Nav: Home

Scientists elaborated upon carbon sink/source patterns of the Yellow Sea and East China Sea

August 24, 2018

The Yellow Sea (YS) and the East China Sea (ECS) locate in the western side of the Pacific Ocean, and are the most important continental marginal seas in our country. The carbon sink/source patterns in the YS and the ECS play vital roles in regulating the coastal ecosystems and the regional climate in China, which are widely concerned by oceanographic scientists from the world.

The Yellow Sea (YS) is a semi-enclosed marginal sea which is located between the China mainland and the Korean Peninsula (31°40'~39°50' N, 119°10'~126°50' E). Annually, the North YS could release 0.5×10 6 t C into the atmosphere. Sea surface temperature generally played a more important role in the annual cycle of air-sea CO2 exchanging than biological processes in most parts of the study area. Meanwhile, the intrusion of Yellow Sea Warm Current and the seasonal variation of thermocline also played important controlling roles in regulating the CO2 sink/source terms of NYS. The South YS could absorbed atmospheric CO2 only in spring, but released CO2 in summer, autumn, and winter. Seasonal large-scale field surveys estimated that net air-sea CO2 flux in the SYS was 7.4×10 6 t C, most of which occurred in winter when vertical mixing process was significant. Control of temperature on pCO2 was predominant in the offshore South YS; the non-temperature factors were predominant in the shallow nearshore area, especially in coast of Shandong Peninsula and the Jiangsu Shallow. The East China Sea (ECS, 23°00'~33°10' N, 117°11'-131°00' E) is a broad continental marginal sea surrounded by the China Mainland, Taiwan, South Korea, Kyushu, and Ryukyu Islands, 66% area of which is located on the continental shelf. Abundant data in recent decades estimate ECS is a net sink for atmospheric CO2 with the annual average CO2 exchanging flux of -2.6 mmol* m-2* d-1. In detail, the ECS could absorb CO2 during winter, spring, and summer, and release CO2 into atmosphere with the air-sea exchange flux of -5.8, -3.7, -3.7, and 2.8 mmol* m-2* d-1, respectively. As a whole, the ECS could absorb 8.5×10 6t C* yr-1annually.

Coastal regions of the YS and the ECS usually have high content of DIC, whereas DIC concentration in the outer shelf of the ECS is relative low. This distribution pattern indicates the profound effects of water mass and current systems on the regional variations of DIC and carbon sink/source. Not only that, the Huangpu River usually discharges abundant DIC into the Changjiang estuary, and this is the key reason why the inner estuary of Changjiang could release CO2 into the atmosphere significantly (15.5~34.2 mol* m-2* yr-1). It is estimated that the total storage of DIC in the YS and ECS is 425×10 6 t C and 1364×10 6 t C, respectively. Seasonal variation and regional discrepancy of DOC in the YS and the ECS are fairly significant. In general, the average content of DOC in autumn, summer, spring, winter is 1.99 mg* L-1, 1.66 mg* L-1, 1.56 mg* L-1, and 1.53 mg* L-1, respectively. Long-term (1997-2015) observation conducted in the SYS indicates there is a reducing trend for DOC content in recent years. Variation range of DOC in western part of ECS is 0.78-0.90 mg* L-1, whereas the DOC content in southern of ECS is basically higher than 1.02. The storages of DOC in the water column of YS and ECS are estimated to be 28.2×10 6 t C and 54.1×10 6 t C. These storages are higher than the magnitude of air-sea CO2 exchanging flux but lower than the reserves of DIC. POC contents in the YS and the ECS is high in spring (230.0 μg* L-1), followed by ummer (147.2 μg* L-1), winter (125.9 μg* L-1), and low in autumn (97.4 μg* L-1). Due to relative low water depth, the vertical profiles of POC in the YS are quite uniform in the function of vertical mixing. However, POC distributions in the Changjiang estuary show obvious discrepancy between the upper layer and the bottom layer. As for the ECS shelf, the combined action of phytoplankton activity and hydrological dynamics jointly control the variation of POC. It is estimated that the total reserves of POC in the YS and the ECS is about 10.6×10 6 t C (Table 3), which is at the same level of the air-sea CO2 exchanging flux. The evaluation about biological sequestration in Chinese marginal seas indicates that the amount of carbon fixed by phytoplankton in YS is about 60.42×10 6 t C* yr-1, and that in ECS is about 153.41×10 6 t C* yr-1. Most of the carbon is fixed during spring and summer. Fishing and mariculture can enhance the carbon sink strength efficiently. In recent years, the yield of large-size economic seaweeds in China marginal seas is about 1.20-1.50×10 6 t C, so the fixed carbon is about 4.0 ×10 5 t C.

