Eco-environmental evolutionprocess during the past century in Lake Changdang, Lake Taihu Basin

Multiple anthropogenic stressors generated by the socioeconomic transitions have far-reaching negative impacts on the water environment and ecosystem services in the Lake Taihu Basin. Lake sediment records contribute to exploring the interactions between humans and the environment and supporting the ecological restoration in catchments. Based on the analyses of sedimentary organic matter, nutrients and major heavy metal elements in the core of Lake Changdang in the Lake Taihu Basin, combining with 210Pb dating results, geochemical normalization and historical documents of human activity in the catchment, this study explored the processes, characteristics and main driving factors of lake eutrophication and heavy metal pollution over the past 100 years. The results show that multiple cores proxies have similar three-stage historical changes. Before the 1950s, sediment organic carbon, total nitrogen and phosphorus were relatively stable, and lake nutrient level was low, corresponding to the quasi-natural evolution phase with the weak influence of human activities. Subsequently, the lake entered into a transition phase dominated by human impacts. Particularly in the 1970s, lake nutrient level, algal productivity and heavy metal pollution (Cd>>Sb>Cu≈Pb≈Zn) increased significantly, which were directly affected by the pollutant discharge resulted from the increase in population, agricultural intensification, industrialization and urbanization in the catchment. Since 1980s, Lake Changdang has deviated from the natural evolution baseline and maintained a state of high eutrophication and heavy pollution, threatening the ecological security of the catchment. This study further highlights that understanding the historical process of lake eco-environmental evolution and anthropogenic impacts helps sustainable lake catchment management. © 2022 by Journal of Lake Sciences.