Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, 210044, China.
School of Life Science, Huaiyin Normal University, Huaian, 223001, China.
Environ Pollut. 2023 Feb 1;318:120872. doi: 10.1016/j.envpol.2022.120872. Epub 2022 Dec 15.
The effects of elevated carbon dioxide (CO) concentration (e[CO]) on nitrous oxide (NO) emissions from paddy fields and the microbial processes involved in NO emissions have recently received much attention. Ammonia-oxidizing microorganisms and denitrifying bacteria dominate the production of NO in paddy soils. To better understand the dynamics of NO production under e[CO], a field experiment was conducted after five years of CO fumigation based on three treatments: CK (ambient atmospheric CO), T1 (CK + increase of 40 ppm per year until 200 ppm), and T2 (CK + 200 ppm). NO fluxes, soil physicochemical properties, and NO production potential were quantified during the rice-growth period. The functional gene abundance and community composition of ammonia-oxidizing archaea (AOA) and bacteria (AOB) were analyzed using quantitative polymerase chain reaction (qPCR) and those of ammonia-denitrifying bacteria (nirS- and nirK-type) were analyzed using Illumina MiSeq sequencing. NO emissions decreased by 173% and 41% under the two e[CO] treatments during grain filling and milk ripening, respectively (P < 0.05). NO emissions increased by 279% and 172% in the T2 treatment compared with T1 during the tillering and milk-ripening stages, respectively (P < 0.05). Furthermore, the NO production potential was significantly higher in the CK treatment than in T1 and T2 during the elongation stage. The NO production potential and abundance of AOA amoA genes in T1 treatment were significantly lower than those in CK treatment during the high NO emission phase caused by mid-season drainage (P < 0.05). Although nirK- and nirS-type denitrifying bacteria community structure and diversity did not respond significantly (P > 0.05) to e[CO], the abundance of nirK-type denitrifying bacteria significantly affected the NO flux (P < 0.05). Linear regression analysis showed that the NO production potential, AOA amoA gene abundance, and nirK gene abundance explained 47.2% of the variation in NO emissions. In addition, soil nitrogen (N) significantly affected the nirK- and nirS-type denitrifier communities. Overall, our results revealed that e[CO] suppressed NO emissions, which was closely associated with the abundance of AOA amoA and nirK genes (P < 0.05).
大气二氧化碳（CO）浓度升高（e[CO]）对稻田一氧化二氮（NO）排放的影响及其涉及的微生物过程最近受到了广泛关注。氨氧化微生物和反硝化细菌主导着稻田中 NO 的产生。为了更好地理解 e[CO]下 NO 产生的动态，在 CO 熏蒸五年后进行了田间试验，该试验基于三种处理：CK（大气 CO）、T1（CK+每年增加 40ppm，直至 200ppm）和 T2（CK+200ppm）。在水稻生长期内，量化了 NO 通量、土壤理化性质和 NO 产生潜力。使用定量聚合酶链反应（qPCR）分析氨氧化古菌（AOA）和细菌（AOB）的功能基因丰度和群落组成，使用 Illumina MiSeq 测序分析氨-反硝化细菌（nirS-和 nirK 型）的功能基因丰度和群落组成。在灌浆和乳熟期，e[CO]处理下的 NO 排放量分别减少了 173%和 41%（P<0.05）。在分蘖和乳熟期，T2 处理下的 NO 排放量分别比 T1 处理增加了 279%和 172%（P<0.05）。此外，在伸长阶段，CK 处理的 NO 产生潜力明显高于 T1 和 T2 处理。在中期排水引起的高 NO 排放阶段（P<0.05），T1 处理的 NO 产生潜力和 AOA amoA 基因丰度明显低于 CK 处理。尽管 e[CO]对 nirK 和 nirS 型反硝化细菌群落结构和多样性没有显著影响（P>0.05），但 nirK 型反硝化细菌的丰度显著影响了 NO 通量（P<0.05）。线性回归分析表明，NO 产生潜力、AOA amoA 基因丰度和 nirK 基因丰度解释了 47.2%的 NO 排放变化。此外，土壤氮（N）显著影响了 nirK 和 nirS 型反硝化菌群落。总的来说，我们的结果表明，e[CO]抑制了 NO 的排放，这与 AOA amoA 和 nirK 基因的丰度密切相关（P<0.05）。
