Investigation on the Hydrogeochemical Characteristics and Controlling Mechanisms of Groundwater in the Coastal Aquifer

• Published in: Water (Basel) Vol. 15; no. 9; p. 1710
• Main Authors: An, Guangnan, Kang, Hao, Fu, Rongbing, Xu, Damao, Li, Jia
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 27.04.2023
• Subjects: Anoxic conditions; Anthropogenic factors; Aquifers; Cation exchange; Cation exchanging; Chemical analysis; Chemical composition; Chemistry; Coastal aquifers; Coastal zone; Coasts; Contamination; dry and wet season; Dry season; Groundwater; Groundwater pollution; Gypsum; Human influences; Hydrogeochemistry; Investigations; Leaching; Nitrogen dioxide; Pollution; pollution source; Pollution sources; Precipitation; Rainfall; Rainy season; Saline water intrusion; Salt water intrusion; Saturation index; Sea-water; Seasons; Seawater; seawater intrusion; Seepage; Sodium; Statistical methods; Water analysis; Water chemistry; Water sampling; Water, Underground; China; Yellow Sea; Shandong China
• ISSN: 2073-4441; 2073-4441
• DOI: 10.3390/w15091710

Groundwater contamination in coastal areas has attracted widespread attention. However, studies on the hydrogeochemical characteristics and controlling mechanisms in coastal aquifers are still lacking. In this study, 71 sets of groundwater samples were collected during the dry and wet seasons in a coastal city, Shandong Province. Correlation and principal component analyses were used to identify pollution sources. Meanwhile, Piper diagrams, Gibbs plots, ion ratios, and saturation indices were employed to investigate the hydrogeochemical controlling mechanisms. The results revealed that pollution components included Na+, NH4+, Cl−, SO42−, NO3−, NO2−, Pb, As, Se, TDS, TH, F−, and Mn. Pollution compositions in the study area were primarily derived from natural processes and anthropogenic activities. The contamination of nitrogen resulted primarily from agricultural activities. The exceedance of SO42− was mainly due to the leaching of waste by rainfall. High Na+, Cl−, and F− were related to sea intrusion. Pb and Se might have been caused by anthropogenic activities. The exceedance of As was caused by anthropogenic inputs and natural factors. The poor seepage conditions and anoxic conditions promoted the enrichment of Mn. The concentration of most components in the dry season was larger than that in the wet season. There were no significant differences in water chemistry type during the wet season and dry season. Groundwater chemical compositions were dominated by the dissolution of halite, gypsum, and anhydrite, as well as the cation exchange reaction. The influence of seawater intrusion on groundwater was not serious.