嵊山岛大气重金属十年干沉降特征变化

以2004-2013年四季(2、5、8、10月)舟山海域嵊山岛大气悬浮颗粒物(TSP)重金属元素(Cu、Pb、Zn、Cd)监测数据为基础,通过单点大气干沉降模型初步估算了舟山海域大气重金属的月、年干沉降通量。结果表明:大气重金属干沉降年通量大小分别为Cu(14.15 mg/m2)Zn(2.16 mg/m2)Pb(1.40 mg/m2)Cd(0.022 mg/m2),所对应的浓度也小于我国空气质量标准限值,Cu大约占重金属总量的80%。各重金属近几年的月通量的季节变化前期(2004-2008)表现为夏、秋较低,春、冬较高;后期(2009-2012)则为夏、冬较高,春、秋较低的趋势。与其他海域相比,舟山海域上的Cu元素月、年沉降通量都高于珠江三角洲、天津港、福建兴化湾海域的对应值,低于黄海青岛海域;Pb、Zn、Cd的值小于上述近海海域的相应元素值,与远洋中监测值相差不大。

Characteristics of atmospheric heavy metals dry deposition in the Shengshan Island

Dry deposition fluxes of heavy metals in Zhoushan sea area were calculated through a single point of dry deposition model based on the monitoring data of selected heavy metal elements in atmospheric particulate matter(Cu, Pb, Zn, Cd) in Shengshan Island in four seasons(February, May, August and October)from 2004 to 2013. The results showed that, the magnitude order of monthly and yearly dry deposition fluxes of heavy metal elements in the atmospheric was Cu(14.15 mg/m²) >Zn(2.16 mg/m²) >Pb(1.40 mg/m²) >Cd(0.022 mg/m²),the corresponding concentration of which was less than the limit value of China's air quality standards. Cu accounted for 80% of the total metals. Monthly flux variation of heavy metals in recent years was complex, the data in winter and spring was higher than that in autumn and summer for the early phases(2004-2008); while the trend turned higher in summer and winter for the late period(2009-2013). Compared with other sea areas,both the monthly and annual deposition fluxes of Cu are higher than those in Pearl River Delta, Tianjin Port, Fujian Xinghua Bay, just below the Qingdao sea area; while Pb, Zn, Cd values are far less than those sea areas, but have little difference with the ocean monitoring values.