Evaluation of seasonal variation of major chemical parameters in the estuaries of southwestern Taiwan

Increased concentrations of heavy metals have been observed in the southwestern coast of Taiwan due to increasing human activities and economic growth; however, comprehensive studies investigating seasonal variations of major chemical parameters such as nutrient salts, trace metals, and physical parameters and their associations in the estuaries of the southwestern coast of Taiwan are scarce. The objective of this study was to investigate the seasonal variation of major chemical parameters and their associations in the coastal waters and estuaries of the southwestern coast of Taiwan. The sampling sites included the Pachang River, Erren River, Gaoping River, Donggang River, and Shiniu River. In addition, one coastal site at Yunlin was considered as a reference. The concentrations of nutrient salts and heavy metals show seasonal variations. According to DO level, Donggang river was considered to be slightly polluted, although the level of DO at Donggang river was significantly less than the other sampling sites. According to suspended solids, Pachang and Gaoping seemed to be slightly polluted. The concentrations of the tested heavy metals (Cd, Cr, Cu, Zn, Pb, and Hg) did not exceed the criteria of water pollution. Based on the results of cluster analysis, the tested marine parameters (DO, saturation percentage of DO, orthophosphate, and citrate) at Donggang River were significantly different from the other sampling sites.

Automated summary

Increased concentrations of heavy metals in the southwestern coast of Taiwan were observed due to human activities and economic growth. However, there are limited studies on the seasonal variations of major chemical parameters and their associations in this region. This study investigated the seasonal variation and associations of major chemical parameters in the coastal waters and estuaries. The results showed that the Donggang River was slightly polluted based on the level of dissolved oxygen (DO), while the Pachang River and Gaoping River were slightly polluted based on suspended solids.