Impact of transport of fine and ultrafine particles from open biomass burning on air quality during 2019 Bangkok haze episode

Transboundary and domestic aerosol transport during 2018–2019 affecting Bangkok air quality has been investigated. Physicochemical characteristics of size-segregated ambient particles down to nano-particles collected during 2017 non-haze and 2018–2019 haze periods were analyzed. The average PM_2.5 concentrations at KU and KMUTNB sites in Bangkok, Thailand during the haze periods were about 4 times higher than in non-haze periods. The highest average organic carbon and elemental carbon concentrations were 4.6 ± 2.1 µg/m³ and 1.0 ± 0.4 µg/m³, respectively, in PM_0.5–1.0 range at KU site. The values of OC/EC and char-EC/soot-EC ratios in accumulation mode particles suggested the significant influence of biomass burning, while the nuclei and coarse mode particles were from mixed sources. PAH concentrations during 2018–2019 haze period at KU and KMUTNB were 3.4 ± 0.9 ng/m³ and 1.8 ± 0.2 ng/m³, respectively. The PAH diagnostic ratio of PM_2.5 also suggested the main contributions were from biomass combustion. This is supported by the 48-hrs backward trajectory simulation. The higher PM_2.5 concentrations during 2018–2019 haze period are also associated with the meteorological conditions that induce thermal inversions and weak winds in the morning and evening. Average values of benzo(a)pyrene toxic equivalency quotient during haze period were about 3–6 times higher than during non-haze period. This should raise a concern of potential human health risk in Bangkok and vicinity exposing to fine and ultrafine particulate matters in addition to regular exposure to traffic emission.     

水环境中溶解性有机物溯源分析及分子结构表征概述

溶解性有机物(DOM)是地球上最大的碳基化合物反应性储层之一,涉及各种生物地化反应并且在污染物溶解度、毒性、生物利用度、流变性和分布中发挥重要作用。本文介绍了当前用于表征水环境中DOM的策略和工具,探讨了当前研究在技术限制(预处理过程复杂、仪器分辨率低、数据处理困)、结构复杂性、结构多变性等方面存在的诸多局限性。分析认为:已有研究主要侧重于溯源分析和分子结构特征解析,未来研究应该在不同的结构层面和角度开展,加强多学科融合、数据库创建、对照实验和协同工作。     

PM2.5 source apportionment in a French urban coastal site under steelworks emission influences using constrained non-negative matrix factorization receptor model

The constrained weighted-non-negative matrix factorization(CW-NMF) hybrid receptor model was applied to study the influence of steelmaking activities on PM_(2.5)(particulate matter with equivalent aerodynamic diameter less than 2.5 μm) composition in Dunkerque,Northern France. Semi-diurnal PM_(2.5)samples were collected using a high volume sampler in winter 2010 and spring 2011 and were analyzed for trace metals, water-soluble ions, and total carbon using inductively coupled plasma – atomic emission spectrometry(ICP-AES),ICP- mass spectrometry(ICP-MS), ionic chromatography and micro elemental carbon analyzer. The elemental composition shows that NO_3~-, SO_4~(2-), NH_4~+and total carbon are the main PM_(2.5)constituents. Trace metals data were interpreted using concentration roses and both influences of integrated steelworks and electric steel plant were evidenced. The distinction between the two sources is made possible by the use Zn/Fe and Zn/Mn diagnostic ratios. Moreover Rb/Cr, Pb/Cr and Cu/Cd combination ratio are proposed to distinguish the ISW-sintering stack from the ISW-fugitive emissions. The a priori knowledge on the influencing source was introduced in the CW-NMF to guide the calculation. Eleven source profiles with various contributions were identified: 8 are characteristics of coastal urban background site profiles and 3 are related to the steelmaking activities. Between them,secondary nitrates, secondary sulfates and combustion profiles give the highest contributions and account for 93% of the PM_(2.5)concentration. The steelwork facilities contribute in about 2%of the total PM_(2.5)concentration and appear to be the main source of Cr, Cu, Fe, Mn, Zn.     

