Hydrogeochemical Characteristics and Potential Risks within a Headwater Catchment, Taihu Lake Basin, China

Abstract

The Yuying River catchment, a hilly watershed serving as a critical drinking water source for Taihu Lake, exhibits hydrogeochemical characteristics essential to regional water supply safety. To assess potential risks to Taihu Lake, this study collected rainwater, surface water, and groundwater samples from the catchment for comprehensive hydrochemical analysis, including isotopic measurements of δ²H, δ¹⁸O, and ³H. Results revealed that groundwater hydrochemical types were predominantly HCO₃·SO₄-Na·Ca and HCO₃-Na·Ca. Groundwater renewal rates in the catchment ranged from 34% to 44% annually, suggesting accelerated recharge processes. Hydrochemical evolution was primarily governed by cation exchange and silicate weathering-driven leaching. Historical data indicated a sharp rise in groundwater NO₃⁻ concentrations from 4.7 mg/L (2000) to 15.8 mg/L (2019), coinciding with a 377.34% expansion in constructed land area. Both metrics increased approximately threefold since 2000. Principal Component Analysis (PCA) of nitrate sources under different land-use types identified domestic sewage discharge as the dominant contributor to anomalous NO₃⁻ elevation. These findings imply that intensified anthropogenic activities—particularly unscientific sewage disposal—have surpassed the catchment’s self-purification capacity. Urgent implementation of scientifically validated wastewater treatment strategies is imperative to safeguard the water environment and ecological security of both the Yuying River catchment and downstream Taihu Lake.

Keywords

hydrogeochemical characteristics / environmental isotope / PCA / Taihu Lake Basin / nitrate / water resources / hydrogeology

References

[1] An R, Liu J T, Gao Z J, et al.. Hydrochemical Characterization, Controlling Factors and Water Quality of Surface Water in Shandong Province, North China. Journal of Earth Science, 2024, 35(1): 155-166.

[2] Blumstock M, Tetzlaff D, Malcolm I A, et al.. Baseflow Dynamics: Multi-Tracer Surveys to Assess Variable Groundwater Contributions to Montane Streams under Low Flows. Journal of Hydrology, 2015, 527: 1021-1033.

[3] Boateng T K, Opoku F, Acquaah S O, et al.. Groundwater Quality Assessment Using Statistical Approach and Water Quality Index in Ejisu-Juaben Municipality, Ghana. Environmental Earth Sciences, 2016, 75(6): 489.

[4] Cao X H, Yang S K, Zheng Y J, et al.. Changes in China’s Groundwater Storage with Natural and Anthropogenic Drivers. Journal of Earth Science, 2025, 36(5): 2296-2307.

[5] China Geological Survey (CGS). Hydrogeological Survey Manual, 2012. Beijing, Geological Publishing House. (in Chinese).

[6] Chen R H, Chen H Y, Song L T, et al.. Characterization and Source Apportionment of Heavy Metals in the Sediments of Lake Tai (China) and Its Surrounding Soils. Science of the Total Environment, 2019, 694: 133819.

[7] Chen Z, Zhou Q P, Lv J S, et al.. Assessment of Groundwater Quality Using APCS-MLR Model: A Case Study in the Pilot Promoter Region of Yangtze River Delta Integration Demonstration Zone, China. Water, 2023, 15(2): 225.

[8] Cook P G. Introduction to Isotopes and Environmental Tracers as Indicators of Groundwater Flow. The Groundwater Project, 2020

[9] Craig H. Isotopic Variations in Meteoric Waters. Science, 1961, 133(3465): 1702-1703.

[10] Danielsen E F. Stratospheric-Tropospheric Exchange Based on Radioactivity, Ozone and Potential Vorticity. Journal of the Atmospheric Sciences, 1968, 25(3): 502-518.

[11] Djodjic F, Bieroza M, Bergström L. Land Use, Geology and Soil Properties Control Nutrient Concentrations in Headwater Streams. Science of the Total Environment, 2021, 772: 145108.

[12] Du Y, Ma T, Deng Y M, et al.. Characterizing Groundwater/Surface-Water Interactions in the Interior of Jianghan Plain, Central China. Hydrogeology Journal, 2018, 26(4): 1047-1059.

[13] Durand P, Neal M, Neal C. Variations in Stable Oxygen Isotope and Solute Concentrations in Small Submediterranean Montane Streams. Journal of Hydrology, 1993, 144(1/2/3/4): 283-290.

[14] Faye S C, Diongue M L, Pouye A, et al.. Tracing Natural Groundwater Recharge to the Thiaroye Aquifer of Dakar, Senegal. Hydrogeology Journal, 2019, 27(3): 1067-1080.

[15] Feth J H. Mechanisms Controlling World Water Chemistry: Evaporation-Crystallization Process. Science, 1971, 172(3985): 870-871.

