Temporal variability of particulate black carbon over Lahore Pakistan

IF 3.4 4区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

International Journal of Environmental Science and Technology Pub Date : 2025-05-16 DOI:10.1007/s13762-025-06504-3

N. Ahmad, M. Razi, M. Z. Shahid, R. Nawaz, M. I. Shahzad, S. Shafiq, I. Shahid

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Abstract

Particulate Black carbon (BC), a critical short-lived climate pollutant, emitted from incomplete combustion of fossil fuel and biomass burning. Due to its strong light-absorbing properties, BC can significantly alter the atmospheric radiation balance and impact air quality and climate. This study investigates the temporal variability of BC mass concentrations over Lahore, Pakistan, using continuous high-resolution measurements from January 2019 to December 2020 with an aethalometer. BC concentrations within PM_2.5 aerosols were recorded at a one-minute temporal resolution and analyzed for daily, monthly, and seasonal trends. The daily mean BC concentrations exhibited substantial variation, averaging 11.77 ± 13.54 µg/m³ (ranging from 0.66 to 148.45 µg/m³) in 2019 and 11.17 ± 8.67 µg/m³ (ranging from 1.55 to 50.52 µg/m³) in 2020. The highest monthly mean BC concentration (32.64 ± 60.64 µg/m³) was recorded in January 2019, with an extreme hourly peak of 1042.71 µg/m³ on January 2 at 21:00 h. For both years, the lowest BC levels were consistently observed in August. Weekly trends revealed that the Sunday observed minimum BC concentrations (10.1 µg/m³) and Wednesdays maximum (13.2 µg/m³). Diurnal variations followed a bimodal pattern, with peaks during morning and evening to midnight, likely driven by traffic emissions and boundary layer dynamics. Correlation analysis showed a robust inverse relationship between BC concentrations and meteorological parameters, with R-values ranging from − 0.46 to − 0.63 for temperature and wind speed. The study highlights the significant contribution of BC to atmospheric aerosol loadings over Lahore, revealing substantial fluctuations across diurnal, daily, monthly, and seasonal scales, and emphasizing the need for effective air pollution control strategies.

Graphical abstract

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巴基斯坦拉合尔上空颗粒物黑碳的时间变异性

颗粒状黑碳（BC）是一种关键的短期气候污染物，由化石燃料和生物质燃烧的不完全燃烧排放。由于其较强的吸光特性，BC可以显著改变大气辐射平衡，影响空气质量和气候。本研究利用浓度计对2019年1月至2020年12月巴基斯坦拉合尔上空的BC质量浓度进行了连续高分辨率测量，研究了其时间变化。以一分钟的时间分辨率记录PM2.5气溶胶中的BC浓度，并分析日、月和季节趋势。BC的日平均浓度变化很大，2019年为11.77±13.54µg/m3（范围从0.66到148.45µg/m3）， 2020年为11.17±8.67µg/m3（范围从1.55到50.52µg/m3）。2019年1月记录的月平均BC浓度最高（32.64±60.64µg/m3）， 1月2日21:00时的极端每小时峰值为1042.71µg/m3。两年来，8月份的BC水平最低。每周趋势显示，周日BC浓度最低（10.1µg/m3），周三最高（13.2µg/m3）。日变化遵循双峰模式，峰值出现在早上、晚上到午夜，可能是由交通排放和边界层动力学驱动的。相关分析表明，BC浓度与气象参数呈显著负相关，温度和风速的r值在- 0.46 ~ - 0.63之间。该研究强调了BC对拉合尔大气气溶胶负荷的重要贡献，揭示了日、日、月和季节尺度上的巨大波动，并强调了有效的空气污染控制策略的必要性。图形抽象

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来源期刊

International Journal of Environmental Science and Technology 环境科学-环境科学

CiteScore

5.60

自引率

6.50%

发文量

806

审稿时长

10.8 months

期刊介绍： International Journal of Environmental Science and Technology (IJEST) is an international scholarly refereed research journal which aims to promote the theory and practice of environmental science and technology, innovation, engineering and management. A broad outline of the journal''s scope includes: peer reviewed original research articles, case and technical reports, reviews and analyses papers, short communications and notes to the editor, in interdisciplinary information on the practice and status of research in environmental science and technology, both natural and man made. The main aspects of research areas include, but are not exclusive to; environmental chemistry and biology, environments pollution control and abatement technology, transport and fate of pollutants in the environment, concentrations and dispersion of wastes in air, water, and soil, point and non-point sources pollution, heavy metals and organic compounds in the environment, atmospheric pollutants and trace gases, solid and hazardous waste management; soil biodegradation and bioremediation of contaminated sites; environmental impact assessment, industrial ecology, ecological and human risk assessment; improved energy management and auditing efficiency and environmental standards and criteria.