Emission of organic carbon, elemental carbon and water-soluble ions from crop straw burning under flaming and smoldering conditions--颗粒学报PARTICUOLOGY

Hong, L., Liu, G., Zhou, L., Li, J., Xu, H., & Wu, D. (2017). Emission of organic carbon, elemental carbon and water-soluble ions from crop straw burning under flaming and smoldering conditions. Particuology, 31, 181-190. https://doi.org/10.1016/j.partic.2016.09.002

Emission of organic carbon, elemental carbon and water-soluble ions from crop straw burning under flaming and smoldering conditions

Lei Hong, Gang Liu ^*, Limin Zhou, Jiuhai Li, Hui Xu, Dan Wu

Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China

10.1016/j.partic.2016.09.002

Volume 31, April 2017, Pages 181-190

Received 7 December 2015, Revised 28 August 2016, Accepted 18 September 2016, Available online 9 January 2017, Version of Record 9 March 2017.

E-mail: liugang650104@sina.com

Highlights

• Emissions from crop straw burning were measured on flaming and smoldering conditions.

• The compositions of TC, OC, EC and WSIs in smoke had been analyzed.

• Diagnostic ratios between OC, EC and WSIs were measured and compared on different conditions.

• The results might be useful to distinguish crop straw burning from other sources pollution.

Abstract

Emissions from major agricultural residues were measured using a self-designed combustion system. Emission factors (EFs) of organic carbon (OC), elemental carbon (EC), and water-soluble ions (WSIs) (K⁺, NH₄⁺, Na⁺, Mg²⁺, Ca²⁺, Cl⁻, NO₃⁻, SO₄^2–) in smoke from wheat and rice straw were measured under flaming and smoldering conditions. The OC₁/TC (total carbon) was highest (45.8% flaming, 57.7% smoldering) among carbon fractions. The mean EFs for OC (EF_OC) and EC (EF_EC) were 9.2 ± 3.9 and 2.2 ± 0.7 g/kg for wheat straw and 6.4 ± 1.9 and 1.1 ± 0.3 g/kg for rice straw under flaming conditions, while they were 40.8 ± 5.6 and 5.8 ± 1.0 g/kg and 37.6 ± 6.3 and 5.0 ± 1.4 g/kg under smoldering conditions, respectively. Higher EC ratios were observed in particulate matter (PM) mass under flaming conditions. The OC and EC for the two combustion patterns were significantly correlated (p < 0.01, R = 0.95 for wheat straw; p < 0.01, R = 0.97 for rice straw), and a higher positive correlation between OC₃ and EC was observed under both combustion conditions. WSIs emitted from flaming smoke were dominated by Cl⁻ and K⁺, which contributed 3.4% and 2.4% of the PM mass for rice straw and 2.2% and 1.0% for wheat straw, respectively. The EFs of Cl⁻ and K⁺ were 0.73 ± 0.16 and 0.51 ± 0.14 g/kg for wheat straw and 0.25 ± 0.15 and 0.12 ± 0.05 g/kg for rice straw under flaming conditions, while they were 0.42 ± 0.28 and 0.12 ± 0.06 g/kg and 0.30 ± 0.27 and 0.05 ± 0.03 g/kg under smoldering conditions, respectively. Na⁺, Mg²⁺, and NH₄⁺ were vital components in PM, comprising from 0.8% (smoldering) to 3.1% (flaming) of the mass. Strong correlations of Cl⁻ with K⁺, NH₄⁺, and Na⁺ ions were observed in rice straw and the calculated diagnostic ratios of OC/EC, K⁺/Na⁺ and Cl⁻/Na⁺ could be useful to distinguishing crop straw burning from other sources of atmospheric pollution.

Graphical abstract

Keywords

Biomass combustion; Organic carbon; Elemental carbon; Water-soluble ion

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