河谷地形气象要素对污染物浓度的影响

气象条件对环境空气质量影响的研究是科学制订大气环境污染防控方案、及时发布重污染天气应急预警的基础.利用兰州市西固区环境空气质量监测点2015年主要污染物小时浓度监测值，分析了污染物浓度的季节性变化和日变化特征，结合同期观测的气温、风速、相对湿度和降水量等气象资料，探讨了气象要素对污染物浓度变化的影响.结果表明:①除O₃外，其他污染物质量浓度呈"冬高夏低""早晚高下午低"的变化特点，这与表征污染物扩散能力的边界层参数变化特征一致. ②ρ（O₃）春季为71.42 μg/m3，夏季为62.74 μg/m3，春季高于夏季的主要原因是春季O₃的前体物NO_x质量浓度高于夏季且春季扩散条件弱于夏季. ③除O₃外，其他污染物质量浓度与气温、风速呈负相关. ④当相对湿度 < 40%时，污染物质量浓度与相对湿度呈正相关；当相对湿度>80%时，污染物质量浓度与相对湿度呈负相关；降雨对不同污染物的清除效果不同.研究显示，河谷地形气温和风速是影响污染物扩散的重要气象因子. 

Influence of Meteorological Elements on Pollutant Concentration in River Valley Terrain

The effect of meteorological elements on ambient air pollutants concentrations play a crucial role in planning air pollution control strategies, and preventing or responding quickly to air quality deterioration. One-year series of hourly average air pollutant concentration observations at a monitoring stations located in Xigu District of Lanzhou City, was analyzed to gain seasonal and diurnal variation of pollutant concentrations. Furthermore, meteorological factors, such as wind speed, temperature, relative humidity, and precipitation at the same station, are employed to evaluate the relationship of meteorological elements and pollutant concentration. The result shows: (1) Except ρ(O₃), other pollutants demonstrate the features of 'higher concentration in winter than in summer' and 'higher concentration in the morning and in the evening than in the afternoon', which is consistent with seasonal and diurnal variation of boundary layer parameters indicating the pollutant diffusion capacity. (2) Ozone concentration is 71.42 μg/m3 in spring and 62.74 μg/m3 in summer, ozone's precursor (NO_x) concentration is higher and diffusion condition is disadvantage in spring than in summer which leads to O₃ higher concentration in spring. (3) Except ρ(O₃), the other pollutants were negatively correlated to air temperature and wind speed. (4) When the relative humidity < 40%, the pollutant concentration positively correlated to the relative humidity, while the pollutant mass concentration was negatively correlated to the relative humidity when the relative humidity > 80%, Rainfall shows different removal depends on the type of pollution.