Environmental sampling of volatile organic compounds during the 2018 Camp Fire in Northern California

Trace analysis of volatile organic compounds (VOCs) during wildfires is imperative for environmental and health risk assessment. The use of gas sampling devices mounted on unmanned aerial vehicles (UAVs) to chemically sample air during wildfires is of great interest because these devices move freely about their environment, allowing for more representative air samples and the ability to sample areas dangerous or unreachable by humans. This work presents chemical data from air samples obtained in Davis, CA during the most destructive wildfire in California's history - the 2018 Camp Fire – as well as the deployment of our sampling device during a controlled experimental fire while fixed to a UAV. The sampling mechanism was an in-house manufactured micro-gas preconcentrator (µPC) embedded onto a compact battery-operated sampler that was returned to the laboratory for chemical analysis. Compounds commonly observed in wildfires were detected during the Camp Fire using gas chromatography mass spectrometry (GC–MS), including BTEX (benzene, toluene, ethylbenzene, m+p-xylene, and o-xylene), benzaldehyde, 1,4-dichlorobenzene, naphthalene, 1,2,3-trimethylbenzene and 1-ethyl-3-methylbenzene. Concentrations of BTEX were calculated and we observed that benzene and toluene were highest with average concentrations of 4.7 and 15.1 µg/m³, respectively. Numerous fire-related compounds including BTEX and aldehydes such as octanal and nonanal were detected upon experimental fire ignition, even at a much smaller sampling time compared to samples taken during the Camp Fire. Analysis of the air samples taken both stationary during the Camp Fire and mobile during an experimental fire show the successful operation of our sampler in a fire environment.     

主动采样法采集博物馆空气中微量污染气体

根据博物馆污染气体的种类,对气体主动采样法进行了采样器种类、吸收液种类和浓度、吸收液体积的选择。验证了气体采样流量、采样时间与气体采样浓度的线性关系,确定了酸性和碱性污染气体的主动采样方法,为监测文物保存环境污染气体提供了可行方法。     

标准气与空气样品同路同效输送的新型采样总管集成技术

经过近20年的发展,监测部门面对日益严峻的环境压力及其对环境监测数据要求的日益严格,要求大气自动监测QA/QC体系必须更加完善。针对传统采样总管标准气不能实现与空气样品同路同效输送的问题进行探讨,并研发出一套实现标准气与空气样品同路同效输送的新型采样总管集成技术。     

西安市某工业园夏季VOCs浓度特征及O3、SOA生成潜势

2020年7月30日—10月10日对西安市某工业园区大气中的70种VOCs开展了为期73 d的VOCs手工采样监测,分析了上、下风向2个点位VOCs浓度组成特征、O₃生成潜势和SOA生成潜势,并运用PMF进一步分析该区域VOCs的主要来源。结果显示：监测期间工业园区平均VOCs浓度为203.50 μg/m³,以甲醛和乙醛为主的醛酮类（148.37 μg/m³）是主要污染物,占TVOC浓度的57%~84%,其次是烷烃。通过上、下风向VOCs成分比较发现,醛酮类为高污染时段特征污染物,工业园区平均OFP为969.66 μg/m³,醛酮类对O₃生成的贡献最大,占TOFP的80%~97%,其次是烯烃。工业园区平均SOAFP为0.50 μg/m³,芳香烃对SOA生成的贡献最大,占TSOAFP的48%~98%,其次是烷烃。PMF源解析得到5个因子,分别为工业源、溶剂涂料、燃烧源、移动源及其他源,贡献率分别占35.2%、20.4%、18.3%、12.8%、13.3%,解析显示该区域受到下风向电子产业影响较大。     

Sorption mechanisms of diphenylarsinic acid on natural magnetite and siderite: Evidence from sorption kinetics,sequential extraction and extended X-ray absorption fine-structure spectroscopy analysis

• DPAA sorption followed pseudo-secondary and intra-particle diffusion models. • Chemical bonding and intra-particle diffusion were dominant rate-limiting steps. • DPAA simultaneously formed inner- and outer-sphere complexes on siderite. • DPAA predominantly formed occluded inner-sphere complexes on magnetite. • Bidentate binuclear bond was identified for DPAA on siderite and magnetite. Diphenylarsinic acid (DPAA) is both the prime starting material and major metabolite of chemical weapons (CWs). Because of its toxicity and the widespread distribution of abandoned CWs in burial site, DPAA sorption by natural Fe minerals is of considerable interest. Here we report the first study on DPAA sorption by natural magnetite and siderite using macroscopic sorption kinetics, sequential extraction procedure (SEP) and microscopic extended X-ray absorption fine-structure spectroscopy (EXAFS). Our results show that the sorption pseudo-equilibrated in 60 minutes and that close to 50% and 20%–30% removal can be achieved for magnetite and siderite, respectively, at the initial DPAA concentrations of 4–100 mg/L. DPAA sorption followed pseudo-secondary and intra-particle diffusion kinetics models, and the whole process was mainly governed by intra-particle diffusion and chemical bonding. SEP and EXAFS results revealed that DPAA mainly formed inner-sphere complexes on magnetite (>80%), while on siderite it simultaneously resulted in outer-sphere and inner-sphere complexes. EXAFS analysis further confirmed the formation of inner-sphere bidentate binuclear corner-sharing complexes (²C) for DPAA. Comparison of these results with previous studies suggests that phenyl groups are likely to impact the sorption capacity and structure of DPAA by increasing steric hindrance or affecting the way the central arsenic (As) atom maintains charge balance. These results improve our knowledge of DPAA interactions with Fe minerals, which will help to develop remediation technology and predict the fate of DPAA in soil-water environments.     

大气持久性有机污染物分析研究进展

对近年来大气持久性有机污染物(POPs)研究中的新污染物、采样方法、检测方法、评价方法进行了扼要的综述,概括总结了大气POPs研究中人们所关注和需要解决的热点问题.     

大气中多环芳烃的来源及采样方式的研究

本文对大气中多环芳烃的来源进行了调查的基础上,对燃源,交通源,等采产方式进行了综述,评价了各种采样方式的优缺点,从而造反我环芳烃污染源解析的采样方式。     

地衣样品的采集和保存技术的研究

本文阐述了地衣样品的规范的采集;无污染的采样工具、运输工具、盛装容器及加工器械是保存技术的先行条件。全程序的质控是保存技术的基础,温度、压力、光则是保存技术决定性的因素。通过三种保存技术的研究筛选出了既经济又简便的保存技术     

利用等速采样原理克服动压平衡型烟尘采样仪在寒冷地区不能正常工作的问题

根据等速采样原理,探讨在标准状态下,采样体积的计算公式.当气温在0℃以下采样时,略去累计流量计、流量计前压力表、流量计前温度表,即不再用上述仪表测得参数求算采样体积,实现了冬季采样又简化了设备的结构.     

排污总量监测若干问题的思考

分析了排污总量监测过程中关于最低检出限、一类污染物的采样点位、监测频次、超标污染物等方面与污染源监督监测的区别以及存在的问题,并提出了相应的对策和措施.