Hydrochemical Characteristics and Genesis analysis of Shallow Groundwater in the Lower reaches of Nanfei River, Anhui Province

doi:10.19657/j.geoscience.1000-8527.2022.028

Abstract

Abstract:

In order to explore the hydrochemical characteristics and genesis of shallow groundwater in the lower reaches of Nanfei River, Anhui Province, 87 groups of shallow groundwater samples were collected. By using Piper trigram, Shukalev classification, Gibbs model, ion ratio method and mathematical statistics, the hydrochemical characteristics and genesis of shallow groundwater in the lower reaches of Nanfei River were analyzed, and their genesis were further revealed. The results show that the average pH value of the shallow groundwater in the lower reaches of Nanfei River is 7.61, showing weak alkalinity. The average value of cation content is in the order of Na⁺ >Ca²⁺ >Mg²⁺ from high to low, and the average value of anion content is in the order of $\mathrm{HCO}_{3}^{-}>\mathrm{SO}_{4}^{2-}>\mathrm{Cl}^{-}$ from high to low. Na⁺ and $\mathrm{HCO}_{3}^{-}$ are the dominant ions in cations and anions respectively. In addition, the distribution of shallow groundwater chemical types in the lower reaches of Nanfei River is relatively rich, with a total of 15 hydrochemistry types, and the main hydrochemistry types can be divided into HCO₃-Na·Ca, HCO₃·Cl-Ca·Na, HCO₃-Ca·Na·Mg, HCO₃·SO₄-Ca·Na, HCO₃·SO₄·Cl-Na·Ca. By considering the influence of water-rock interaction, we find that the hydrochemical composition of the shallow groundwater in the lower reaches of Nanfei River is mainly controlled by rock weathering and dissolution and affected by dissolution of carbonate mineral. Meanwhile, cation exchange plays an important role in the hydrochemical characteristics of shallow groundwater.

Key words: lower reaches of Nanfei river, shallow groundwater, hydrochemical characteristics, genesis analysis

CLC Number:

P641.1

WANG Runtao, QIAN Jiazhong, WANG Xiuxuan, MA Haichun, WANG Xiaoyong. Hydrochemical Characteristics and Genesis analysis of Shallow Groundwater in the Lower reaches of Nanfei River, Anhui Province[J]. Geoscience, 2025, 39(02): 440-446.

Figures/Tables 6

Fig.1 Location of the Nanfei river basin and distribution of sample points

Table 1 Descriptive statistical results of major ions in groundwater

统计指标	检测项目(mg/L, pH除外)
统计指标	pH	Na⁺	Ca²⁺	Mg²⁺	Cl^-	S $O 4 2 -$	HC $O 3 -$	TDS
最大值	8.47	536.50	235.70	80.53	356.44	788.60	758.87	1755.45
最小值	6.69	31.86	17.81	7.44	6.88	0.18	119.64	282.76
平均值	7.61	111.90	92.43	31.59	83.33	121.10	373.00	626.85
标准差	0.32	82.45	43.49	14.20	65.65	127.43	118.13	274.47

Table 1 Descriptive statistical results of major ions in groundwater

统计指标	检测项目(mg/L, pH除外)
统计指标	pH	Na⁺	Ca²⁺	Mg²⁺	Cl^-	S $O 4 2 -$	HC $O 3 -$	TDS
最大值	8.47	536.50	235.70	80.53	356.44	788.60	758.87	1755.45
最小值	6.69	31.86	17.81	7.44	6.88	0.18	119.64	282.76
平均值	7.61	111.90	92.43	31.59	83.33	121.10	373.00	626.85
标准差	0.32	82.45	43.49	14.20	65.65	127.43	118.13	274.47

Fig.2 Piper diagram of hydrochemistry in the Nanfei river basin

Table 2 Results for Shukalev classification

水化学类型	水样点个数	水化学类型	水样点个数
HC $O 3 -$ -Na⁺·Ca²⁺	18	HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Na⁺·Mg²⁺	3
HC $O 3 -$ ·Cl^--Ca²⁺·Na⁺	14	HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Mg²⁺	2
HC $O 3 -$ -Ca²⁺·Na⁺·Mg²⁺	14	HC $O 3 -$ -Ca²⁺	2
HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Na⁺	10	Cl^-·HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Mg²⁺	1
HC $O 3 -$ ·S $O 4 2 -$ ·Cl^--Na⁺·Ca²⁺	9	S $O 4 2 -$ -Ca²⁺·Mg²⁺	1
HC $O 3 -$ -Na⁺	4	HC $O 3 -$ -Mg²⁺·Ca²⁺	1
Cl^-·HC $O 3 -$ -Ca²⁺·Na⁺·Mg²⁺	4	HC $O 3 -$ ·Cl^-·S $O 4 2 -$ -Ca²⁺·Na⁺·Mg²⁺	1
S $O 4 2 -$ ·HC $O 3 -$ -Na⁺	3

Table 2 Results for Shukalev classification

水化学类型	水样点个数	水化学类型	水样点个数
HC $O 3 -$ -Na⁺·Ca²⁺	18	HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Na⁺·Mg²⁺	3
HC $O 3 -$ ·Cl^--Ca²⁺·Na⁺	14	HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Mg²⁺	2
HC $O 3 -$ -Ca²⁺·Na⁺·Mg²⁺	14	HC $O 3 -$ -Ca²⁺	2
HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Na⁺	10	Cl^-·HC $O 3 -$ ·S $O 4 2 -$ -Ca²⁺·Mg²⁺	1
HC $O 3 -$ ·S $O 4 2 -$ ·Cl^--Na⁺·Ca²⁺	9	S $O 4 2 -$ -Ca²⁺·Mg²⁺	1
HC $O 3 -$ -Na⁺	4	HC $O 3 -$ -Mg²⁺·Ca²⁺	1
Cl^-·HC $O 3 -$ -Ca²⁺·Na⁺·Mg²⁺	4	HC $O 3 -$ ·Cl^-·S $O 4 2 -$ -Ca²⁺·Na⁺·Mg²⁺	1
S $O 4 2 -$ ·HC $O 3 -$ -Na⁺	3

Fig.3 Gibbs diagram of groundwater in the Nanfei river basin

Fig.4 Ratios of main ions in groundwater in the Nanfei river basin

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