Phosphorus emission from open burning of major crop residues in China

Biomass burning has been recognized as an important primary source of atmospheric phosphorus (P), but the measurements of P from biomass burning particles are lacking. In this work, emission factors of different P forms, including total P (TP), total dissolved P (TDP), dissolved inorganic P (DIP) and dissolved organic P (DOP), in emission particles from four types of crop residues burning were measured in a number of chamber experiments. Based on the measured emission factors and the amount of crop residue burned, a high-resolution (0.25 degrees x 0.25 degrees) emission inventory of P for China during 2011-2015 was firstly developed. The emission factors of TP, DIP and DOP were 0.23, 0.06 and 0.13 g/kg, 0.57, 0.17 and 0.27 g/kg, 0.52, 0.15 and 0.27 g/kg, 0.43, 0.13 and 0.25 g/kg for wheat, corn, soybean and rice straw burning, respectively. The total emissions of TP, TDP, DIP, and DOP from the four types of crop straw open burning were 72.0 x 10(3) + 6.7 x 10(3) Tons, 56.3 x 10(3) + 5.5 x 10(3), 20.9 x 10(3) + 2.0 x 10(3) and 35.4 x 10(4) + 3.4 x 10(3) Tons, respectively. TDP dominated the TP fraction, indicating that biomass burning was the important source of bioavailable P. The high P emission areas were mainly distributed in the Northeast and North China Plain, where were the main grain production areas in China, while P emission in economically developed areas such as Beijing and Shanghai and western areas such as Tibet and Qinghai was lower. Affected by the harvesting periods of crops, high P emissions peaked in March, April, June and October. The results herein can provide a dataset for modeling research in calculating the contribution of biomass burning sources to atmospheric P; therefore reduce uncertainties in estimating atmospheric P deposition.

Automated summary

The study measured the atmospheric phosphorus emissions from burning different types of crop residues through experimental chamber tests and developed a high-resolution emission inventory for China. It found that biomass burning was an important source of bioavailable phosphorus, with different crop straw types emitting varying amounts of total P, total dissolved P, dissolved inorganic P, and dissolved organic P. The high P emission areas were concentrated in major grain production regions, with emissions peaking in months affected by crop harvesting periods. The results can provide valuable data for modeling research and improve the accuracy of estimating atmospheric P deposition.