State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2022 Sep 15;839:156288. doi: 10.1016/j.scitotenv.2022.156288. Epub 2022 May 27.
Litterfall mercury (Hg) deposition represents one of the biggest Hg inputs to forest ecosystems through assimilation of atmospheric gaseous elemental Hg (Hg) to foliage. However, due to the availability of litterfall production and Hg concentration data, a comprehensive quantification of litterfall Hg deposition is still lacking in China. In this study, the forest litterfall production of five major forest types in China was modeled by using the random forest (RF) method and multi-source datasets. A substantial nationwide dataset of litterfall Hg concentration was compiled including the investigation of our research group and previous published data. The litterfall Hg flux of forest was quantified by integrating litterfall production map and litterfall Hg concentration data. The nationwide litterfall Hg concentration ranged from 12.75 to 178.00 ng g with a mean of 51.99 ± 34.23 ng g. For litterfall production, the mean value was simulated to be 5.07 Mg ha yr, with the highest values in tropical areas and the lowest in the northeast and northwest arid regions. The litterfall Hg flux of forest in China was characterized by high in the south and low in the north, ranging from 5.57 to 137.05 μg m yr, with an average value of 25.88 ± 12.53 μg m yr. Total Hg deposition from forest litterfall in China was estimated to be 27.0 ± 13.0 Mg yr, and that of evergreen broadleaf forest, mixed forest, deciduous broadleaf forest, evergreen needleleaf forest and deciduous needleleaf forest were 10.8 ± 5.3 Mg yr, 8.5 ± 4.0 Mg yr, 6.1 ± 2.6 Mg yr, 1.5 ± 1.0 Mg yr and 0.2 ± 0.1 Mg yr, respectively. This is the primary quantitative evaluation of the forest litterfall Hg deposition in China, which is essential for understanding the role and status of Chinese forest in the global Hg cycle.
凋落物汞（Hg）沉降代表了大气气态元素汞（Hg）通过同化到树叶中向森林生态系统输入 Hg 的最大途径之一。然而，由于凋落物产量和 Hg 浓度数据的可用性，中国仍缺乏对凋落物 Hg 沉降的全面量化。在这项研究中，使用随机森林（RF）方法和多源数据集对中国 5 种主要森林类型的凋落物产量进行了建模。我们编制了一个包括本研究组和先前发表数据的大量全国性凋落物 Hg 浓度数据集。通过整合凋落物产量图和凋落物 Hg 浓度数据，量化了森林凋落物 Hg 通量。全国凋落物 Hg 浓度范围为 12.75 至 178.00ng/g，平均值为 51.99±34.23ng/g。对于凋落物产量，模拟的平均值为 5.07 Mg/ha/yr，热带地区最高，东北和西北干旱地区最低。中国森林凋落物 Hg 通量的特点是南高北低，范围为 5.57 至 137.05μg/m/yr，平均值为 25.88±12.53μg/m/yr。估计中国森林凋落物 Hg 的总沉降量为 27.0±13.0Mg/yr，其中常绿阔叶林、混交林、落叶阔叶林、常绿针叶林和落叶针叶林分别为 10.8±5.3Mg/yr、8.5±4.0Mg/yr、6.1±2.6Mg/yr、1.5±1.0Mg/yr 和 0.2±0.1Mg/yr。这是对中国森林凋落物 Hg 沉降的首次定量评估，对于了解中国森林在全球 Hg 循环中的作用和地位至关重要。
