这项工作评估了从矿石山的酸性沉积中恢复的森林研究区Načetín(NAC)的云杉凋落物中汞(Hg)浓度和通量的25年趋势(1994-2018年),捷克共和国。平均凋落物汞沉积平均为51±18µgm-2year-1,这是迄今为止欧洲大陆报道的最高凋落物汞沉积。相比之下,湿沉降(2017-2019年)平均低了一个数量级,为2.5±1.5µgm-2year-1。所有的云杉凋落物成分树皮,树枝,针头,锥体,与背景位点相比,未知片段的混合物的平均Hg浓度分别升高,平均为256±77、234±62、119±23、95±14和44±15µgkg-1。凋落物汞的沉积和浓度升高归因于附近的当地汞排放源-燃煤发电厂。暂时,自1990年代以来,捷克汞排放量的减少反映在凋落物树皮中汞浓度的下降趋势上,锥体,和树枝,在针头和其他材料中,Hg增加但不明显。汞/碳的总落物比,Hg/N,和Hg/S分别低于土壤O层,平均分别为0.23±0.04、9.5±2.0和170±37μgg-1。自从开始监测以来,总凋落物Hg/C没有趋势,Hg/N下降,Hg/S增加。平均为469±176gm-2year-1的凋落物生物量沉积随时间增加,尽管捷克汞排放量减少,但NAC的汞凋落物沉积增加了1.1µgm-2year-1。在25年的监测过程中,由于极端天气,例如雾雪堆积,NAC的年度垃圾汞沉积峰值高达96µgm-2year-1,阵风,干旱,和昆虫侵扰,所有这些都显着影响了年度生物量沉积。根据我们的观察,由于树皮甲虫的侵染和气候变化引起的干旱数量的增加,预计生物量和凋落物汞的沉积率将进一步增加。
This work evaluated the 25-year-long trends (1994-2018) in mercury (Hg) concentrations and fluxes in spruce litterfall at a forest research plot Načetín (NAC) recovering from acidic deposition in the Ore Mountains, Czech Republic. The mean litterfall Hg deposition averaged 51 ± 18 µg m-2 year-1, which has been the highest litterfall Hg deposition reported up to date on the European continent. In contrast, the wet deposition (2017-2019) was an order of magnitude lower averaging at 2.5 ± 1.5 µg m-2 year-1. All the spruce litterfall components bark, twigs, needles, cones, and a mixture of unidentified fragments had elevated mean Hg concentrations relative to background sites averaging 256 ± 77, 234 ± 62, 119 ± 23, 95 ± 14, and 44 ± 15 µg kg-1, respectively. Elevated litterfall Hg deposition and concentrations were attributed to the nearby local Hg emission source-coal-fired power plants. Temporally, the decrease of Czech Hg emissions since the 1990s was reflected by the decreasing trend of Hg concentrations in litterfall bark, cones, and twigs, while in needles and other material, Hg increased but insignificantly. Total litterfall ratios of Hg/C, Hg/N, and Hg/S were lower than those in soil O horizons averaging at 0.23 ± 0.04, 9.5 ± 2.0, and 170 ± 37 μg g-1, respectively. Since the beginning of monitoring, total litterfall Hg/C exhibited no trend, Hg/N decreased, and Hg/S increased. The litterfall biomass deposition averaging at 469 ± 176 g m-2 year-1 increased through time resulting in an increased Hg litterfall deposition at NAC by 1.1 µg m-2 year-1 despite the decreases in Czech Hg emissions. Peaks of annual litterfall Hg deposition up to 96 µg m-2 year-1 at NAC during the 25 years of monitoring resulted from weather extremes such as rime-snow accumulation, wind gusts, droughts, and insect infestation, which all significantly affected the annual biomass deposition. Based on our observations, further increases in biomass and litterfall Hg deposition rates can be expected due to the onset of bark beetle infestation and the increasing number of droughts caused by climate change.