State Key Laboratory of Environmental Aquatic Chemistry, 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 Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Water Res. 2024 Nov 15;266:122316. doi: 10.1016/j.watres.2024.122316. Epub 2024 Aug 22.
Submerged macrophytes remediation is a commonly used technique for improving water quality and restoring habitat in aquatic ecosystems. However, the drivers of success in the submerged macrophytes assembly process and their specific impacts on methane emissions are poorly understood. Thus, we conducted a mesocosm experiment to test the growth plasticity and carbon fixation of widespread submerged macrophytes (Vallisneria natans) under different nutrient conditions. A refined dynamic chamber method was utilized to concurrently collect and quantify methane emission fluxes arising from ebullition and diffusion processes. Significant correlations were found between methane flux and variations in the physiological activities of V. nantas by the fluorescence imaging system. Our results show that exceeding tolerance thresholds of ammonia in the water significantly interfered with the photosynthetic systems in submerged leaves and the radial oxygen loss in adventitious roots. The recovery process of V. natans accelerated the consumption of dissolved oxygen, leading to increase in the populations of methanogen (153.3 % increase of mcrA genes) and subsequently elevating CH emission fluxes (23.7 %) under high nutrient concentrations. Conversely, V. natans increased the available organic carbon under low nutrient conditions by radial oxygen loss, further increasing CH emission fluxes (94.7 %). Quantitative genetic and modeling analyses revealed that plant restoration processes drive ecological niche differentiation of methanogenic and methane oxidation microorganisms, affecting methane release fluxes within the restored area. The speciation process of V. natans is incapable of simultaneously meeting improved water purification and reduced methane emissions goals.
沉水植物修复是改善水质量和恢复水生生态系统生境的常用技术。然而，沉水植物组装过程中的成功驱动因素及其对甲烷排放的具体影响还知之甚少。因此，我们进行了一个中观实验，以测试广泛分布的沉水植物（苦草）在不同营养条件下的生长可塑性和碳固定能力。我们利用改良的动态室方法同时收集和量化了由鼓泡和扩散过程引起的甲烷排放通量。荧光成像系统的结果表明，甲烷通量与 V. nantas 的生理活动变化之间存在显著相关性。我们的结果表明，水中氨的耐受阈值的增加会显著干扰沉水叶的光合作用系统和不定根的径向氧气损失。V. natans 的恢复过程加速了溶解氧的消耗，导致产甲烷菌（mcrA 基因增加 153.3%）的种群增加，进而在高营养浓度下提高 CH 排放通量（增加 23.7%）。相反，V. natans 通过径向氧气损失在低营养条件下增加了可用有机碳，进一步提高了 CH 排放通量（增加 94.7%）。定量遗传和建模分析表明，植物恢复过程驱动了产甲烷菌和甲烷氧化微生物的生态位分化，影响了恢复区域内的甲烷释放通量。苦草的特化过程不能同时满足改善水净化和减少甲烷排放的目标。
