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Water-level alterations modified nitrogen cycling across sediment-water interface in the Three Gorges Reservoir

文献类型: 外文期刊

作者: Yu, Juhua 1 ; Zhang, Yushu 1 ; Zhong, Jicheng 2 ; Ding, Hong 1 ; Zheng, Xiangzhou 1 ; Wang, Zhiyuan 3 ; Zhang, Yinlong 4 ;

作者机构: 1.Fujian Acad Agr Sci, Inst Soil & Fertilizer, Fuzhou 350013, Fujian, Peoples R China

2.Chinese Acad Sci, Nanjing Inst Geog & Limnol, State Key Lab Lake Sci & Environm, Nanjing 210008, Jiangsu, Peoples R China

3.Nanjing Hydraul Res Inst, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210029, Jiangsu, Peoples R China

4.Nanjing Forestry Univ, Coinnovat Ctr Sustainable Forestry Southern China, Nanjing 210037, Jiangsu, Peoples R China

关键词: Nitrogen cycle; Water-level regimes; Sediment-water interface; Reservoir

期刊名称:ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH ( 影响因子:4.223; 五年影响因子:4.306 )

ISSN: 0944-1344

年卷期:

页码:

收录情况: SCI

摘要: Water-level regime alteration-associated redox fluctuation plays a primary role in governing exchange and transformation of nitrogen (N) in water-level fluctuation zones (WLFZs), while few understanding of how hydrological regimes under reservoir operation affected N cycling across the sediment-water interface (SWI), giving rise to uncertainties in reservoir N nutrient management. Batch microcosm simulation experiments with intact sediment cores from WLFZs of the Three Gorges Reservoir (TGR) were conducted for 24 days to identify holistic flooding-drying process mechanism on N-cycling patterns. Our results showed a distinct transition of N-cycling mode across the SWI, shifting from biological denitrogen loss dominated in initial period of flooding to enhance endogenous N retention. A dramatic source-sink switch of nitrous oxide (N2O) occurred in the first 1.5 days during the flooding period. However, combined accelerating migration of NH4+-N from sediment to overlying water, and subsequently enhanced transformation of NH4+-N to NO3--N formed from flooding to drying rotation, thereby increasing N loading to overlying water. The reason for this investigation could be attributed to intensive N loss through coupled nitrification and denitrification in oxic-anoxic microenvironments after flooding. With oxygen replenishment from atmosphere during drying phase, persistent ammonification of organic N in sediments provided sufficient source of NH4+-N for the formation of NO3--N fraction in a more oxic overlying water. Therefore, water-level regime alteration by reservoir operation was capable of weakening N removal from water body and lengthening internal N turnover time across redox-variable SWI. These findings elucidate new understanding of holistic hydrological regime mechanisms on N cycling across SWI and provide insight to biogenic N nutrient management for improving the green credentials of hydroelectric reservoir.

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