Improving nitrogen use efficiency of chemical fertilizers is essential to mitigate the negative environmental impacts of nitrogen. Nitrification, the conversion of ammonium to nitrate via nitrite by soil microbes, is a prominent source of nitrogen loss in soil systems. The effectiveness of nitrification inhibitors in reducing nitrogen loss through inhibition of nitrification is well-documented, however, their efficacy in heavy metals-contaminated soils needs thorough investigations. The current study assessed the efficacy of nitrification inhibitor 3, 4-dimethylpyrazole phosphate (DMPP) in reducing nitrous oxide (NO) emissions in cadmium (Cd) contaminated paddy and red soils under lab-controlled environment. Obtained results indicated the substantial reduction in NO emissions with DMPP in paddy and red soil by 48 and 35 %, respectively. However, Cd contamination resulted in reduced efficacy of DMPP, thus decreased the NO emissions by 36 and 25 % in paddy and red soil, respectively. It was found that addition of DMPP had a significant effect on the abundance of ammonia oxidizing bacteria (AOB) and archaea (AOA). Notably, the reduction in NO emissions by DMPP varied with the abundance of AOB. Moreover, Cd pollution resulted in a significant reduction in the abundance of archaeal and bacterial amoA genes, as well as bacterial , , and genes. The combined treatment of Cd and DMPP had a detrimental impact on denitrifiers, thereby influencing the overall efficiency of DMPP. These findings provide novel insights into the application of DMPP to mitigate nitrification and its potential role in reducing NO emissions in contaminated soils.

中文翻译：

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评估 3, 4-二甲基吡唑磷酸盐 (DMPP) 抑制剂在减少对比镉污染土壤中 N2O 排放方面的有效性

提高化肥氮肥利用率对于减轻氮肥对环境的负面影响至关重要。硝化作用，即土壤微生物通过亚硝酸盐将铵转化为硝酸盐的过程，是土壤系统中氮流失的一个重要来源。硝化抑制剂通过抑制硝化作用来减少氮素损失的有效性已得到充分证明，但其在重金属污染土壤中的功效需要彻底研究。目前的研究评估了硝化抑制剂 3, 4-二甲基吡唑磷酸盐 (DMPP) 在实验室控制环境下减少镉 (Cd) 污染水稻和红壤中一氧化二氮 (NO) 排放的功效。获得的结果表明，DMPP 可使水稻和红壤中的 NO 排放量分别大幅减少 48% 和 35%。然而，Cd污染导致DMPP的功效降低，从而使水稻和红壤的NO排放量分别减少了36%和25%。结果发现，DMPP的添加对氨氧化细菌（AOB）和古细菌（AOA）的丰度有显着影响。值得注意的是，DMPP 减少的 NO 排放量随 AOB 的丰度而变化。此外，镉污染导致古菌和细菌 amoA 基因以及细菌 、 和 基因的丰度显着减少。 Cd和DMPP的联合处理对反硝化菌产生不利影响，从而影响DMPP的整体效率。这些发现为 DMPP 在减轻硝化作用中的应用及其在减少污染土壤中 NO 排放方面的潜在作用提供了新的见解。