Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Sci Total Environ. 2021 Apr 10;764:142924. doi: 10.1016/j.scitotenv.2020.142924. Epub 2020 Oct 19.
Inputs of nitrogen (N) to peatlands in the form of fertilizers have rapidly increased due to the intensification of agricultural systems, impacting ecological processes, and the carbon storage function of peatland. However, detailed information on the impacts of long-term N inputs on the individual steps of N transformation processes in peatland soils still needs to be fully understood. We investigated N mineralization and nitrification rates as well as nitrite dependent anaerobic methane oxidation (n-damo), anaerobic ammonium oxidation (anammox), denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) in a peatland affected by N inputs for >50 years, using isotope tracing technique and quantitative PCR. Based on the results, N inputs increased N mineralization and nitrification rates by 77 and 43%, respectively. Notably, the contributions of n-damo and anammox to N production were enhanced by 242 and 170%, accounting for 30 and 12%, respectively. The contributions of denitrification and DNRA to N production decreased by 27 and 52%, accounting for 48 and 10% of N production, respectively. Nitrifier abundance increased significantly, with AOA being the dominant prokaryote (from 696 to 1090 copies g), but AOB responded more strongly to N inputs (from 5 to 68 copies g). The N inputs also promoted the growth of n-damo and anammox bacteria, whose abundances increased by 3.7% (from 565 to 586 copies g) and 85.7% (from 305 to 567 copies g), respectively, while denitrifier abundance was significantly reduced, with nirK and nirS abundances decreasing by 58% (from 738 to 308 copies g) and 50% (from 218 to 109 copies g), respectively. Soil pH was the key environmental factor influencing N transformations. We show that n-damo plays important roles in N cycling in peatland subjected to N inputs, providing a scientific basis for improved peatland management.
由于农业系统的集约化，以肥料形式输入到泥炭地的氮（N）迅速增加，从而影响了生态过程和泥炭地的碳储存功能。然而，关于长期 N 输入对泥炭地土壤中 N 转化过程各个步骤的影响的详细信息仍需充分了解。我们使用同位素示踪技术和定量 PCR 研究了受 N 输入影响超过 50 年的泥炭地中的氮矿化和硝化速率以及亚硝酸盐依赖型厌氧甲烷氧化（n-damo）、厌氧氨氧化（anammox）、反硝化和异化硝酸盐还原为铵（DNRA）。结果表明，N 输入分别使氮矿化和硝化速率增加了 77%和 43%。值得注意的是，n-damo 和 anammox 对 N 产生的贡献分别增加了 242%和 170%，分别占 30%和 12%。反硝化和 DNRA 对 N 产生的贡献分别减少了 27%和 52%，分别占 N 产生的 48%和 10%。氨氧化古菌（AOA）丰度显著增加，成为优势原核生物（从 696 拷贝 g 增加到 1090 拷贝 g），但氨氧化细菌（AOB）对 N 输入的响应更强（从 5 拷贝 g 增加到 68 拷贝 g）。N 输入还促进了 n-damo 和 anammox 细菌的生长，其丰度分别增加了 3.7%（从 565 拷贝 g 增加到 586 拷贝 g）和 85.7%（从 305 拷贝 g 增加到 567 拷贝 g），而反硝化细菌的丰度显著降低，nirK 和 nirS 的丰度分别降低了 58%（从 738 拷贝 g 降低到 308 拷贝 g）和 50%（从 218 拷贝 g 降低到 109 拷贝 g）。土壤 pH 是影响 N 转化的关键环境因素。我们表明，n-damo 在受 N 输入影响的泥炭地 N 循环中发挥重要作用，为改进泥炭地管理提供了科学依据。
