通风量对堆肥化过程中氮素转化及nirK基因多样性和数量的影响

通过研究不同通风量对堆肥化过程中nir K基因多样性和丰度的影响,阐明通风量与氮素转化和氮损失之间的关系。堆肥共设置3个处理,即对照不通风(静态堆肥CK)、通风量0.05 L·min-1·kg-1(微好氧堆肥TF1)和通风量0.2 L·min-1·kg-1(好氧堆肥TF4),分析不同时期堆肥样品的铵态氮、硝态氮、全氮等理化指标,以及不同时期堆肥样品中反硝化功能基因nir K基因数量和63 d样品中nir K基因多样性的变化规律。结果表明,堆肥过程中,CK、TF1、TF4三个处理的氨气速率和氮素总损失量随着通风量增大而增大,NO-3-N含量和总氮在堆肥结束时均达到最大,与通风量呈正相关。通过对堆肥样品中nir K基因多样性和数量分析发现,CK、TF1、TF4三个处理堆肥63 d样品中nir K基因克隆文库中OTU数量分别为9、5、3个;在堆肥高温期和腐熟期,nir K基因拷贝数与通风量呈现负相关。实验结果证明通风量显著影响堆肥化过程中各种形态氮的转化以及nir K基因多样性和数量,并增加了总氮和硝态氮含量。

Effects of ventilation on nitrogen transformation and nirK gene diversity and abundance during composting process

Ventilation is one of the most important parameters affecting composting process. In this study, the effects of ventilation on nitrogen transformation and loss and nirK gene diversity and abundance during composting process were examined. Three treatments, CK:0 L·min^-1·kg^-1(Static compost), TF1:0.05 L·min^-1·kg^-1(Microaerobic compost) and TF4:0.2 L·min^-1·kg^-1(Aerobic compost), were designed. The content of ammonium-nitrogen, nitrate nitrogen, and total nitrogen during different periods were measured. The abundance of nirK gene during different periods and the diversity of nirK gene on the 63rd day of composting were analyzed. Results showed that the NH₃ emissions and total nitrogen losses in three treatments increased with increasing amount of ventilation. The highest content of NO₃^--N and TN was observed in CK, TF1, and TF4 on the 63rd day, and was significantly affected by ventilation.The OTU number of nirK gene clone library of the 63rd day samples from CK, TF1 and TF4 was 9, 5, and 3, respectively. During the thermophilic and maturity periods, the abundance of nirK gene was negatively correlated with ventilation amount. The present results showed that ventilation significantly affects the transformation of nitrogen, and the diversity and abundance of nirK gene during composting, and increases TN and NO₃^--N content.