高寒草甸氧化亚氮排放特征对不同种类硝化抑制剂响应

Alpine meadows were the main type of the Tibetan Plateau and atmosphere greenhouse gases nitrous oxide (N2O) source. Those were distributed over a wide area. Annual nitrogen input from livestock excreta improved significantly with the increasing of grazing animals. Furthermore, anthropogenic disturbance increased significantly the amount of atmospheric nitrogen deposition. Priming effects were reported between livestock excreta and nitrogen deposition and N2O emission rates. Thus, more and more attention was paid to the mitigation effect on N2O emission from applying nitrification inhibitors, and improving biomass in alpine meadow. Here, nitrous oxide emission was measured by a static chamber method and an improved gas chromatograph. Based on the former researches of mechanism model and acetylene inhibition manipulation, nitrification was considered as the dominant process for N2O produce. The responses were studied of N2O emission characteristic, soil nitrification intensity and mineral nitrogen content, ammonia-oxidizing archaea and ammonia-oxidizing bacteria gene abundance, and grassland production to different kinds of nitrification inhibitor and its dose in the growing season. To make sure the adaptive nitrification inhibitor and dose, and quantify the potential mitigation stock of soil N2O flux. Meanwhile, the main microorganism groups were studied participating in soil nitrification at the molecule level, and the inhibiting mechanism was revealed in connection with environmental factors. In addition, this study would help to crack the long-term bottleneck of lacking available nitrogen in alpine grassland. To explore the strategy of increasing grassland biomass, this contributed to coping with global warming and upgrading the production function with important scientific significance.

高寒草甸是青藏高原主体类型之一，在高原地区广域分布，为温室气体N2O排放源。随着放牧家畜数量不断增加，以粪尿斑输入土壤氮素数量显著提高，此外人类活动导致大气氮沉降增加，两者均可能对高寒草甸N2O存在激发效应。解析硝化抑制剂对高寒草地N2O排放与草地生产功能的影响，日益受到广泛关注。本研究采用密闭箱—气相色谱法，在基于机理模型和乙炔抑制试验，已确定硝化作用为草地土壤N2O排放主导过程基础上，研究生长季高寒草地N2O排放特征，土壤硝化作用和矿质态氮含量、氨氧化古菌和氨氧化细菌丰度、草地生产力、对不同种类和施用量硝化抑制剂的响应特征。确定适宜的硝化抑制剂种类、施用剂量，定量高寒草甸土壤N2O减排潜力；从分子水平认识参与氨氧化作用的主要微生物类群，结合环境因素揭示其抑制机理、破解高寒草地速效氮长期匮乏的瓶颈，探索增加草地生物量策略，这对于积极应对全球变暖，提升高寒草甸生产功能具有重要的科学意义。

气候是人类赖以生存的自然环境，2022年1月，世界气象组织发布全球气候状况公报，指出全球气候变化仍在继续，2021年全球平均气温比工业化前约增长1.11 摄氏度，氧化亚氮是引起全球增温的重要温室气体。氮素是高寒草甸重要养分，高寒草地全量养分丰富而速效养分缺乏，氮素亏缺已成为限制草地生产功能的主要瓶颈。硝化抑制剂可通过选择性抑制土壤硝化菌群数量及活性，有效延缓土壤铵态氮向硝态氮的转化，降低土壤N2O排放量，提高土壤氮素供给水平。本研究采用密闭箱—气相色谱法，研究生长季高寒草地N2O排放特征，土壤硝化作用和矿质态氮含量、氨氧化古菌和氨氧化细菌丰度、草地生产力、对不同种类和施用量硝化抑制剂的响应特征。确定适宜的硝化抑制剂种类、施用剂量，定量高寒草甸土壤N2O减排潜力；从分子水平认识参与氨氧化作用的主要微生物类群，结合环境因素揭示其抑制机理、破解高寒草地速效氮长期匮乏的瓶颈，探索增加草地生物量策略。研究结果表明：两种硝化抑制剂双氰胺(DCD)，3,4-二甲基吡唑磷酸盐(DMPP)均可以显著降低高寒草甸氧化亚氮排放速率，提升高寒草甸生产功能。基于结构方程模型发现地上生物量和AOA对硝化抑制剂处理草地氧化亚氮排放起到显著性的负向直接作用(P<0.05)AOB、铵态氮含量和土壤有机质起到正向直接调控作用。地上生物量主要受到铵态氮含量影响，而土壤硝态氮含量主要受到AOA调控。双氰胺(DCD)抑制效果优于DMPP，DCD剂量3.40kg ha-1对降低大气温室气体氧化亚氮排放和提升草地生产力效果最优，分别为26.73%和26.21%。DCD和DMPP可显著增加铵态氮含量，高寒草地土壤氨氧化古菌的丰度显著高于氨氧化细菌，施用硝化抑制剂DCD和DMPP之后均明显降低土壤氨氧化古菌和氨氧化细菌丰度，硝化抑制剂对对AOA的抑制效果较好AOB。已发表第一和通讯作者SCI论文13篇、CSCD论文2篇，其中第一作者SCI6篇。协助培养博士生1名，培养硕士生3名，均已获得硕士学位，项目组1名副研究员晋升研究员、博士生导师，2名助理研究员分别晋升高级工程师和副研究员。本研究对于积极应对全球气候变暖，提升青藏高原高寒草甸生产功能和生态屏障功能均具有重要的科学意义。