不同碳源条件下污水生物脱氮过程中N_2O的释放规律

以3类常用的碳源(乙酸钠、葡萄糖和甲醇)为研究对象,在3个稳定运行的SBR系统内考察了碳源种类对污水生物脱氮过程中N_2O释放的影响。结果显示,各系统内N_2O的释放主要发生在好氧硝化阶段,且在以乙酸钠为碳源的系统内氨氧化速率最快,TN去除率最大,但同时N_2O的释放速率、累积释放量(4.44 mg)和转化率(1.3%)也最大。而以甲醇为碳源的小试系统脱氮效果较差,TN去除率仅为59.5%,但N_2O的释放速率、累积释放量和转化率均最低。在实际污水处理过程中,当以温室气体N_2O释放作为判断标准时,此研究结果可为碳源的选择提供依据。     

基于时差收敛算法的声发射源定位方法研究

本文针对传统基于时差的声发射定位方法精度及稳定性不足且易受检测环境影响的问题,提出了一种基于收敛算法的声发射源定位方法,经过循环迭代不断优化声发射信号的到达时刻计算方式,使得定位计算重构的定位源稳定收敛在近似同一区域,从而提高声发射源的定位准确度。     

Echolocation signals of the bat Eptesicus serotinus recorded using a vertical microphone array: effect of flight altitude on searching signals

The acoustic behaviour of Eptesicus serotinus was investigated in the field using a 13.5-m vertical, linear microphone array that allowed for simultaneous recordings at three different heights and for the calculation of flight altitude and distance from the array. Recordings were made at two locations that differed in bat species diversity. E. serotinus hunted on average at an altitude of 10.7 m (±2.7) at one location and 6.8 m (±3.6) at the other location. Search signals were 5–17 ms long depending on flight altitude, and consisted of two to three frequency-modulated harmonics. For bats flying below 8–10 m altitude, signal duration decreased with decreasing flight altitude, whereas signal interval, terminal frequency, peak frequency and frequency range of the first harmonic increased. Above 8–10 m flight altitude, the signal parameters were fairly constant. The –10 dB bandwidth and duty cycle did not change with flight altitude. Source levels were calculated to between 121 and 125 dB peSPL re 20 μPa at 10 cm. For bats flying higher than 9 m, the microphone placed 1.5 m above the ground recorded significantly reduced signal durations and frequency ranges of the first harmonic compared to the same signals recorded with the microphones at heights of 7 or 15 m. We caution the use of ground recordings to fully describe the echolocation signals of high-flying bats. We demonstrate that flight altitude significantly influences the structure of sonar signals from E. serotinus. Received: 17 May 1999 / Received in revised form: 20 September 1999 / Accepted: 25 September 1999     

Physico-chemical characterization and source tracking of black carbon at a suburban site in Beijing

Particles from ambient air and combustion sources including vehicle emission, coal combustion and biomass burning were collected and chemically pretreated with the purpose of obtaining isolated BC (black carbon) samples. TEM (transmission electron microscopy) results indicate that BC from combustion sources shows various patterns, and airborne BC appears spherical and about 50 nm in diameter with a homogeneous surface and turbostratic structure. The BET (Barrett–Emmett–Teller) results suggest that the surface areas of these BC particles fall in the range of 3–23 m²/g, with a total pore volume of 0.03–0.05 cm³/g and a mean pore diameter of 7–53 nm. The nitrogen adsorption–desorption isotherms are indicative of the accumulation mode and uniform pore size. O₂-TPO (temperature programmed oxidation) profiles suggest that the airborne BC oxidation could be classified as the oxidation of amorphous carbon, which falls in the range of 406–490°C with peaks at 418, 423 and 475°C, respectively. Generally, the BC characteristics and source analysis suggest that airborne BC most likely comes from diesel vehicle emission at this site.     

碳源及电子受体对厌氧微生物降解对氯硝基苯的影响

为考察氯代硝基苯的共代谢降解过程中,有机碳源类型和电子受体对氯代硝基苯厌氧降解过程的影响,以对氯硝基苯(p-CNB,para-chloronitrobenzene)为目标污染物,通过间歇试验考察了葡萄糖、乙醇、乙酸钠等有机碳源及SO2--4、NO3等竞争性电子受体对厌氧微生物降解对氯硝基苯的影响。结果显示,葡萄糖、乙醇和乙酸钠作为碳源时,菌种获得的还原能力大小依次为:乙醇葡萄糖乙酸钠。SO2-4对菌种降解对氯硝基苯过程不产生竞争性抑制。NO-3对对氯硝基苯降解过程的影响与碳源的量有关,当乙醇-COD为100 mg/L时,硝酸盐产生竞争性抑制,且抑制作用随着NO-3浓度升高而增强;当乙醇-COD为600 mg/L时,硝酸盐对菌种降解对氯硝基苯过程不产生竞争性抑制作用。     

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.     

水污染源解析技术与应用研究进展

阐述了水污染源解析的概念,将水污染源解析方法归纳总结为基于污染负荷估算的方法、基于污染潜力指数的方法及基于源受体污染物特征的方法 3种类型,并分别概述了各种方法的特点,综述了国内外水污染源解析研究的类型与应用进展。最后指出了我国水污染源解析研究在基础资料、研究对象及方法上存在的问题,提出了未来的研究重点。