E-mail alert
Rss
Characteristics and genesis of groundwater salinization in coastal areas of the Lower Reaches of Oujiang Basin
-
Abstract: The coastal areas of the lower reaches of Oujiang River Basin are rich in groundwater resources. However, the unsustainable exploitation and utilization of groundwater have led to significant changes in the groundwater environment. Understanding the characteristics and genesis of groundwater salinization is crucial for preventing its deterioration and ensuring sustainable utilization. In this study, a comprehensive approach combining the ion ratio method, mineral saturation index method and multivariate statistical analysis was employed to investigate the hydrochemical characteristics and main controlling factors in the study area. The findings reveal that: (1) Groundwater samples in study area exhibit a neutral to slightly alkaline pH. The predominant chemical types of unconfined water are HCO3-Ca·Na, HCO3·Cl-Na·Ca and HCO3·SO4-Ca·Na, while confined water mainly exhibits Cl·HCO3-Na and Cl-Na types. (2) Salinity coefficients indicate an increase in salinity from unconfined to confined water. TDS, Na+ and Cl– concentrations show an increasing trend from mountainous to coastal areas in unconfined water, while confined water displays variability in TDS, Na+ and Cl– concentrations. (3) Groundwater salinity is mainly influenced by water-rock interactions, including the dissolution of halite and gypsum, cation exchange, and seawater intrusion etc. Additionally, human activities and carbonate dissolution contribute to salinity in unconfined water. Seawater intrusion is identified as the primary factor leading to higher salinity in confined water compared to unconfined water, with increasing cation exchange and seawater interaction observed from unconfined to confined water.
-
Key words:
- Hydrochemical /
- Multivariate statistical analysis /
- Seawater intrusion
-
Figure 1. Schematic map of hydrogeology and locations of sampling points in the study area
Figure 10. The ratio plots of γ(SO42–/ Na+) and γ(NO3–/ Na+), Cl– and NO3– in unconfined and confined water
Figure 12. Spatial distribution map of seawater intrusion for unconfined (left) and confined water (right)
Table 1. Statistics on the content of chemical indices of unconfined and confined water in the lower reaches of Oujiang Basin
Groundwater type pH TDS K+ Na+ Ca2+ Mg2+ Cl– HCO3– SO42– NO3––N Br– mg·L–1 Standard 6.5–8.5 1,000 \(1) 200 \ \ 250 \ 250 20 \ Unconfined water Min 6.36 60 1.63 5.65 5.53 1.12 3.36 24.14 5.05 ND(2) ND Max 8.81 2,254 122.00 607.50 94.03 100.06 950.41 889.87 65.26 7.44 1.41 Mean 7.05 350 15.00 70.39 30.74 13.81 88.45 181.81 24.07 2.06 0.17 Median 6.90 148 5.36 17.46 21.20 4.22 17.29 85.51 20.69 1.71 0.00 SD 0.60 457 24.54 127.59 21.57 21.33 195.26 208.52 17.62 1.93 0.34 CV/% 8 130 164 181 70 154 221 115 73 94 201 Confined water Min 6.54 450 3.14 168.80 12.18 8.44 59.01 28.95 0.10 ND 0.20 Max 7.93 9,700 21.73 3,066.00 302.67 282.70 6,393.59 414.04 8.74 4.44 5.45 Mean 7.41 2628 11.55 719.39 114.68 100.74 1,553.26 267.20 2.18 1.75 2.07 Median 7.46 1,102 8.18 262.40 65.23 52.2 457.95 344.55 0.37 1.35 1.24 SD 0.49 3,022 6.92 968.04 98.35 94.48 2,074.70 142.50 2.92 1.73 2.12 CV/% 7 115 60 135 86 94 134 53 134 99 103 Note: (1) \: There is no equivalent groundwater quality standard in China. (2) ND, not detected 
下载: 导出CSV
Table 2. Salinization coefficient of groundwater
Salinization All samples Unconfined water Confined water Sample number Ratio/% Sample number Ratio/% Sample number Ratio/% ≤1 24 80.00 22 95.65 2 28.57 1~2 3 10.00 1 4.35 2 28.57 >2 3 10.00 0 0.00 3 42.86
下载: 导出CSV
Table 3. Table of main ion principal components analysis of groundwater
Name of index Loading coefficient PC1 PC2 PC3 K+ 0.96 −0.13 0.17 Na+ 0.96 −0.25 0.09 Ca2+ 0.59 0.73 −0.06 Mg2+ 0.98 −0.12 0.10 Cl– 0.94 −0.25 0.14 SO42– 0.21 0.80 0.50 HCO3– 0.97 0.01 −0.06 NO3– −0.53 −0.25 0.53 pH 0.49 0.18 −0.68 TDS 0.99 −0.11 0.12 Characteristic value 6.53 1.45 1.07 Variance contribution rate% 65.26 14.47 10.74 Accumulating contribution rate% 65.26 79.73 90.47
下载: 导出CSV
Table 4. Classification and representative value of seawater intrusion index
Characterization
factors (mg·L–1)No seawater
