Sedimentary biogeochemical record in Lake Gonghai: Implications for recent lake changes in relatively remote areas of...

Owing to rapid socio-economic development and climate warming, lakes even in remote areas have experienced marked changes in the last century. However, there are few studies revealing the multi-faceted biogeochemical changes and disentangling impacts of human and climate in relatively remote lakes in China. In this study we reconstructed historical changes of geochemistry, nutrition, primary production, ecology, and pollution in an alpine lake (Gonghai) in central North China, and revealed coherent changes and drivers in relatively remote Chinese lakes by compiling other records. Results show that Lake Gonghai has experienced considerably biogeochemical changes since the 1980s induced mainly by increased regional human activities, with detected human-related changes occurring in the 1950s-70s. The most important change is a shift of diatom primary producers in the 1980s, caused mainly by an increase of regional atmospheric N and P deposition associated with rapid socio-economic development. Another remarkable change is the increase of pollution levels since the 1980s, represented by heavy metals, also caused by atmospheric deposition. Compiled sediment records demonstrate similar biogeochemical changes in most lakes from relatively remote areas of China since the 1970s-80s, associated closely with increased inputs of human-induced atmospheric N, P and pollutants, whereas the influence of climate warming is likely limited. This study highlights markedly human-related biogeochemical changes in relatively remote Chinese lakes during the Anthropocene epoch.