[16] Gaillardet J, Dupré B, Louvat P, et al.. Global Silicate Weathering and CO₂ Consumption Rates Deduced from the Chemistry of Large Rivers. Chemical Geology, 1999, 159(1/2/3/4): 3-30.

[17] Gao Z J, Liu J T, Feng J G, et al.. Hydrogeochemical Characteristics and the Suitability of Groundwater in the Alluvial-Diluvial Plain of Southwest Shandong Province, China. Water, 2019, 11(8): 1577.

[18] Gattacceca J C, Vallet-Coulomb C, Mayer A, et al.. Isotopic and Geochemical Characterization of Salinization in the Shallow Aquifers of a Reclaimed Subsiding Zone: The Southern Venice Lagoon Coastland. Journal of Hydrology, 2009, 378(1/2): 46-61.

[19] Ghahremanzadeh H, Noori R, Baghvand A, et al.. Evaluating the Main Sources of Groundwater Pollution in the Southern Tehran Aquifer Using Principal Component Factor Analysis. Environmental Geochemistry and Health, 2018, 40(4): 1317-1328.

[20] Gibbs R J. Mechanisms Controlling World Water Chemistry. Science, 1970, 170(3962): 1088-1090.

[21] Guo Q, Wang Y. Simulation of Geochemical Processes Affecting Groundwater in Quaternary Porous Aquifers of Taiyuan Basin: A Typical Cenozoic Rift Basin. Earth Science Frontiers, 2014, 21(4): 83-90. (in Chinese with English Abstract).

[22] He B N, He J T, Zeng Y, et al.. Coupling of Multi-Hydrochemical and Statistical Methods for Identifying Apparent Background Levels of Major Components and Anthropogenic Anomalous Activities in Shallow Groundwater of the Liujiang Basin, China. Science of the Total Environment, 2022, 838: 155905.

[23] Hernández-Pérez E, Levresse G, Carrera-Hernandez J, et al.. Identification of Recharge Processes and Mixing Patterns by Using CFC’s and Isotopic Multi-Tracing (δ¹⁸O, δ²H) of Groundwater in a Stratified Volcanoclastic Aquifer of the Semiarid Amazcala Basin in Central Mexico. Applied Geochemistry, 2023, 159: 105834.

[24] Huang G X, Zhang M, Liu C Y, et al.. Heavy Metal (Loid)s and Organic Contaminants in Groundwater in the Pearl River Delta that Has Undergone Three Decades of Urbanization and Industrialization: Distributions, Sources, and Driving Forces. Science of the Total Environment, 2018, 635: 913-925.

[25] International Atomic Energy Agency (IAEA). Global Network of Isotopes in Precipitation, 2011. [2024-11-26].

[26] Krakowian K, Jasik M, Małek S. Air Pollution with Nitrates as One of the Major Factors in the Chemical Composition of Water in Shallow-Supplied Mountain Springs. Science of the Total Environment, 2021, 781: 146678.

[27] Le Gal La Salle C, Marlin C, Leduc C, et al.. Renewal Rate Estimation of Groundwater Based on Radioactive Tracers (³H, ¹⁴C) in an Unconfined Aquifer in a Semi-Arid Area, Iullemeden Basin, Niger. Journal of Hydrology, 2001, 254(1/2/3/4): 145-156.

[28] Li P Y, Zhang Y T, Yang N, et al.. Major Ion Chemistry and Quality Assessment of Groundwater in and around a Mountainous Tourist Town of China. Exposure and Health, 2016, 8(2): 239-252.

[29] Li Q L, Zhang H, Guo S S, et al.. Groundwater Pollution Source Apportionment Using Principal Component Analysis in a Multiple Land-Use Area in Southwestern China. Environmental Science and Pollution Research, 2020, 27(9): 9000-9011.

[30] Liu C, Gong X L, Liang Y, et al.. Characteristics of Seasonal Changes in Organic Matter of Groundwater in Binhai, Jiangsu Province and Its Impact on Nitrogen Transport and Transformation. Earth Science, 2025, 50(6): 2400-2415. (in Chinese with English Abstract).

[31] Liu L, Zhou X, Ye Y H. Screening of Characteristic Indexes for Shallow Groundwater Influenced by Human Activities Using Multivariate Statistics. Resources Survey and Environment, 2014, 35(4): 305-310. (in Chinese with English Abstract).

[32] Liu S X, Wu M J. Regional Hydrogeological Survey Report of Deqing County, Zhejiang Province, 2000. Beijing, China National Geological Data Center. (in Chinese).

[33] Liu Y H, Yin M S, Guo Y H, et al.. Numerical Simulation of Groundwater Pollution Caused by Leakage of Urban Pipe Network: A Case Study on an Interfluve in Shenzhen City. East China Geology, 2025, 46(1): 104-113. (in Chinese with English Abstract).

