河北秸秆露天焚烧排放及其对京津冀地区空气质量影响

Impacts of Emissions From Crop Residue Open Burning in Hebei on the Air Quality of the Beijing-Tianjin-Hebei Region

秸秆露天焚烧是重要的大气污染来源之一.河北是农业大省,研究其秸秆露天焚烧排放特征及其对京津冀地区空气质量影响具有重要意义.研究建立了日尺度、1 km×1 km分辨率的2014年河北秸秆露天焚烧排放清单,分析了其时空分布特征;进一步综合利用WRF-CAMx-PSAT模式、排放清单与卫星火点数据,对2014年6月和10月河北秸秆露天焚烧排放的空气质量贡献进行了模拟分析研究.研究结果显示,2014年河北秸秆露天焚烧排放SO、NO、PM、PM、NMVOC、NH、CO、EC、OC、CO和CH分别为0.3、1.9、5.1、5.0、4.6、0.3、27.3、0.2、2.1、685.3和2.0万t;玉米和小麦是各污染物排放的主要贡献者,两者对不同污染物排放的贡献占比分别为46.6%~71.4%和20.5%~47.8%;月尺度排放呈现双峰现象,分别为6月与10月,其中6月排放量最高,占全年总排放的26.9%;日排放波动较大,PM峰值出现在6月末(0.3万t)和11月初(0.2万t).空气质量影响方面,2014年6月和10月河北秸秆露天焚烧排放对京津冀地区PM、EC、SO和NO的月均浓度贡献占比分别为4.2%和5.5%、2.6%和2.8%、0.4%和0.5%、2.5%和1.9%,除NO外,其他污染物贡献浓度10月占比均高于6月;受秸秆焚烧特点影响,日尺度的贡献呈现明显波动变化特征,河北的秸秆露天焚烧对北京、天津和河北的PM日均浓度贡献占比最高分别可达25.7%、23.1%和21.0%.

Crop residue open burning(CROB) is an important emission source in China. Hebei is a major agricultural province, and it is of great significance to study its emission characteristics and impacts on the air quality of the Beijing-Tianjin-Hebei(BTH) region. Based on the bottom-up method, the high temporal(day) and spatial(1 km×1 km) emission inventory of CROB in Hebei was developed in 2014, and the spatial-temporal characteristics were further analyzed. Furthermore, based on the emission inventory, fire spots data and WRF-CAMx-PSAT model, the impacts of CROB emissions on the air quality of BTH region was studied and analyzed of June and October. Results show that the emissions of SO, NO, PM, PM, NMVOC, NH, CO, EC, OC, COand CHfrom CROB in Hebei in 2014 were 0.3×10~4, 1.9×10~4, 5.1×10~4, 5.0×10~4, 4.6×10~4, 0.3×10~4, 27.3×10~4, 0.2×10~4, 2.1×10~4, 685.3×10~4 and 2.0×10~4 t, respectively. Corn and wheat were primary contributors to the emission, and the emission fraction was 46.6%-71.4% and 20.5%-47.8%, respectively. Two monthly emission peaks were found in June and October, and the emission in June was the highest among all the year, accounting for 26.9% of the total emission. Daily emissions fluctuated greatly, and the top value happened in the end of June(0.3×10~4 t) and early November(0.2×10~4 t). In June and October, the average contribution ratios of CROB emissions to atmospheric PM, EC, SOand NOconcentrations in the BTH region were 4.2% and 5.5%, 2.6% and 2.8%, 0.4% and 0.5%, and 2.5% and 1.9%, respectively. Except NO, the contribution ratios of other pollutants in October were all higher than those in June. Affected by the characteristics of straw burning, the daily-scale contribution showed obvious fluctuation characteristics. The highest contributions from the emission of CROB in Hebei to the daily PMconcentration of Beijing, Tianjin and Hebei can reach 25.7%, 23.1% and 21.0%, respectively.