Emission Characteristics of PM_2.5 and Trace Gases from Household Wood Burning in Guanzhong Plain, Northwest China

Considering woods used as the primary fuel in the countryside of Guanzhong Plain and its emission impacts on environment and human health. Five kinds of common wood fuels (Persimmon tree, Pear tree, Apple tree, Jujube, and Peach) were collected and burned in a laboratory combustion chamber with a common stove to identify emission characteristics of PM_2.5 and trace gases (i.e., CO₂, CO, NO_x, and SO₂). The average EFs of wood burning were estimated to be 1401 ± 71 g kg⁻¹ for CO₂, 53.48 ± 11.83 g kg⁻¹ for CO, 1.48 ± 0.54 g kg⁻¹ for NO_x, 0.53 ± 0.19 g kg⁻¹ for SO_2, and 3.01 ± 0.72 g kg⁻¹ for PM_2.5, respectively. PM_2.5 mass reconstruction for the five tree samples demonstrated excellent results, ranged from 80.7 to 98.4%. OC, EC, and water-soluble ions (sum of Na⁺, NH₄ ⁺, K⁺, Mg²⁺, Ca²⁺, SO₄ ²⁻, NO₃ ⁻, and Cl⁻) are major constituents of PM_2.5, accounting for average abundance of 29.86 ± 2.03, 15.65 ± 1.07, and 17.51 ± 6.24% of the mass, respectively. The average EFs of OC and EC in PM_2.5 were 910 ± 279 mg kg⁻¹ and 465 ± 279 mg kg⁻¹, and EC1 was the dominant carbon fraction with average abundance of 44 ± 3% of total carbon. Sodium (Na⁺), potassium (K⁺), and chloride (Cl⁻) were the dominant water-soluble ions, with average abundance of 4.69 ± 2.51, 3.81 ± 2.13, and 3.30 ± 2.45% of PM_2.5 mass. Similarity measures (i.e., Student’s t test, coefficient of divergence) showed that the five profiles derived in this study were similar for the species measured, which indicates that those profiles could be replaced by each other for PM_2.5 source apportionment. Finally, the emission of woods burning in Guanzhong Plain was estimated. The total emission in 2016 was 14,924.6 Gg for CO₂, 569.9 Gg for CO, 15.8 Gg for NO_x, 5.6 Gg for SO_2, and 32.1 Gg for PM_2.5, respectively.