长沙地区樟树林土壤水稳定同位素的变化及影响因素  

Variation of Stable Isotopes in Soil Water under Cinnamomum camphora Woods in Changsha and Its Influencing Factors

作　　者：戴军杰 章新平[1,2] 罗紫东 王锐 刘福基[3] 贺新光[1,2] DAI Junjie;ZHANG Xinping;LUO Zidong;WANG Rui;LIU Fuji;HE Xinguang(College of Resources and Environmental Sciences,Hunan Normal University,Changsha 410081,China;Key Laboratory of Geospatial Big Data Mining and Application,Hunan Normal University,Changsha 410081,China;Management Engineering Department,Wuxi Vocational College of Science and Technology,Wuxi,Jiangsu 214028,China)

机构地区：[1]湖南师范大学资源与环境科学学院,长沙410081 [2]湖南师范大学地理空间大数据挖掘与应用湖南省重点实验室,长沙410081 [3]无锡科技职业学院管理工程系,江苏无锡214028

出　　处：《土壤学报》2020年第6期1514-1525,共12页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41571021)资助。

摘　　要：为揭示季风区土壤水稳定同位素的变化规律,基于长沙地区樟树林0~130 cm土壤水、降水和地下水稳定同位素以及环境因子连续2年的监测数据,分析了土壤水稳定同位素的变化特征。结果表明:0~60 cm土壤水稳定同位素的季节变化明显,与降水稳定同位素存在不同程度的时滞,60 cm以下土壤水和地下水稳定同位素的季节变化均不明显。不同深度土壤水中氢稳定同位素比率(δ2H)与区域大气水线(Local meteoric water line,LMWL)的差值(Line-conditioned excess,lc)均与δ2H呈显著正相关,即土壤水中δ2H越大时,δ2H偏离LMWL的程度越小,土壤水经历的蒸发作用越弱;土壤水中δ2H越小时,δ2H偏离LMWL的程度越大,土壤水经历的蒸发作用越强。相关分析表明,前期大气的累积蒸发(ΣE)和累积温度(ΣTA)对0~60 cm土壤水中lc的影响显著。研究显示,各土壤层中相对较低的水稳定同位素比率多散布于ΣE和ΣTA较大的暖季,由于期间经历的蒸发富集作用更强,土壤水中lc更小,土壤水稳定同位素散点更偏离LMWL;反之亦然,从而表现出不同深度土壤水线(Soil water line,SWL)的斜率较LMWL的斜率明显偏高。综上,大气降水稳定同位素是影响土壤水稳定同位素变化的直接因素;土壤水中稳定同位素的丰度与前期大气的湿热程度有关;SWL斜率较LMWL斜率偏高的原因与降水稳定同位素及土壤水稳定同位素蒸发富集作用强度的反向季节性变化有关。【Objective】In order to explore temporal variation of stable isotopes in soil water and distribution in soil profile,and to characterize the soil water line(SWL)in the monsoon region,this research project was launched,which was expected to be stable isotopes in ground water in the soil profile(0–130 cm),precipitation and groundwater,and relevant environmental factors(including soil water content,soil temperature and meteorological variables),in a Cinnamomum camphora forest in Changsha from March 2017 to February 2019,and the monitoring data were collated and analyzed to determine variation of stable isotopes in soil water and rain water and its influencing factors.【Result】Stable isotopic composition of the soil water in the 0–60 cm soil layer varied significantly with the season,and the variation lagged by a varying degree behind that in rain water.The mean monthly maximum hydrogen stable isotope ratios(δ2H)in soil water regardless of soil depth all appeared all in May,and the mean monthly minimum one did in the period from September to December.However,no obvious seasonal variations were observed in the soil water and ground water below 60 cm in depth.All the above findings suggest that rain water may directly affect the soil water in the 0–60 cm soil layer and the soil water in the soil layers below and groundwater may preserve more data of stable isotopes in rain water accumulated from preceding rainfall events.Difference of theδ2H in soil water from the local meteoric water line(LMWL)increased in mean lc(Line-conditioned excess)with soil depth,decreased in standard deviation and gradually leveled off,which suggests that evaporation of soil water gradually decreases with soil depth.Significant and positive relationships were found between lc andδ2H in soil water at all soil depths.That is to say,the higher theδ2H in soil water,the lower the deviation degree ofδ2H in soil water from the LMWL,and the weaker the evaporation of soil water;and likewise the lower theδ2H in soil water,the higher th

关 键 词：土壤水 降水 地下水 稳定同位素 土壤水线 

分 类 号：S152.7[农业科学—土壤学] X144[农业科学—农业基础科学]