Ocean acidification off the south coast of Japan: A result from time series observations of CO<sub>2</sub>parameters from 1994 to 2008

Ishii, Masayoshi; Kosugi, Naohiro; Sasano, Daisuke; Saito, Shu; Midorikawa, Takashi; Inoue, Hisayuki

doi:10.1029/2010jc006831

Cited by 70 publications

(76 citation statements)

References 49 publications

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“…The observed pH changes in the surface ocean are consistent with those predicted based on equilibration of atmospheric CO 2 with the seawater (about −0.002 yr −1 ) (Dore et al, 2009;Byrne et al, 2010;Midorikawa et al, 2010;Ishii et al, 2011). In subsurface water, pH decreases (-0.003 yr −1 at Station ALOHA (22.75 • N; 158 • W; Dore et al (2009) and 0.004 yr −1 in North Pacific Intermediate Water; Byrne et al (2010)) have been enhanced by the accumulation of anthropogenic CO 2 and by natural variability related to temporal changes in physical and biogeochemical processes such as ocean ventilation, and remineralization of organic matter related to apparent oxygen utilization (AOU).…”

Section: Introductionsupporting

confidence: 85%

“…Ocean acidification of surface and subsurface waters of the North Pacific Ocean has been clearly documented in time series and repeat hydrography data (direct basin-wide observations) over the past two decades (e.g., Dore et al, 2009;Byrne et al, 2010;Midorikawa et al, 2010, Ishii et al, 2011Feely et al, 2004;Feely et al, 2012;Murata and Saito, 2012). The observed pH changes in the surface ocean are consistent with those predicted based on equilibration of atmospheric CO 2 with the seawater (about −0.002 yr −1 ) (Dore et al, 2009;Byrne et al, 2010;Midorikawa et al, 2010;Ishii et al, 2011).…”

Section: Introductionsupporting

confidence: 66%

“…In the winter mixed layer, pH decreased at -0.0011 ± 0.0004 pH in situ T yr −1 from 1997 to 2011, whereas aragonite , calcite , and CO 2− 3 remained unchanged. This decreasing trend of pH was slower than that predicted based on equilibration of atmospheric CO 2 with the seawater (−0.002 pH in situ T yr −1 ) and slower than decrease rates in other regions (Dore et al, 2009;Midorikawa et al, 2010;Ishii et al, 2011;Byrne et al, 2010). We attribute this lower rate to a reduction of CO 2 emission in winter caused by increased TA win .…”

Section: Discussionmentioning

confidence: 51%

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Ocean acidification from 1997 to 2011 in the subarctic western North Pacific Ocean

et al. 2013

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Abstract. Rising atmospheric CO 2 contents have led to greater CO 2 uptake by the oceans, lowering both pH due to increasing hydrogen ions and CaCO 3 saturation states due to declining carbonate ion (CO 2− 3 ). Here we used previously compiled data sets and new data collected in 2010 and 2011 to investigate ocean acidification of the North Pacific western subarctic gyre. In winter, the western subarctic gyre is a source of CO 2 to the atmosphere because of convective mixing of deep waters rich in dissolved inorganic carbon (DIC). We calculated pH in winter mixed layer from DIC and total alkalinity (TA), and found that it decreased at the rate of −0.0011 ± 0.0004 yr −1 from 1997 to 2011. This decrease rate is slower than that expected under the condition of seawater/atmosphere equilibration, and it is also slower than the rate in the subtropical regions (−0.002 yr −1 ). The slow rate is caused by a reduction of CO 2 emission in winter due to an increase in TA. Below the mixed layer, the calcite saturation horizon (∼ 185 m depth) shoaled at the rate of 2.9 ± 0.9 m yr −1 as the result of the declining CO 2− 3 concentration (−0.03 ± 0.01 µmol kg −1 yr −1 ). Between 200 m and 300 m depth, pH decline during the study period (−0.0051 ± 0.0010 yr −1 ) was larger than ever reported in the open North Pacific. This enhanced acidification rate below the calcite saturation horizon reflected not only the uptake of anthropogenic CO 2 but also the increase in the decomposition of organic matter evaluated from the increase in AOU, which suggests that the dissolution of CaCO 3 particles increased.

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Section: Introductionsupporting

confidence: 85%

Section: Introductionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 51%

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Ocean acidification from 1997 to 2011 in the subarctic western North Pacific Ocean

et al. 2013

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“…The uptake of anthropogenic CO 2 by the ocean and the subsequent increase in the partial pressure of CO 2 in surface seawater (pCO 2 sea ) are not constant, however, but exhibit substantial interannual to decadal variability (e.g., in the North Pacific; Brix et al, 2004;Midorikawa et al, 2006;Ishii et al, 2011). Furthermore, possible future ocean acidification and global warming could reduce the capacity of the ocean to take up additional CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Ocean acidification in the subtropical North Pacific estimated from accumulated carbonate data

Midorikawa¹,

Ishii²,

Sasano³

et al. 2011

Pap. Meteor. Geophys.

