Research progress on the dissolved and particulate carbon of reservoirs in karst areas of Southwest China

Southwest China is the largest concentrated karst landscape distribution area in the world, with dense river networks and abundant hydroelectric resources in the area, which is an important area for the development of hydroelectric power generation in China. To elucidate the impact of karst reservoirs on the carbon cycle of the river system, this work summarizes the research progress of damming in karst watersheds on different forms of carbon transport transformation and the environment in recent years. Through the study of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate inorganic carbon (PIC) and particulate organic carbon (POC) transport and transformation and their control mechanisms in the river-reservoir system in the karst region by spectroscopy, stability and radioisotopes, this work found that the carbon cycle in karst reservoirs exhibits obvious seasonal distribution characteristics, as well as cascade reservoirs, which may further amplify a single reservoir's environmental influence. These results not only contribute to the understanding of the reservoir carbon cycle but also help to explore the "missing" carbon sinks in the river carbon cycle and to more accurately assess the role of karst reservoirs in the global river carbon cycle. In general, karst reservoirs are likely to be more responsive to increased anthropogenic activities than nonkarst reservoirs, which implies that the role of karst reservoirs in the global warming trend needs to be more accurately assessed, and in future research, a systematic characterization of the carbon transport and transformation of different forms from microscopic to macroscopic levels by different analytical tools will more accurately answer this question.