Advances in research of airborne microbes in subway systems北大核心CSCD

Subway systems are indispensable for transportation in modern cities, with the air being easily polluted by microbes owing to the enclosed and crowded environment. The microbiological characteristics of subway aerosols have attracted the attention of researchers worldwide during recent years. This review aimed to evaluate the sampling and analyzing methods suitable for detecting airborne microbes in subway systems. Active air sampling methods and molecular biology techniques based on polymerase chain reaction (PCR) such as 16S rRNA gene sequencing, metagenomics, and quantitative PCR demonstrated great potential in microbial analysis of aerosols because they can provide accurate and comprehensive information. Temporal and spatial distributions of airborne microbes, as well as the factors influencing their distribution characteristics, were also discussed by critically reviewing worldwide literature on subway microbiome studies. The concentration and composition of airborne bacteria and fungi in subway can vary dramatically with time and space. The critical factors determining microbial community structure and composition include temperature, relative humidity, carbon dioxide concentration, number of passengers, presence of platform screen door, ventilation systems, and so on. The review suggests that future studies on standardized sampling and analyzing protocols are required to obtain contamination levels of subway airborne microbes and to establish the relationship between microbial monitoring data and public health risks. © 2018 Science Press. All rights reserved.     

大气颗粒物的形态、成分分布的透射电镜、X-射线衍射研究

本文利用透射电镜和X-射线衍射技术,对酸雨危害较为严重的重庆市市区大气颗粒物样品进行了较力细致的研究工作。通过对大气飘尘的表面状态、元素组成以及其结合形态的研究,发现粒度较小的球状颗粒物及粗柱状矿物飘尘对酸雨形成影响较大。同时,本文还对酸雨的形成机理进行了一些探讨。      

天水市空气微生物含量分析

用平皿沉降法测定了天水市空气微生物含量,结果证实其空气细菌、真菌及总菌的平均含量分别为5312.3、13．1和5325．4CFU／m3．空气真菌占总菌量的0．2％左右,空气微生物以细菌为主十分明显,所测风景区空气细菌含量与城区的平均水平间差异很大,说明天水市空气已受到较轻的中度污染,闹市区的一些测点空气污染已相当严重。     

昆明市不同功能区夏季空气微生物污染监测

为了监测和评价昆明市空气微生物污染状况,通过平皿自然沉降法,于2010年夏季对其不同功能区空气真菌和细菌进行了初步监测。结果表明:昆明市夏季空气微生物以细菌为主;以空气真菌含量评价为清洁;8月空气真菌含量最高,7月空气细菌含量最低;空气微生物含量日变化不明显。     

Spatial variations in selected metal contents and particle size distribution in an urban and rural atmosphere of Islamabad, Pakistan

Spatial variations in total suspended particulate matter (TSP) were investigated for distribution of metals and particle size fractions in the urban and rural atmosphere of Islamabad, Pakistan. The metals Na, K, Fe, Mn, Pb, Cd, Cr, Zn, Ni and Co, and the particle fractions <2.5, 2.5-10, 10-100 and >100 microm were included in the study. TSP samples were trapped on glass fibre filters using high volume samplers and quantification of metals was done using Atomic Absorption Spectrometry employing HNO(3) based wet digestion. At the urban site, Na was dominant at 2.384 microg/m(3) followed by K, Fe and Zn with 0.778, 0.667 and 0.567 microg/m(3) as mean concentrations, respectively. The metal levels for the rural site ranged from 0.002 microg/m(3) for Cd to 1.077 microg/m(3) for Na. However, compared with the urban site, mean Pb concentration showed an almost two-fold enhancement, i.e., 0.163 Vs. 0.327 microg/m(3). Metals and particle size source identification was done using Principal Component Analysis and Cluster Analysis. Five sources were traced out for the urban site: industrial, soil, automobile emissions, metallurgical industries and excavation activities. For the rural site, four sources were recorded: agricultural, automotive emissions, excavation activities and metallurgical units. Collectively, for both the sites, PM(10-100) emerged as a major contributor to TSP, followed by PM(2.5-10), PM(<2.5) and PM(>100) in that order. The metals showed in general positive relationship with fine particulate fractions (PM(2.5-10), PM(<2.5)), and negative correlation with coarse fractions (PM(10-100), PM(>100)). Comparison with the corresponding data from various Asian sites revealed that the levels of Na, K, Fe, Mn, Co and Ni for the present study were lower than those reported for grossly polluted cities of the world.     