intrusionMild seawater intrusion Moderate seawater intrusion Severe seawater intrusion Cl– ≤250 ≤600 ≤1,500 ＞1,500 TDS ≤1,000 ≤2,000 ≤3,000 ＞3,000 SO42– ≤200 ≤450 ≤1,200 ＞1,200 γCl–/γHCO3– ≤0.5 ≤1 ≤6.6 ＞6.6 SAR ≤2 ≤3.55 ≤10 ＞10
下载: 导出CSV
-
Alhassan HI, Muntasir AS, Wesam M. 2018. Hydrochemical characterization of groundwater in Balad district, Salah Al-Din Governorate, Iraq. Journal of Groundwater Science and Engineering, 6(4): 306−322 DOI: 10.19637/j.cnki.2305-7068.2018.04.006. Bahir M, Ouhamdouch S. 2020. Groundwater quality in semi-arid environments (Essaouira Basin, Morocco). Carbonates Evaporites, 35: 1−16. DOI: 10.1007/s13146-020-00576-7. Dang XZ. 2022. The formation and evolution mechanism of saline groundwater since Hlocene in Luanhe River Delta, China. Ph. D. thesis. Wuhan: China University of Geosciences Wuhan: 2−3. (in Chinese) DOI: 10.27492/d.cnki.gzdzu.2022.000142. Divya P, Padmaja P, Debjani C. 2024. Groundwater quality evaluation of Narmada district, Gujarat using principal component analysis. Groundwater for Sustainable Development, 24: 101050. DOI: 10.1016/j.gsd.2023.101050. Ez-Zaouy Y, Bouchaou L, Saad A, et al. 2022. Morocco's coastal aquifers: Recent observations, evolution and perspectives towards sustainabilit. Environmental pollution (Barking, Essex: 1987), 293: 118498. DOI: 10.1016/j.envpol.2021.118498. Gang S, Jia T, Deng Y, et al. 2023. Hydrochemical characteristics and formation mechanism of groundwater in Qingdao City, Shandong Province, China. Water, 15 (1348): 1348. DOI: 10.3390/w15071348 Gibbs RJ. 1970. Mechanisms controlling world water chemistry. Science (New York, NY), 170 (3962): 1088−1090. DOI: 10.1126/science.170.3962.1088. Huang WW, Jiang CL, Chen X. 2020. Chemical characteristics and genesis of deep groundwater in the Xinji mining area. Earth and Environment, 48(4): 432−442. DOI: 10.14050/j.cnki.1672-9250.2020.48.075. Jabed MA, Paul A, Nath TK. 2018. Peoples' perception of the water salinity impacts on human health: A case study in south-eastern coastal region of Bangladesh. Exposure and Health, 12(1): 41−50. DOI: 10.1007/s12403-018-0283-0. Jia HY, Chu M. 2007. Present situation and countermeasures of groundwater exploitation and utilization in Wenzhou city. Zhejiang Hydrotechnics, 2007, 35(5): 65−69 (in Chinese) DOI: 10.13641/j.cnki.33-1162/tv.2007.05.028. Kazakis N, Pavlou A, Vargemezis G, et al. 2016. Seawater intrusion mapping using electrical resistivity tomography and hydrochemical data. An application in the coastal area of eastern Thermaikos Gulf, Greece. Science of the Total Environment, 543: 373−387. DOI: 10.1016/j.scitotenv.2015.11.041. Larsen F, Tran LV, Van H, et al. 2017. Groundwater salinity influenced by Holocene seawater trapped in incised valleys in the Red River delta Plain. Nature Geoscience, 10: 376−381. DOI: 10.1038/NGEO2938. Leybourne M, Goodfellow WD, View C. 2008. Br/Cl ratios and O, H, C, and B isotopic constraints on the origin of saline waters from eastern Canada. Geochimica et Cosmochimica Acta, 71(9): 2209−2223. DOI: 10.1016/j.gca.2007.02.011. Li W, Liu J. 2023. Contamination, sources and leval of heavy metals in the sediments of Oujiang River. Journal of Xinyang Normal University, 36(2): 274−279. (in Chinese) DOI: 10.3969/J.issn.1003-0972.2023.02.019. Liu JT. 2020. Hydrochemical evolution mechanism and optimization of monitoring network for groundwater in Pearl River Delta, China. Ph. D. thesis. Xi'an: Northwest University: 100. (in Chinese) DOI: 10.27405/d.cnki.gxbdu.2020.002275. Liu Y, Jiao JJ, Liang W, et al. 2017. Hydrogeochemical characteristics in coastal groundwater mixing zone. Applied Geochemistry, 85 (Part A): 49−60. DOI: 10.1016/j.apgeochem.2017.09.002. Lou MF. 2015. The preliminary study of land subsidence in Yongqiang plain Wenzhou city Zhejiang Province. The Chinese Journal of Geological Hazard and Control, 26(3): 133−139. (in Chinese) DOI: 10.16031/j.cnki.issn.1003-8035.2015.03.24. Pan LS. 2020. Evaluation of groundwater quality. Metallurgical management, (1): 154, 24. (in Chinese) Panneerselvam B, Paramasivam SK, Karuppannan S, et al. 2020. A GIS-based evaluation of hydrochemical characterisation of groundwater in hard rock region, South Tamil Nadu, India. Arabian Journal of Geosciences, 13 (17): 1−22. DOI: 