The online measured black carbon aerosol and source orientations in the Nam Co region, Tibet

Xin Zhang,Feiteng Wang,Jing Ming,Zhongqin Li,Guoshuai Zhang

doi:10.1007/s11356-017-0165-1

Abstract

Equivalent black carbon (eBC) mass concentrations were measured by an aethalometer (AE-31) in the Nam Co, central Tibet from 2010 to 2014. Different from previous filter-sampling studies (Ming et al., J Environ Sci 22(11):1748–1756, 2010; Zhao et al., Environ Sci Pollut Res 20:5827–5838, 2013), the first high-resolution online eBC measurement conducted in central Tibet is reported here, allowing to discuss the diurnal variations as well as seasonal variabilities of eBC. Average daily eBC concentration was 74 ± 50 ng/m3, reflecting a global background level. Meteorological conditions influenced eBC concentrations largely at seasonal scale, which are higher in February–May but lower in June–January. The highest eBC concentrations (greater than 210 ng/m3) were more associated with the W and WSW winds smaller than 6 m/s. The diurnal variations of eBC showed plateaus from 10:00 to 15:00 with seasonal variations, associated with local anthropogenic activities, such as indigenous Tibetan burning animal waste and tourism traffic. The PBLHs showed a co-variance with eBC concentrations, implicating close sources. The aerosol optical depths derived from the MODIS data over the Nam Co Observatory Station (NCOS)-included sub-area (30° N–40° N, 90° E–100° E) showed significant relationship with eBC concentrations. This suggests that nearby or short-distance sources other than long-distance transported pollutants could be important contributors to eBC concentrations at the NCOS, different from the conclusions suggested by previous studies.

Highlights

Carbonaceous aerosols, which primarily consist of black carbon (BC) and organic carbon (OC), impact on global climate and environment largely. Equivalent black carbon (eBC) is produced mainly from incomplete combustion of biomass and fossil fuels, which is the second most important agent of global warming after CO2 (Bond et al 2013; Panicker et al 2010)
1 Northwest Normal University, Lanzhou 730070, China 2 Biogeo/Multiphase Chemistry Department, Max Planck Institute for Chemistry, 55128 Mainz, Germany 3 State Key Laboratory of Cryospheric Sciences, Chinese Academy of Sciences, Lanzhou 730000, China 4 Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China (NCOS)-included sub-area (30° N–40° N, 90° E–100° E) showed significant relationship with eBC concentrations. This suggests that nearby or short-distance sources other than long-distance transported pollutants could be important contributors to eBC concentrations at the Nam Co Observatory Station (NCOS), different from the conclusions suggested by previous studies
The highest daily eBC concentration occurred on May 23, 2014 (417 ng/m3), while the lowest was on July 19, 2011 (3 ng/m3)

Summary

Introduction

Carbonaceous aerosols, which primarily consist of black carbon (BC) and organic carbon (OC), impact on global climate and environment largely. eBC is produced mainly from incomplete combustion of biomass and fossil fuels, which is the second most important agent of global warming after CO2 (Bond et al 2013; Panicker et al 2010). A high temporal resolution data of equivalent BC (eBC) concentration measured by an aethalometer instrument (Model AE-31) at the NCOS are firstly presented over Tibet to our knowledge.

Results

Conclusion