Soils affected by animal wastes have simultaneously high N and P contents. Despite the reports of high nitrous oxide (N2O) emissions in such environments, the role that P plays in N2O dynamics has not yet been systematically investigated. Here, we report the enhancement effect of orthophosphate (PO43−-P) abundance on N2O yields from abiotic NH2OH decomposition, which may have substantial implications to N2O emissions from nitrification in such P-rich soils. The axenic cultures of Nitrosomonas europaea, an ammonia-oxidizing bacterium previously reported to leak NH2OH, exhibited significantly higher N2O yields when incubated at higher PO43−-P concentrations. As NH4+-to-NO2− turnover and growth rates were unaffected even at the highest PO43−-P concentration examined, the abiotic interaction between extracellularly released NH2OH and PO43−-P was the most plausible mechanism of enhanced N2O emission in these nitrifier cultures. This proposed mechanism was supported by the results of abiotic NH2OH incubation whereby higher PO43−-P concentration resulted in higher N2O yield. Orthophosphate enhancement of NH2OH-to-N2O turnover was then simulated with addition of 5 μmol NH2OH to an ornithogenic soil with high PO43−-P content (23.9 ± 6.7 g/kg wet soil) and active nitrification activity after sterilization. The N2O yield, 69.0 ± 4.6%, was significantly higher than the N2O yields for other examined soils with lower PO43−-P contents (0–1.94 g/kg wet soil), and the PO43−-P contents of the examined soils exhibited strong correlation with the N2O yields. These findings suggest that N2O production from nitrification via abiotic turnover of released NH2OH may be a consequential mechanism of N2O emissions in PO43−-P-rich soils.

中文翻译：

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正磷酸盐提高有氧羟胺分解产生的 N2O：对鸟类和施肥土壤中硝化作用产生的 N2O 排放的影响

受动物粪便影响的土壤同时具有高 N 和 P 含量。尽管有报告称此类环境中一氧化二氮 (N2O) 排放量较高，但尚未系统研究 P 在 N2O 动力学中的作用。在这里，我们报告了正磷酸盐 (PO43--P) 丰度对非生物 NH2OH 分解产生的 N2O 产量的增强作用，这可能对这种富含 P 的土壤中硝化作用产生的 N2O 排放产生重大影响。Nitrosomonas europaea 的无菌培养物是一种先前报道会泄漏 NH2OH 的氨氧化细菌，当在较高 PO43--P 浓度下培养时，其 N2O 产量显着提高。由于即使在所检查的最高 PO43--P 浓度下，NH4+ 到 NO2- 的周转率和增长率也不受影响，细胞外释放的 NH2OH 和 PO43--P 之间的非生物相互作用是这些硝化菌培养物中 N2O 排放增强的最合理机制。这种提议的机制得到了非生物 NH2OH 孵化结果的支持，即更高的 PO43--P 浓度导致更高的 N2O 产量。然后通过向具有高 PO43--P 含量（23.9 ± 6.7 g/kg 湿土壤）和活性硝化活性的鸟类土壤中添加 5 μmol NH2OH 来模拟正磷酸盐对 NH2OH 到 N2O 转换的增强。N2O 产量为 69.0 ± 4.6%，显着高于其他具有较低 PO43−-P 含量（0-1.94 g/kg 湿土壤）的受检土壤的 N2O 产量，并且受检土壤的 PO43−-P 含量表现出与 N2O 产量密切相关。