珠江口海域大气中重金属季节变化特征及其与气象因子的关系

Seasonal variation characteristics of heavy metals in the atmosphere and its relationship with meteorological factors over the Pearl River Estuary

利用2013—2015年珠江口海域代表春、夏、秋、冬4个季节的气溶胶质量浓度资料及同期的气象观测数据，分析得出大气中重金属（Cu、Pb、Zn）质量浓度具有秋季最高，冬季次之，春、夏季较低的季节变化特征，这一特征与气象因子及污染来源关系密切。除春季外，夏、秋、冬季，大气中Cu、Ph、Zn之间具有良好的显著相关性，说明大气中赋存Cu、Pb、Zn的颗粒物一部分来源相同。春、夏季，当主导风向为东南向时，气团较清洁，大气污染物浓度低；秋、冬季，当主导风向为偏东向及北风向时，污染物由内陆源及沿海源输送，大气污染物浓度高。气象条件对大气中重金属含量具有重要的影响，且其相关性随季节变化明显。通过SPSS19．0软件对大气中Cu、Pb、Zn的质量浓度与近地面风速、气温、气压、相对湿度等做曲线回归分析，尝试找出各污染物浓度变化与气象因子的定量关系。结果表明，春、夏季，当气温〉27℃时，Cu、Pb、Zn的质量浓度与气温呈显著正相关；夏季，Cu、Pb、Zn的质量浓度与气压、相对湿度（〉90％）呈显著负相关；秋季，Cu、Pb、Zn的质量浓度与风速和相对湿度（〉65％）具有显著负相关；冬季，当气压在1005．0～1015．0hPa范围内，Cu、Pb、Zn的质量浓度与气压呈显著正相关。

The variation characteristics of aerosol chemical compositions in four seasons from 2013 to 2015 and their relationship with meteorological factors were analyzed. The highest concentrations of heavy metals （Cu, Pb and Zn） were recorded in autumn, lower concentrations in winter and lowest in spring and summer, which was closely related to the meteorological factors and the pollution sources. Good significant correlations between the concentrations of Cu, Pb and Zn were found in summer, autumn and winter, which indicated the three heavy metals coming from the same pollution source. The concentrations of atmospheric pollutants were relatively low in spring and summer when the prevailing wind is from the southeast, while the higher concentrations were found in autumn and winter when the pollutants were apt to be transported from the inland to the coastal area by the north and north-east wind. The heavy metal concentrations in the aerosol were affected significantly by the meteorological conditions, and their correlations varied with the seasonal change. Regression analysis of pollutant concentrations and the meteorological factors, including wind speed, air temperature, air pressure and relative humidity, were performed using software SPSS 19.0, trying to figure out the quantitative relation between the concentration of each pollutant and the meteorological factors. In spring and summer, when the temperature is greater than27 ℃, the concentrations of Cu, Pb and Zn were significantly positively related to temperature. In summer, when the humidity is greater 90%, the concentrations of Cu, Pb and Zn were significantly negative related to air pressure and humidity. In autumn, when the humidity is greater 65%, the concentrations of Cu, Pb and Zn were significantly negative related to wind speed and humidity. In winter, when the air pressure within the scope of 1 005.0 to 1 015.0 hPa, the concentrations of Cu, Pb and Zn were positively related to air pressure.