Characteristics and Causes of Coastal Water Chemistry in Qionghai City, China.

The coastal zone area of Qionghai City is one of the important coastal zones in the South China Sea, and its water environment has been affected by human activities such as urbanization and industrialization. In order to protect the water resources and ecological environment of this area, the water chemistry characteristics of the main watersheds and their causes in the coastal zone area of eastern Hainan Island were investigated to provide a scientific basis for environmental protection and sustainable development. In this study, the characteristics and sources of water chemical ion components were analyzed using a Piper trilinear diagram, Gibbs diagram, and correlation analysis with the coastal zone area of Qionghai city as the research object. The results show the following: (1) the dominant cation of water chemistry in the coastal zone of Qionghai City is Na⁺ with a mean value of 35.001 mg·L⁻¹, and the dominant anion is Cl⁻ with a mean value of 30.69 mg·L⁻¹; (2) the dominant cation content in the coastal zone of Qionghai City is Na⁺ > Ca²⁺ > Mg²⁺ > K⁺, and the dominant anion content is Cl⁻ > SO₄²⁻ > HCO₃⁻ > CO₃²⁻; (3) at the five collection sites in the study area, the ion concentrations showed different trends, with the highest ion concentration in the water samples collected from aquaculture ponds, and the main water chemistry type was Na-Cl; the lowest ion concentration was in the water samples collected from the rivers, and the main type of water chemistry was Ca·Mg-HCO₃. The source of water chemistry ions in the study area mainly included seawater, rock weathering, atmospheric precipitation, and evaporation concentration. The results of this study can provide a scientific basis for the development, utilization, and management of local water resources and provide basic data for environmental protection and sustainable development. [ABSTRACT FROM AUTHOR]