[Gridded Emission Inventories of Major Criteria Air Pollutants and Source Contributions in Lan-Bai Metropolitan Area, Northwest China].

Lan-Bai Metropolitan Area in Gansu province is an important heavy-industry base with the highest level of total air pollutant emissions in Northwest China. It is significant to study the high-resolution pollutant emission inventory to forecast regional air quality and to simulate pollutant emission reduction, as well as provide early warnings and forecasts, and to control air pollution. Taking Lanzhou and Baiyin as the main research areas, this study established the gridded emission inventories of seven major criteria air pollutants in the Lan-Bai Metropolitan Area based on emission data and statistical yearbooks of 2015-2016. The spatial pollution characteristics and emission source contributions were also studied. The results showed that the total annual emissions of seven major criteria air pollutants in the Lan-Bai Metropolitan Area were as followings:NO 2.22×10 t, NH 4.53×10t, VOCs 7.74×10t, CO 5.62×10 t, PM 4.95×10 t, PM 1.91×10 t, and SO 1.37×10 t. Among them, annual CO emissions were the highest, while the annual emissions of NH were the lowest. The comparison of this gridded emission inventories with the Peking and Tsinghua University's MEIC inventories, found that the consistency of the three inventories for traffic source was relatively high, but for the total emissions and industrial source emissions of CO, a 30%-40% difference was found when compared with emissions in the Peking and Tsinghua University's inventories. The main differences were from the collected emission factors and the different resolution and years for collected data. The industrial non-combustion process sources, accounting for the largest proportion, were mainly concentrated in urban areas for the other six major criteria air pollutants except for NH. The main contributing sources of NH were from the use of nitrogen fertilizers and livestock emissions, so its spatial pollution distribution was mainly affected by farmland distribution and other factors. It can be concluded that countermeasures, such as controlling industrial non-combustion process sources, integrating high-quality and high-efficiency power supply, using clean energy, strict dust emission control on construction sites and industrial production facilities, as well as urban greening could effectively reduce the emissions of six major criteria air pollutants including NO, VOCs, CO, PM, PM, and SO in the Lan-Bai Metropolitan Area. The reduction of NH emission mainly depends on reducing the use of nitrogen fertilizer and controlling livestock emissions in the rural regions of Lan-Bai Metropolitan Area. This paper also used Monte Carlo uncertainty analysis to evaluate uncertainty in the gridded emission inventories, in which the maximum uncertainty was -31%-30% for NH, the uncertainty of CO at -18%-16% was minimal. Therefore, the overall credibility was high for the established gridded emission inventories in this study.