Sedimentary records and environmental responses of organic carbon sources and carbon stock in the Jiaozhou Bay

In order to explore the sources and burial of OC in the sediments of Jiaozhou Bay and to evaluate the carbon stock, three cores sediments were collected from different areas of Jiaozhou Bay. The radionuclide, mineralogical parameters and total organic carbon parameters were determined. Based on the binary end member model, the average contribution of terrestrial OC from cores JZB28, JZB20 and JZB14 is 39% ± 14%, 37% ± 6% and 17% ± 5%,the highest terrestrial contribution in the core JZB28 was located near the eastern estuary of the bay. Before the 1980s, the higher contribution of terrestrial OC in Jiaozhou Bay was mainly influenced by sufficient precipitation and sediment transport; by the year 2000, the OC contribution from marine sources increased due to a combination of decreasing of precipitation and sediment transport, as well as increasing of high-nutrient wastewater input; after 2000, the OC composition was stable. The average carbon stock of the cores JZB28, JZB20 and JZB14 is (0.78 ± 0.09) t/ha, (0.50 ± 0.07) t/ha and (0.45 ± 0.06) t/ha, respectively. Compared to bays and coastal seas, the relatively high carbon stock reveals that the Jiaozhou Bay is an important sedimentary carbon reservoir. The results based on this study could provide scientific basis for the sustainable development of the ecological service function of carbon storage in the Jiaozhou Bay.