基于CMAQ模型的大连市大气氮湿沉降模拟研究

Simulation of atmospheric nitrogen wet deposition in Dalian City based on CMAQ model

为了探讨大连市大气氮氧化物湿沉降的污染特征,通过监测站采集2012年内大连市的雨水样品,分析了氮氧化物的沉降浓度及沉降规律.同时,采用CMAQ模型MM5气象模式对大连市大气氮湿沉降进行了模拟研究,并在相关模拟模型的预报因子中增加氮氧化物污染源动态变化信息进行修正.结果表明:大连市大气氮湿沉降中硝酸根离子的平均当量浓度值为71.73μeq·L-1,铵根离子为98.91μeq·L-1;大连大气中氮氧化物沉降当量浓度随季节变化明显,且不同时期波动显著.CMAQ模型的模拟结果与实测数据相比存在偏差;经修正后模型模拟的结果更加逼近观测值,充分说明利用该修正模型在一定程度上修正了源清单不确定性对模拟结果造成的影响,利用修正后模型进行模拟具有可靠的准确性与可行性,可为大连市环境影响评估及控制效益评价提供科学依据.

In order to explore the contamination characteristics of atmospheric nitrogen wet deposition in Dalian,the rain water samples during 2012 was collected,and the concentration of nitrogen oxides and settlement law were analyzed. The atmospheric nitrogen wet deposition was numerically studied by using MM5 meteorological model in CMAQ model,and the increased nitrogen oxide pollution dynamic information was corrected for the predictive factors of the related simulation. The results showed that the average concentrations of nitrate and ammonium ion was 71.73 μeq·L-1and 98.91 μeq·L-1during the atmospheric nitrogen wet deposition. The concentrations of ion significantly changed with the seasonal fluctuation and different periods. There was a deviation between the simulated results by using CMAQ model and the measured data. The simulated results were closer to the observation values by applying the amended model,which suggested that the amended model corrects the effect of source inventory uncertainty on the simulation results to a certain extent. The corrected model provided a scientific basis for environmental impact assessment and control benefit evaluation in Dalian.