VOCs Monitoring System Status and Development Direction in Key Regions of China
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摘要: 科学开展大气挥发性有机物(VOCs)的监测是臭氧(O3)与细颗粒物(PM2.5)复合污染成因机制和防控的关键基础,对持续改善我国空气质量具有重要意义. 为优化提升我国VOCs监测体系和效能,提出未来光化学监测发展方向和路径,通过调研、数据挖掘总结评估了国内外VOCs监测体系设计、监测布点、监测项目和时段、监测技术和质控技术等监测要素,结果表明:①我国初步建成了覆盖重点区域的光化学监测网,但监测点位功能相对单一,缺乏区域、输送、排放高值区等关键点位,其优化和完善是提升我国VOCs监测效能的重要途径. ②5—9月是我国O3污染的重要时段,影响O3的重要组分则主要为美国环境保护局(US EPA)光化学评估监测站(Photochemical Assessment Monitoring Stations, PAMS)所涉及的组分以及醛酮类组分,其中乙烯、苯系物、甲醛、乙醛等尤为关键,并应关注部分支链烯烃和α-蒎烯、β-蒎烯等天然源烯烃对O3或颗粒物的影响,最终需结合本地化特点优化监测项目. ③我国VOCs监测技术体系中手工监测和自动监测各具优势,未来发展趋势以自动监测为主、手工监测为辅,监测技术体系应向高精准度化、标准化、小型化、模块化、智能化,以及高时间分辨率和低成本等方向发展;同时持续进行质量体系标准研究,补足空白,提升监测数据质量. 研究显示,我国环境大气VOCs监测应优化监测布点,加强监测技术体系和质量体系标准化,并聚焦重点时段形成我国本地化监测项目,从而科学地优化和完善我国光化学监测体系.
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关键词:
- 挥发性有机物(VOCs) /
- 监测网络 /
- 监测技术 /
- 优化
Abstract: Scientific monitoring of volatile organic compounds (VOCs) in the atmosphere is the key basis for the formation mechanism and prevention and control of the combined pollution of O3 and PM2.5. It is of great significance to continuously improve the air quality in China. In order to optimize and improve the VOCs monitoring system and efficiency in China and put forward the development direction and path of photochemical monitoring in the future, the key elements of VOCs monitoring system design, monitoring sites, monitoring items and periods, monitoring technology and quality control technology at home and abroad are evaluated through research, data mining and other methods. This research is carried out from the development history, monitoring points, monitoring items and time periods, monitoring technology and quality of VOCs monitoring at home and abroad. The results show that: (1) China has initially established photochemical monitoring network covering key areas, but in the VOCs monitoring network, key points such as regions, transportation and high emission areas are lacking. It is important to optimize and improve the performance of VOCs monitoring network in China. (2) May to September is an important period of O3 pollution in China. The components involved in Photochemical Assessment Monitoring Stations (PAMS) under the US Environmental Protection Agency (US EPA) aldehydes and ketones are important components affecting O3, especially ethylene, benzene series, formaldehyde and acetaldehyde. And the impact of some branched chain olefins and natural source olefins such as α-pinene, and β-pinene on O3 or particulate matters is also noteworthy. Finally, the monitoring project should be optimized according to the localization characteristics. (3) In terms of monitoring technology, manual monitoring and automatic monitoring have their own advantages, showing the development trend of automatic monitoring as the main and manual monitoring as the auxiliary. The monitoring technology system should be developed in the direction of high precision, standardization, miniaturization, modularization, intelligence, high time resolution and low monitoring cost. At the same time, quality system standard research should be continued to fill in the gaps and improve the quality of monitoring data. The research shows the monitoring points of atmospheric VOCs in China should be optimized, the standardization of monitoring technology system and quality system should be strengthened, and the localized monitoring projects in China should be formed focusing on key periods, so as to scientifically optimize and improve the photochemical monitoring program in China. -
表 1 2018—2021年我国开展VOCs、NMHC监测的城市数量
Table 1. The number of VOCs and NMHC monitored cities in China from 2018 to 2021
年份 开展VOCs监测的城市个数 开展NMHC监测的城市个数 2018 81 79 2019 119 176 2020 155 252 2021 165 270 表 2 我国VOCs监测点位类型
Table 2. Type of VOCs monitoring points in China
VOCs监测点位类型 自动点位个数 手工点位个数 人口密集区内的O3浓度高值区 122 92 O3高浓度点 9 17 VOCs高浓度点 2 12 区域点 4 16 地区影响边缘监测点(下风向点位) 15 20 城市上风向点 6 28 背景点 9 3 其他 9 8 合计 176 196 表 3 2017—2020年我国重点区域O3超标天数
Table 3. Total number of days of O3 exceeding the standard in key regions of China from 2017 to 2020
区域 超标天数(城市超标天之和)/d 4年城市平均超标天数/d 重点超标时段的超标天数/d 超标极值月份的超标天数/d 2017年 2018年 2019年 2020年 京津冀及周边地区 1 479 1 688 2 251 1 727 64 1 241(5—7月) 585(6月) 汾渭平原 510 441 569 426 44 386(6—8月) 158(6月) 苏皖鲁豫交界区域 767 836 1 387 865 44 671(5—6月、9月) 355(6月) 珠三角及周边地区 228 252 452 216 32 194(8—10月) 83(9月) 长三角地区 1 135 1 164 1 713 1 126 31 827(5—7月) 373(6月) 成渝地区 212 270 313 325 18 174(4月、7—8月) 78(8月) 表 4 VOCs手工及自动监测技术特点比较
Table 4. Comparison of VOCs manual and automatic monitoring techniques
对比指标 手工监测技术 自动监测技术 应用基础 20~30年技术积累,标准规范配套齐全 5~10年的应用基础,仅有方法标准 监测组分 可满足国家规划的116项组分 57种PAMS组分监测能力,部分GC-MS可监测116项组分 稳定性 实验室环境和仪器稳定性均较强 GC-FID较稳定,GC-MS稳定性欠缺,易受站点内外环境影响 检出限 绝大多数组分检出限在0.1×10−9以下 90%以上组分检出限在0.1×10−9以下 准确性 准确性好,质控可控 准确性好,质控可控 前处理 三级冷阱,除水性能好 一级冷阱,除水性能不足,易偏差 布点要求 可定制,空间灵活布点 布点要求高,选定后更换难度大 数据回溯核实 可重复分析、回溯分析 一次性分析,无法回溯 采样代表性 涵盖采样、运输、稀释、分析等技术环节,易组分流失,采样代表性不足 原位连续采样分析,样品仅需要通过采样总管,原位采样,样品损失小,采样代表性强 数据时间分辨率 数据时间分辨率较低, 周期长,从采样时刻到数据输出,整体需24 h 数据时间分辨率较高,具备小时或小时以下数据时间分辨率 人员要求 需采样人员、运输人员、分析人员,对人员要求较高 人员需求少,仅需仪器运维人员 质控要求 质控环节多. 涉及采样罐质控、现场采样质控、运输质控、平行样质控等外部质控和仪器质控 仅需仪器质控,但质控难度较大 运维成本 环节多、人员多、成本高 人力物力投入相对较少 -
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