A 150-year record of black carbon (soot and char) and polycyclic aromatic compounds deposition in Lake Phayao, north Thailand. (15th January 2021)

• Record Type: Journal Article
• Authors: Han, Yongming; Bandowe, Benjamin A. Musa; Schneider, Tobias; Pongpiachan, Siwatt; Ho, Steven Sai Hang; Wei, Chong; Wang, Qiyuan; Xing, Li; Wilcke, Wolfgang
• Is Part Of: Environmental pollution. Volume 269(2021)
• Publication Date: 2021-01-15
• Subjects: Atmospheric Brown cCloud -- Biomass burning -- Black carbon -- Soot and char -- Polycyclic aromatic compounds; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2020.116148
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: An improved understanding of the historical variation in the emissions and sources (biomass burning, BB vs. fossil fuel, FF combustion) of soot and char, the two components of black carbon (BC), and polycyclic aromatic compounds (PACs) may help in assessing the environmental effects of the Atmospheric Brown Cloud (ABC) in SE Asia. We therefore determined historical variations of the fluxes of soot, char, and PACs (24 polycyclic aromatic hydrocarbons (PAHs), 12 oxygenated PAHs (OPAHs), and 4 azaarenes) in a dated sediment core (covering the past ∼150 years) of Phayao Lake in Thailand. The soot fluxes have been increasing in recent times, but at a far lower rate than previously estimated based on BC emission inventories. This may be associated with a decreasing BB contribution as indicated by the decreasing char fluxes from old to young sediments. The fluxes of high- and low-molecular-weight (HMW and LMW) PAHs, OPAHs, and azaarenes all sharply increased after ∼1980, while the ΣLMW-/ΣHMW-PAHs ratios decreased, further supporting the reduction in BB contribution at the expense of increasing FF combustion emissions. We also suggest that the separate record of char and soot, which has up to now not been done in aerosol studies, is useful to assess the environmental effects of ABC because of the different light-absorbing properties of these two BC components. Our results suggest that besides the establishment of improved FF combustion technology, BB must be further reduced in the SE Asian region in order to weaken the ABC haze. Graphical abstract: Image 1 Highlights: Deposition of black carbon, soot and PACs to a Thai sediment core sharply increased since ∼1980. Variations in char and soot deposition in Thailand over the past 150 years were decoupled. Decreasing biomass burning offset the recent increase in other soot emissions to the atmosphere.