| 摘要: |
| 农作物秸秆燃烧是大气中黑碳（black carbon，BC）气溶胶的主要来源之一。目前农作物秸秆燃烧排放黑碳的研究主要集中在通过离线样品分析获得的BC排放特征，缺少实时在线排放特征的研究。本研究收集了我国具有代表性的4种农作物秸秆（小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆），通过在实验室燃烧平台模拟农作物秸秆露天燃烧的过程，利用黑碳仪获得农作物秸秆燃烧过程中BC的实时浓度排放变化；利用质量重建，获得BC在线排放因子。结果表明：农作物秸秆在明燃过程中BC的排放因子较为稳定。通过平均排放因子的计算，获得小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆的BC排放因子分别为(0.32±0.05) g∙kg−1、(0.31±0.13) g∙kg−1、(0.31±0.09) g∙kg−1和(0.44±0.01) g∙kg−1。在排放因子的基础上，结合我国农作物秸秆露天燃烧量，最终建立了2015年我国省级（不含港澳台地区）典型农作物秸秆燃烧的BC排放清单。 |
| 关键词: 黑碳 农作物秸秆燃烧 高时间分辨率 在线排放因子 |
| DOI：10.7515/JEE182072 |
| CSTR： |
| 分类号: |
| 基金项目:国家自然科学基金项目（41661144020，41503118）；国家杰出青年科学基金项目（41625015） |
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| High time resolution emission characteristics and emission inventory of black carbon in typical crop residues burning in China |
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WANG Wenjie, TIAN Jie, ZHANG Yong, ZHANG Yonggang, WANG Qiyuan, HAN Yongming, CAO Junji
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1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Key Laboratory of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
4. Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
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| Abstract: |
| Background, aim, and scope Biomass burning is a major source of black carbon (BC). China is a large agricultural country, with an average annual straw output of about 600 million tons. Open burning of crop residues accounts for about 26.8% of the total biomass burning. There are still limited studies focusing on the characteristics of BC from crop residues emissions. In this study, a custom-made combustion chamber was used to simulate the open burning of several representative types of crop residues. We obtained the characteristics of real-time emission factors of BC, and its emission inventory was established based on the crop yields in 2015 in China (not including Hong Kong, Macao and Taiwan of China). Materials and methods The crop residues were mainly collected in the main grain producing areas of China. Test burns were conducted in a custom-made combustion chamber at the Institute of Earth Environment, Chinese Academy of Sciences (IEECAS) to simulate the open burning of crop residues. The combustion chamber is a ~8 m3 cavity container with a length, width, and height of 1.8 m, 1.8 m, and 2.2 m, respectively. The combustion chamber was equipped with a thermocouple, a thermoanemometer, and an air purification system. A dilution sampler (Model 18, Baldwin Environmental Inc., Reno, NV, USA) was installed downstream of the chamber to dilute the smoke before sampling. Results BC emission stability of crop residues during the process of flaming. The BC average emission factors for wheat straw, rice straw, corn stalk and soybean straw were (0.32±0.05) g·kg−1, (0.31±0.13) g·kg−1, (0.31±0.09) g·kg−1, and (0.44±0.01) g·kg−1. The estimated BC emissions for open burning of wheat, rice, corn and soybean were 13900 tons, 7100 tons, 8550 tons and 1330 tons, respectively, in China in 2015. Discussion The carbon content of straw calculated by mass balance and the average emission factors are consistent with those of previous studies. The four kinds of crop residue mass did not change much during the initial combustion, and the mass decreased rapidly during the steady combustion process. The real-time emission factor of BC has little change in stable combustion. The quality reconstruction is inaccurate in this experiment at the initial and end of the combustion, and the BC emission factor is based on the mean value of the stable combustion stage. Conclusions Calculating the carbon content of crop residue can well reflect the changes of straw burning quality. The BC average emission factor of soybean straw was higher than that of the other three straws. The quality reconstruction method is not accurate due to the less BC emission in the initial and end of combustion. According to the estimation of BC emissions of opening burning crop straw in all Chinese mainland provinces in 2015, we can see that BC emissions are mainly concentrated in Jiangsu, Anhui, Henan and Hunan provinces. Recommendations and perspectives This experiment mainly simulates the change of BC emission in crop straw open burning during flaming stage, and the BC emissions from crop straw smoldering process is less. |
| Key words: black carbon crop residues burning high time resolution real-time emission factor |
