Time-series observation of dissolved inorganic carbon and nutrients in the northwestern North Pacific

2007 ◽  
Vol 63 (6) ◽  
pp. 967-982 ◽  
Author(s):  
Hajime Kawakami ◽  
Makio C. Honda ◽  
Masahide Wakita ◽  
Shuichi Watanabe
Keyword(s):  
Time Series ◽  
North Pacific ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon

scholarly journals Evaluation of the seasonal formation of subsurface negative preformed nitrate anomalies in the subtropical North Pacific and North Atlantic

2018 ◽  
Vol 15 (21) ◽  
pp. 6461-6480 ◽  
Author(s):  
Robert T. Letscher ◽  
Tracy A. Villareal
Keyword(s):  
Time Series ◽  
Organic Matter ◽  
Water Column ◽  
North Atlantic ◽  
North Pacific ◽  
Nitrate Uptake ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Euphotic Zone ◽  
The North

Abstract. Summertime mixed-layer drawdown of dissolved inorganic carbon in the absence of measurable nutrients in the ocean's subtropical gyres and non-Redfieldian oxygen : nitrate relationships in the underlying subsurface waters are two biogeochemical phenomena that have thus far eluded complete description. Many processes are thought to contribute to one or both, including lateral nutrient transport, carbon overconsumption or non-Redfield C:N:P organic matter cycling, heterotrophic nutrient uptake, and the actions of vertically migrating phytoplankton. To obtain insight into the likely magnitude of potential contributing mechanisms that can remove nitrate from the nutricline while supporting dissolved inorganic carbon (DIC) drawdown tens of meters higher in the water column, we investigated the seasonal formation rates for negative preformed nitrate (preNO3) 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 (A Long-Term Oligotrophic Habitat Assessment) in the North Pacific and BATS (Bermuda Atlantic Time-series Study) in the North Atlantic. Non-Redfield -O2:N stoichiometry for dissolved organic matter (DOM) remineralization accounts for up to ∼15 mmol N m−2 yr−1 of negative preNO3 anomaly formation at both stations. We present a new formulation for calculating preNO3 (residual preNO3) that includes components resulting from non-Redfield DOM cycling. 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 residual positive preNO3 anomaly formation rates from the euphotic zone located immediately above the nutricline in the water column. We evaluate three mechanisms to explain these anomalies, calculating that transparent exopolymer particle (TEP) cycling and heterotrophic nitrate uptake can contribute to the formation of both residual preNO3 anomalies. However, a significant fraction, estimated at ∼50 %–95 %, is unexplained by the sum of these processes. Vertically migrating phytoplankton possess the necessary distribution, nutrient acquisition strategy, and biogeochemical signature to simultaneously remove nitrate at depth and transport it above the nutricline. Reported transport rates by known migrators equal or exceed the residual preNO3 anomaly formation rates and potentially explain both the negative and positive residual preNO3 anomalies as well as the mixed-layer DIC drawdown at the stations ALOHA and BATS within the limits of scarce detailed abundance profiles. However, the three processes examined are not independent and mutually exclusive. The model Rhizosolenia mat system (and perhaps other migrators) produces TEPs, suggesting that migration could provide accelerated vertical transport of TEPs and provide labile carbon for heterotrophic nitrate uptake. These results based on geochemical distributions suggest that, in the absence of additional mechanisms and rates, phytoplankton vertical migrators, although rare and easily overlooked, play a larger role in subtropical ocean nutrient cycling and the biological pump than generally recognized.

scholarly journals North Pacific dissolved inorganic carbon variations related to the Pacific Decadal Oscillation

2014 ◽  
Vol 41 (3) ◽  
pp. 1005-1011 ◽  
Author(s):  
Sayaka Yasunaka ◽  
Yukihiro Nojiri ◽  
Shin-ichiro Nakaoka ◽  
Tsuneo Ono ◽  
Hitoshi Mukai ◽  
...  
Keyword(s):  
Pacific Decadal Oscillation ◽  
North Pacific ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
The Pacific

scholarly journals Inorganic Radiocarbon in Time-Series Sediment Trap Samples: Implication of Seasonal Variation of 14C in the Upper Ocean

Radiocarbon ◽  
1996 ◽  
Vol 38 (3) ◽  
pp. 583-595 ◽  
Author(s):  
Makio C. Honda
Keyword(s):  
Time Series ◽  
Bering Sea ◽  
Sediment Trap ◽  
Seasonal Variability ◽  
Sea Of Okhotsk ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Sediment Traps ◽  
Upper Ocean ◽  
The Bering Sea

