Hydrochemical characteristics and formation mechanism of groundwater in Lhasa area, China

doi:10.13745/j.esf.sf.2021.2.2

Abstract

Abstract:

Tibet is an important ecological barrier in China. Studies on the chemical characteristics and formation mechanism of groundwater in the Lhasa area play an important role in revealing the mechanism of current epigenetic changes on the Qinghai-Tibet Plateau, and they are of great significance in building ecological security in the nation. In this paper, we analyzed the chemical characteristics of groundwater and the mechanism of water-rock interaction by means of groundwater survey and water sample collection and analysis in the Lhasa area, combined with Gibbs model simulation and hydrochemical analysis. The results showed that the groundwater conductivity ranged from 38.80 to 1 193.00 μS/cm, averaging at 123.99 μS/cm; the TDS ranged from 44.05 to 1 050.55 mg/L, or 150.75 mg/L on average; the pH level of groundwater was greater than 7, weakly alkaline; and groundwater is HCO₃-Ca and Cl-Na types, with the latter attributed to underground spring water. The groundwater formation process is mainly associated with the dissolution of carbonate and silicate rocks, cation exchange, and so on, and affected by human factors to a certain extent. The Na⁺, K⁺ and Cl^- in groundwater are mainly from the weathering of salt minerals; the excess Na⁺, K⁺ are from the dissolution of silicate minerals, such as sodium and potassium feldspars; and $HCO 3 -$ , Ca²⁺, Mg²⁺ and $SO 4 2 -$ come mainly from the dissolution of calcite, dolomite, gypsum and other calcium-magnesium minerals.

Key words: Lhasa area, groundwater, hydrochemical characteristics, water-rock model, ion ratios

CLC Number:

LIN Congye, SUN Zhanxue, GAO Bai, HUA Enxiang, ZHANG Haiyang, YANG Fen, GAO Yang, JIANG Wenbo, JIANG Xinyue. Hydrochemical characteristics and formation mechanism of groundwater in Lhasa area, China[J]. Earth Science Frontiers, 2021, 28(5): 49-58.

Figures/Tables 9

Fig.1 Geological map of the Lhasa area showing the locations of groundwater sampling sites

Table 1 Results of hydrochemical composition analysis

Fig.2 Piper trilinear plots for groundwater in the Lhasa area

Fig.3 Gibbs diagram showing the hydrochemical characteristics of groundwater in the Lhasa area

Fig.4 Correlations of concentration ratios between (a) Mg2+/Na+ and Ca2+/Na+ or (b) HCO 3 -/Na+ and Ca2+/Na+in the groundwater in study area

Table 2 Saturation index of common minerals in groundwater in the study area calculated by PHREEQC software

采样点	矿物的饱和度指数
采样点	方解石	白云石	石膏	盐岩	菱镁矿	芒硝
G1	0.20	-0.27	-2.02	-8.72	-1.02	-9.01
G2	0.29	0.07	-2.38	-9.07	-0.78	-9.37
G3	0.48	0.50	-2.43	-9.35	-0.55	-9.74
G4	0.10	-0.34	-2.05	-7.93	-0.98	-8.19
G5	0.50	0.38	-2.58	-8.93	-0.67	-9.42
G6	0.46	0.08	-2.77	-10.57	-0.93	-10.44
G7	0.35	0.04	-3.84		-0.87	-10.32
G8	0.74	0.57	-2.47	-8.54	-0.70	-8.65
G9	0.01	-0.71	-3.16		-1.27	-11.06
G10	0.39	-0.18	-3.61	-5.54	-1.09	-8.05

Fig.5 The relationship of major ions in groundwater

Fig.6 Relationship between CAI and TDS (a) or between (Ca2++Mg2+)-( O 3 -+S O 4 2 -) and (Na++K+-Cl-) (b) concentrations

Fig.7 Correlation between SO 4 2 -/Ca2+ and NO 3 -/Ca2+ ratios (a) or between K+and NO 3 - concentrations (b)