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The recent uptake of anthropogenic carbon by the ocean brings about changes in the surface-ocean carbon cycle that could result in ocean acidification with subsequent serious effects on marine ecosystems. We evaluated the trend of ocean acidification in the surface layer of extensive regions of the subtropical North Pacific using synthesized data for partial pressure of CO 2 for the past 40 years because no precise pH data were available. The results show significant trends of acidification (a pH decrease of 0.01 to 0.02 per decade) over the subtropical North Pacific. The rate of pH decrease, after excluding the contribution from changes in sea surface temperature, was highest in the eastern subtropical region. In this region in particular, the intrusion of subarctic waters with high concentrations of dissolved inorganic carbon could have contributed to the relatively high rate of acidification. Comparisons of the estimated rate of pH decrease for the past 26 years with those for the decade following 1969 and for 50 years into the future suggest an acceleration of acidification in recent years, as well as in the future, depending on the scenario of future anthropogenic CO 2 emission.

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“…AzetsuScott et al, 2010) and undersaturation of aragonite has already occurred in surface water in some regions of the Arctic, such as the south-eastern Hudson Bay (AzetsuScott et al, 2014) and the Canadian Arctic archipelago (Chierici and Fransson, 2009). A decrease of pH and aragonite saturation state was also observed off the south coast of Japan from a time series at 136Á1408E over the period 1998Á2004 (Ishii et al, 2011). In different regions of the world ocean, a decrease of pH has been reported, for example, in the Atlantic subtropical gyre such as the European Station for Time series in the Ocean at the Canary Islands (ESTOC) and the Bermuda Atlantic Time-series Study (BATS), for periods over 15 years (Bates et al, 2014), at a time series station in the North Pacific near Hawaii over 20 years (Dore et al, 2009).…”

Section: Introductionmentioning

confidence: 93%

Variability and trends of carbon parameters at a time series in the eastern tropical Atlantic

Lefèvre¹,

Veleda²,

Araújo³

et al. 2016

Tellus B: Chemical and Physical Meteorology

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A B S T R A C THourly fCO 2 is recorded at a time series at the PIRATA buoy located at 68S 108W in the eastern tropical Atlantic since June 2006. This site is located south and west of the seasonal Atlantic cold tongue and is affected by its propagation from June to September. Using an alkalinityÁsalinity relationship determined for the eastern tropical Atlantic and the observed fCO 2 , pH and the inorganic carbon concentration are calculated. The time series is investigated to explore the intraseasonal, seasonal and interannual timescales for these parameters, and to detect any long-term trends. At intraseasonal timescales, fCO 2 and pH are strongly correlated. On seasonal timescales, the correlation still holds between fCO 2 and pH and their variations are in agreement with those of sea surface salinity. At interannual timescales, some important differences appear in 2011Á2012: lower fCO 2 and fluxes are observed from September to December 2011 and are explained by higher advection of salty waters at the mooring, in agreement with the wind. In early 2012, the anomaly is still present and associated with lower sea surface temperatures. No significant long-term trend is detected over the period 2006Á2013 on CO 2 and any other physical parameter. However, as atmospheric fCO 2 is increasing over time, the outgassing of CO 2 is reduced over the period 2006Á2013 as the flux is mainly controlled by the difference of fCO 2 between the ocean and the atmosphere. A longer time series is required to determine if any significant trend exists in this region.

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Ocean acidification off the south coast of Japan: A result from time series observations of CO₂parameters from 1994 to 2008

Cited by 70 publications

References 49 publications

Ocean acidification from 1997 to 2011 in the subarctic western North Pacific Ocean

Ocean acidification from 1997 to 2011 in the subarctic western North Pacific Ocean

Ocean acidification in the subtropical North Pacific estimated from accumulated carbonate data

Variability and trends of carbon parameters at a time series in the eastern tropical Atlantic

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Ocean acidification off the south coast of Japan: A result from time series observations of CO2parameters from 1994 to 2008

Cited by 70 publications

References 49 publications

Ocean acidification from 1997 to 2011 in the subarctic western North Pacific Ocean

Ocean acidification from 1997 to 2011 in the subarctic western North Pacific Ocean

Ocean acidification in the subtropical North Pacific estimated from accumulated carbonate data

Variability and trends of carbon parameters at a time series in the eastern tropical Atlantic

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Ocean acidification off the south coast of Japan: A result from time series observations of CO₂parameters from 1994 to 2008