珠三角某垃圾焚烧厂周边植物叶片汞含量空间格局影响因素影响因素

为研究珠三角某城市生活垃圾焚烧厂周边汞污染空间格局及影响因素,于2014年1月,采集了马占相思、荔枝和芒萁等优势种的叶片样品192份,并同步采集相应表层土壤样品64份,采用冷原子吸收法测定样品总汞含量,并运用ADMS模型对2013年大气汞年均浓度进行模拟,分析了植物叶片汞含量与土壤和大气汞浓度之间的关系。结果表明,植物叶片的汞含量范围为0.0029~0.1741 mg·kg-1,荔枝叶片汞含量最高,为(0.0766±0.0395)mg·kg-1,其次为芒萁((0.0599±0.0370)mg·kg-1)和马占相思((0.0556±0.0396)mg·kg-1)。植物叶片汞含量与土壤汞含量无显著相关性,而受风向和距污染源的距离影响显著,与ADMS模拟的大气年均汞浓度存在显著相关性。研究表明,植物叶片汞含量变化与烟气扩散浓度的空间分异格局基本吻合,叶片对大气中汞的吸收在植物与环境的汞交换中占据主导地位,对叶片的生物监测可以反映城市生活垃圾焚烧厂汞排放对生态环境的实际影响。

Spatial Pattern and Influencing Factors of Mercury Levels in Leaves of Plants Surrounding a Solid Waste Incinerator in the Pearl River Delta

The spatial pattern of mercury (Hg) around a municipal solid waste incinerator (MSWI) in the Pearl River Delta was surveyed, and factors influencing the distribution of Hg were examined. A total of 192 leaf samples from three local dominant tree species, including Acacia mangium, Litchi chinensis, and Dicranopteris dichotoma, and 64 soil samples were collected in January 2014 from nearby area. The total Hg contents in the samples were measured by a cold vapor atomic absorption spectrometry. Hg contents in the leaves ranged from 0.0029 to 0.1741 mg?kg-1. The leaves of L. chinensis had the highest Hg contents (0.0766±0.0395 mg?kg-1), followed by D. dichotoma (0.0599±0.0370 mg?kg-1) and A. mangium (0.0556±0.0396 mg?kg-1). Hg concentrations in the leaves did not correlate with those in the soils, but correlated well with the annual average Hg concentration in the atmosphere according to the simulation by ADMS. Leaf Hg levels were significantly influenced by the distance from the MSWI stack and the wind direction. These findings indicated that the major source of Hg in the tree leaves were the airborne Hg released from the MSWI. This study demonstrated that leafy vegetables can be used to monitor the influences of MSWI mercury emissions on the ecosystem nearby.