摘要
研究水淹持续时间、水淹深度对消落带土壤有机氮和无机氮形态及其含量的影响,为准确预测消落带土壤氮形态及其含量的演变趋势提供支撑。在重庆市开州区渠口镇三峡水库消落带,通过原位浮台装置,将盛有消落带土壤的试验组塑料盆悬挂于水深2、5和15 m处,水淹60、180 d,出露180 d,再次水淹180d;对照组塑料盆置于原位浮台上。结果表明:水淹处理的土壤pH高于对照组,土壤氮形态及含量也发生了显著变化;水淹环境会导致消落带土壤不同形态氮之间发生相互转化,对照组土壤全氮、酸解全氮和氨基糖态氮含量均值分别为(1188.11±83.46)、(702.79±154.81)、(170.78±70.86)mg/kg,水淹处理的土壤全氮含量(1287.25±15.93)mg/kg、酸解全氮含量(872.04±20.73)mg/kg,氨基糖态氮含量均值(148.13±18.99)mg/kg;随着水淹深度的增加,土壤全氮、酸解全氮含量呈增加趋势,氨基糖态氮、铵态氮和硝态氮含量呈下降趋势;水淹-出露-再水淹会导致消落带土壤碳、氮等营养元素的流失,再次水淹180 d,消落带土壤全碳、全氮、酸解氨态氮、氨基糖态氮、硝态氮含量低于对照组;消落带土壤氮的形态相互转化过程受土壤酶活性及水淹环境(光照和水温等)的影响,土壤脲酶与全氮、氨基酸态氮、酸解氨态氮、硝态氮显著正相关,与非酸解氮显著负相关。硝酸还原酶与全氮、酸解全氮显著负相关;亚硝酸还原酶活性与酸解全氮、氨基酸氮和酸解氨态氮显著正相关,羟胺还原酶活性与硝态氮显著正相关。
The water-level-fluctuation zone(WLFZ)in Three Gorges Reservoir spans up to 30 m(145-175 m)and WLFZ soils emerge in summer and submerge in winter.Several investigators have studied the seasonal variation of soil total nitrogen and inorganic nitrogen in the WLFZ.However,little is known about seasonal changes in the speciation of nitrogen resulting from the wet-dry cycle.In this study,we explored the transformation of nitrogen from one form to another in WLFZ soils,aiming to reveal the effects of flooding duration and water depth on the concentration and form of organic and inorganic nitrogen.To characterize soil nitrogen transformations,an 18 month in-situ experiment was carried out at four water depths(0 m,2 m,5 m and 15 m)in Kaizhou County,Chongqing City.Plastic pots with soil were suspended from a floating platform and the pots at each depth were submerged for 60 days,sampled and resubmerged for another 120 days to give 180 days total.Soil was again sampled and the pots were placed on the platform and exposed to weather for 180 days,and then submerged again for 180 days before the soil was sampled for the last time.The pH,total C,total N,forms of organic and inorganic nitrogen,and enzyme activity of soil samples from each treatment were determined at the end of each period.Water environmental parameters were measured and analyzed to identify that affect the form of nitrogen.The pH of submerged soil was higher than the pH of emerged soil.Inundation led to changes in nitrogen concentration and transformation of nitrogen form in the soil treatments.During the flooding-drying cycle,the average total nitrogen(TN)content,total hydrolysable N and amino sugar N in the unsubmerged soil were(1188.11±83.46)mg/kg,(702.79±154.81)mg/kg and(170.78±70.86)mg/kg,respectively.In submerged soils TN and hydrolysable N increased to(1287.25±15.93)mg/kg and(872.04±20.73)mg/kg,while amino sugar N decreased(148.13±18.99)mg/kg.The forms and content of soil nitrogen were affected by submergence depth.With increasing water depth,TN and total hydrolysable N increased,while amino sugar N,ammonium N and nitrate N decreased.Periodic inundation and the wet-dry cycle leads to a loss of carbon and nitrogen in the soil.When again flooded for 180 d,total carbon,TN,ammonia N,amino sugar N,nitrate N in flooded soil treatments were lower than in unflooded soil treatments.The transformation of nitrogen in the soils were influenced by enzyme activity in the soil and the water environment(light,water temperature,etc.).Soil urease was positively correlated with total N,amino acid N,ammonia N and nitrate N,but negatively correlated with acid-insoluble N.Nitrate reductase activity was negatively correlated with TN and total hydrolysable N.Nitrite reductase was positively correlated with total hydrolysable N,amino acid nitrogen and ammonia N.Hydroxylamine reductase activity was positively correlated with nitrate nitrogen.
作者
张志永
胡红青
鲁泽禹
朱稳
张钽
邹曦
ZHANG Zhi-yong;HU Hong-qing;LU Zeyu;ZHU Wen;ZHANG Tan;ZOU Xi(Key Laboratory of Ecological Impacts of Hydraulic Projects and Restoration of Aquatic Ecosystem of Ministry of Water Resources,Institute of Hydroecology.Ministry of Water Resources and Chinese Academy of Sciences.Wuhan 430079,P.R.China;College of Resource and Environment,Huazhong Agricultural University,Wuhan 430070,P.R.China)
出处
《水生态学杂志》
CSCD
北大核心
2020年第4期63-72,共10页
Journal of Hydroecology
基金
国家重点研发计划项目(2016YFC0502208)
国家自然科学基金项目(51679154)
重庆市技术创新与应用示范项目(cstc2018jszx-zdyfxmX0021)。
关键词
三峡水库
消落带
土壤氮
酶
Three Gorges Reservoir
water-level-fluctuation zone
soil nitrogen
soil enzymes
