Abstract Heavy metal concentrations (HMCs) may alter nitrification activity in soil. However, the levels of HMCs in paddy soil and the relations among HMCs, net nitrification rates, and nitrifying archaea/bacteria in paddy soils of Bangladesh remain unknown. The goal of this study was to determine the effect of HMCs on net nitrification rates and ammonia-oxidizing archaea (AOA) and bacteria (AOB), and nitrite-oxidizing bacteria (NOB) in paddy soils. HMCs and net nitrification rates were assayed through an atomic absorption spectrophotometer (AAS) and mass spectrophotometer (MS), respectively, and the abundance of AOA, AOB, and NOB was quantified by q-PCR. According to the contamination factor (Cf), concentrations of Cd were found to be a very severe pollutant in all soils. On the other hand, concentrations of Fe and Cu were found to be moderately contaminated and slightly polluted in paddy soils as compared to control soils. The net nitrification rates (8.67 to 12.75 mg kg−1 h−1) and the abundance of AOA, AOB, and NOB were significantly higher (p

中文翻译：

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孟加拉国水稻土中重金属浓度水平及其对净硝化率和硝化古细菌/细菌的影响

摘要 重金属浓度 (HMC) 可能会改变土壤中的硝化活性。然而，孟加拉国水稻土中 HMCs 的水平以及 HMCs、净硝化率和硝化古菌/细菌之间的关系仍然未知。本研究的目的是确定 HMC 对稻田土壤中净硝化速率和氨氧化古菌 (AOA) 和细菌 (AOB) 以及亚硝酸盐氧化细菌 (NOB) 的影响。分别通过原子吸收分光光度计 (AAS) 和质谱仪 (MS) 测定 HMC 和净硝化率，并通过 q-PCR 定量 AOA、AOB 和 NOB 的丰度。根据污染因子 (Cf)，发现 Cd 浓度是所有土壤中非常严重的污染物。另一方面，与对照土壤相比，水稻土壤中的 Fe 和 Cu 浓度被发现中度污染和轻度污染。净硝化速率（8.67 至 12.75 mg kg−1 h−1）和 AOA、AOB 和 NOB 的丰度显着更高（p