Investigation of carbonyl compound sources at a rural site in the Yangtze River Delta region of China

Carbonyl compounds are important intermediates in atmospheric photochemistry, but their primary sources are still not understood well. In this work, carbonyls, hydrocarbons, and alkyl nitrates were continuously measured during November 2011 at a rural site in the Yangtze River Delta region of China. Mixing ratios of carbonyls and hydrocarbons showed large fluctuations during the entire measurement. The average level for total measured volatile organic compounds during the pollution episode from 25th to 27th November, 2011 was 91.6 ppb, about 7 times the value for the clean period of 7th–8th, November, 2011. To preliminarily identify toluene sources at this site, the emission ratio of toluene to benzene (T/B) during the pollution episode was determined based on photochemical ages derived from the relationship of alkyl nitrates to their parent alkanes. The calculated T/B was 5.8 ppb/ppb, significantly higher than the values of 0.2–1.7 ppb/ppb for vehicular exhaust and other combustion sources, indicating the dominant influence of industrial emissions on ambient toluene. The contributions of industrial sources to ambient carbonyls were then calculated using a multiple linear regression fit model that used toluene and alkyl nitrates as respective tracers for industrial emission and secondary production. During the pollution episode, 18.5%, 69.0%, and 52.9% of measured formaldehyde, acetaldehyde, and acetone were considered to be attributable to industrial emissions. The emission ratios relative to toluene for formaldehyde, acetaldehyde, and acetone were determined to be 0.10, 0.20 and 0.40 ppb/ppb, respectively. More research on industrial carbonyl emission characteristics is needed to understand carbonyl sources better.     

微孔曝气国内外研究进展及趋势分析

分析比较了国内外微孔曝气研究和应用实例,指出了目前微孔曝气技术的研究重点。同时,综合国内外研究人员的研究成果,分别叙述了曝气量、安装水深、安装面积、孔径、水质和气孔堵塞状况对微孔曝气充氧性能的影响,对不同影响因素的作用效果做了总结,并指出目前研究存在的问题。以期对污水处理厂曝气系统的优化提供借鉴,对拟采用微孔曝气法进行生态修复的研究提供参考。     

Role of secondary aerosols in haze formation in summer in the Megacity Beijing

A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 10 km and RH(relative humidity) 90%. Four haze episodes, which accounted for ~ 60% of the time during the whole campaign, were characterized by increases of SNA(sulfate, nitrate, and ammonium) and SOA(secondary organic aerosol) concentrations. The average values with standard deviation of SO2-+4, NO-3, NH4 and SOA were 49.8(± 31.6), 31.4(±22.3), 25.8(±16.6) and 8.9(±4.1) μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH+4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR(sulfur oxidation ratio) and NOR(nitrogen oxidation ratio) increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.     

Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China

Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM10 and PM1.8mass concentrations were 166.0 ± 120.5 and 91.6 ± 69.7 μg/m~3, respectively,throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM1.8/PM10 ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM(organic matter = 1.6 × OC(organic carbon)) and SIA(secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca_2+were major components in coarse particles. Moreover, secondary components, mainly SOA(secondary organic aerosol) and SIA,accounted for 46%–96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of(NH_4)_2SO_4, NH_4NO_3, Ca SO_4, Na_2SO_4 and K_2SO_4, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons.     

Antimony leaching release from brake pads: Effect of pH, temperature and organic acids

Metals from automotive brake pads pollute water, soils and the ambient air. The environmental effect on water of antimony (Sb) contained in brake pads has been largely untested. The content of Sb in one abandoned brake pad reached up to 1.62 × 10⁴ mg/kg. Effects of initial pH, temperature and four organic acids (acetic acid, oxalic acid, citric acid and humic acid) on Sb release from brake pads were studied using batch reactors. Approximately 30% (97 mg/L) of the total Sb contained in the brake pads was released in alkaline aqueous solution and at higher temperature after 30 days of leaching. The organic acids tested restrained Sb release, especially acetic acid and oxalic acid. The pH-dependent concentration change of Sb in aqueous solution was best fitted by a logarithmic function. In addition, Sb contained in topsoil from land where brake pads were discarded (average 9 × 10³ mg/kg) was 3000 times that in uncontaminated soils (2.7 ± 1 mg/kg) in the same areas. Because potentially high amounts of Sb may be released from brake pads, it is important that producers and environmental authorities take precautions.     

印染废水处理技术研究进展探析

印染废水的主要特点是色度、BOD、COD、pH值、温度和浊度高,分子量大,生物降解性低,且废水成分复杂,含有有机高分子化合物和助凝剂等.综述了印染废水处理技术的研究及应用现状,介绍了印染废水中常用的物理处理法、化学处理法和生物法,分析了不同处理方法的研究及应用效果及优缺点,提出了各处理方法的技术缺陷及存在的问题,并对印染废水处理未来的研究方向进行了展望,不同处理方法间的组合可以较好地发挥它们各自的优点,是未来可靠处理印染废水的有效方法.     

废旧金属回收熔炼辐射安全管理研究

介绍了一起废旧金属熔炼导致的放射性污染事件,以及环保部门在事件中采取的措施.反思了废旧金属回收熔炼辐射安全监管存在的问题,指出相关的法律法规不够明确,对熔炼企业辐射监测的监管力度不足,废金属进出口的放射性管理存在漏洞,熔炼企业缺乏辐射安全意识和手段,提出了完善标准体系,强化口岸监测,实施分级管理,加强企业辐射安全管理等对策措施.     

Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community

Estuarine wetland, where freshwater mixes with salt water, comprises different regions（rivers and marine ecosystems） with significantly varying tidal salinities. Two sampling areas, ZXS and JS, were selected to investigate the effect of tidal salinity on soil respiration（SR）. ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively, with similar elevation and plant species, but significantly different in salinity. The results showed that with almost identical plant biomass, the SR and soil microbial respiration（SMR） of the tidal wetland with lower salinity（JS） were significantly higher than those of the tidal wetland with higher salinity（ZXS）（p 〈 0.05）. However, unlike SMR and SR, the difference in the soil microbial biomass（SMB） was not significant（p 〉 0.05）with the SMB of ZXS a little higher than that of JS. The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria. Abundant β- and γ-Proteobacteria and Actinobacteria in JS soil, which have strong heterotrophic metabolic capabilities, could be the main reason for higher SMR and SR,whereas a high number of ε-Proteobacteria in ZXS, some of which have carbon fixation ability, could be responsible for relatively lower carbon output. Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors, suggesting that higher soil salinity, restricting highly heterotrophic bacteria, is the principle reason for lower SMR and SR in the ZXS.     

集中供热项目环境效益分析——以某市集中供热项目为例

介绍了某市新区供热现状,并对预测模型AERMOD的运行参数及数据来源进行了简要说明,根据区内供热现状及采取集中供热方式后新区冬季采暖集中供热锅炉烟气污染物排放源强的变化情况,采用AERMOD模型分别进行了预测。在此基础上,通过对比分析,得出了大型集中供热工程具有明显环境效益的结论。