A 1 900-year record of marine productivity in the upwelling area of east continental shelf of Hainan Island, South China Sea

A 45 cm long sediment core was collected from the upwelling area of the east continental shelf of Hainan Island, South China Sea. Via chronological and geochemical analyses, marine productivity (in terms of Ba_bio) over the past 1 900 years was reconstructed for the study area. The results show that the marine productivity changed significantly over the past 1 900 years, with relatively high productivity during the Medieval Warm Period (MWP), but relatively low productivity during the Little Ice Age (LIA). Marine productivity has increased rapidly over the last century (currently Ba_bio is about 210 μg/g), reaching its highest level over the past 1 900 years. By comparison with the climatic and environmental records, it was found that the marine productivity in the upwelling area was highly affected by the East Asian summer monsoon and also displayed some kind of correlation with temperature. In a warm climate, the intensity of the East Asian summer monsoon enhanced, resulting in an increase in coastal upwelling, which led to increase in marine productivity. Solar activity may also impact on the marine productivity of the upwelling area by affecting climate and intensity of the East Asian monsoon. In the context of global warming, human-induced climate change may impose some effects on marine productivity as well in the study area.