Spatio-Temporal Heterogeneity And Its Influencing Factors Of The “Biomass Burning-Air Pollution” Relationship In China

Biomass burning（including forest fires or straw burning,etc.）is an important source of air pollution,and the temporal and spatial characteristics and influencing factors of its relationship with air pollution are important research contents to explore the formation mechanism of air pollution.However,it is still difficult to analyze the relationship between biomass burning and air pollution due to the complex interaction of meteorological,socio-economic,and surface factors and their regional differences.Multi-source data such as air pollution,biomass burning,meteorology,surface and socio-economic data were used to explore the temporal and spatial evolution characteristics and future trend of biomass burning and air pollution in the past 20 years（2001～2020）,and then the temporal and spatial heterogeneity and potential influencing factors of the correlation between biomass burning and air pollution in China were explored.The main research results are as follows:（1）Biomass burning in China mainly distributed in three hot spots including Northeast China（average burning frequency:0.056）,Central China（0.063）and South China（0.057）,and the burning areas showed a weak downward trend(-190.8km²·yr^-1).In the past 20 years,the multi-year average value of aerosol optical depth（AOD）in China was0.283,and showed a significant downward trend（y=-0.0032x+0.3185,R²=0.3287,p<0.01）.The overall distribution of AOD was high in the Southeast（0.398）and low in the Northwest（0.191）,and the heavily polluted areas mainly occurred in the North China Plain,Sichuan Basin and the middle and lower reaches of the Yangtze River.Analysis of future trends shows that biomass burning in most regions of China will still show a continuous decreasing trend,but there may be a certain increasing trend in a small part of regions such as Northeast China.In this context,air pollution is expected to continue to improve,but there is still the possibility of increasing in some areas.（2）Biomass burning had a significant positive correlation with air pollution,accounting for 93.82%of the total burning area.The regions with strong positive correlation were mainly distributed in Heilongjiang Province in Northeast China,the northeast of Inner Mongolia,Jiangsu Province and Anhui Province in Central China and Guangdong Province in southern China.On the seasonal scale,the positive correlation between biomass burning and air pollution covered 96.08%of the total burning area in spring,followed by summer（92.33%）and autumn（83.60%）,while the positive correlation covered the least area in winter（71.48%）.On the other hand,the area passing the significance test of p<0.05 was relatively small,suggesting the high complexity and uncertainty of the impact of biomass burning on air pollution under the interaction of multiple factors.On the national scale,the correlation coefficient of"biomass burning-air pollution"was 0.603,and the area with significant correlation only accounted for 15.89%of the total burning area.The correlation coefficients between biomass burning and air pollution in Northeast,Central and South China were 0.654,0.562 and 0.551respectively,and the regions with significant correlation covered 25.65%,17.51%and 7.47%of the total burning area.（3）On the national scale,the dominant factor of the correlation between biomass burning and air pollution was temperature,while on the regional scale,the dominant driving factors of the correlation in Northeast,Central and South China were GDP,humidity and population,respectively.In addition,there were significant interactions among different factors.The interaction of"temperature-DEM"was the most significant in China,and the interactions of"temperature-GDP","temperature-DEM"and"temperature-population"were the strongest in Northeast,Central and South China.The simulation of multiple linear regression model（MLR）showed that the contribution of temperature to the correlation between biomass burning and air pollution was the strongest（contribution weight was-0.229）,followed by humidity（0.133）and DEM（0.119）,and the contributions of factors such as population（-0.037）,GDP（0.018）and wind speed（0.005）were relatively weak.This study systematically reveals the temporal and spatial evolution characteristics of biomass burning and air pollution in China from 2001to 2020,and explores the temporal and spatial heterogeneity and potential influencing factors of the correlation between biomass burning and air pollution.The research results are helpful to grasp the relationship between biomass burning and air pollution,provide scientific support for a deep understanding of the cause of air pollution in China,and provide scientific theoretical support for atmospheric environmental governance and planning.30 figures,4 tables,109 references...