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引用本文:刘添文,潘越,胡成,王清,陈植华,史婷婷. 应用D、18O同位素示踪孝感市厚层黏性土中土壤水入渗补给及其生态环境效应[J]. 中国地质, 2021, 48(5): 1429-1440.
LIU Tianwen,PAN Yue,HU Cheng,WANG Qing,CHEN Zhihua,SHI Tingting. Tracing infiltration and recharge of thick silt by using D and 18O isotopes of soil moisture in Xiaogan, Hubei and its ecological efffects[J]. Geology in China, 2021, 48(5): 1429-1440(in Chinese with English abstract).
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应用D、18O同位素示踪孝感市厚层黏性土中土壤水入渗补给及其生态环境效应
刘添文1, 潘越1,2, 胡成1, 王清3, 陈植华1, 史婷婷4
1.中国地质大学(武汉)环境学院, 湖北 武汉 430074;2.广西壮族自治区水利科学研究院, 广西 南宁 530023;3.中国地质调查局武汉地质调查中心(中南地质科技创新中心), 湖北 武汉 430205;4.教育部长江三峡库区地质灾害研究中心, 湖北 武汉 430074
摘要:
黏性土的渗透系数极低,水分及溶质在黏性土中运移速率慢、耗时长,本次研究通过分析大别山区-江汉平原三水转换野外科学试验场(下文简称"试验场")ZK1、ZK2钻孔剖面土壤水、大气降雨D、18O同位素测试数据与孝感站(站号57482)多年年降雨量数据,确定了厚层黏性土土壤水入渗补给年份与深度的对应关系。结果表明:试验场区黏性土垂向岩性差异较小,无明显分层现象,土壤水分以"活塞流"的方式向下运移,夏、秋季的大气降雨为土壤水的主要补给来源;ZK1(取样间隔0.5~2.7 m,深度15 m)的土壤水δD、δ18O值随着埋深的增大出现周期性的波动,ZK2(取样间隔0.1 m,深度6.2 m)的土壤水δD、δ18O值随着埋深的增大出现分层波动现象;确定了黏性土层0~6.2 m深度对应的降雨入渗补给年份,并通过18O的峰值位移法计算得出降雨入渗补给在黏性土层的垂向运移速度为10.8~15.0 cm/a,年均入渗补给量为43.1~58.1 mm,占多年年均降雨量的4.01%,推算出降雨入渗补给需要近130年的时间才能穿透试验场厚层黏性土补给至地下水含水层,表明该厚层黏性土的防污性能良好。本研究所揭示大气-土壤界面下黏性土土壤水分入渗迁移历史演化特征及补给年际对应关系,对江汉平原区地下水环境保护、生态环境改善、旱涝灾害防治等具有重要意义。
关键词:  D、18O同位素  土壤水  18O峰值位移法  补给量  水文地质调查工程  孝感市  湖北省
DOI:10.12029/gc20210509
分类号:P641.131
基金项目:中国地质调查局项目(121201009000172522、DD20190315、DD201900823)资助。
Tracing infiltration and recharge of thick silt by using D and 18O isotopes of soil moisture in Xiaogan, Hubei and its ecological efffects
LIU Tianwen1, PAN Yue1,2, HU Cheng1, WANG Qing3, CHEN Zhihua1, SHI Tingting4
1.School of Environmental Studies, China University of Geosciences, Wuhan 430074, Hubei, China;2.Guangxi Water Conservancy Science Research Institute, Nanning 530023, Guangxi, China;3.Central South China Center for Geoscience Innovation, Wuhan Center of Geological Survey, Wuhan 430205, Hubei, China;4.Three Gorges Research Center for Geohazards, Ministry of Education, Wuhan 430074, Hubei, China
Abstract:
As well known, the permeability coefficient of cohesive soil is extremely low, and the transport rate of water and solute in the cohesive soil is slow and time-consuming. Stable isotopes δD and δ18O data of soil moisture and rainfall of two boreholes (ZK1, ZK2) in Dabie Mountain Area-Jianghan Plain rainfall-soil moisture-groundwater transformation scientific field test site were studied to trace the characteristics of historical infiltration and recharge of cohesive soil. The results show that there's no obvious layer boundary but just a little difference among the 15 m deep cohesive soil, and soil water moves in the way of "piston flow" vertically. The closer relation of rainfalls in summer and autumn to soil moisture in δD and δ18O value indicates that the main recharge of soil moisture comes from rainfall infiltration in summer and autumn. The δD and δ18O values of soil water in ZK1 (sampling interval 0.5-2.7 m, depth 15 m) fluctuate periodically with the increase of buried depth, while the δD and δ18O values of soil water in ZK2 (sampling interval 0.1m, depth 6.2 m) fluctuate stratified with the increase of buried depth. On the basis of determining the rainfall infiltration recharge years corresponding to the 0-6.2 m depth in the cohesive soil layer, based on 18O isotopes peak displacement method,it is calculated that the vertical migration velocity of rainfall infiltration recharge in the cohesive soil layer is 10.8-15.0 cm/a, and the annual infiltration recharge is 43.1-58.1 mm, accounting for 4.01% of the annual average rainfall. It takes about 130 years for rainfall infiltration to penetrate the thick cohesive soil for groundwater recharge, which means the thick cohesive soil has good antifouling properties. The historical evolution characteristics of soil water infiltration and migration at the air-soil interface and the inter-annual correspondence of soil water recharge are of great significance for groundwater environmental protection, ecological environment improvement, drought and flood disaster prevention and control in Jianghan Plain.
Key words:  D, 18O isotopes  soil moisture  18O isotopes peak displacement method  infiltration recharge  hydrogeological survey project  Xiaogan  Hubei Province