水泥厂大气污染物健康风险评价初探

根据大气污染物的环境行为,沿着污染物排放-迁移转化-人体吸收这条途径,提出了以致残调整生命年为最终评价指标的大气污染物人体健康风险定量评价方法.对广东某水泥厂实例分析说明,水泥生产过程排放的各种大气污染物中,NOx的人体健康风险最大,占水泥生产过程所有大气污染物健康风险的43.9%,SO2的人体健康风险最小.     

Natural and anthropogenic radionuclides in airborne particulate samples collected in Barcelona (Spain)

Results for naturally occurring ⁷Be, ²¹⁰Pb, ⁴⁰K, ²¹⁴Bi, ²¹⁴Pb, ²¹²Pb, ²²⁸Ac and ²⁰⁸Tl and anthropogenic ¹³⁷Cs in airborne particulate matter in the Barcelona area during the period from January 2001 to December 2005 are presented and discussed. The ²¹²Pb and ²⁰⁸Tl, ²¹⁴Bi and ²¹⁴Pb, ⁷Be and ²¹⁰Pb radionuclide levels showed a significant correlation with each other, with correlation coefficients of 0.99, 0.78 and 0.69, respectively, suggesting similar origin/behaviour of these radionuclides in the air. Caessium-137 and Potassium-40 were transported to the air as resuspended particle from the soil. The ⁷Be and ²¹⁰Pb concentrations showed similar seasonal variations, with a tendency for maximum concentrations during the summer months. An inverse relationship was observed between the ⁷Be, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs concentrations and weekly rainfall, indicating washout of atmospheric aerosols carrying these radionuclides.     

PCBs in air, soil and milk in industrialized and urban areas of KwaZulu-Natal, South Africa

Information regarding polychlorinated biphenyls (PCBs) in environmental media in Africa is limited. This paper presents results of a monitoring program conducted in KwaZulu-Natal Province, South Africa designed to characterize levels, trends and sources of airborne PCBs. Particulate and vapor samples were sampled over the 2004-2005 period at three sites. The total PCB concentration averaged 128 ± 47 pg m⁻³, and levels were highest in winter. Tri- through hexa-congeners predominated, and the vapor fraction was predominant. Several tetra- through hexa-chlorinated congeners had levels comparable to those at urban sites in the northern hemisphere, but hepta- through deca-congeners resembled levels at background sites. PCB source areas, deduced using spatial and temporal patterns, compositional information and trajectory analyses, likely included local, regional and global sources. Soils at three rural sites showed high PCB concentrations, and milk from a local dairy showed PCB concentrations comparable to USA levels in year 2000.     

Comparison of endotoxin levels and gram-negative bacteria under different conditions in microbial laboratories and a biowaste site

In this study, we assessed airborne endotoxin levels in university laboratories, hospital diagnostic laboratories, and a biowaste site. We also investigated indoor and outdoor sampling, sampling site, type of ventilation system, presence of open biowaste boxes, weather, and detection of Gram-negative bacteria (GNB). A total of 69 air samples were collected from 11 facilities in three institutions. Average total airborne endotoxin levels ranged from <0.01 to 10.02 EU m⁻³, with an overall mean of 1.03 EU m⁻³. Endotoxin levels were high in window-ventilated facilities, in facilities in which GNB were detected; levels were also high when it was rainy (all ps < 0.05). Endotoxin levels were significantly correlated with humidity (r = 0.70, p < 0.01). The presence of HVAC; humidity; and the presence of open biowaste boxes affect endotoxin levels in laboratories.     

Study on the initial velocity distribution of exhaled air from coughing and speaking

Increasing concerns about the spread of airborne pathogens such as severe acute respiratory syndrome (SARS) and novel swine-origin influenza A (H1N1) have attracted public attention to bioaerosols and protection against them. The airborne pathogens are likely to be expelled from coughing or speaking, so the physical data of the exhaled particles plays a key role in analyzing the pathway of airborne viruses. The objective of this study was to analyze the initial velocity and the angle of the exhaled airflow from coughing and speaking of 17 males and 9 females using Particle Image Velocimetry (PIV) and acrylic indoor chamber. The results showed that the average initial coughing velocity was 15.3 m/s for the males and 10.6 m/s for the females, while the average initial speaking velocity was 4.07 m/s and 2.31 m/s respectively. The angle of the exhaled air from coughing was around 38° for the males and 32° for the females, while that of the exhaled air from speaking was around 49° and 78° respectively. Also, the linear relation between the tested subject’s height and their coughing and speaking velocity was shown in this study.