沿海城市大气汞的数值模拟研究

Simulating Atmospheric Mercury in Coastal City

通过建立箱式模型对大气汞浓度进行模拟,对气象因子(如温度、相对湿度、压强)和化学因子(如某些氧化剂)进行敏感性测试,研究它们对大气汞浓度变化的定性和定量影响,并计算大气元素态汞的转换率。结果表明,大气元素汞浓度随着温度和相对湿度的增加而增加,季节变化会对模拟结果产生较大影响,而压强及氧化剂对模拟结果影响并不显著。此外,采用三维CMAQ-Hg模型对典型沿海城市大气汞的空间分布特征进行模拟,发现元素态汞是大气汞中的主要存在形态,并且春季大气元素态汞的模拟浓度要低于秋季,主要是因为温度、相对湿度、季节的影响,进一步验证了箱式模型的结果。

A box-model was constructed to simulate atmospheric mercury. Sensitivity studies were done on the qualitative and quantitative effects of meteorological factors such as temperature, relative humidity and pressure as well as chemical factors such as some oxidants on simulated atmospheric mercury concentrations. Conversion rates of gaseous elemental mercury （GEM） were calculated as well. Results showed that concentration of GEM would increase with increased temperature and relative humidity, and seasons had obvious influence on simulation results, while pressure and some oxidants did not show significant effect. CMAQ-Hg model was applied to simulate spatial distribution of atmospheric mercury in a typical coastal city, showing GEM was the majority of atmospheric mercury and its concentration in spring was lower than that in fall due to the effects of temperature, relative humidity and season, which further validated the box-model results.