Climate change-related warming and increased precipitation may alter winter snow cover and thawing events, and therefore, may carry significant consequences for nitrous oxide (N₂O) production pathways such as denitrification, and the abundance and expression of denitrifying microorganisms. We used a soil microcosm study to investigate the combined effect of soil thaw temperature, initial water filled pore space (WFPS) prior to soil freezing, and snowmelt infiltration simulated by the addition of water on N₂O emission and denitrification rates, soil respiration rate, and the abundance and transcription of denitrifying (nirK, nirS, and nosZ) bacteria during a single freeze-thaw event. Soil respiration rate was primarily controlled by an increase in soil thaw temperature, whereas soil N₂O emission and denitrification rates were generally greater in soils with a higher initial WFPS and soil thaw temperature. In contrast, snowmelt infiltration generally had a negligible effect on these rates, which may be related to pre-existing soil conditions that were already conducive to denitrification. Unexpectedly, the nosZ transcript/nosZ gene abundance ratio was lower in soils thawed at 8.0 °C compared to 1.5 °C; however, this may have resulted in a lower N₂O reduction, thus explaining the greater levels of N₂O emitted from soils thawed at 8.0 °C. Overall, this study demonstrated that increased N₂O production during a single freeze-thaw event was primarily linked to antecedent conditions of high initial WFPS, soil thaw temperature, and a synergistic interplay between these two environmental parameters, and provides evidence that an increase in annual temperature and precipitation, along with the timing of precipitation, may further stimulate N₂O production pathways.

与气候变化相关的变暖和降水增加可能会改变冬季积雪和融化事件，因此可能会对一氧化二氮（N ₂ O）生产途径（例如反硝化以及反硝化微生物的丰度和表达）产生重大影响。我们使用土壤微观研究来研究土壤解冻温度、土壤冻结前的初始充水孔隙空间（WFPS）以及加水模拟的融雪入渗对 N ₂ O 排放和反硝化速率、土壤呼吸速率的综合影响。 ，以及单次冻融过程中反硝化细菌（ nirK、nirS和nosZ ）的丰度和转录。土壤呼吸速率主要受土壤解冻温度升高的控制，而初始WFPS和土壤解冻温度较高的土壤N ₂ O排放和反硝化速率通常较高。相比之下，融雪渗透对这些速率的影响通常可以忽略不计，这可能与已有利于反硝化的现有土壤条件有关。出乎意料的是，在 8.0 °C 解冻的土壤中， nosZ转录本/ nosZ基因的丰度比低于 1.5 °C 解冻的土壤；然而，这可能导致 N ₂ O 减少量较低，从而解释了在 8.0 °C 解冻的土壤中排放的N ₂ O水平较高的原因。总体而言，这项研究表明，单次冻融事件期间N ₂ O 产量的增加主要与高初始 WFPS、土壤解冻温度以及这两个环境参数之间的协同相互作用有关，并提供了证据表明 N 2 O 产量的增加年气温和降水量以及降水时间可能会进一步刺激 N ₂ O 的产生途径。