In order to verify sediment trap samples as indicators of upper ocean 14C concentrations, particulate inorganic radiocarbon (PICΔ14C) collected by time-series sediment traps in the Sea of Okhotsk and the Bering Sea was measured by accelerator mass spectrometry (AMS). All of the PICΔ14C measurements were < 0‰, in contrast to GEOSECS 14C data in the upper ocean from the northwestern North Pacific. This difference is attributed to the upwelling of deepwater that contains low Δ14C of dissolved inorganic carbon (DICΔ14C) and to the decrease over time of surface DICΔ14C owing to the decrease of atmospheric Δ14C values. In addition, PICΔ14C values showed significant seasonal variability: PICΔ14C collected in the fall was the greatest (-22‰ on average), whereas PICΔ14C collected in winter showed an average minimum of −48‰. It is likely that this difference was caused by changes in mixed layer thickness. Although some uncertainties remain, further study on PICΔ14C will enable us to estimate seasonal variability in DICΔ14C and air-sea CO2 exchange rate.

Temporal Change of Dissolved Inorganic Carbon in the Subsurface Water at Station KNOT (44°N, 155°E) in the Western North Pacific Subpolar Region

2005 ◽  
Vol 61 (1) ◽  
pp. 129-139 ◽  
Author(s):  
Masahide Wakita ◽  
Shuichi Watanabe ◽  
Yutaka W. Watanabe ◽  
Tsuneo Ono ◽  
Nobuo Tsurushima ◽  
...  
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Inorganic Carbon ◽  
Temporal Change ◽  
Dissolved Inorganic Carbon ◽  
Subsurface Water

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.

scholarly journals Rising surface ocean dissolved inorganic carbon at the Hawaii Ocean Time-series site

1998 ◽  
Vol 60 (1-2) ◽  
pp. 33-47 ◽  
Author(s):  
Christopher D. Winn ◽  
Yuan-Hui Li ◽  
Fred T. Mackenzie ◽  
David M. Karl
Keyword(s):  
Time Series ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Surface Ocean

scholarly journals Decadal change of dissolved inorganic carbon in the subarctic western North Pacific Ocean

Tellus B ◽  
2010 ◽  
Vol 62 (5) ◽  
pp. 608-620 ◽  
Author(s):  
M. Wakita ◽  
S. Watanabe ◽  
A. Murata ◽  
N. Tsurushima ◽  
M. Honda
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Western North Pacific ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
North Pacific Ocean ◽  
Decadal Change ◽  
Western North Pacific Ocean

scholarly journals Nutrient and dissolved inorganic carbon variability in the North Pacific

2020 ◽  
Author(s):  
Sayaka Yasunaka ◽  
Humio Mitsudera ◽  
Frank Whitney ◽  
Shin-ichiro Nakaoka
Keyword(s):  
Mixed Layer ◽  
North Pacific ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Mixed Layer Depth ◽  
Local Maximum ◽  
Boundary Region ◽  
Chl A ◽  
The North ◽  
The North Pacific

AbstractA compilation of surface water nutrient (phosphate, nitrate, and silicate) and partial pressure of CO2 (pCO2) observations from 1961 to 2016 reveals seasonal and interannual variability in the North Pacific. Nutrients and calculated dissolved inorganic carbon (DIC) reach maximum concentrations in March and minimum in August. Nutrient and DIC variability is in-phase (anti-phase) with changes in the mixed layer depth (sea surface temperature) north of 30 °N, and it is anti-phase (in-phase) with changes in Chl-a north of 40 °N (in 30 °N–40 °N). Seasonal drawdown of nutrients and DIC is larger toward the northwest and shows a local maximum in the boundary region between the subarctic and subtropics. Stoichiometric ratios of seasonal drawdown show that, compared to nitrate, silicate drawdown is large in the northwestern subarctic including the Bering and Okhotsk seas, and drawdown of carbon is larger toward the south. Net community production in mixed layer from March to July is estimated to be more than 6 gC/m2/mo in the boundary region between the subarctic and subtropics, the western subarctic, the Gulf of Alaska, and the Bering Sea. Nutrient and DIC concentrations vary with the Pacific Decadal Oscillation and the North Pacific Gyre Oscillation which cause changes in horizontal advection and vertical mixing. The DIC trend is positive in all analysis area and large in the western subtropics (> 1.0 μmol/l/yr). Averaged over the analysis area, it is increasing by 0.77 ± 0.03 μmol/l/yr (0.75 ± 0.02 μmol/kg/yr).

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