湿地中的有机碳保护:氧化铁保护与热力学限制
Fu-Sheng Sun1, Chao Ma1, Guang-Hui Yu1
1Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin Bohai Rim Coastal Earth Critical Zone National Observation and Research Station, Tianjin 300072, China.
Water research
|June 1, 2023
概括
湿地有机碳 (OC) 封存取决于氧气水平. 反应性铁 (Fe) 在富含氧气的地区保护OC,而无氧条件限制了由于能量限制而导致的OC分解.
科学领域:
- 环境科学 环境科学
- 地质化学 地质化学
- 土壤科学 土壤科学
背景情况:
- 湿地有机碳 (OC) 封存受氧化还原条件的影响.
- 在氧化还原波动下OC封存的机制,涉及铁 (Fe) 保护和热力学限制,尚未完全理解.
- 天津的湿地面积在过去26年中因人为活动而显著下降,影响了沉积物OC条件.
研究的目的:
- 在不同的氧化还原条件下,研究湿地沉积物中有机碳 (OC) 封存的机制.
- 探索反应性铁 (Fe) 和OC能量在OC保存中的相互作用.
- 评估日益减少的湿地面积对沉积物OC的影响.
主要方法:
- 现场调查和远程传感图像分析超过26年.
- 在不同沉积物深度和水深 (WD) 处分析结合铁的OC (使用CBD提取).
- 高分辨率的光谱显微镜测定Fe (oxyhydr) 氧化物和OC的同位素定位.
- 测量碳的氧化还原潜力和标称氧化状态 (NOSC),以评估OC能量含量.
主要成果:
- 铁结合的OC随着沉积物深度的增加而显著减少 (2至10倍).
- 发现Fe (oxyhydr) 氧化物与沉积物OC结合在一起.
- 随着沉积物深度的增加,碳的标称氧化状态 (NOSC) 变得更加负面 (表明能量含量增加),与较低的氧化还原潜力相关.
结论:
- 沉积物OC的保存取决于当前的氧化还原条件.
- 在富含氧气的环境中,反应性Fe保护OC.
- 在无氧环境中,热力学约束限制了OC氧化,提高了保存.
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