[1] M A Ansari, S Sharma, U S Kumar et al. Hydrogeological controls of radon in a few hot springs in the Western Ghats at Ratnagiri district in Maharashtra India. Current Science, 107, 1587-1590(2014).

[2] C Cao, X Y Li. Temporal and spatial characteristics and density of agriculture and animal husbandry of the water footprint at the district and county scales: A case study of Zhangjiakou city. China Rural Water and Hydropower, 124-131(2019).

[3] W G Cao, H F Yang, C L Liu et al. Hydrogeochemical characteristics and evolution of the aquifer systems of Gonghe Basin, northern China. Geoscience Frontiers, 9, 907-916(2018).

[4] S Chatterjee, U K Sinha, M A Ansari et al. Application of lumped parameter model to estimate mean transit time (MTT) of the thermal water using environmental tracer (³H): Insight from Uttarakhand geothermal area (India). Applied Geochemistry, 94, 1-10(2018).

[5] Z Chen, W G Jiang, W J Wang et al. The impact of precipitation deficit and urbanization on variations in water storage in the Beijing-Tianjin-Hebei urban agglomeration. Remote Sensing, 10, 1-12(2017).

[6] I D Clark. Groundwater Geochemistry and Isotopes(2015).

[7] I D Clark, P Fritz. Environmental Isotopes in Hydrogeology. New York: Lewis, 328(1997).

[8] . Isotopic variation in meteoric waters. Science, 133, 1702-1703(1961).

[9] W Dansgaard. Stable isotopes in precipitation. Tellus, 16, 436-446(1964).

[10] P Döll, H Hoffmann-Dobrev, F T Portmann et al. Impact of water withdrawals from groundwater and surface water on continental water storage variations. Journal of Geodynamics, 59/60, 143-156(2012).

[11] W Feng, M Zhong, J M Lemoine et al. Evaluation of groundwater depletion in North China using the Gravity Recovery and Climate Experiment (GRACE) data and ground-based measurements. Water Resources Research, 49, 2110-2118(2013).

[12] S Foster, P Chilton. Groundwater: The processes and global significance of aquifer degradation. Philosophical Transactions of the Royal Society of London: Series B, Biological Sciences, 358, 1957-1972(2003).

[13] J R Gat. Palaeoclimates and Palaeowaters: A Collection of Environmental Isotope Studies. In: Proceedings of an Advisory Group Meeting on the Variations of the Isotopic Composition of Precipitation and of Groundwater During the Quaternary as a Consequence of Climatic Changes, IAEA(1983).

[14] J Gibson, S Birks, Y Yi. Stable isotope mass balance of lakes: A contemporary perspective. Quaternary Science Reviews, 131, 316-328(2016).

[15] T Gleeson, K M Befus, S Jasechko et al. The global volume and distribution of modern groundwater. Nature. Geoscience, 9, 161-167(2015).

[16] C Y Guo, J S Shi, Z J Zhang et al. Using tritium and radiocarbon to determine groundwater age and delineate the flow regime in the Taiyuan Basin, China. Arabian Journal of Geosciences, 12, 185(2019).

[17] M A Gusyev, U Morgenstern, M K Stewart et al. Application of tritium in precipitation and river water in Japan: A case study of groundwater transit times and storage in Hokkaido watersheds. Hydrology and Earth System Sciences, 20, 3043-3058(2016).

[18] B Hagedorn, N Clarke, M Ruane et al. Assessing aquifer vulnerability from lumped parameter modeling of modern water proportions in groundwater mixtures: application to California’s south coast range. Science of the Total Environment, 624, 1550-1560(2018).

[19] S Hao, F D Li, Y H Li et al. Stable isotope evidence for identifying the recharge mechanisms of precipitation, surface water, and groundwater in the Ebinur Lake basin. Science of the Total Environment, 657, 1041-1050(2019).

[20] L Hou, W Q Peng, X D Qu et al. Runoff changes based on dual factors in the upstream area of Yongding river basin. Polish Journal of Environmental Studies, 28, 143-152(2019).

