Investigation of the biochemical controls on mercury uptake and mobility in trees
Investigation of the biochemical controls on mercury uptake and mobility in trees
复制标题
树木汞吸收和迁移的生化控制研究
DOI：
10.1016/j.scitotenv.2022.158101
复制
发表时间：
2022
影响因子：
9.8
通讯作者：
Johnson, Marcus W.
中科院分区：
文献类型：
--
作者：
Gustin, Mae Sexauer;Dunham-Cheatham, Sarrah M.;Harper, Jeffrey F.;Choi, Won-Gyu;Blum, Joel D.;Johnson, Marcus W.
大气元素汞（Hg(0)）进入植物气孔，被氧化，然后转移到年轮，提供空气中汞(0)浓度的档案。为了更好地了解汞的积累和转运过程，在夏季，通过根将白杨和奥地利松的叶片暴露于汞(0)、甲基汞（MeHg）或甲基汞（Me198Hg）的控制暴露下。同位素测量表明，在实验室环境中，观察到的自然质量依赖分馏与实地研究中测量的相同，较轻的同位素优先被叶子吸收。不同季节测量了植物组织中的汞含量。杨树暴露后立即将汞移入新枝，秋季吸收汞，春季再将汞分配到新枝组织。奥地利松没有重新分配汞。在暴露于汞(0)的树木的白杨叶片中测量的汞表明，85%的汞在细胞壁中。研究还发现，氧化还原活性分子，如H2O2，可以增强杨树叶片细胞壁结合汞的释放，为再活化提供了一种潜在的机制。无论其机制如何，杨树将汞重新分配给新组织的能力表明，杨树年轮中的汞分布不能提供大气汞年变化的可靠记录(0)。
Atmospheric elemental mercury (Hg(0)) enters plant stomata, becomes oxidized, and is then transferred to annual growth rings providing an archive of air Hg(0) concentrations. To better understand the processes of Hg accumulation and translocation, the foliage of quaking aspen and Austrian pine were exposed to Hg(0), and methylmercury (MeHg) or Me198Hg via roots, in controlled exposures during the summer. Isotopic measurements demonstrated, in a laboratory setting, that the natural mass-dependent fractionation observed was the same as that measured in field studies, with the lighter isotopes being preferentially taken up by the leaves. Hg was measured in plant tissues across seasons. Aspen trees moved Hg into new growth immediately after exposure, resorbed Hg in the fall, and then distributed Hg to new growth tissues in the spring. Austrian pine did not reallocate Hg. Mercury measured in aspen leaf fractions of trees exposed to Hg(0) demonstrated that 85 % of Hg was in the cell wall. It was also found that redox-active molecules, such as H2O2, could potentiate the release of cell wall-bound Hg from aspen leaves, providing a potential mechanism for remobilization. Regardless of the mechanism, the ability of aspen to reallocate Hg to new tissues indicates that Hg distribution in tree rings from aspen do not provide a reliable record of yearly changes in atmospheric Hg(0).