2014年8月至2015年5月对上海市26个公园绿地中香樟树叶进行采集,共获取104份样品进行总汞含量测定.结果表明,上海市叶汞平均含量为64.8±26.6 μg·kg-1,范围为16.6-132.6 μg·kg-1.叶汞含量随生长周期不断累积,季节变化表现为春季＞冬季＞秋季＞夏季,而叶汞累积量均值按季节表现为秋季＞冬季＞春季.叶片总汞含量空间差异明显,呈由城市西北向东南逐渐递减的趋势,叶汞累积量在工业园区与中心城区具有较高的值,城市东南沿海地区与远郊区叶汞累积量较低,在局地气象因子影响下,不同季节略有不同.叶汞累积量高值区域主要出现在污染源的下风向,并且风速越大,叶汞累积量高值区域的范围越大,而海洋气团下风向的累积量较小;年降水量越大的区域叶汞含量越低,春秋季节叶汞累积量与降水量呈显著负相关(P＜0.05);臭氧浓度与叶汞累积量的变化趋势暗示着臭氧浓度是影响叶汞累积量的一个重要因素.
Camphora leaves in urban parks in Shanghai were collected during the period of August 2014 to May 2015 for mercury content analyses.The results show that mercury contents in Camphora leaves varied from 16.6 to 132.6 μg·kg-1,with a mean value of 64.8±26.6 tg·kg-1.The leaves.accumulated mercury along with its growth,and the contents exhibited distinct seasonal variation by the following order:spring＞winter＞ autumn＞summer,while the accumulations are in the order of autumn＞winter＞spring.The distribution of mercury contents had significant spatial variation,which trends to decrease gradually from the northwest to southeast in the study area.It can be seen that heavily polluted industry areas and city center have higher accumulation,while it is much lower in the coastal areas in the southeast of the city and outer suburban areas.Furthermore,influenced by the local meteorological conditions,seasonal accumulation displayed different degrees of variation.However,climatic factors are of great influence to the mercury distribution.Higher accumulation appeared in the downwind areas primarily,and pollution area increased with the wind speed the mercury concentration is low.In the areas where annual precipitation is high,and correlation analysis shows a significant negative correlation (P＜0.05).Seasonal accumulation devreased with the ozone concentration,which suggests ozone is a significant factor for mercury accumulation in leaves.
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