Distribution And Influence Factors Of Inorganic Carbon In Main Rivers Around Bohai And Bohai Sea In Summer

After the industrial revolution,carbon in the lithosphere was quickly transferred to the atmosphere which led to a rapid rise in atmospheric CO2.On April 18,2017,USA Today reported that the average carbon dioxide concentration of the Earth in April 2017 was 410 ppm at the Mauna Loa Observatory in Hawaii.Ocean is the largest“active”carbon reservoir of the surface system.From 1750 to 2010,about 28%of the CO2 emitted by humans enters the ocean.Therefore,the study of marine carbon cycle process and its mechanisms are important for us to predict global climate change and take appropriate measures.Rivers play an important role in the terrestrial-ocean carbon cycle as a bridge and link linking land and sea.The estuary is a channel for transporting carbon from terrestrial carbon storage to marine carbon storage.Each year,a large amount of organic matter and inorganic carbon are input into the marginal continental shelf seas.The increase in the number of POC,DOC,DIC and anthropogenic pollutants have led to the continuous enhancement of biological activities in the offshore,and changed the pattern of carbon sinks and their changing mechanisms.Compared with other sea areas,the carbon chemistry of the Bohai Sea has its particularity.At the same time,with the development of industry and cities,a large amount of nutrients are imported into the Bohai Sea,which makes the Bohai Sea eutrophication and other environmental problems such as frequent occurrence of red tide.It is necessary for the study of the inorganic carbon pattern of the Bohai Sea and the influence of major rivers around the Bohai Sea.From August 17th to August 25th,2016,the inorganic carbon-related samples in the Bohai Sea were collected and analyzed.At the same time,in order to further understand the influence of river input on the inorganic carbon pattern of the Bohai Sea,A total of 28 major rivers were selected for sampling from July 29th to August 4th,2018.The number of the stations in these rivers is 32.The distribution of inorganic carbon in the Bohai Sea is relatively consistent.The concentrations of Laizhou Bay and Liaodong Bay are higher affected by the high suspended matter input of the Yellow River and Liaohe River,respectively.The sea area near Laotieshan is low affected by the North Yellow Sea wate.In August 2016,the total pGO2 of Bohai Seawater was the source of the atmospheric CO2,and the sea-gas CO2 exchange flux was 7.6 mmol m-2 d-1.The DO of the surface layer is basically supersaturated or saturated,and the DO of the bottom water body in a large number of stations is unsaturated,and the pH is correspondingly low which showing typical seasonal hypoxic acidification characteristics.The aragonite saturation of the bottom layer is reduced to 1.5,and the FR value is over 13.As the mineral mineralization DIC continues to increase,the pH will decrease more rapidly,and the aragonite saturation will be further reduced.The seasonal low oxygen and acidification in the Bohai Sea area will be aggravated.The nature of the rivers entering the sea in the Bohai Sea is quite different.Most rivers present the high temperature,high pH,high DO,high DIC and high TA.The rivers DIC and TA in the Bohai Bay River are higher than the Liaodong Bay River,while the Liaodong Bay River is higher than Laizhou Bay River.Affected by biological activities,the pCO2 of the Liaodong Bay River is higher than that of the Bohai Bay River,while the Bohai Bay River is higher than the Laizhou Bay River.The overall performance is the source of atmospheric CO2 for these rivers.In 2018 summer,the C fluxes of surface runoff into Laizhou Bay,Liaodong Bay and Bohai Bay were 2.95×1O8 t,2.06×108t and 1.02×108t,respectively.The mixing of water mass is one of the dominant factors in the change of inorganic carbon pattern in Bohai Sea.At the same time,pCO2 and DO have a good negative correlation,indicating that the pattern is affected by both bio-photosynthesis and respiration.