Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China.
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China.
J Environ Manage. 2023 Dec 15;348:119387. doi: 10.1016/j.jenvman.2023.119387. Epub 2023 Oct 23.
Labile organic carbon (LOC) input strongly affects soil organic matter (SOM) dynamics, including gains and losses. However, it is unclear how redox fluctuations regulate these processes of SOM decomposition and formation induced by LOC input. The objective of this study was to explore the impacts of LOC input on SOM turnover under different redox conditions. Soil samples were collected in a subtropical forest. A single pulse of C-labeled glucose (i.e., LOC) was applied to the soil. Soil samples were incubated for 40 days under three redox treatments, including aerobic, anoxic, and 10-day aerobic followed by 10-day anoxic conditions. Results showed that LOC input affected soil priming and C-SOM accumulation differently under distinct redox conditions by altering the activities of various microorganisms. C-PLFAs (phospholipid fatty acids) were analyzed to determine the role of microbial groups in SOM turnover. Increased activities of fungi and gram-positive bacteria (i.e., the K-strategists) by LOC input could ingest metabolites or residues of the r-strategists (e.g., gram-negative bacteria) to result in positive priming. Fungi could use gram-negative bacteria to stimulate priming intensity via microbial turnover in aerobic conditions first. Reduced activities of K-strategists as a result of the aerobic to anoxic transition decreased priming intensity. The difference in LOC retention in SOM under different redox conditions was mainly attributable to C-particulate organic carbon (C-POC) accumulation. Under aerobic conditions, fungi and gram-positive bacteria used derivatives from gram-negative bacteria to reduce newly formed POC. However, anoxic conditions were not conducive to the uptake of gram-negative bacteria by fungi and gram-positive bacteria, favoring SOM retention. This work indicated that redox-regulated microbial activities can control SOM decomposition and formation induced by LOC input. It is extremely valuable for understanding the contribution of soil affected by redox fluctuations to the carbon cycle.
不稳定有机碳（LOC）输入强烈影响土壤有机质（SOM）动态，包括增益和损耗。然而，尚不清楚氧化还原波动如何调节这些由 LOC 输入引起的 SOM 分解和形成过程。本研究的目的是探索 LOC 输入对不同氧化还原条件下 SOM 周转的影响。在亚热带森林中采集土壤样本。向土壤中施加单一脉冲的 C 标记葡萄糖（即 LOC）。在有氧、缺氧和 10 天有氧 followed by 10 天缺氧三种氧化还原处理下培养土壤样品 40 天。结果表明，LOC 输入通过改变各种微生物的活性，对不同氧化还原条件下的土壤激发和 C-SOM 积累产生不同的影响。分析 C-PLFAs（磷脂脂肪酸）以确定微生物群在 SOM 周转中的作用。LOC 输入增加真菌和革兰氏阳性菌（即 K-策略者）的活性，可以吞噬 r-策略者（如革兰氏阴性菌）的代谢物或残留物，从而导致正激发。真菌可以在有氧条件下首先通过微生物周转利用革兰氏阴性细菌来刺激激发强度。有氧到缺氧转变导致 K-策略者活性降低，降低了激发强度。不同氧化还原条件下 SOM 中 LOC 保留的差异主要归因于 C-颗粒有机碳（C-POC）的积累。在有氧条件下，真菌和革兰氏阳性菌利用革兰氏阴性细菌的衍生物来减少新形成的 POC。然而，缺氧条件不利于真菌和革兰氏阳性菌对革兰氏阴性细菌的吸收，有利于 SOM 的保留。这项工作表明，氧化还原调节的微生物活性可以控制由 LOC 输入引起的 SOM 分解和形成。这对于理解受氧化还原波动影响的土壤对碳循环的贡献具有极高的价值。
