不同干燥方式对喀斯特流域土壤氮形态测定的影响  

Effects of Different Drying Methods on the Determination of Soil Nitrogen Forms in Karst Watershed

作　　者：顾永波 白莉[1] 王小霞[1,2] 魏来 邢文聪[1,2] 李军 刘小龙 GU Yongbo;BAI Li;WANG Xiaoxia;WEI Lai;XING Wencong;LI Jun;LIU Xiaolong(Tianjin Key Laboratory of Water Resources and Water Environment,Tianjin Normnal University,Tianjin 300387,China;School of Geography and Environmental Science,Tianjn Normal University,Tianjin 300387,China)

机构地区：[1]天津师范大学天津市水资源与水环境重点实验室,天津300387 [2]天津师范大学地理与环境科学学院,天津300387

出　　处：《地球与环境》2022年第5期744-753,共10页Earth and Environment

基　　金：国家自然科学基金项目(41672351、41403082);天津市自然科学基金项目(18JCYBJC91000)。

摘　　要：不同预处理方式对不同类型土壤样品氮含量的分析结果具有不同程度的影响,尤其是对喀斯特流域石灰性土壤氮含量测定影响的相关研究较少,其影响程度和机理尚不清楚。本研究通过采集喀斯特流域乌江中上游四种不同土壤质地表层土壤(0~20 cm),对比了实验室内不同干燥方式和野外现场提取对氮含量测定结果的影响。结果发现石灰性土壤在干燥过程中,不同氮形态含量总体均表现出烘干土>风干土>新鲜土,表明烘干和风干过程会造成氮含量的测定结果相对于现场提取有不同程度的增加。在不同温度烘干过程中,NH^(+)_(4)-N和有机氮(N_(org))的增加量与温度成正比,并且在不同的温度条件下可能受不同氮转化机理的控制,升温会促进土壤的矿化作用以及N_(org)的转化,而当温度较高(105℃)时,土壤中氮的增加还可能来自于微生物自身在高温条件下的分解;烘干过程中,不同温度处理下的NO^(-)_(3)-N含量之间没有明显差异,但均显著高于现场提取测定的结果,其中40℃下的烘干土中NO^(-)_(3)-N含量最高,表明在该温度条件下硝化作用和矿化作用达到峰值,造成了NO^(-)_(3)-N的累积。不同质地的土壤在干燥过程中各氮形态的增加量也有差异,可能由于不同土壤中微生物种类和活性的差异在烘干过程中对氮的固定效率不同。本研究明确了喀斯特流域石灰性土壤中不同形态氮在不同预处理方式下具有区别于其它地区土壤的特征,研究结果可以为未来研究喀斯特地区土壤氮循环过程以及氮评价等提供参考和技术示范。Different pretreatment methods have different effects on the nitrogen(N)content in different types of soil samples,while currently there are few studies revealing their effects on the determination of nitrogen content influenced by different mechanisms in lime soil in the karst basin.Hence,we collected surface soils(0-20 cm)from four different soil textures in the middle and upper reaches of the Wujiang River in the karst basin,and compared the effects of different drying methods in the laboratory and field extraction on the results of nitrogen content.The results demonstrated that different fractions of N varied following the order of drying soil>air-dried soil>fresh soil in the drying process of calcareous soil,indicating that the N contents with drying and air-drying pretreatments were higher than the field extraction.The contents of NH^(+)_(4)-N and organic nitrogen were positively correlated with temperature under different drying treatments that might be dominated by various nitrogen transformation mechanisms in changeable temperature.It demonstrated that the higher temperature conditions would promote the processes of mineralization and the high nitrogen contents might originate from the decomposition of microorganisms under high-temperature conditions(105℃).The contents of NO^(-)_(3)-N with different drying treatments varied little while were significantly higher than that of fresh soils.Additionally,the highest NO^(-)_(3)-N contents in oven-dried soils at 40℃were related to the concomitance of nitrification and mineralization led to the accumulation of NO^(-)_(3)-N.The differences in microbial species and activities of various soils in drying processes would be the dominant reason for the increasing contents of nitrogen species of different types of soil textures.This study clarifies that different forms of N in calcareous soils in karst watersheds were distinguished from soils in other regions under different pretreatment methods,and the results can provide references and technical demonstrations fo

关 键 词：干燥方式 喀斯特流域 土壤氮测定 氮形态 

分 类 号：P592[天文地球—地球化学]