[34] Luo M H, Zhang Y, Li H L, et al.. Pollution Assessment and Sources of Dissolved Heavy Metals in Coastal Water of a Highly Urbanized Coastal Area: The Role of Groundwater Discharge. Science of the Total Environment, 2022, 807: 151070.

[35] Manning A H, Ball L B, Wanty R B, et al.. Direct Observation of the Depth of Active Groundwater Circulation in an Alpine Watershed. Water Resources Research, 2021, 57(2): 2020WR028548.

[36] Mao R, Guo H, Gu Y, et al.. Distribution Characteristics and Genesis of Fluoride Groundwater in the Hetao Basin, Inner Mongolia. Earth Science Frontiers, 2016, 23(2): 260-268. (in Chinese with English Abstract).

[37] McKay J, Lenczewski M, Leal-Bautista R M. Characterization of Flowpath Using Geochemistry and ⁸⁷Sr/⁸⁶Sr Isotope Ratios in the Yalahau Region, Yucatan Peninsula, Mexico. Water, 2020, 12(9): 2587.

[38] Monjerezi M, Vogt R D, Aagaard P, et al.. Using ⁸⁷Sr/⁸⁶Sr, δ¹⁸O and δ²H Isotopes along with Major Chemical Composition to Assess Groundwater Salinization in Lower Shire Valley, Malawi. Applied Geochemistry, 2011, 26(12): 2201-2214.

[39] Musgrove M. The Occurrence and Distribution of Strontium in U. S. Groundwater. Applied Geochemistry, 2021, 126: 104867.

[40] National Health Commission of the People’s Republic of China, State Administration for Market Regulation of China. National Food Safety Standard: Drinking Natural Mineral Water: GB 8537-2018, 2018. Beijing, China Standards Press. (in Chinese).

[41] Pang Z H, Kong Y L, Li J, et al.. An Isotopic Geoindicator in the Hydrological Cycle. Procedia Earth and Planetary Science, 2017, 17: 534-537.

[42] Qian H, Wu J H, Zhou Y H, et al.. Stable Oxygen and Hydrogen Isotopes as Indicators of Lake Water Recharge and Evaporation in the Lakes of the Yinchuan Plain. Hydrological Processes, 2014, 28(10): 3554-3562.

[43] Qin B Q, Xu P Z, Wu Q L, et al.. Environmental Issues of Lake Taihu, China. Hydrobiologia, 2007, 581(1): 3-14.

[44] Qu S, Shi Z M, Liang X Y, et al.. Origin and Controlling Factors of Groundwater Chemistry and Quality in the Zhiluo Aquifer System of Northern Ordos Basin, China. Environmental Earth Sciences, 2021, 80(12): 439.

[45] Raju N J, Shukla U K, Ram P. Hydrogeochemistry for the Assessment of Groundwater Quality in Varanasi: A Fast-Urbanizing Center in Uttar Pradesh, India. Environmental Monitoring and Assessment, 2011, 173(1): 279-300.

[46] Reyes-Toscano C A, Alfaro-Cuevas-Villanueva R, Cortés-Martínez R, et al.. Hydrogeochemical Characteristics and Assessment of Drinking Water Quality in the Urban Area of Zamora, Mexico. Water, 2020, 12(2): 556.

[47] Schoeller H. Qualitative Evaluation of Groundwater Resources. Methods and Techniques of Groundwater Investigations and Development. Water Research, 1967, 33: 44-52

[48] Singh K P, Malik A, Sinha S. Water Quality Assessment and Apportionment of Pollution Sources of Gomti River (India) Using Multivariate Statistical Techniques—A Case Study. Analytica Chimica Acta, 2005, 538(1/2): 355-374.

[49] Sun Y, Zhou Y, Zhou J, et al.. Iodine Species and Causes of Iodine Enrichment in Saline Groundwater in Plain Area of Lower Reaches of Kashigar River. Earth Science, 2024, 49(2): 781-792. (in Chinese with English Abstract).

[50] Torres-Martínez J A, Mora A, Knappett P S K, et al.. Tracking Nitrate and Sulfate Sources in Groundwater of an Urbanized Valley Using a Multi-Tracer Approach Combined with a Bayesian Isotope Mixing Model. Water Research, 2020, 182: 115962.

[51] Traore A, Mao X M, Traore A, et al.. Multivariate Statistical Analysis of Dominating Groundwater Mineralization and Hydro-chemical Evolution in Gao, Northern Mali. Journal of Earth Science, 2024, 35(5): 1692-1703.

[52] van Rooyen J D, Watson A W, Miller J A. Using Tritium and Radiocarbon Activities to Constrain Regional Modern and Fossil Groundwater Mixing in Southern Africa. Journal of Hydrology, 2022, 614: 128570.

