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宁夏第三排水沟岸边带湿地土壤硝化速率潜势及其影响因素研究

Soil potential nitrification rate and influencing factors in the riparian wetlands of the Third Drainage Ditch in Ningxia

  • 摘要: 硝化作用是岸边带湿地土壤氮循环的关键环节,硝化速率潜势(Potential Nitrification Rate, PNR)可反映土壤硝化作用的潜在能力和速率。为探究宁夏第三排水沟岸边带湿地土壤硝化速率潜势及影响因素,于2023年3月、6月和8月采集沿线12个代表性岸边带湿地土壤样品,测定土壤理化指标和PNR,利用荧光定量qPCR技术测定硝化微生物功能基因丰度,分析PNR与土壤理化指标、硝化微生物功能基因丰度之间的关系。研究结果表明,第三排水沟岸边带湿地土壤PNR为0.025~0.266 mg/(kg·h),呈现8月>6月>3月的趋势,并且下游高于中上游。氨氧化细菌(AOB)和氨氧化古菌(AOA)的 amoA功能基因丰度均在8月最大,贺兰县段以AOA amoA占主导,平罗县段和惠农区段则由AOB amoA占主导。PNR与土壤全氮、铵态氮、有机碳、AOA amoA和AOB amoA呈显著正相关,铵态氮通过影响AOB amoA和AOA amoA丰度间接影响PNR。研究揭示了宁夏第三排水沟岸边带湿地土壤硝化过程的时空变化规律及其影响因素,为排水沟环境管理提供了科学依据。

     

    Abstract: Nitrification is a key process in the soil nitrogen cycle of riparian wetlands, and the potential nitrification rate (PNR) can reflect the potential capacity and rate of soil nitrification. To explore the PNR and its influencing factors in the riparian wetland soils of the Third Drainage Ditch in Ningxia, soil samples were collected from 12 representative riparian wetland sites along the ditch in March, June and August 2023. Soil physicochemical properties and PNR were measured, and the abundances of nitrification-related functional genes were determined using quantitative PCR (qPCR). The relationships between PNR and soil physicochemical properties as well as the abundances of nitrification functional genes were analyzed. The results showed that the PNR in the riparian wetland soils of the Third Drainage Ditch ranged from 0.025 to 0.266 mg/kg/h, following a trend of August>June>March, with higher values observed in the downstream section compared to the midstream and upstream sections. The abundances of both AOA amoA and AOB amoA functional genes peaked in August, however, AOA amoA dominated in the Helan County section, whereas AOB amoA dominated in the Pingluo County and Huinong District sections. PNR was significantly positively correlated with soil total nitrogen, ammonium nitrogen, organic carbon, and the abundances of AOA amoA and AOB amoA. Ammonium nitrogen indirectly influenced PNR by affecting the abundances of AOB amoA and AOA amoA. This study elucidates the spatiotemporal variations and influencing factors of the nitrification process in the riparian wetland soils of the Third Drainage Ditch in Ningxia, and provides a scientific basis for the environmental management of drainage ditches.

     

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