Challenges and policy implications of long-term changes in mass absorption cross-section derived from equivalent black carbon and elemental carbon measurements in London and south-east England in 2014-2019.
Challenges and policy implications of long-term changes in mass absorption cross-section derived from equivalent black carbon and elemental carbon measurements in London and south-east England in 2014-2019.
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DOI：
10.1039/d1em00200g
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发表时间：
2021-11
期刊：
影响因子：
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通讯作者：
K. Ciupek;P. Quincey;D. C. Green;D. Butterfield;G. Fuller
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文献类型：
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作者：
K. Ciupek;P. Quincey;D. C. Green;D. Butterfield;G. Fuller
确定环境空气中含碳颗粒物的浓度对于气候建模、来源归属和空气质量管理非常重要。这项研究提出了与解释伦敦和英格兰东南部碳质颗粒的质量吸收截面（MAC）的明显长期变化相关的困难，这些变化基于2014年至2019年之间的等效黑碳（eBC）和元素碳（EC）测量。虽然这两种测量技术被用来确定含碳气溶胶的浓度，eBC和EC的浓度在所有站点以不同的速率变化，并表现出不同的长期趋势。使用大气蒸发仪对交通和城市背景站点进行的eBC测量显示出一致的趋势，表明浓度下降幅度高达-12.5%。EC浓度在城市背景位置没有变化，在交通站点与eBC的变化相似，在农村站点观察到+10%y-1的显著上升趋势。尽管存在这些差异，但所有研究中心的MAC值趋势均以相似的方式下降，变化率为-5.5% y-1至-10.1% y-1。eBC和EC浓度的不同趋势和变化幅度可能导致量化干预措施的效果方面的不确定性，并导致政策制定的不同结论。本文提供了可能的解释，观察到的MAC值随时间的推移而下降。
Determining the concentration of carbonaceous particles in ambient air is important for climate modelling, source attribution and air quality management. This study presents the difficulties associated with the interpretation of apparent long-term changes in the mass absorption cross section (MAC) of carbonaceous particles in London and south-east England based on equivalent black carbon (eBC) and elemental carbon (EC) measurements between 2014 and 2019. Although these two measurement techniques were used to determine the concentration of carbonaceous aerosols, the concentrations of eBC and EC changed at different rates at all sites, and exhibited different long-term trends. eBC measurements obtained using aethalometer instruments for traffic and urban background sites demonstrated consistent trends, showing decreases in concentrations of up to -12.5% y-1. The EC concentrations showed no change at the urban background location, a similar change to eBC at the traffic site and a significant upward trend of +10% y-1 was observed at the rural site. Despite these differences, the trends in the MAC values decreased at all sites in a similar way, with rates of change from -5.5% y-1 to -10.1% y-1. The different trends and magnitudes of change for the eBC and EC concentrations could lead to uncertainty in quantifying the efficacy of intervention measures and to different conclusions for policy making. This paper provides possible explanations of the observed decrease in MAC values over time.