引用本文:戴军杰,章新平,罗紫东,王 锐,刘福基,贺新光.长沙地区樟树林土壤水稳定同位素的变化及影响因素[J].土壤学报,2020,57(6):1514-1525. DOI:10.11766/trxb201905050241
DAI Junjie,ZHANG Xinping,LUO Zidong,WANG Rui,LIU Fuji,HE Xinguang.Variation of Stable Isotopes in Soil Water under Cinnamomum Camphora woods in Changsha and Its Influencing Factors[J].Acta Pedologica Sinica,2020,57(6):1514-1525. DOI:10.11766/trxb201905050241
【打印本页】   【HTML】   【下载PDF全文】   查看/发表评论  【EndNote】   【RefMan】   【BibTex】
←前一篇|后一篇→ 过刊浏览    高级检索
本文已被:浏览 392次   下载 326 本文二维码信息
码上扫一扫!
分享到: 微信 更多
长沙地区樟树林土壤水稳定同位素的变化及影响因素
戴军杰1, 章新平1, 罗紫东1, 王 锐1, 刘福基2, 贺新光1
1.湖南师范大学资源与环境科学学院;2.无锡科技职业学院管理工程系
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(∑E)和累积温度(∑TA)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∑E和∑TA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。
关键词:  土壤水  降水  地下水  稳定同位素  土壤水线
基金项目:国家自然科学基金项目(41571021)资助
Variation of Stable Isotopes in Soil Water under Cinnamomum Camphora woods in Changsha and Its Influencing Factors
DAI Junjie1, ZHANG Xinping1, LUO Zidong1, WANG Rui1, LIU Fuji2, HE Xinguang1
1.College of Resources and Environmental Sciences, Hunan Normal University;2.Management Engineering Department, Wuxi Vocational College of Science and Technology
Abstract:
【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 conducive to a better knowledge of redistribution processes of soil water. 【Method】 In this study, monitoring was carried out of 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 the δ2H 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 the δ2H in soil water, the lower the deviation degree of δ2H in soil water from the LMWL, and the weaker the evaporation of soil water; and likewise the lower the δ2H in soil water, the higher the deviation degree of δ2H in soil water from the LMWL, and the stronger the evaporation of soil water. Correlation analyses of lc in soil water at various soil depths with accumulated atmospheric evaporation (∑E) and accumulated atmospheric temperature (∑TA) in the preceding period shows that the latters significantly affected lc in soil water in the 0-60 cm soil layer, but insignificantly in soil layers below 60 cm in depth. Moreover, a certain relationship was found between soil water content (θ) and lc in soil water. The study also shows that relatively low stable isotope ratios in soil water in all soil layers were observed mostly during warm seasons relatively high in ∑E and ∑TA, and during the seasons evaporation enrichment grew stronger, while lc in soil water did lower, thus making scatter points of stable isotopes in soil water deviate further from LMWL; while relatively high stable isotope ratios in soil water in all soil layers appeared mostly during cold seasons, relatively low in ∑E and ∑TA, and relatively weak evaporation enrichment and relatively high lc in soil water during the seasons made scatter points of stable isotopes in soil water close to LMWL. Therefore, the slope of SWL was higher than that of LMWL in all soil layers in this study area. 【Conclusion】Stable isotopes contained in atmospheric precipitation are a direct factor affecting stable isotopes in soil water. Abundance of the stable isotopes in soil water is related to atmospheric heat and humidity in the preceding period. The cause why the slope of SWL is higher than that of LMWL in all soil layers is negatively and seasonally related to stable isotopes in precipitation and evaporation enrichment intensity of stable isotopes in soil water.
Key words:  Soil water  Precipitation  Groundwater  Stable isotope  Soil water line