Water Quality Assessment and Analysis of Causes at Dajin Lake, a World Natural Heritage Site in Danxia, China

The World Heritage Convention requires that heritage sites submit periodic reports every six years. During the preparation of the third periodic report for the Danxia Series of World Natural Heritage Sites in China, it was found that previous reports were relatively brief, particularly lacking supplementary materials regarding pollution factors. Therefore, this study takes Dajin Lake within the Danxia Taining World Natural Heritage Site in China as its research object. Based on water quality monitoring data from 2019, seven water quality indicators were selected, including permanganate index (CODMn), chemical oxygen demand (COD), dissolved oxygen (DO), biochemical oxygen demand (BOD5), ammonia nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP), to evaluate the water quality of Dajin Lake and analyze the causes, with the aim of understanding the current state of Dajin Lake's water quality.