References 34

[1]	周嘉欣, 丁永建, 曾国雄, 等. 疏勒河上游地表水水化学主离子特征及其控制因素[J]. 环境科学, 2014, 35(9):3315-3324.
[2]	唐玺雯, 吴锦奎, 薛丽洋, 等. 锡林河流域地表水水化学主离子特征及控制因素[J]. 环境科学, 2014, 35(1):131-142.
[3]	REDWAN M, ABDEL MONEIM A A . Factors controlling groundwater hydrogeochemistry in the area west of Tahta, Sohag, Upper Egypt[J]. Journal of African Earth Sciences, 2016, 118:328-338. DOI URL
[4]	张艳, 吴勇, 杨军, 等. 阆中市思依镇水化学特征及其成因分析[J]. 环境科学, 2015, 36(9):3230-3237.
[5]	CHANG J, WANG G X. Major ions chemistry of groundwater in the arid region of Zhangye Basin, northwestern China[J]. Environmental Earth Sciences, 2010, 61(3):539-547. DOI URL
[6]	QIN H H, GAO B, HE L, et al. Hydrogeochemical characteristics and controlling factors of the Lhasa River under the influence of anthropogenic activities[J]. Water, 2019, 11(5):948. DOI URL
[7]	HE L, GAO B, QIN H H, et al. Health risk assessment of heavy metals in surface water of the Lhasa River, China[J]. E3S Web of Conferences, 2019, 98:09011. DOI URL
[8]	周文武, 陈冠益, 穷达卓玛, 等. 拉萨市垃圾填埋场地下水水质的居民健康风险评价[J]. 环境化学, 2020, 39(6):1513-1522.
[9]	周鹏, 穷达卓玛, 李扬, 等. 拉萨市瓶巴日吾垃圾简易堆放场地下水环境质量评价研究[J]. 高原科学研究, 2019, 3(1):71-78.
[10]	吴凤芝. 论拉萨市地下水开发利用及保护措施探讨[J]. 西藏科技, 2012(1):36-37.
[11]	王秀娟. 浅谈人类活动对拉萨城区地下水资源的影响[J]. 西藏科技, 2016(2):23-25.
[12]	何锦, 张幼宽, 赵雨晴, 等. 鲜水河断裂带虾拉沱盆地断面地下水化学特征及控制因素[J]. 环境科学, 2019, 40(3):1236-1244.
[13]	龚晨. 西藏拉萨河流域水化学时空变化及影响因素研究[D]. 天津: 天津大学, 2015.
[14]	张清华, 孙平安, 何师意, 等. 西藏拉萨河流域河水主要离子化学特征及来源[J]. 环境科学, 2018, 39(3):1065-1075.
[15]	刘久潭. 拉萨市河谷平原区地下水资源评价与合理开发利用[D]. 青岛: 山东科技大学, 2017.
[16]	张凤熔. 拉萨河流域水化学特征及水体重金属源解析[D]. 天津: 天津大学, 2018.
[17]	LI P Y, QIAN H, WU J H, et al. Occurrence and hydrogeochemistry of fluoride in alluvial aquifer of Weihe River, China[J]. Environmental Earth Sciences, 2014, 71(7):3133-3145. DOI URL
[18]	XIAO J, JIN Z D, ZHANG F, et al. Major ion geochemistry of shallow groundwater in the Qinghai Lake catchment, NE Qinghai-Tibet Plateau[J]. Environmental Earth Sciences, 2012, 67(5):1331-1344. DOI URL
[19]	何柳. 拉萨河流域水文地球化学特征及其风化指示[D]. 南昌: 东华理工大学, 2019.
[20]	SONG X F, LIU X C, XIA J, et al. A study of interaction between surface water and groundwater using environmental isotope in Huaisha River basin[J]. Science in China Series D: Earth Sciences, 2006, 49(12):1299-1310.
[21]	侯国华, 高茂生, 党显璋. 唐山曹妃甸浅层地下水水化学特征及咸化成因[J]. 地学前缘, 2019, 26(6):49-57.
[22]	周训. 深层地下卤水的基本特征与资源量分类[J]. 水文地质工程地质, 2013, 40(5):4-10.
[23]	李洲, 李晨曦, 华琨, 等. 黄土区洛川塬地下水化学特征及影响因素分析[J]. 环境科学, 2019, 40(8):3559-3567.
[24]	张涛, 何锦, 李敬杰, 等. 蛤蟆通河流域地下水化学特征及控制因素[J]. 环境科学, 2018, 39(11):4981-4990.
[25]	LI C C, GAO X B, WANG Y X. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, Northern China[J]. Science of the Total Environment, 2015, 508:155-165. DOI URL
[26]	刘江涛, 蔡五田, 曹月婷, 等. 沁河冲洪积扇地下水水化学特征及成因分析[J]. 环境科学, 2018, 39(12):5428-5439.
[27]	MA J Z, HE J H, QI S, et al. Groundwater recharge and evolution in the Dunhuang Basin, northwestern China[J]. Applied Geochemistry, 2013, 28:19-31. DOI URL
[28]	SCHOELLER H. Hydrodynamique dans le karst[J]. Chronique d’hydrogeologie, 1967, 10:7-21.
[29]	BELLO M, KETCHEMEN-TANDIA B, NLEND B, et al. Shallow groundwater quality evolution after 20 years of exploitation in the southern Lake Chad: Hydrochemistry and stable isotopes survey in the far north of Cameroon[J]. Environmental Earth Sciences, 2019, 78(15):1-19. DOI URL
[30]	FISHER R S, MULLICAN III W F . Hydrochemical evolution of sodium-sulfate and sodium-chloride groundwater beneath the northern Chihuahuan Desert, Trans-Pecos, Texas, USA[J]. Hydrogeology Journal, 1997, 5(2):4-16.
[31]	WANG L H, DONG Y H, XU Z F, et al. Hydrochemical and isotopic characteristics of groundwater in the northeastern Tennger Desert, Northern China[J]. Hydrogeology Journal, 2017, 25(8):2363-2375. DOI URL
[32]	CHANAKYA H N, SHARATCHANDRA H C. Nitrogen pool, flows, impact and sustainability issues of human waste management in the city of Bangalore[J]. Current Science, 2008, 94(11):1447-1454.
[33]	SAKA D, AKITI T T, OSAE S, et al. Hydrogeochemistry and isotope studies of groundwater in the Ga West Municipal Area, Ghana[J]. Applied Water Science, 2013, 3(3):577-588. DOI URL
[34]	MOSTAZA-COLADO D, CARREÑO-CONDE F, RASINES-LADERO R , et al. Hydrogeochemical characterization of a shallow alluvial aquifer: 1 baseline for groundwater quality assessment and resource management[J]. Science of the Total Environment, 2018, 639:1110-1125. DOI URL