[21] T Huang, Z Pang. China: Evidence from environmental isotopes and water chemistry. Journal of Hydrology, 387, 188-201(2010).

[22] T M Huang, Z H Pang, J Li et al. Mapping groundwater renewability using age data in the Baiyang alluvial fan, NW China. Hydrogeology Journal, 25, 743-755(2017).

[23] C Ian, M Uwe. Constraining groundwater recharge and the rate of geochemical processes using tritium and major ion geochemistry: Ovens catchment, southeast Australia. Journal of Hydrology, 475, 137-149(2012).

[24] B C Jurgens, J K Böhlke, Kauffman et al. A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells. Journal of Hydrology, 543, 109-126(2016).

[25] E Kalbus, F Reinstorf, M Schirmer. Measuring methods for groundwater-surface water interactions: A review. Hydrology and Earth System Science, 10, 873-887(2006).

[26] B T Kamtchueng, W Y Fantong, M J Wirmvem et al. A multi-tracer approach for assessing the origin, apparent age and recharge mechanism of shallow groundwater in the lake Nyos catchment, northwest, Cameroon. Journal of Hydrology, 523, 790-803(2015).

[27] C Kendall, J J McDonnell. Isotope Tracers in Catchment Hydrology. Amsterdam. The Netherlands: Elsevier Science(1998).

[28] A J Li, O J Schmitz, S Stephan et al. Photocatalytic transformation of acesulfame: Transformation products identification and embryotoxicity study. Water Research, 89, 68-75(2015).

[29] J Liu, Z Y Chen, W Wei et al. Using chlorofluorocarbons (CFCs) and tritium (³H) to estimate groundwater age and flow velocity in Hohhot basin, China. Hydrological Processes, 28, 1372-1382(2014).

[30] P Maloszewski, A Zuber. Determining the turnover time of groundwater systems with the aid of environmental tracers: 1. Models and their applicability. Journal of Hydrology, 57, 207-231(1982).

[31] P Maloszewski, A Zuber. Lumped parameter models for the interpretation of environmental tracer data, chap. 2 in International Atomic Energy Agency. In: Manual on Mathematical Models in Isotope Hydrogeology, TECDOC-910(1996).

[32] R L Michel. Tritium hydrology of the Mississippi River basin. Hydrology Process, 18, 1255-1269(2004).

[33] U Morgenstern, C J Daughney. Groundwater age for identification of baseline groundwater quality and impacts of land-use intensification: The National Groundwater Monitoring Programme of New Zealand. Journal of Hydrology, 456/457, 79-93(2012).

[34] B D Newman, K Osenbrück, H Aeschbach et al. Dating of ‘young’ groundwater using environmental tracers: Advantages, applications, and research needs. Isotopes Environmental Health Studies, 46, 259-278(2010).

[35] Z H Pang, Y L Kong, F Klaus et al. Processes affecting isotopes in precipitation of an arid region. Taylor Journal, 63, 352-359(2011).

[36] E Perry, A Paytan, B Pedersen et al. Groundwater geochemistry of the Yucatan Peninsula, Mexico: Constraints on stratigraphy and hydrogeology. Journal of Hydrology, 367, 27-40(2009).

[37] P Shao, L L Wang, J L An et al. Observation and analysis of air pollution in Zhangjiakou, Hebei. Environmental Science, 33, 2538-2550(2012).

[38] P L Sun, Y Q Xu, S Wang. Terrain gradient effect analysis of land use change in poverty area around Beijing and Tianjin. Transactions of the Chinese Society of Agricultural Engineering, 30, 277-288(2014).

[39] L D Tian, T D Yao, W Z Sun et al. Relationship between δD and δ¹⁸O in precipitation from north to south of the Tibetan Plateau and moisture cycling. Science in China(Series D : Earth Sciences), 44, 789-796(2001).

