为疏远的关系,微生物群落区别明显.受强紫外线辐照的抑制,高原高寒污水处理系统微生物多样性的平均水平显著低于非高原污水厂,较低的微生物多样性是导致高原高寒地区污染物去除效果不佳的一项重要原因.群落构成方面,共鉴定出16个优势菌属,对应Proteobacteria、Bacteroidetes、Firmicutes、Verrucomicrobia 4个门.组间差异分析结果发现,高原组中丰度显著偏高的菌属只有Prosthecobacter,该菌在污水厂内分布广泛,且能够适应高原低温的条件.对于大多数活性污泥微生物而言,高原强紫外线是不利的生存条件.因此,减少高原露天污水处理系统的紫外辐照,是提升污水处理效能的一个潜在措施.     

红树林土壤解磷菌的分离鉴定及解磷特性

从罗源湾红树林根际土壤中分离解磷菌,筛选出洋葱伯克霍尔德菌（Burkholderia cepacia, NR 113645.1）和短小芽孢杆菌（Bacillus pumilus, NR 043242.1）,研究它们的解磷特性和动态解磷过程. HPLC结果表明, B. cepacia菌液上清中含葡萄糖酸、丙酮酸、乳酸、乙酸、丁二酸, 这些有机酸的产生导致磷酸盐溶解. B.pumilus菌液上清中仅检测到少量的葡萄糖酸, 因此该菌溶磷效果不佳. 在细菌动态溶磷过程中发现, 经B. cepacia菌处理的磷酸钙, 其X射线衍射（XRD）特征峰强度随时间的增长降低, 显微镜图像显示磷酸钙颗粒随时间增长变小, 甚至消失. 而经B.pumilus菌处理的结果表明, 在试验期间内磷酸钙峰强度和颗粒大小没有明显变化. 细菌产生有机酸是溶解磷酸盐的重要前提, 这是解决板结土壤中难溶性磷源转化为生物可利用磷源问题的关键.     

酸性紫色水稻土颗粒有机质对镉的吸附特性

采集典型的酸性紫色水稻土（APPS）,从中分离出颗粒有机质（POM）,通过批量试验研究POM及其来源土壤Cd²⁺的吸附动力学、等温吸附和热力学特征,通过扫描电镜-能谱仪、傅里叶红外光谱仪等手段及吸附前后镉的形态变化的测定,研究了POM对Cd²⁺的吸附机制.结果表明：POM对Cd²⁺的亲和力远高于其来源土壤.POM及土壤对Cd²⁺的吸附动力学最优模型均为准二级动力学.Langmuir、Freundlich方程均能较好地描述其等温吸附特征,其中对POM,以Freundlich方程更优,表明POM对Cd²⁺的吸附属于多分子层的非均质吸附.吸附热力学参数△G^θ均小于0、△H^θ和△S^θ均大于0,表明吸附属于自发吸热过程.根据△H^θ值及解吸试验判定POM对Cd²⁺的吸附以化学吸附为主,土壤对Cd²⁺的吸附过程以物理吸附为主.吸附平衡后,土壤中可交换态镉比例提高,而POM中交换态和络合态镉比例增加.综上及吸附前后POM的表征结果说明,POM对Cd²⁺的吸附机制包括含氧官能团的络合、离子交换、阳离子-π键、沉淀作用和静电吸附.     

北方湖库沉积物重金属区域特征及生态风险评价

以白洋淀、衡水湖、于桥水库、松花湖、大伙房水库和小兴凯湖沉积作为研究对象,通过对北方六湖库沉积物中Cu、Zn、Pb、Cr、Ni等重金属元素进行分析,并与国内外其他水域重金属污染情况进行多因素比较,探讨了六湖库主要重金属污染源的差异性,区域分布特征以及与国内外其他水域污染的相似性和区别.结果表明,六湖库沉积物重金属污染处于中等偏下水平.六湖库之间主要重金属污染源存在差别.沉积物重金属含量未出现明显上升的趋势.其中Zn、Pb存在富集现象,但Pb含量与历史数据相比出现下降,Zn的含量与其他地区相比整体偏高.大伙房水库沉积物重金属污染较重,Cu、Zn、Pb、Cr、Ni含量平均值分别为56.28,142.3,17.44,97.9,44.44mg/kg.小兴凯湖沉积物重金属含量最低,Cu、Zn、Pb、Cr、Ni含量平均值分别为2.41,63.90,13.37,56.36,26.09mg/kg.六湖库综合风险评价结果为大伙房水库>于桥水库>白洋淀>衡水湖>松花湖>小兴凯湖,重金属整体潜在生态风险指数为低.     