10.1007/s12517-020-05813-w Sheng D, Meng X, Wen X, et al. 2023. Hydrochemical characteristics, quality and health risk assessment of nitrate enriched coastal groundwater in northern China. Journal of Cleaner Production, 403: 136872. DOI: 10.1016/j.jclepro.2023.136872. Subba Rao N, Dinakar A, Sun L. 2022. Estimation of groundwater pollution levels and specific ionic sources in the groundwater, using a comprehensive approach of geochemical ratios, pollution index of groundwater, unmix model and land use/land cover – A case study. Journal of Contaminant Hydrology, 248: 103990. DOI: 10.1016/j.jconhyd.2022.10399. Sui Y. 2022. Hydrochemical characteristics and genetic analysis of karst water in Tai'an City, Shandong Province. International Core Journal of Engineering, 8(4): 816−828. DOI: 10.6919/icje.202204_8(4).0097. Sun L. 1980. A regional hydrogeological survey report of 1: 200,000 scale for H-51-31 Wenzhou and H-51-32 Huangyan maps in Zhejiang Province. Zhejiang Institute of Hydrogeology and Engineering Geology, 47. (in Chinese) Sun Q, Gao M, Wen Z, et al. 2023. Hydrochemical evolution processes of multiple-water quality interfaces (fresh/saline water, saline water/brine) on muddy coast under pumping conditions. Science of the Total Environment, 857: 159297. DOI: 10.1016/j.scitotenv.2022.159297. Thilagavathi R, Chidambaram S, Ganesh N, et al. 2021. Geochemical variations due to salinization in groundwater along the southeast coast of India. SN Applied Sciences. 3(5): 1−15. DOI: 10.1007/s42452-021-04551-2 Trabelsi R, Zouari K. 2019. Coupled geochemical modeling and multivariate statistical analysis approach for the assessment of groundwater quality in irrigated areas: A study from North Eastern of Tunisia. Groundwater for Sustainable Development, 8: 413−427 DOI: 10.1016/j.gsd.2019.01.00. Troudi N, Hamzaoui-Azaza F, Tzoraki O, et al. 2020. Assessment of groundwater quality for drinking purpose with special emphasis on salinity and nitrate contamination in the shallow aquifer of Guenniche (Northern Tunisia). Environmental monitoring and assessment, 192 (10): 641. DOI: 10.1007/s10661-020-08584-9. Wang S, Chen J, Zhang SX, et al. 2023. Hydrochemical evolution characteristics, controlling factors, and high nitrate hazards of shallow groundwater in a typical agricultural area of Nansi Lake Basin, North China. Environmental Research. 223: 115430. DOI: 10.1016/j.envres.2023.115430. Wang XY. 2019. Hydrochemical characteristics of groundwater in Heihe River Basin, Shaanxi, China. Journal of Desert Research, 39(4): 168−176. DOI: 10.7522/j.issn.1000-694X.2019.00028. Xiao J, Jin Z. D, Wang J, et al. 2015. Hydrochemical characteristics, controlling factors and solute sources of groundwater within the Tarim River Basin in the extreme arid region, NW Tibetan Plateau. Quaternary International, 380-381: 237−246. DOI: 10.1016/j.quaint.2015.01.021. Yang Z, Hu L, Ma H, et al. 2023. Hydrochemical characteristics of groundwater and their significance in arid inland hydrology. Water, 15 (1641): 1641. DOI: 10.3390/w15091641. Zamrsky D, Karssenberg ME, Cohen KM, et al. 2020. Geological heterogeneity of coastal unconsolidated groundwater systems worldwide and its influence on offshore fresh groundwater occurrence. Frontiers Earth Science, 7: 1−23. DOI: 10.3389/feart.2019.00339. Zhai Z, Zhang C, Tang T, et al. 2022. Hydrochemical characteristics and genetic analysis of shallow high-fluorine groundwater in Fuyang River Basin. Geofluids, 2022: 9682371. DOI: 10.1155/2022/9682371. Zhang B, Song XF, Han DM, et al. 2013. Seawater intrusion degree evaluation based on mathematical statistics and fuzzy mathematics in Qinhuangdao Yangdai River Plain. Scientia Geographica Sinca, 33(3): 342−348. DOI: 10.13249/j.cnki.sgs.2013.03.001. Zhang Y, Fu CC, Mao L, et al. 2017. Hydrochemical characteristics and formation mechanism of the grounwater in YanChe, Jiangsu Province. Resources and Environment in the Yangtze Basin, 26(4): 598−605. DOI: 10.11870/cjlyzyyhj201704013. Zhu XX. 2009. Environmental geological survey and evaluation report of Wenzhou City, Zhejiang Province. Zhejiang provincial geological environment monitoring station, 30−31. (in Chinese) -
点击查看大图
图(12) / 表ll (4)
计量
- 文章访问数: 217
- HTML全文浏览量: 110
- PDF下载量: 109
- 被引次数: 0