[53] Wang J J, Liang X, Ma B, et al.. Using Isotopes and Hydrogeochemistry to Characterize Groundwater Flow Systems within Intensively Pumped Aquifers in an Arid Inland Basin, Northwest China. Journal of Hydrology, 2021, 595: 126048.

[54] Wang Y, Qu S, Li D, et al.. Characteristics of Hydrogen and Oxygen Isotopes in Rainfall-Runoff in Small Watershed and Their Implications for Runoff Separation. Journal of Hohai University (Natural Sciences), 2017, 45(4): 365-371. (in Chinese with English Abstract).

[55] Wu C, Wu X, Qian C, et al.. Hydrogeochemistry and Groundwater Quality Assessment of High Fluoride Levels in the Yanchi Endorheic Region, Northwest China. Applied Geochemistry, 2018, 98: 404-417.

[56] Wu J H, Sun Z C. Evaluation of Shallow Groundwater Contamination and Associated Human Health Risk in an Alluvial Plain Impacted by Agricultural and Industrial Activities, Mid-West China. Exposure and Health, 2016, 8(3): 311-329.

[57] Wu X J, Liu J K, Niu Z G, et al.. Projection of Population Exposure to Compound Extreme Climate Events in the Yangtze River Basin. Journal of Earth Science, 2025, 36(6): 2771-2788.

[58] Xie S, Yan D, Zhu Z, et al.. Earth System Science in Drainage Regions Connected with Societal Development. Earth Science, 2025, 50(3): 815-829. (in Chinese with English Abstract).

[59] Xing J, Li X, Zhou A, et al.. Multi-Isotope Tracing of the Impact of Human Activities on the Hydrological Environment in the Muli Permafrost Region. Earth Science, 2024, 49(5): 1891-1906. (in Chinese with English Abstract).

[60] Xu N Z, Gong J S, Tao X H, et al.. Hydrogeochemical Processes and Potential Exposure Risk of Arsenic-Rich Groundwater from Huaihe River Plain, China. Water, 2022, 14(5): 693.

[61] Xu N Z, Gong J S, Yang G Q. Using Environmental Isotopes along with Major Hydro-Geochemical Compositions to Assess Deep Groundwater Formation and Evolution in Eastern Coastal China. Journal of Contaminant Hydrology, 2018, 208: 1-9.

[62] Yan Y N, Zhang J W, Wu N, et al.. Co-Occurrence of Elevated Arsenic and Fluoride Concentrations in Wuliangsu Lake: Implications for the Genesis of Poor-Quality Groundwater in the (Paleo-)Huanghe (Yellow River) Catchment, China. Water Research, 2024, 258: 121767.

[63] Yin Z Y, Luo Q K, Wu J F, et al.. Identification of the Long-Term Variations of Groundwater and Their Governing Factors Based on Hydrochemical and Isotopic Data in a River Basin. Journal of Hydrology, 2021, 592: 125604.

[64] Yu H, Ma T, Deng Y, et al.. Hydrochemical Characteristics of Shallow Groundwater in Eastern Jianghan Plain. Earth Science, 2017, 42(5): 685-692. (in Chinese with English Abstract).

[65] Yu L, Zheng T Y, Yuan R Y, et al.. APCS-MLR Model: A Convenient and Fast Method for Quantitative Identification of Nitrate Pollution Sources in Groundwater. Journal of Environmental Management, 2022, 314: 115101.

[66] Zhang M, Huang G X, Liu C Y, et al.. Distributions and Origins of Nitrate, Nitrite, and Ammonium in Various Aquifers in an Urbanized Coastal Area, South China. Journal of Hydrology, 2020, 582: 124528.

[67] Zhang Y X, Zhang Y J, Liu J T. Hydrochemical Characteristics of Groundwater in Tongchuan City, China. Scientific Research and Essays, 2014, 9(9): 343-351.

[68] Zhang Y, Zeng J, Zhang Z, et al.. Hydrogeochemical Characteristics and Genetic Mechanism of Groundwater in Sandu Bay Coastal Zone of Ningde. East China Geology, 2025, 46(4): 552-565. (in Chinese with English Abstract).

[69] Zhao D, Wang G C, Liao F, et al.. Groundwater-Surface Water Interactions Derived by Hydrochemical and Isotopic (²²²Rn, Deuterium, Oxygen-18) Tracers in the Nomhon Area, Qaidam Basin, NW China. Journal of Hydrology, 2018, 565: 650-661.

[70] Zhou P P, Wang Z M, Zhang J Y, et al.. Study on the Hydrochemical Characteristics of Groundwater along the Taklimakan Desert Highway. Environmental Earth Sciences, 2016, 75(20): 1378.

[71] Zhou Y, Wang Y X, Li Y L, et al.. Hydrogeochemical Characteristics of Central Jianghan Plain, China. Environmental Earth Sciences, 2013, 68(3): 765-778.

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