[40] Y Tian, Y Q Xu, H F Guo et al. Simulation of farmland use pattern in Zhangjiakou based on multinomial logistic regression model. Resources Science, 34, 1493-1499(2012).

[41] B J Tipple. Stable hydrogen and oxygen isotopes of tap water reveal structure of the San Francisco Bay Area’s water system and adjustments during a major drought. Water Research, 119, 212-224(2017).

[42] Y Wada, L P H Van beek, M F P Bierkens. Nonsustainable groundwater sustaining irrigation: A global assessment. Water Resources Research, 48, 2055-2072(2012).

[43] C X Wang, Z W Dong, X Qin et al. Glacier meltwater runoff process analysis using δD and δ¹⁸O isotope and chemistry at the remote Laohugou glacier basin in western Qilian Mountains, China. Journal of Geographical Sciences, 26, 722-734(2016).

[44] P Wang, G Hu, J H Cao. Stable carbon isotopic composition of submerged plants living in karst water and its eco-environmental importance. Aquatic Botany, 140, 78-83(2017).

[45] S J Wang, M J Zhang, Y J Chen et al. Contribution of recycled moisture to precipitation in oases of arid central Asia: A stable isotope approach. Water Resources Research, 52, 3246-3257(2016).

[46] X Wang, F B Ma, C H Li et al. A Bayesian method for water resources vulnerability assessment: A case study of the Zhangjiakou region, North China. Physics and Chemistry of the Earth, 47, 99-113(2015).

[47] X Wen, Y Wu, J Su et al. Hydrochemical characteristics and salinity of groundwater in the Ejina basin, northwestern China. Environmental Geology, 48, 665-675(2005).

[48] W Xu, X S Su, Z X Dai et al. Multi-tracer investigation of river and groundwater interactions: A case study in Nalenggele River basin, northwest China. Hydrogeology Journal, 25, 2015-2029(2017).

[49] H Yangui, I Abidi, K Zouari et al. Deciphering groundwater flow between the complex terminal and plio-Quaternary aquifers in Chott Gharsa Plain (southwestern Tunisia) using isotopic and chemical tools. Hydrological Sciences Journal, 57, 967-984(2012).

[50] T C Yao, X P Zhang, I G L et al. Characteristics of the stable isotopes in different water bodies and their relationships in surrounding areas of Yuelu mountain in the Xiangjiang river basin. Journal of Natural Resources, 31, 1198-1210(2016).

[51] Y Yi, J J Gibson, J-F Hélie et al. Synoptic and time-series stable isotope surveys of the Mackenzie River from Great Slave Lake to the Arctic Ocean, 2003 to 2006. Journal of Hydrology, 383, 223-232(2010).

[52] F Yuan, B Mayer. Chemical and isotopic evaluation of sulfur sources and cycling in the Pecos River, New Mexico, USA. Chemical Geology, 291, 13-22(2012).

[53] Y Yurtsever. Worldwide Survey of Stable Isotope in Precipitation. Vienna: IAEA(1975).

[54] D C Zemp, C F Schleussner, H M J Barbosa et al. On the importance of cascading moisture recycling in South America. Atmospheric Chemistry and Physics, 14, 13337-13359(2014).

[55] B Zhang, X F Song, Y H Zhang et al. The renewability and quality of shallow groundwater in Sanjiang and Songnen plain, northeast China. Journal of Integrative Agriculture, 16, 229-238(2017).

[56] S H Zheng, F G Hou, B L Ni. Study on the meteoric hydrogen and oxygen isotope in China. Science Bulletin, 13, 801-806(1982).

[57] Y W Zhu, F P Zhang, H W Wang et al. Analysis on characteristics of stable hydrogen and oxygen isotopes in precipitation in Shijiazhuang. Shandong Agricultural Sciences, 49, 116-123(2017).

[58] A Zuber, S Witczak, K Rozanski et al. Groundwater dating with³H and SF6 in relation to mixing patterns, transport modelling and hydrochemistry. Hydrological Process, 19, 2247-2275(2005).