Lv Baoyi, Cui Yuxue, Wei Huawei, Chen Qihao, Zhang Di
College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, China; Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, East China Normal University, Shanghai 200241, China.
Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, East China Normal University, Shanghai 200241, China.
J Hazard Mater. 2020 Dec 5;400:123215. doi: 10.1016/j.jhazmat.2020.123215. Epub 2020 Jun 17.
Vermicomposting is a sustainable option for the recycling of biodegradable organic waste. However, it also produces nitrous oxide (NO), which is a highly potent greenhouse gas. In this study, the NO stable isotope and functional genes for nitrogen cycling were determined to investigate the sources of NO during vermicomposting. The results showed that vermicomposting promoted the organic degradation and nitrogen nitrification, and the presence of earthworms increased the emission of NO during vermicomposting compared to that during the control treatment with no earthworms. The site preference analysis of NO stable isotope showed that both nitrification and denitrification were present during the early stages of vermicomposting, while nitrification was the dominant contributor to NO production in the later stages. Moreover, earthworms increased the gene copies of amoA, and stimulated the nitrifying bacteria, and hence, increased the NO emission via nitrification. In addition, the activity of earthworms reduced the gene number of nosZ during vermicomposting, while the denitrification was the main source of NO in the earthworm gut, as the conditions inside the gut inhibited nosZ. Overall, nitrification was the major pathway (55.8-88.7 %) for NO production, which was promoted by the introduction of earthworms through nitrification.
蚯蚓堆肥是可生物降解有机废物回收利用的一种可持续选择。然而，它也会产生一氧化二氮（N₂O），这是一种强效温室气体。在本研究中，测定了N₂O稳定同位素和氮循环功能基因，以探究蚯蚓堆肥过程中N₂O的来源。结果表明，蚯蚓堆肥促进了有机物质降解和氮硝化作用，与无蚯蚓的对照处理相比，蚯蚓的存在增加了蚯蚓堆肥过程中N₂O的排放。N₂O稳定同位素的位点偏好分析表明，蚯蚓堆肥早期硝化作用和反硝化作用均存在，而后期硝化作用是N₂O产生的主要贡献者。此外，蚯蚓增加了amoA基因拷贝数，刺激了硝化细菌，因此通过硝化作用增加了N₂O排放。另外，蚯蚓的活动在蚯蚓堆肥过程中减少了nosZ基因数量，而反硝化作用是蚯蚓肠道内N₂O的主要来源，因为肠道内环境抑制了nosZ。总体而言，硝化作用是N₂O产生的主要途径（55.8 - 88.7%），蚯蚓通过硝化作用促进了这一过程。
