Biogeochemical generation of dissolved inorganic carbon and nitrogen in the North Branch of inner Changjiang Estuary in a dry season

2017 ◽  
Vol 197 ◽  
pp. 136-149 ◽  
Author(s):  
Wei-Dong Zhai ◽  
Xiu-Li Yan ◽  
Di Qi
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Dry Season ◽  
Changjiang Estuary ◽  
Carbon And Nitrogen ◽  
The North

scholarly journals Development of a Biogeochemical and Carbon Model Related to Ocean Acidification Indices with an Operational Ocean Model Product in the North Western Pacific

2019 ◽  
Vol 11 (9) ◽  
pp. 2677 ◽  
Author(s):  
Miho Ishizu ◽  
Yasumasa Miyazawa ◽  
Tomohiko Tsunoda ◽  
Xinyu Guo
Keyword(s):  
Ocean Acidification ◽  
General Circulation ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Ocean Model ◽  
Western Pacific ◽  
Total Alkalinity ◽  
The North ◽  
North Western ◽  
North Western Pacific

We developed a biogeochemical and carbon model (JCOPE_EC) coupled with an operational ocean model for the North Western Pacific. JCOPE_EC represents ocean acidification indices on the background of the risks due to ocean acidification and our model experiences. It is an off-line tracer model driven by a high-resolution regional ocean general circulation model (JCOPE2M). The results showed that the model adequately reproduced the general patterns in the observed data, including the seasonal variability of chlorophyll-a, dissolved inorganic nitrogen/phosphorus, dissolved inorganic carbon, and total alkalinity. We provide an overview of this system and the results of the model validation based on the available observed data. Sensitivity analysis using fixed values for temperature, salinity, dissolved inorganic carbon and total alkalinity helped us identify which variables contributed most to seasonal variations in the ocean acidification indices, pH and Ωarg. The seasonal variation in the pHinsitu was governed mainly by balances of the change in temperature and dissolved inorganic carbon. The seasonal increase in Ωarg from winter to summer was governed mainly by dissolved inorganic carbon levels.

scholarly journals The seasonal cycle of δ<sup>13</sup>C<sub>DIC</sub> in the North Atlantic Subpolar Gyre

2013 ◽  
Vol 10 (8) ◽  
pp. 14515-14537
Author(s):  
V. Racapé ◽  
N. Metzl ◽  
C. Pierre ◽  
G. Reverdin ◽  
P. D. Quay ◽  
...  
Keyword(s):  
North Atlantic ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Subpolar Gyre ◽  
The North ◽  
Winter Convection ◽  
North Atlantic Subpolar Gyre ◽  
The North Atlantic ◽  
First Time ◽  
Strong Linear Relationship

Abstract. This study introduces for the first time the δ13CDIC seasonality in the North Atlantic Subpolar Gyre (NASPG) using δ13CDIC data obtained between 2005 and 2012 with Dissolved Inorganic Carbon (DIC) and nutrient observations. On the seasonal scale, the NASPG is characterized by higher δ13CDIC values during summer than during winter with seasonal amplitude of 0.77‰. This is attributed to biological activity in summer and to deep remineralization process during winter convection. During all seasons, we observed a strong linear relationship between δ13CDIC and DIC. Results also revealed a negative anomaly for DIC and nutrients in August 2010 that could be explained by a coccolithophore bloom associated to a warming up to +2 °C. Winter data also showed a large decrease in δ13CDIC associated with an increase in DIC between 2006 and 2011–2012 but with observed time rates (−0.04‰ yr−1and +1.7 μmol kg−1 yr−1) much larger than the expected anthropogenic signal.

scholarly journals Vertically migrating phytoplankton drive seasonal formation of subsurface negative preformed nitrate anomalies in the subtropical North Pacific and North Atlantic

2018 ◽  
Author(s):  
Robert T. Letscher ◽  
Tracy A. Villareal
Keyword(s):  
Organic Matter ◽  
Mixed Layer ◽  
North Atlantic ◽  
North Pacific ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Euphotic Zone ◽  
The North ◽  
Station Aloha ◽  
Biological Nitrogen

Abstract. Summertime drawdown of dissolved inorganic carbon in the absence of measurable nutrients from the mixed layer and subsurface negative preformed nitrate (preNO3) anomalies observed for the ocean's subtropical gyres are two biogeochemical phenomena that have thus far eluded complete description. Many processes are thought to contribute including biological nitrogen fixation, lateral nutrient transport, carbon overconsumption or non-Redfield C : N : P organic matter cycling, heterotrophic nutrient uptake, and the actions of vertically migrating phytoplankton. Here we investigate the seasonal formation rates and potential contributing mechanisms for negative preformed nitrate anomalies (oxygen consumption without stoichiometric nitrate release) in the subsurface and positive preformed nitrate anomalies (oxygen production without stoichiometric nitrate drawdown) in the euphotic zone at the subtropical ocean time series stations ALOHA in the North Pacific and BATS in the North Atlantic. Non-Redfield −O2 : N stoichiometry for dissolved organic matter (DOM) remineralization is found to account for up to ~ 15 mmol N m−2 yr−1 of negative preNO3 anomaly formation at both stations. Residual negative preNO3 anomalies in excess of that which can be accounted for by non-Redfield DOM cycling are found to accumulate at a rate of ~ 32–46 mmol N m−2 yr−1 at station ALOHA and ~ 46–87 mmol N m−2 yr−1 at the BATS station. These negative anomaly formation rates are in approximate balance with positive preNO3 anomaly formation rates from the euphotic zone located immediately above the nutricline in the water column. Cycling of transparent exopolymer particles (TEP) and heterotrophic nitrate uptake can contribute to the formation of these preNO3 anomalies, however a significant fraction, estimated at ~ 50–95 %, is unexplained by the sum of these processes. Vertically migrating phytoplankton possess the necessary nutrient acquisition strategy and biogeochemical signature to quantitatively explain both the residual negative and positive preNO3 anomalies as well as the mixed layer dissolved inorganic carbon drawdown at stations ALOHA and BATS. TEP production by the model Rhizosolenia mat system could provide accelerated vertical transport of TEP as well as link the three processes together. Phytoplankton vertical migrators, although rare and easily overlooked, may play a large role in subtropical ocean nutrient cycling and the biological pump.

Phytoplankton Biogeochemical Cycles

2017 ◽  
Author(s):  
Carol Robinson
Keyword(s):  
Inorganic Carbon ◽  
North Atlantic Ocean ◽  
Dissolved Inorganic Carbon ◽  
Deep Ocean ◽  
Biogeochemical Cycles ◽  
Essential Elements ◽  
Nitrogen And Phosphorus ◽  
The North ◽  
Life On Earth ◽  
Fish And Shellfish

This chapter describes how the activity of phytoplankton, bacteria, and Archaea drive the marine biogeochemical cycles of carbon, nitrogen, and phosphorus, and how climate driven changes in plankton abundance and community composition influence these biogeochemical cycles in the North Atlantic Ocean and adjacent seas. Carbon, nitrogen, and phosphorus are essential elements required for all life on Earth. In the marine environment, dissolved inorganic carbon, nitrogen, and phosphorus are utilized during phytoplankton growth to form organic material, which is respired and remineralized back to inorganic forms by the activity of bacteria, Archaea, and zooplankton. The net result of the photosynthesis, calcification, and respiration of marine plankton is the uptake of carbon dioxide from the atmosphere, its sequestration to the deep ocean as organic and inorganic carbon, and its availability to fuel all fish and shellfish production.

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