京津风沙源地表释尘到达典型城市沙尘量及其源解析

Dust amount reaching typical cities from dust emissions due to soil wind erosion in Beijing-Tianjin sandstorm source regions and its source analysis

土壤风蚀引起的地表沙尘释放是大气环境中可吸入颗粒的重要来源.准确估算地表沙尘释放对城市大气环境中可吸入颗粒物的贡献,是国家制定大气环境治理规划和决策的依据.本文结合地面调查、野外观测、遥感影像解译等手段,估算了风力作用下京津风沙源土壤风蚀引起的0~2.5、2.5~5、5~10、10~20μm沙尘输移到北京、张家口、赤峰、大同、呼和浩特、锡林浩特、包头、榆林的量,揭示了到达各城市不同粒径组沙尘量的变化规律,并从区域、土地利用、风向等方面进行了源解析,提出了京津风沙源治理的核心是PM_(10)(尤其是PM_(2.5)),治理区域需优先考虑农牧交错带、荒漠草原、燕山丘陵,治理的地类依次是耕地、沙地(漠)和草(灌)地,为京津风沙源治理宏观战略部署、总体方案优化与调整提供决策依据.

Dust emissions caused by soil wind erosion are a significant and concerning source of respirable particles in the atmospheric environment.Accurately estimating the contribution of dust emissions resulting from soil wind erosion to inhalable particulate matter in the urban atmospheric environment is required for the central government to formulate atmospheric environmental governance plans and decisions.By combining ground investigation,field observation,remote sensing image interpretation and other strategies,this paper first estimated the dust amount of four different particle sizes of 0–2.5,2.5–5,5–10,and 10–20μm arriving in Beijing,Zhangjiakou,Chifeng,Datong,Huhehaote,Xilinhaote,Baotou and Yulin,which derived from dust emissions caused by soil wind erosion due to wind force in Beijing-Tianjin sandstorm source regions.The total dust amounts reaching above cities were 274.49×10^(4),146.96×10^(4),151.83×10^(4),91.03×10^(4),68.61×10^(4),65.42×10^(4),41.46×10^(4),and 26.21×10^(4)t,respectively.Among these dust amounts,PM_(2.5)and PM_(10)accounted for35.40%and 84.16%,respectively.To improve the living environment,the Beijing-Tianjin sandstorm source control project targets both PM_(10)and PM_(2.5),with an emphasis on PM_(2.5).Second,the contributions of subregions in the Beijing-Tianjin sandstorm source to dust amounts of different particle sizes for each city were distinctly different.For the contributions of each subregion to the total dust amount for above eight cities,the maximum came from the subregion of interlaced belt of agriculture and animal husbandry,followed by the subregions of desert steppe,the Yanshan Hills water source reserve,the mountainous and hilly areas in northern Shanxi,Hunshandake sandy land,the Greater Khingan Mountains,Kubuqi desert,Horqin sandy land,the typical steppe and Mu Us Sandy Land.The cumulative contributions for the first three subregions and four deserts(of sandy land)were 80.52%and 9.84%,respectively.The former’s cumulative contributions to the dust amounts of four particle sizes ranged from 73.06%to 83.40%,respectively,while the latter’s cumulative contributions were only between 5.56%and 12.42%.These indicated that the management of the Beijing-Tianjin sandstorm sources should focus on the subregions of the interlaced belt agriculture and animal husbandry,desert steppe and the Yanshan Hills water source reserve rather than desert(of sandy land)subregions.Third,the contributions of the cultivated land,desert(or sandy land)and grass and shrub land to the total dust amounts for above eight cities were 576.27×10^(4),186.30×10^(4),and 103.44×10^(4)t,respectively.At the same time,their contributions to the dust amounts of 0–2.5,2.5–5,5–10,and 10–20μm were 138.18×10^(4),94.42×10^(4),182.54×10^(4) and 161.14×10^(4)t;23.16×10^(4),12.44×10^(4),41.89×10^(4) and 8.81×10^(4)t;and 28.94×10^(4),20.79×10^(4),42.65×10^(4),11.06×10^(4)t,respectively.Hence,the management of the Beijing-Tianjin sandstorm sources should focus on the management of cultivated land,followed by desert(or sandy land)and finally grass and shrub land.In addition,the dust amounts reaching above eight cities mainly derived from the westward wind direction,such as SW,WSW,W,WNW,NW,and NNW,although a few came from N and NNE directions.85.15%–93.28%of dust in Baotou,Beijing,Datong,Huhehaote and Zhangjiakou originated from W,WNW,and NW;96.16%of dust in Chifeng originated from W,WNW,and WSW;93.68%of dust in Xilinhaote originated from WSW,W,SW,and WNW;and 81.16%of dust in Chifeng originated from NW,NNW,and NNE.There were obvious differences in the contribution of wind direction to the dust amount in different particle size groups in each city.These results provide a basis for the optimization and adjustment of the Beijing-Tianjin sandstorm source control project.