Preparation of hydrophobic hierarchical pore carbon–silica composite and its adsorption performance toward volatile organic compounds

Carbon–silica materials with hierarchical pores consisting of micropores and mesopores were prepared by introducing nanocarbon microspheres derived from biomass sugar into silica gel channels in a hydrothermal environment.The physicochemical properties of the materials were characterized by nitrogen physical adsorption(BET),scanning electron microscopy(SEM),and thermogravimetric(TG),and the adsorption properties of various organic waste gases were investigated.The results showed that microporous carbon materials were introduced successfully into the silica gel channels,thus showing the high adsorption capacity of activated carbon in high humidity organic waste gas,and the high stability and mechanical strength of the silica gel.The dynamic adsorption behavior confirmed that the carbon–silica material had excellent adsorption capacity for different volatile organic compounds(VOCs).Furthermore,the carbon–silica material exhibited excellent desorption characteristics:adsorbed toluene was completely desorbed at 150℃,thereby showing superior regeneration characteristics.Both features were attributed to the formation of hierarchical pores.     

2018年春节期间京津冀地区污染过程分析

为了解2018年春节期间京津冀地区空气污染情况,利用近地面污染物浓度数据、激光雷达组网观测数据,结合WRF气象要素、颗粒物输送通量和HYSPLIT气团轨迹综合分析污染过程.结果表明,春节期间出现3次污染过程.春节前一次污染过程,各站点PM_2.5浓度均未超过200μg/m³;除夕夜,廊坊站点PM_2.5峰值浓度达到504μg/m³,是清洁天气的26倍;年初二~初五,各站点PM_2.5始终高于120μg/m³,且污染主要聚集在500m高度以下,北京地区存在高空传输,800m处最大输送通量达939μg/（m³·s）,此次重污染过程为一次典型的区域累积和传输过程.京津冀地区处于严格管控状态时,燃放烟花爆竹期间PM_2.5峰值浓度可达无燃放时PM_2.5峰值的3.2倍.为防止春节期间重污染现象的发生,需对静稳天气下燃放烟花炮竹采取预防对策.     

Effect of NOx and SO2 on the photooxidation of methylglyoxal: Implications in secondary aerosol formation

Methylglyoxal(CH_3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3) K,atmospheric pressure,(18±2)% relative humidity,and under different NOx and SO_2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS) and the results showed that the addition of SO_2 can promote SOA formation,while different NOx concentrations have different influences on SOA production.High NOx suppressed the SOA formation,whereas the particle mass concentration,particle number concentration and particle geometric mean diameter increased with the increasing NOx concentration at low NOx concentration in the presence of SO_2.In addition,the products of the OH-initiated oxidation of MG and the functional groups of the particle phase in the MG/OH/SO_2 and MG/OH/NOx/SO_2 reaction systems were detected by gas chromatography mass spectrometry(GC-MS) and attenuated total reflection fourier transformed infrared spectroscopy(ATR-FTIR) analysis.Two products,glyoxylic acid and oxalic acid,were detected by GC-MS.The mechanism of the reaction of MG and OH radicals that follows two main pathways,H atom abstraction and hydration,is proposed.Evidence is provided for the formation of organic nitrates and organic sulfate in particle phase from IR spectra.Incorporation of NOx and SO_2 influence suggested that SOA formation from anthropogenic hydrocarbons may be more efficient in polluted environment.     

Recent advances in catalytic decomposition of ozone

Ozone (O₃), as a harmful air pollutant, has been of wide concern. Safe, efficient, and economical O₃ removal methods urgently need to be developed. Catalytic decomposition is the most promising method for O₃ removal, especially at room temperature or even subzero temperatures. Great efforts have been made to develop high-efficiency catalysts for O₃ decomposition that can operate at low temperatures, high space velocity and high humidity. First, this review describes the general reaction mechanism of O₃ decomposition on noble metal and transition metal oxide catalysts. Then, progress on the O₃ decomposition performance of various catalysts in the past 30 years is summarized in detail. The main focus is the O₃ decomposition performance of manganese oxides, which are divided into supported manganese oxides and non-supported manganese oxides. Methods to improve the activity, stability, and humidity resistance of manganese oxide catalysts for O₃ decomposition are also summarized. The deactivation mechanisms of manganese oxides under dry and humid conditions are discussed. The O₃ decomposition performance of monolithic catalysts is also summarized from the perspective of industrial applications. Finally, the future development directions and prospects of O₃ catalytic decomposition technology are put forward.