室内木柴燃烧排放水溶性离子粒径分布特征

基于实验室模拟燃烧和稀释通道采样系统,采用荷电低压撞击采样器采集了6种典型木柴燃烧排放的14级粒径段颗粒物.采用离子色谱分析了8种水溶性离子,获得水溶性离子的分粒径排放因子和排放特征.结果表明,Ca²⁺的排放因子呈双峰分布,在0.25~0.38和2.5~3.6μm粒径段出现峰值,分别为0.14和0.16mg/kg.其余离子的排放因子为单峰分布.NH₄⁺、NO₃^-和SO₄^2-的排放因子在0.25~0.38μm粒径段出现峰值,分别为0.41、0.58和0.84mg/kg.K⁺和Cl^-的排放因子在0.15~0.25μm内出现峰值,分别为0.89和0.99mg/kg.木柴燃烧排放总水溶性离子的质量中值粒径为（0.30±0.07）μm,各离子的质量中值粒径范围为0.24~0.44μm.PM_0.094、PM_0.94、PM_2.5和PM₁₀中水溶性离子的排放因子变化范围分别为1.04~9.33、5.00~48.87、5.46~52.00和6.14~53.68mg/kg.木柴燃烧排放颗粒物中K⁺/Cl^-、K⁺/NO₃^-、K⁺/SO₄^2-和SO₄^2-/NO₃^-比值随粒径变化而变化,其排放初始值在应用于源解析和生物质燃烧排放气溶胶传输老化研究时需引起关注.木柴燃烧排放PM₁₀中的阴阳离子当量比值为0.80±0.11,颗粒物的酸度随颗粒物粒径而改变,亚微米颗粒物和细颗粒物的酸度高于超细颗粒物和粗颗粒物的酸度.本研究对构建生物质燃烧排放分粒径水溶性离子清单,更新和改进相关气候和空气质量模型的参数设置,识别烟气传输过程中的老化具有重要意义.     

Effect of NOx and RH on the secondary organic aerosol formation from toluene photooxidation

The secondary organic aerosol (SOA) formation mechanism and physicochemical properties can highly be influenced by relative humidity (RH) and NOx concentration. In this study, we performed a laboratory investigation of the SOA formation from toluene/OH photooxidation system in the presence or absence of NOx in dry and wet conditions. The chemical composition of toluene-derived SOA was measured using Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). It was found that the mass concentration of toluene decreased with increasing RH and NOx concentration. However, the change of SOA chemistry composition (f₄₄, O/C) with increased RH was not consistent in the condition with or without NOx. The light absorption and mass absorption coefficient (MAC) of the toluene-derived SOA only increased with RH in the presence of NOx. In contrast, MAC is invariant with RH in the absence of NOx. HR-ToF-AMS results showed that, in the presence of NOx, the increased nitro-aromatic compounds and N/C ratio concurrently caused the increase of SOA light absorption and O/C in wet conditions, respectively. The relative intensity of CHON and CHO_xN family to the total nitrogen-containing organic compounds (NOCs) increased with the increasing RH, and be the major components of NOCs in wet condition. This work revealed a synergy effect of NOx and RH on SOA formation from toluene photooxidation.     

Removal of refractory organics and heavy metals in landfill leachate concentrate by peroxi-coagulation process

Landfill leachate is a complex effluent and it is difficult to deal with. Electrochemical methods have been considered as a promising alternative technology for treatment of landfill leachate with refractory organic contaminants and heavy metals. Peroxi-coagulation (PC) process with iron anode and modified graphite felt cathode was developed for efficient landfill leachate concentrate treatment. Compared to electro-Fenton (EF) and electrocoagulation (EC) processes, the PC process was more cost-effective due to the combined action of ^•OH oxidation and iron hydroxides coagulation. A maximal TOC removal of 77.2% ± 1.4% was obtained after 360 min at initial pH = 5.0 and current density of 10 mA/cm². After the PC process, concentrations of all seven heavy metals in the final effluents were below the allowable emission limits given by the present regulatory standards. The method preference for heavy metal removal was PC > EC > EF. Based on the three-dimensional fluorescence spectroscopy coupled with regional integration analysis during the PC treatment, the florescence peaks of both humic acids and fulvic acids disappeared after treatment for 360 min. Decreasing trends were observed in the fluorescent regional standard volumes for aromatic protein I (31.4%), aromatic protein II (63.7%), fulvic acid-like (69.5%), soluble microbial by-product-like (75%) and humic acid-like regions (76.3%). The results indicate that comparing to the EF and EC process, the PC process provide a promising and more cost-effective alternative for the treatment of landfill leachate concentrate.     

Deactivation of Cu-SAPO-34 by urea-related deposits at low temperatures and the regeneration

Selective catalytic reduction(SCR) with urea catalyzed by Cu-SAPO-34 is an effective method to eliminate NO_x from diesel exhaust. However, urea-related deposits may form during cold-start and urban driving due to low exhaust temperatures. The activity of CuSAPO-34 at 175°C is significantly degraded by urea exposure, and 300°C is required for regeneration. Through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) and temperature-programmed hydrolysis studies, the dominant stable deposit at 175°C is identified as biuret, which can be eliminated at 300°C. The urea-derived deactivation and regeneration mechanisms of Cu-SAPO-34 were compared with those of anatase-supported catalysts.     