Generally, organic carbon content in sediment is the most important index for carbon burial in the ocean. Concentration of organic carbon in surface sediment of YS and ECS range from 0.08~1.07% and 0.10~1.30%, respectively. The deposition flux of organic carbon in the YS and the ECS is calculated to be 4.75×10 6 t C* yr-1and 7.40×10 6 t C* yr-1, respectively, approximately accounts for 9% of the total deposition flux of organic carbon in the global ocean. Considering the area of YS and ECS cover only about 3% of the world continental marginal area (2.5×107 km2), the burial of carbon in YS and ECS is fairly significant. Summary about the data in recent research shows there are 1.72×10 6 t C* yr-1 of TOM and 3.03×10 6 t C* yr-1 of MOM depositing in the YS, whereas the TOM and MOM deposited in the ECS is 1.9×10 6 t C* yr-1and 5.5×10 6 t C* yr-1, respectively. Distribution terms of TOM in the YS and the ECS are controlled profoundly by riverine discharge and hydrological dynamics. The increase in nutrient supply caused by intensified human activities (e.g., fertilization and sewage discharge), along with a strengthened Kuroshio Current and East Asian Winter Monsoon (EAWM), led to an enhanced MOM contribution and increased sedimentary organic matter abundance in the ECS sediments over the past 100 years.
-end-
This research was funded by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA11020102)

See the article:

Song J, Qu B, Li X, Yuan H, Li N, Duan L. 2018. Carbon sinks/sources in the Yellow and East China Seas--Air-sea interface exchange, dissolution in seawater, and burial in sediments. Science China Earth Sciences, 61, https://doi.org/10.1007/s11430-017-9213-6

Science China Press

Related Carbon Articles:

Can wood construction transform cities from carbon source to carbon vault?
A new study by researchers and architects at Yale and the Potsdam Institute for Climate Impact Research predicts that a transition to timber-based wood products in the construction of new housing, buildings, and infrastructure would not only offset enormous amounts of carbon emissions related to concrete and steel production -- it could turn the world's cities into a vast carbon sink.
Investigation of oceanic 'black carbon' uncovers mystery in global carbon cycle
An unexpected finding published today in Nature Communications challenges a long-held assumption about the origin of oceanic black coal, and introduces a tantalizing new mystery: If oceanic black carbon is significantly different from the black carbon found in rivers, where did it come from?
First fully rechargeable carbon dioxide battery with carbon neutrality
Researchers at the University of Illinois at Chicago are the first to show that lithium-carbon dioxide batteries can be designed to operate in a fully rechargeable manner, and they have successfully tested a lithium-carbon dioxide battery prototype running up to 500 consecutive cycles of charge/recharge processes.
How and when was carbon distributed in the Earth?
A magma ocean existing during the core formation is thought to have been highly depleted in carbon due to its high-siderophile (iron loving) behavior.
New route to carbon-neutral fuels from carbon dioxide discovered by Stanford-DTU team
A new way to convert carbon dioxide into the building block for sustainable liquid fuels was very efficient in tests and did not have the reaction that destroys the conventional device.
How much carbon the land can stomach with more carbon dioxide in the air
Researchers from 28 institutions in nine countries succeeded in quantifying carbon dioxide fertilization for the past five decades, using simulations from 12 terrestrial ecosystem models and observations from seven field carbon dioxide enrichment experiments.
'Charismatic carbon'
According to the Intergovernmental Panel on Climate Change (IPCC), addressing carbon emissions from our food sector is absolutely essential to combatting climate change.
Extreme wildfires threaten to turn boreal forests from carbon sinks to carbon sources
A research team investigated the impact of extreme fires on previously intact carbon stores by studying the soil and vegetation of the boreal forest and how they changed after a record-setting fire season in the Northwest Territories in 2014.
Can we still have fun if the UK goes carbon neutral?
Will Britain going carbon neutral mean no more fun? Experts from the University of Surrey have urged local policy makers to put in place infrastructure that will enable people to enjoy recreation and leisure while keeping their carbon footprint down.
Could there be life without carbon? (video)
One element is the backbone of all forms of life we've ever discovered on Earth: carbon.
More Carbon News and Carbon Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Biology Of Sex
Original broadcast date: May 8, 2020. Many of us were taught biological sex is a question of female or male, XX or XY ... but it's far more complicated. This hour, TED speakers explore what determines our sex. Guests on the show include artist Emily Quinn, journalist Molly Webster, neuroscientist Lisa Mosconi, and structural biologist Karissa Sanbonmatsu.
Now Playing: Science for the People

#569 Facing Fear
What do you fear? I mean really fear? Well, ok, maybe right now that's tough. We're living in a new age and definition of fear. But what do we do about it? Eva Holland has faced her fears, including trauma and phobia. She lived to tell the tale and write a book: "Nerve: Adventures in the Science of Fear".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.