摘要
在一些云雾林系统中,林冠截留雾水对水文生态过程具有重要贡献,但其对地下水系统的重要性仍缺乏认识。以赤水河下游云雾森林为例,基于同位素水文学方法,揭示截留雾水对地下水系统的贡献。选择在赤水桫椤保护区内的金沙沟集水区,于2021年3月—2022年2月对降水、雾水和泉水开展持续采样和2H、18O同位素分析。基于长时间序列数据,揭示了雨、雾、地下水同位素时间变化规律及成因,在此基础上建立同位素混合模型并进一步量化了地下水中雾水的贡献比率。结果显示,降水的δ^(2)H、δ^(18)O、氘盈余(d-excess)均呈现出明显的季节性变化,体现了水汽来源组成的季节性差异。相较于其他西南地区,研究区降水d-excess值偏高,特别是在旱季,表明降水中包含更高的陆地二次循环水汽成分。雾水的重同位素比率高于同期降水,其季节性变化规律与降水一致,形成雾水和降水的水汽来源相似,但因雾水形成时的凝结温度相对较高,其d-excess值略低于降水。泉水同位素组成无季节性变化,表明地下水滞留时间长,是大气水多年补给和充分混合的结果。地下水同位素平均值高于全年降水加权平均值,体现出降水、雾水共同补给的特征。同位素混合模型估算赤水桫椤保护区地下水中雾水的比例为25.5%—28.1%,水量输入367—419 mm。研究在前人基础上进一步考虑了水体同位素的季节性变化,降低了量化结果的不确定性。由此可见,林冠截留雾水对研究区地下水系统的水量贡献明显,其生态水文效应对于维持当地桫椤种群具有重要意义。
In some cloud forest systems,fog water intercepted by the canopy plays a significant role in ecohydrological processes,while its importance on groundwater systems remains poorly understood.In this study,a cloud forest system in the lower reaches of the Chishui River was selected as an example to explore the contribution of fog interception to the local groundwater system using isotope hydrology methods.From March 2021 to February 2022,samples of rainwater,fog water,and spring water in the Jinshagou catchment of the Chishui Cyathea Reserve were collected and analyzed for 2H and 18O isotopes.Using long time-series data,temporal variation rules and causes of isotopic composition in rainwater,fog interception,and groundwater were revealed,based on which an isotope mixing model was established to quantify fog interception′s proportion in groundwater.Results showed thatδ^(2)H,δ^(18)O,and d-excess values of rainwater exhibited obvious seasonal fluctuations,indicating the seasonal alternation of water vapor sources.Compared to other southwestern regions,the rainwater of the study area was characterized by higher d-excess values especially during the dry season,indicating a more significant component of terrestrial recirculated water vapor source.Fog interception water was more enriched in heavier isotopes than rainwater,but they had a similar seasonal variation pattern,suggesting their similar water vapor source.Due to the relatively higher condensation temperature of fog,however,the d-excess of fog water was slightly lower than that of rainwater.No seasonal isotopic variation was observed in spring water,suggesting that groundwater has a long residence time and is a long-term mixture of atmospheric water recharge.The averaged isotopic values of groundwater were higher than the weighted mean of annual rainwater,proving the joint recharge from both rainwater and fog water.The isotope mixing model estimated that the proportion of fog water in the groundwater of the Chishui Cyathea Reserve was 25.5%—28.1%,corresponding to a water input of 367—419 mm.Compared with previous studies,this study further considers the seasonal changes of water isotopes,thus reducing uncertainties in the quantitative results.In summary,fog interception has a significant water contribution to the groundwater system in the study area,and its ecohydrological effect is important for sustaining the local Cyathea population.
作者
詹泸成
何晓冬
赵娜
ZHAN Lucheng;HE Xiaodong;ZHAO Na(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210024,China;PowerChina Beijing Engineering Corporation Limited,Beijing 100024,China)
出处
《生态学报》
CAS
CSCD
北大核心
2024年第23期10817-10826,共10页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(41803001)。
关键词
赤水河
雾水
地下水
同位素
氘盈余
桫椤
Chishui River
fog water
groundwater
stable isotope
d-excess
Cyathea
作者简介
通讯作者:詹泸成.E-mail:luchengzhan@hhu.edu.cn。
