Database_ESECAE_Soil

Wildfires are increasingly recognized as drivers of mercury (Hg) mobilization in tropical ecosystems, yet their effects on soil biogeochemistry across Cerrado vegetation formations remain poorly constrained. This study evaluated total mercury (THg) stocks, soil composition, and fire-induced Hg losses in forest, savanna, and grassland soils from the Águas Emendadas Ecological Station, central Brazil. Laboratory heating experiments simulated low (200 °C), intermediate (350 °C), and high (500 °C) fire intensities, combined with elemental and mineralogical characterization and regional emission estimates based on burned area data. Forest soils exhibited significantly higher THg concentrations, organic carbon content, and C/N ratios than savanna and grassland soils, reflecting stronger Hg association with organic matter and reduced ultraviolet radiation exposure. Simulated burning resulted in substantial Hg mobilization, with losses exceeding 70% even at low intensity and reaching near-total depletion at moderate and high temperatures. Mercury emission factors were consistently highest in forest soils ( 3.85 ± 0.74 g Hg ha-1), compared to savanna (2.47 ± 0.46 g Hg ha-1) and grassland formations (1.2 ± 0.59 g Hg ha-1). Regional scaling indicated that fires mobilized up to 173 kg of Hg in the Federal District (Capital of Brazil) over the last decade. Alterations in organic matter quantity and quality closely paralleled Hg release, highlighting the central role of soil carbon in regulating Hg stability during combustion. Our results demonstrate that although forest areas burn less frequently, they act as critical hotspots for Hg emissions when affected by fire, with important implications for biogeochemical cycling and regional emission inventories under increasing wildfire regimes

野火作为热带生态系统中汞（Hg）动员的关键驱动因子，其重要性日益得到学界认可，但目前针对野火对巴西塞拉多（Cerrado）各植被群落类型下土壤生物地球化学过程的影响，仍缺乏精准的定量约束。本研究针对巴西中部埃瓜什埃曼达达斯生态站（Águas Emendadas生态站）的森林、稀树草原与草原土壤，开展了总汞（THg）储量、土壤组成及火烧诱导汞损失的评估。研究通过实验室加热实验模拟了低（200℃）、中（350℃）、高（500℃）三种火烧强度，并同步开展元素与矿物学表征，同时基于火烧面积数据完成区域排放估算。结果显示，森林土壤的总汞浓度、有机碳含量及C/N比均显著高于稀树草原与草原土壤，这反映出汞与有机质的结合作用更强，且土壤受到的紫外线辐射暴露程度更低。模拟火烧引发了显著的汞动员效应：即使在低强度火烧下，汞损失率也超过70%；在中、高强度火烧下，汞则近乎完全耗尽。森林土壤的汞排放因子始终最高，为(3.85±0.74) g Hg·ha⁻¹，显著高于稀树草原土壤的(2.47±0.46) g Hg·ha⁻¹与草原群落的(1.2±0.59) g Hg·ha⁻¹。区域尺度推演结果表明，过去十年间巴西联邦区（巴西首都辖区）内的火烧事件共动员了高达173 kg的汞。土壤有机质的数量与质量变化与汞释放过程高度同步，这凸显了土壤碳在火烧过程中调控汞稳定性的核心作用。本研究结果证实，尽管森林区域的火烧发生频率更低，但一旦遭遇火烧，其会成为汞排放的关键热点区域；该发现对于野火频发背景下的生物地球化学循环及区域排放清单具有重要意义。