Influence Of Atmospheric Transport On Carbon Emissions From Farmland Ecosystems In Northeast China

Both agricultural straw burning and wind erosion result in large amounts of carbon loss from ecosystems.As the commercial grain base in China,the three northeastern provinces naturally produce a large amount of straw,thus leading to serious straw burning activities.With the increasing of grain production,the soil quality in the three northeastern provinces began to gradually decrease,leading to increased wind erosion activities on agricultural soils.In this paper,we estimated the emission and spatial characteristics of carbonaceous gas and carbonaceous aerosol from straw burning on farmland in three northeastern provinces based on multi-source satellite data and measured data by the improved FRP(Fire Radiative Power)algorithm.Furthermore,we also estimated the dust emission from cropland in three northeastern provinces by the improved CMAQFENGSHA(Community Multiscale Air Quality Model-FENGSHA)module.Then combined with the organic carbon weight percentage data in the three northeastern provinces,the amount and spatial characteristics of organic carbon loss from wind erosion on farmland were calculated and analyzed.The main conclusions are as follows.(1)The annual total carbon emissions from straw burning were 102 Mt,30Mt,56 Mt,52Mt and 51Mt(million tons)from 2017-2021,respectively.The emissions were decreasing year by year.and the total carbon emissions in 2021 will decrease by approximately 50% compared to 2017.In terms of the contribution of carbon emissions from straw burning in the three northeastern provinces,Heilongjiang province accounts for the most,with the contribution of 60%,and the remaining two provinces account for about 30%.The monthly carbon emissions due to straw burning in the three northeastern provinces start to decrease after the harvest in autumn and start to increase gradually in spring before spring planting.In terms of spatial distribution,two east-west strip emission belts are formed in the three northeastern provinces;a strip emission belt of Heihe,Harbin,Changchun and Panjin cities in the west side of the three northeastern provinces,and a strip emission belt of Jiamusi,Shuangyashan,Qitaihe,Jixi and Mudanjiang cities in the east side.(2)The loss of organic carbon from cropland in three northeastern provinces from2017 to-2021 is 51.17 Gg,56.08 Gg,68.64 Gg,60.06 Gg and 69.92 Gg,respectively,with an average annual growth rate of 8.11%.The contribution of the three northeastern provinces to organic carbon loss is about 70% in Heilongjiang Province,and the change of annual total organic carbon loss is consistent with the change of Heilongjiang Province.The loss of organic carbon is mainly concentrated in Heilongjiang Province among the three northeastern provinces.(3)The total carbon emissions from 2017-2021 were 101564.78 Gg,30195.64 Gg,56544.04 Gg,52548.18 Gg and 51079.59 Gg,respectively,and the total carbon emissions decreased by about 50% by 2021.In terms of carbon emissions,the contribution of straw burning is about 98% and the contribution of wind erosion activities is about 2%.The spatial distribution is still almost consistent with the northeastern provinces in the two east-west emission belts of straw burning and dust emission.