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Underestimated Sink of Atmospheric Mercury in a Deglaciated Forest Chronosequence.
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2020-06-08 , DOI: 10.1021/acs.est.0c01667 Xun Wang 1, 2 , Wei Yuan 2 , Che-Jen Lin 3, 4 , Ji Luo 5 , Feiyue Wang 6 , Xinbin Feng 2, 7 , Xuewu Fu 2, 7 , Chen Liu 2
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2020-06-08 , DOI: 10.1021/acs.est.0c01667 Xun Wang 1, 2 , Wei Yuan 2 , Che-Jen Lin 3, 4 , Ji Luo 5 , Feiyue Wang 6 , Xinbin Feng 2, 7 , Xuewu Fu 2, 7 , Chen Liu 2
Affiliation
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Mercury (Hg) deposition through litterfall has been regarded as the main input of gaseous elemental mercury (Hg0) into forest ecosystems. We hypothesize that earlier studies largely underestimated this sink because the contribution of Hg0 uptake by moss and the downward transport to wood and throughfall is overlooked. To test the hypothesis, we investigated the Hg fluxes contributed via litterfall and throughfall, Hg pool sizes in moss covers and woody biomass as well as their isotopic signatures in a glacier-to-forest succession ecosystem of the Southeast Tibetan Plateau. Results show that Hg0 depositional uptake and pool sizes stored in moss and woody biomass increase rapidly with the time after glacier retreat. Using the flux data as input to a Hg isotopic mixing model, Hg deposition through litterfall accounts for 27–85% of the total accumulation rate of Hg0 in organic soils of glacial retreat over 20–90 years, revealing the presence of additional sources of Hg0 input. Atmospheric Hg0 accounts for 76 ± 24% in ground moss, 86 ± 15% in tree moss, 62–92% in above ground woody biomass (branch–bark–stem), and 44–83% in roots. The downward decreasing gradient of atmospheric Hg0 fractions from the above ground woody biomass to roots suggests a foliage-to-root Hg transport in vegetation after uptake. Additionally, 34–82% of atmospheric Hg0 in throughfall further amplifies the accumulation of Hg0 from atmospheric sources. We conclude that woody biomass, moss, and throughfall represent important Hg0 sinks in forest ecosystems. These previously unaccounted for sink terms significantly increase the previously estimated atmospheric Hg0 sink via litterfall.
中文翻译：
在冰期森林时序中低估了大气汞汇。
通过凋落物产生的汞（Hg）沉积被认为是森林生态系统中气态元素汞（Hg 0）的主要输入。我们假设较早的研究在很大程度上低估了该汇，因为忽略了苔藓吸收Hg 0以及向下迁移至木材和穿透物的贡献。为了检验该假设，我们调查了青藏高原东南部冰川-森林演替生态系统中凋落物和穿透物，苔藓覆盖物和木质生物量中汞库的大小以及同位素特征。结果表明Hg 0冰川退缩后，随着时间的推移，苔藓和木质生物量中的沉积物吸收量和库大小迅速增加。使用通量数据作为汞同位素混合模型的输入，通过凋落物的汞沉积占20- 90年间冰川退缩有机土壤中Hg 0总积累率的27-85％，表明存在其他来源的汞。汞0输入。大气中Hg 0占地面苔藓的76±24％，树木苔藓的86±15％，地上木质生物量（分支-树皮-茎）的62-92％和根的44-83％。大气Hg 0的下降梯度从地上木质生物量到根的分数表明摄取后植物中的叶根汞迁移。另外，大气汞的34-82％0在穿透进一步放大汞柱的积累0从大气压源。我们得出的结论是，木质生物量，苔藓和穿透物是森林生态系统中重要的Hg 0汇。这些先前无法解释的汇术语通过凋落物大大增加了先前估计的大气Hg 0汇。
更新日期：2020-07-07
中文翻译：
在冰期森林时序中低估了大气汞汇。
通过凋落物产生的汞（Hg）沉积被认为是森林生态系统中气态元素汞（Hg 0）的主要输入。我们假设较早的研究在很大程度上低估了该汇，因为忽略了苔藓吸收Hg 0以及向下迁移至木材和穿透物的贡献。为了检验该假设，我们调查了青藏高原东南部冰川-森林演替生态系统中凋落物和穿透物，苔藓覆盖物和木质生物量中汞库的大小以及同位素特征。结果表明Hg 0冰川退缩后，随着时间的推移，苔藓和木质生物量中的沉积物吸收量和库大小迅速增加。使用通量数据作为汞同位素混合模型的输入，通过凋落物的汞沉积占20- 90年间冰川退缩有机土壤中Hg 0总积累率的27-85％，表明存在其他来源的汞。汞0输入。大气中Hg 0占地面苔藓的76±24％，树木苔藓的86±15％，地上木质生物量（分支-树皮-茎）的62-92％和根的44-83％。大气Hg 0的下降梯度从地上木质生物量到根的分数表明摄取后植物中的叶根汞迁移。另外，大气汞的34-82％0在穿透进一步放大汞柱的积累0从大气压源。我们得出的结论是，木质生物量，苔藓和穿透物是森林生态系统中重要的Hg 0汇。这些先前无法解释的汇术语通过凋落物大大增加了先前估计的大气Hg 0汇。
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