The influence of soil acidification on N2O emissions derived from fungal and bacterial denitrification using dual isotopocule mapping and acetylene inhibition

文献类型： 外文期刊

第一作者： Zheng, Qian

作者： Zheng, Qian;Ding, Junjun;Li, Qiaozhen;Xu, Chunying;Zhuang, Shan;Kou, Xinyue;Li, Yuzhong;Lin, Wei;Li, Yuzhong;Lin, Wei;Yao, Zhipeng

作者机构：

关键词： N2O; pH; Denitrification; N2O reduction; SP/delta O-18 MAP; Acetylene inhibition

期刊名称：ENVIRONMENTAL POLLUTION （ 影响因子：9.988； 五年影响因子：10.366 ）

ISSN： 0269-7491

年卷期： 2022 年 303 卷

页码：

收录情况： SCI

摘要： Denitrification, as both origins and sinks of N2O, occurs extensively, and is of critical importance for regulating N2O emissions in acidified soils. However, whether soil acidification stimulates N2O emissions, and if so for what reason contributes to stimulate the emissions is uncertain and how the N2O fractions from fungal (f(fD)) and bacterial (f(bD)) denitrification change with soil pH is unclear. Thus, a pH gradient (6.2, 7.1, 8.7) was set via manipulating cropland soils (initial pH 8.7) in North China to illustrate the effect of soil acidification on fungal and bacterial denitrification after the addition of KNO3 and glucose. For source partitioning, we used and compared SP/delta O-18 mapping approach (SP/delta O-18 MAP) and acetylene inhibition technique combined isotope two endmember mixing model (AIT-IEM). The results showed significantly higher N2O emissions in the acidified soils (pH 6.2 and pH 7.1) compared with the initial soil (pH 8.7). The cumulative N2O emissions during the whole incubation period (15 days) ranged from 7.1 mg N kg(-1) for pH 8.7-18.9 mg N kg(-1) for pH 6.2. With the addition of glucose, relative to treatments without glucose, this emission also increased with the decrement of pH values, and were significantly stimulated. Similarly, the highest N2O emissions and N2O/(N2O + N-2) ratios (rN(2)O) were observed in the pH 6.2 treatment. But the difference was the highest cumulative N2O + N-2 emissions, which were recorded in the pH 7.1 treatment based on SP/delta O-18 MAP. Based on both approaches, f(fD) values slightly increased with the acidification of soil, and bacterial denitrification was the dominant pathway in all treatments. The SP/delta O-18 MAP data indicated that both the rN(2)O and f(fD) were lower compared to AIT-IEM. It has been known for long that low pH may lead to high rN(2)O of denitrification and f(fD), but our documentation of a pervasive pH-control of rN(2)O and f(fD) by utilizing combined SP/delta O-18 MAP and AIT-IEM is new. The results of the evaluated N2O emissions by acidified soils are finely explained by high rN(2)O and enhanced f(fD). We argue that soil pH management should be high on the agenda for mitigating N2O emissions in the future, particularly for regions where long-term excessive nitrogen fertilizer is likely to acidify the soils.

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