Abstract

Abstract. Multi-pollutants in smoke particulate matter (SPM) were identified and quantified for the biomass burning of five major agricultural residues (wheat, rice, corn, cotton, and soybean straw) in China by an aerosol chamber system combined with various measurement techniques. The primary emission factors (EFs) for PM1. 0 and PM2. 5 are 3.04–12.64 and 3.25–15.16 g kg−1. Organic carbon (OC), elemental carbon (EC), water-soluble inorganics (WSIs), water-soluble organic acids (WSOAs), water-soluble amine salts (WSAs), trace mineral elements (THMs), polycyclic aromatic hydrocarbons (PAHs), and phenols in smoke PM1. 0/PM2. 5 are 1.34–6.04/1.54–7.42, 0.58–2.08/0.61–2.18, 0.51–3.52/0.52–3.81, 0.13–0.64/0.14–0.77, (4.39–85.72/4.51–104.79) × 10−3, (11.8-51.1/14.0-131.6) × 10−3, (1.1–4.0/1.8–8.3) × 10−3, and (7.7–23.5/9.7–41.5) × 10−3 g kg−1, respectively. Black carbon (BC) mainly exists in PM1. 0; heavy-metal-bearing particles favour residing in the range of smoke PM1. 0−2. 5, which is also confirmed by individual particle analysis. With respect to the five scenarios of burning activities, the average emissions and overall propagation of uncertainties at the 95 % confidence interval (CI) of SPM from agricultural open burning in China in 2012 were estimated to be 1005.7 (−24.6, 33.7 %), 901.4 (−24.4, 33.5 %), 432.4 (−24.2, 33.5 %), 134.2 (−24., 34.0 %), 249.8 (−25.4, 34.9 %), 25.1 (−33.3, 41.4 %), 5.8 (−30.1, 38.5 %), 8.7 (−26.6, 35.6 %), 0.5 (−26.0, 34.9 %), and 2.7 (−26.1, 35.1 %) Gg for PM2. 5, PM1. 0, OC, EC, WSI, WSOA, WSA, THM, PAHs, and phenols , respectively. The emissions were further spatio-temporally characterized using a geographic information system (GIS) in different regions in the summer and autumn post-harvest periods. It was found that less than 25 % of the total emissions were released during the summer harvest, which was mainly contributed by the North Plain and the centre of China, especially Henan, Shandong, and Anhui, which are the top three provinces regarding smoke particle emissions. Flux concentrations of primarily emitted smoke PM2. 5 that were calculated using the box-model method based on five versions of emission inventories all exceed the carcinogenic-risk permissible exposure limits (PEL). The health impacts and health-related economic losses from the smoke PM2. 5 short-term exposure were assessed. The results show that China suffered from 7836 cases (95,% CI: 3232, 12362) of premature mortality and 7 267 237 cases (95 % CI: 2 961 487, 1 130 784) of chronic bronchitis in 2012, which led to losses of USD 8822.4 million (95 % CI: 3574.4, 13 034.2) or 0.1 % of the total GDP. We suggest that the percentage of open-burnt crop straw in the post-harvest period should be cut down by over 97 % to ensure a reduction in carcinogenicity risk, especially in the North Plain and the northeast, where the emissions should decrease at least by 94 % to meet the PEL. With such emission control, over 92 % of the mortality and morbidity attributed to agricultural fire smoke PM2. 5 can be avoided in China.

Highlights

  • Biomass burning (BB) is a significant source of particulate and gaseous pollutants (Andreae and Merlet, 2001; Clarke et al, 2007; Ram et al, 2011; Saikawa et al, 2009; Tian et al, 2008)

  • wide-range particle spectrometer (WPS) integrates the function of a scan mobility particle sizer (SMPS) and a laser particle sizer (LPS); 0.3 L min−1 flow is introduced to the SMPS to classify the mobility size from 10 to 500 nm in 48 bins, and 0.7 L min−1 flow is introduced to the LPS part to measure the aerodynamic diameter from 350 nm to 10 μm in 18 bins

  • Where E represents the number of estimated cases of mortality and morbidity, C is the incremental concentration of particulate matter (PM) or flux concentration, Pop is the population exposed to the incremental particulate concentration of C, IR is short for incidence rate of the mortality and morbidity endpoints, and β is the coefficient of exposureresponse function, defined as the change in the number of cases per unit change in concentration per capita

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Summary

Introduction

Biomass burning (BB) is a significant source of particulate and gaseous pollutants (Andreae and Merlet, 2001; Clarke et al, 2007; Ram et al, 2011; Saikawa et al, 2009; Tian et al, 2008). China is the major contributor with over 24 % of global emissions of carbonaceous aerosols, especially from agricultural field burning; about 0.04–0.5 Tg EC (elemental carbon) and 0.4–2.1 Tg OC are released annually (Bond, 2004; Cao et al, 2006; Qin and Xie, 2012; Saikawa et al, 2009), resulting in great radiative forcing, air quality deterioration, visibility reduction, premature mortality, and economic loss regionally and globally (Bølling et al, 2009; Bond et al, 2013; Huang et al, 2014; Janssen et al, 2011; Rosenfeld, 2006; Saikawa et al, 2009; Shindell et al, 2012). An emission reduction strategy that was implemented at a field burning rate control regarding the carcinogenic risk was proposed, which should help establish policy and provide an idea for emission control

Methodology
Crop straw
Burning experiments
Size and morphology of smoke aerosol
Chemical sampling and analysis
Calculation of emission factors
Agricultural field fire survey
Crop straw production
Field burning rate
Emission and flux concentration
Estimate health impacts and health-related economic losses
Human exposure and health impacts
Economic valuation of the health impacts
Organic carbon and elemental carbon
Water-soluble organic acids
Water-soluble aminiums
PAHs and phenols
Inorganic components
Open-burning rate
Agricultural open-burning emissions
Uncertainties of the emissions
Carcinogenic risk
Health impacts
Health-related economic losses
Findings
Conclusion
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