# Characteristics and Causes of Coastal Water Chemistry in Qionghai City, China
## 3 Results
### Spatial Variation Characteristics of Major Ion Components  
The trend of all types of ion concentrations is given in Figure 2. The trend of all ion concentrations is the trend of water chemical ions. Figure 2 shows the temporal trends of the water chemical ion fraction content in the coastal zone area of Qionghai City, and it was found that the overall trend showed the ion concentration to gradually decrease. The trends of different ions also showed their different characteristics, and ion concentrations were affected by many disturbing factors due to the different environments and conditions in which different collection sites were located.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ions** & **Maximum Value** & **Minimum Value** & **Average Value** & **Standard** & **Coefficient of** \\  & **(mg\(\cdot\)L\({}^{-1}\))** & **(mg\(\cdot\)L\({}^{-1}\))** & **(mg\(\cdot\)L\({}^{-1}\))** & **(mg\(\cdot\)L\({}^{-1}\))** & **Variation (\%)** \\ \hline Ca\({}^{2+}\) & 86.47 & 10.61 & 34.43 & 17.72 & 52.00 \\ Mg\({}^{2+}\) & 66.84 & 2.14 & 22.47 & 13.04 & 58.00 \\ Na\({}^{+}\) & 90.90 & 20.20 & 35.00 & 13.39 & 38.00 \\ K\({}^{+}\) & 11.85 & 0.45 & 3.75 & 2.81 & 75.00 \\ Cl\({}^{-}\) & 107.00 & 4.01 & 30.69 & 25.68 & 84.00 \\ SO\({}_{4}\)\({}^{2-}\) & 69.30 & 0.34 & 18.49 & 15.05 & 81.00 \\ CO\({}_{3}\)\({}^{2-}\) & 5.56 & 0.12 & 1.34 & 1.05 & 78.00 \\ HCO\({}_{3}\)\({}^{-}\) & 55.03 & 1.34 & 15.36 & 9.90 & 64.00 \\ TDS & 852.00 & 12.00 & 203.60 & 150.44 & 74.00 \\ Total hardness & 3.51 & 0.14 & 0.95 & 0.66 & 70.00 \\ pH & 9.08 & 2.41 & 6.93 & 0.98 & 14.00 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Analysis results of major ion components in the Qionghai coastal basin.  
Figure 2: Spatial variation characteristics of water chemical ion component content in Qionghai coastal water.  
The spatial distribution map shows (Figure 3) that the ionic concentration content of the cation Na+ was higher at 40.90 mg\(\cdot\)L\({}^{-1}\), while the anion Cl\({}^{-}\) had the highest ionic concentration content of 41.10 mg\(\cdot\)L\({}^{-1}\). Among the selected collection sites, the water column ion concentration was highest in the aquaculture ponds and lowest in the rivers. In general, the trend of ion concentration was the result of the combined influence of many factors.  
Through the mathematical and statistical analysis of the water chemistry indexes of water bodies in the coastal zone of Qionghai City, we could obtain a preliminary understanding of the enrichment degree and the changing pattern of the water chemistry of water bodies in the study area [27]. Figure 4 shows that the average pH value of water bodies in the area was 6.93, with a coefficient of variation of 14%. In addition, the concentration of total dissolved substance (TDS) values showed a gradual decrease and varied between 12 and 852 mg\(\cdot\)L\({}^{-1}\), with an average value of 203.6 mg\(\cdot\)L\({}^{-1}\).  
Figure 4: Trends of chemical TDS and pH in Qionghai coastal water (TDS: total dissolved solids; pH: Pondus Hydrogenii).  
Figure 3: Spatially variable characteristics of the average concentration of major ions on the Wanning coast.