Di-(2-ethylhexy)-phthalate在细菌及细菌-矿物复合体表面的吸附解吸行为

以土壤中分离出的邻苯二甲酸二异辛酯(DEHP)高耐性细菌(伯克霍尔德菌,Burkholderia sp.)及3种常见矿物为实验材料,研究Burkholderia sp.及其矿物复合体对DEHP的吸附解吸行为,包括吸附动力学、吸附等温曲线、pH的影响、FTIR分析等.结果显示,Burkholderia sp.能在较短时间内完成对DEHP的吸附;DEHP在细菌表面的吸附符合Langmuir等温吸附方程(R20.97);Burkholderia sp.吸附DEHP的最适pH为7.0~8.0.蒙脱石、针铁矿、高岭土及细菌对DEHP的吸附能力大小依次为:蒙脱石针铁矿伯克霍尔德菌高岭土;同时,蒙脱石-细菌复合体系对DEHP结合能力最强,而高岭土和针铁矿-细菌复合体系对DEHP的结合强度较小.FTIR分析结果表明细菌表面的蛋白质及脂质部分在DEHP吸附过程中的作用较大,而疏水性作用等是DEHP与细菌及复合体相互结合的主要作用力.这些结果都与DEHP在环境中的迁移转化行为密切相关,对评估该类化合物的环境生态风险以及控制环境污染都具有重要的指导意义.     

Numerical simulation study on air quality in aircraft cabins

Air pollution is one of the main factors that affect the air quality in aircraft cabins, and the use of different air supply modes could influence the distribution of air pollutants in cabins. Based on the traditional ceiling air supply mode used on the B737NG, this study investigated another 3 different kinds of air supply modes for comparison: luggage rack air supply mode, joint mode combining ceiling and luggage rack air supply, and joint mode combining ceiling and individual air supply. Under the above 4 air supply modes, the air velocity, temperature and distribution of air pollutants in a cabin full of passengers were studied using computational fluid dynamics (CFD), and carbon dioxide (CO₂) and formaldehyde were selected as 2 kinds of representative air pollutants. The simulation results show that the joint mode combining ceiling and individual air supply can create a more uniform distribution of air velocity and temperature, has a better effect on the removal of CO₂ and formaldehyde, and can provide better air quality in cabins than the other 3 modes.     

海洋环境中的Fe及其对浮游植物的限制

在海洋环境中,痕量元素Fe成为了继N、P、Si三大生源要素后又一限制浮游植物初级生产力的重要元素.本文介绍了海洋中Fe的各种存在形态、生物可利用性,以及Fe的多种途径的输入来源、沉降过程.着重探讨了Fe对浮游植物初级生产力的限制作用以及对生物量、生长率、生化组成等的影响.了解海洋中Fe的生物地球化学特征对阐明海洋生态系统的循环机制有着深远的意义,并可为赤潮治理提供有益的帮助.     

Spatial distribution of phosphorus forms in sediments with different distances to the estuary of the Dianchi Lake, China

Effects of human activity on the distribution of phosphorus (P) forms were investigated for the sediments and porewaters in Daqinghe Estuary of Dianchi Lake, China. The concentrations of total P (TP), inorganic-P (I-P),and organic-P (Org-P), and the ratio of iron-bound P (Fe-P)/calcium-bound P (Ca-P) in the sediments decreased with the increasing distance from the sampling site to the estuary. This is probably due to the flocculant materials, e.g., ferric and aluminous salts, usually being added in the wastewater treatment processes. The concentration of ammonia in the sediment porewaters significantly decreased with the increasing distance from the sampling site to the estuary. Both concentrations of total nitrogen and nitrogen in the sediment porewaters decreased to some content with the increasing distance from the sampling site to the estuary. However, the concentrations of nitrate, dissolved total P (DTP), and TP did not have strong relationship with the distances from the sampling sites to the estuary. Pollution load and water quantity also had an important influence on the concentrations of P in sediments and its interstitial water in estuary sedimentary area.     

关于危险源与隐患的新见解

为统一危险源和隐患的分歧,本文首先分析2个术语概念混乱的原因,然后根据2个术语的本质特征,给出它们的新定义、新分类和新分级,最后基于新的分类分级体系,给出新的隐患管理模式.研究表明:2个术语服从内外因作用原理,即危险源是内因,隐患是外因.危险源按源头可划分为3类,按载体形式可划分为4类;隐患按安全防护功能可划分为7类,根据产生阶段,可将这7类隐患再归为3类,若按内容和表现形式可将隐患划分为3类.根据隐患影响安全防护功能的程度将隐患分为1、2、3级.隐患管理新模式可简化现行隐患管理体制机制,有助于让政府、企业/单位等落实各自的安全生产主体责任.     

羧基功能化螯合纤维对In(Ⅲ)的吸附行为及机理研究

以聚丙烯腈纤维为基质,通过化学接枝的方式将羧基引入纤维表面,制备得到含有羧基的螯合纤维,并应用于水溶液中In(Ⅲ)吸附分离.采用傅里叶变换红外光谱、扫描电镜、X射线光电子能谱和热重分析技术对样品进行表征.间歇吸附试验表明,所制备螯合纤维对In(Ⅲ)的最大吸附容量为37.5 mg/g,整个吸附过程在120 min以内达到基本平衡,吸附过程复合准二级动力学模型.竞争性吸附试验表明,在含有In(Ⅲ)、Fe(Ⅲ)、Zn(Ⅱ)和Hg(Ⅱ)的混合溶液中,吸附材料对In(Ⅲ)显示出一定的亲和能力.研究依靠路易斯酸碱理论在纤维表面构建了能用于In(Ⅲ)捕捉的吸附位点,为In(Ⅲ)的吸附分离提供了新的思路或方法.