Chemical characteristics of groundwater and source identification in a coastal city.

Qun Miao,Ruikang Xie,Chao Liu,Zhihan Lv,Xuefei Li,Youqin Xu,Haibin Lv

doi:10.1371/journal.pone.0256360

Qun Miao, Ruikang Xie + Show 5 more

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https://doi.org/10.1371/journal.pone.0256360

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Abstract

A coastal city is studied in this paper. Based on 42 groundwater sampling points, a Piper diagram, the Shukarev classification, the Pearson correlation analysis, Gibbs plots and the ion proportional coefficient method are used to analyze the chemical characteristics and material source. The results show that the groundwater quality in the study area varies greatly from north to south. In the northern inland area (AREA I), the main anions and cations are and Ca2+, and the hydrochemical characteristics are mainly HCO3 − Ca, HCO3 ⋅ SO4 − Ca and HCO3 − Mg. The ion concentration distribution is uniform, and the groundwater quality is good. By using Gibbs plots and the ion proportional coefficient method, the main source of ions is the dissolution of potassium feldspar, albite and carbonate rock. In contrast, in the southern coastal area (AREA II), the main anions and cations are Cl− and Na+, and the hydrochemical characteristics are mainly Cl − Na. The ion concentration distribution presents a strong spatial difference. The closer the groundwater sampling point is to seawater, the worse the overall groundwater quality. Evaporite dissolution, seawater intrusion, cation exchange effects and human activities are the main factors affecting the groundwater quality in this area. In conclusion, the groundwater quality in northern inland area (AREA I) is better, mainly controlled by the dissolution of rocks. The groundwater quality in southern coastal area (AREA II) changes greatly, mainly controlled by seawater.

Highlights

With the accelerated process of global climate change, researchers have gradually realized that environmental changes and human activities have a huge impact on natural resources [1]
The Shukarev classification is based on the six ion concentrations (Naþ; Kþ; Ca2þ; Mg2þ; ClÀ ; HCOÀ3 þ CO23À ; and SO24À ) in groundwater and total dissolved solids (TDS)
By combining the analysis of the indicator concentration distribution map, the results revealed that except for HCOÀ3, the other six ions and TDS had similar distribution patterns: low concentration in the hinterland and high concentration in the surrounding area, lower ion concentration in the north than that in the south, and lower concentration in the east than in the west

Summary

Introduction

With the accelerated process of global climate change, researchers have gradually realized that environmental changes and human activities have a huge impact on natural resources [1]. Groundwater resources are ignored because of their strong concealment, long water quality evolution time and complex components [2]. Groundwater resources are an important part of industry and agriculture in northern China. In arid and semiarid areas, groundwater resources are used for industrial and agricultural development and play an important role in ecological and environmental construction [3, 4]. Since the 1970s, owing to the steady development of the economy, water resources have been exploited on a large scale. There is the phenomenon of overexploitation and unreasonable

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Conclusion