Evidences of N2O Emissions in Chloropicrin-Fumigated Soil

The mechanism of N2O production following chloropicrin (CP) fumigation was investigated in this study. Our results showed that CP fumigation increased N2O production from 23 to 25 times in comparison with the control and significantly decreased the abundance of 16S rRNA and N-cycling functional genes. CP also decreased the soil bacterial diversity and caused a shift in the community composition. The N2O emissions in fumigated soil were significantly correlated with soil environmental factors (NH4+, dissolved amino acid, microbial biomass nitrogen, and NO3–) but were not correlated with the abundance of functional genes. Metatranscriptomes and dual-label 15N–18O isotope analysis revealed that CP fumigation inhibited the expression of gene families involved in N2O production and sink processes and shifted the main pathway of N2O production from nitrification to denitrification. These results provided useful information for environmental safety assessments of CP in China, to improve our understanding of the N-cycling pathways in fumigated soils.

本研究针对氯化苦（chloropicrin，CP）熏蒸后一氧化二氮（N₂O）的产生机制开展了系统探究。研究结果表明，与对照组相比，CP熏蒸可使N₂O产生量提升23至25倍，且显著降低了16S rRNA基因与氮循环功能基因的丰度；同时，CP熏蒸还会降低土壤细菌多样性，并导致土壤细菌群落组成发生显著偏移。熏蒸土壤中的N₂O排放量与土壤环境因子（铵态氮NH₄⁺、溶解性氨基酸、微生物生物量氮以及硝态氮NO₃⁻）显著相关，但与功能基因丰度无显著关联。元转录组学分析与双标记¹⁵N–¹⁸O同位素示踪结果显示，CP熏蒸抑制了参与N₂O产生与消汇过程的基因家族表达，并将N₂O产生的主要途径从硝化作用转变为反硝化作用。本研究结果可为中国范围内CP的环境安全评估提供重要参考依据，同时有助于深化对熏蒸土壤氮循环途径的科学认知。