乌鲁木齐树木叶片汞浓度时空特征及环境意义

城市大气环境由于受人为活动影响，具有较高大气汞浓度和时空分布不均一特征。植被叶片虽具有较强富集大气汞的能力，但能否指示城市大气汞时空变化，目前尚有存疑。本文通过连续监测新疆乌鲁木齐市区内6个采样点5种常见树种叶片，在生长季（2019年5～10月）内的汞浓度，分析树叶汞浓度的时空分布变化特征，进而寻找潜在的最优树种叶片，反演乌鲁木齐大气汞污染程度。结果表明，城市内的局地污染能够显著提高叶片汞浓度；树种叶片对大气汞浓度的敏感性存在明显差异（P<0.01）；落叶阔叶树的叶汞浓度与叶片生长时间呈显著正相关关系（P<0.01），即叶片在整个生长期不断积累大气汞；而针叶汞浓度一年之内与生长时间无显著关系。考虑到圆冠榆叶片对大气汞浓度敏感性较高且分布范围更广，圆冠榆作为乌鲁木齐城市大气汞的生物监测器较为合适。本研究为研究城市大气汞浓度生物监测提供了典型的案例与借鉴。

Spatial and Temporal Variations of Leaf Mercury Concentration in Urumqi: Implications of Environmental Significance

Due to the great influence of anthropogenic emissions, the atmospheric mercury (Hg) displays the elevated concentration and heterogeneous spatial and temporal distributions. Foliage has the high enrichment of atmospheric Hg, however with large knowledge gaps in displaying the spatial and temporal variations of urban environment. In this study, five tree species at six sampling plots in Urumqi were systematically monitored during growing season (May-October 2019), to demonstrate the spatial and temporal variations, and to select the suitable foliage of tree species as an atmospheric Hg biomonitor in Urumqi. Our results showed local atmosphere pollution can significantly increase leaf mercury concentrations. Additionally, we observed a significant positive correlation between deciduous broadleaf leaf mercury concentration and growth time, suggesting the continuous mercury assimilation during growing period, but insignificant correlation between needle leaf mercury concentration and growth time. In addition, different deciduous broadleaf tree species also showed variations in atmospheric Hg assimilation (P<0.01). Given the highest Hg assimilation and wide distribution,the round crown elm is suggested to be a suitable atmospheric Hg biomonitor in Urumqi. Our study provides a typical case for selecting the atmospheric Hg biomonitor in urban regions.