On the Contribution of Biomass Burning to POPs (PAHs and PCDDs) in Air in Africa

Abstract

Forest, savannah, and agricultural fires in the tropics and subtropics are sources for widespread pollution and release many organic substances into the air and soil, including persistent organic pollutants, i.e., polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs). The significance of this source for the exposure of humans and the environment in Africa toward phenanthrene, fluoranthene, pyrene, benzo(a)pyrene, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin, and octachlorodibenzo-p-dioxin is studied using daily global emissions from vegetation fires observed by satellite and a global multicompartment chemistry-transport model. Near-ground atmospheric concentrations of model-predicted vegetation fire related concentrations of PAHs and PCDDs were in the 10-1000 and 10(-5)-10(-3) pg m(-3) ranges, respectively. Vegetation fires in Africa are found to emit 180 ± 25 kg yr(-1) of PCDD/Fs. By comparison with observations, it is found that fires explain 1-10% of the PCDD (5% of 2,3,7,8- tetrachlorodibenzo-p-dioxin) concentrations in the rural and background atmosphere of sub-Saharan Africa. The contribution of vegetation fires to exposure to PAH is probably>10%, but cannot be quantified due to lack of knowledge with regard to both emission factors and photochemistry. A sensitivity analysis suggests that the heterogeneous reaction of PAHs with ozone is effectively limiting atmospheric lifetime and long-range transport.

Are pet dogs good sentinels of human exposure to environmental polycyclic aromatic hydrocarbons, organochlorine pesticides and polychlorinated biphenyls?

“…Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants containing two or more fused benzene rings that are produced during the incomplete combustion of organic matter and during human or industrial activities (Guo et al 2012). Because of their efficient metabolization, strictly speaking, PAHs cannot be considered as POPs, but due to their high prevalence in the environment and their lipophilicity, PAHs are usually considered as POPs (Lammel et al 2013). Numerous studies have revealed that POPs, individually and in combination, may contribute to the development of severe health problems such as immune suppression, genotoxic effects or cancer and are of public health concern worldwide (WHO 2003;Kortenkamp 2007;Kortenkamp et al 2007Kortenkamp et al , 2011Valeron et al 2009;Lauby-Secretan et al 2013;Jarvis et al 2014).…”

Long-range atmospheric transport of polycyclic aromatic hydrocarbons is worldwide problem - results from measurements at remote sites and modelling

“…the hydroxyl radical, and of particle-associated PAH molecules) should be closed and the uncertainty of emission factors for some sources (e.g., biomass burning 30 ) need to be reduced. Phase information from field data requires artefact-free sampling, which is not commonly used, [41][42] or an in situ determination and quantification method, which is not yet available for ambient conditions (except for the parameter sum of PAHs 43 ).…”

“…5 A sensitivity analysis suggests that the heterogeneous reaction of PAH with ozone is effectively limiting atmospheric lifetime and long-range transport. 30 In this study, heterogeneous reactions are neglected. Several models for the processes determining gasparticle partitioning were tested in separate substance scenarios.…”

“…It is concluded that current knowledge overestimates degradation of (at least) some 4-ring PAHs during atmospheric transport. A modelling study 30 showed that the contribution of vegetation fires to exposure to PAHs in Africa is probably >10%, but cannot be quantified due to lack of knowledge with regard to both emission factors and photochemistry.…”

Microwave-assisted synthesis of Ag-doped MOFs-like organotitanium polymer with high activity in visible-light driven photocatalytic NO oxidization

“…The sweep-gas from cars, power-plants, chemical industries and plant-burning usually contains nitrogen oxides (NO x ), sulfur oxides (SO x ), carbon monoxide (CO), persistent organic pollutants (POPs) and even mercury (Hg), which were considered as the most important reason for the air pollution, which were considered as the most important reason for the air pollution, which were considered as the most important reason for the air pollution [1][2][3] Thus, removal NO x is one of common targets in treating air pollution [4]. Recently, photocatalysis has received increasing attention in environmental cleaning [5][6][7] and the photocatalytic NO oxidization represents one of the most promising ways in removing NO x owing to the simple operation, low cost, high efficiency, and strong durability etc.…”