Temporal and spatial distribution characteristics of air pollutants from open burning of rice straw in Guangdong Province

Objective  To understand the emission of air pollutants from open burning of rice straw in Guangdong province, and provide certain reference for utilization of rice straw resources and control of air pollutant.

Method  Based on the statistical data of rice yield, the ratio of straw to grain, combustion ratio and efficiency of rice straw in Guangdong province from 1990 to 2016, we calculated rice straw yield and air pollutant emission from open burning of rice straw using the emission factor method. The temporal and spatial distribution characteristics of air pollutant emission were analyzed using the ArcGIS 10.2 software.

Result  From 1990 to 2016, the total amount of rice straw resources in Guangdong Province showed a trend of “decline-rise-decline-rise”, which decreased from 16.87 million tons in 1990 to 10.87 million tons in 2016 with an average annual decrease rate of 1.7%. During the period, the amounts of PM, BC, OC, SO₂, NO_x, NH₄, CO and CO₂ emissions decreased by 8 800, 200, 5 200, 1 100, 800, 2 900, 106 500 and 2 585 800 tons, respectively. Their decrease rates were 48.09%, 50.00%, 48.60%, 50.00%, 50.00%, 48.33%, 48.45% and 48.45%, respectively. The spatial distribution of total amount of pollutant emission from open burning of rice straw was unbalanced in different regions of Guangdong province. In 1990, the amounts of PM pollutant emissions were greater than 1 000 t in Maoming, Yangjiang, Zhaoqing, Guangzhou, Huizhou, Heyuan, Shanwei Jieyang and Chaozhou. In 2000, the PM pollutant emissions were above 1 000 t in most cities of Guangdong province. From 2010 to 2016, except for Jieyang, PM pollutant emissions were below 1 000 t.

Conclusion  From 1990 to 2000, except for some counties in northern Guangdong, the pollutant emission intensity are high in most cities of Guangdong province. The high value areas of pollutant emission before 2010 are mainly concentrated in Zhanjiang, Maoming, Yangjiang, Zhaoqing, Meizhou, Huizhou, Jieyang and Chaozhou. In 2016, the high intensity of pollutant emission was only concentrated in a small number of counties in western and eastern Guangdong.