Reconciliation of pH25 and pHinsitu acidification rates of the surface oceans: A simple conversion using only in situ temperature

Lui, Hon-Kit; Chen, Chen‐Tung Arthur

doi:10.1002/lom3.10170

Cited by 18 publications

(10 citation statements)

References 33 publications

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“…This is not completely unsurprising given the limits of the equation, although other work shows it to work reasonably well for temperature differences < ∼ 5°C (Millero et al ). The values calculated using Lui and Chen () averaged 0.0033 ± 0.0041 pH units higher than the CO2sys calculated values. Although not entirely unreasonable, the noise in the values is high relative to values calculated from CO2sys.…”

Section: Methodsmentioning

confidence: 64%

Internal consistency of the inorganic carbon system in the Arctic Ocean

Woosley

Millero

Takahashi

2017

Limnology & Ocean Methods

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Highly accurate and precise measurements of the inorganic carbon system are crucial for monitoring and assessing the uptake of anthropogenic CO2 by the ocean. The Arctic Ocean is an area of particular interest due to Arctic amplification of climate change. Internally consistent constants are essential for making high quality CO2 system measurements and for calculating the full suite of carbon parameters. Temperatures and salinities in the Arctic are near or below the valid ranges of most carbon system constants, but the applicability has never been fully assessed in the Arctic. Using measurements of all four carbon parameters (total alkalinity, total CO2, pH, and pCO2) made on the Arctic GEOTRACES/GO‐SHIP cruise in summer 2015, we evaluate the internal consistency of six different sets of constants for surface waters at in situ temperature. Five of the six sets of constants are generally internally consistent, but each is statistically significantly different from each other. Although differences among constants are generally within the uncertainty of the calculations, these results indicate caution should be used when comparing data using different constants as biases may result from the choice of constants. We also find significant uncertainty in converting measured pH to pH at in situ temperature. The uncertainty in the pH temperature conversion limits our ability to determine the accuracy of pH measurements, particularly in polar regions. Measurements in marginal ice zones indicate that dissolution of semi‐stable ikaite (CaCO3) may bias total alkalinity measurements, and should therefore be analyzed immediately upon collection or filtered before storage.

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Section: Methodsmentioning

confidence: 64%

Internal consistency of the inorganic carbon system in the Arctic Ocean

Woosley

Millero

Takahashi

2017

Limnology & Ocean Methods

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“…5b shows the lowest temperature and maximum pHinsitu data. The value of pH25 was estimated using the method of Lui and Chen (2017). Table 2 Average mutual correlation coefficients among water temperature and pHinsitu measurements at adjacent monitoring sites in the same prefecture.…”

Section: Discussionmentioning

confidence: 99%

“…Our analysis was based on the pHinsitu data, so the difference between the trends might reflect long-term changes in water temperature that To evaluate the direct thermal effects related to process D in equation 2, we estimated the pH values normalized to 25°C (pH25), assuming that the minimum (maximum) pHinsitu and highest (lowest) temperature and other parameters were measured at the same time. By assuming the other parameters that affected the pH calculation in the CO2sys software (Lewis and Wallace 1998, csys.m), such as salinity, DIC, and alkalinity, did not change (these parameters are not measured as part of the WPCL program), we used the method of Lui and Chen (2017) to calculate the pH25, as follows:…”

Section: Seasonal Variations In Phinsitu Trendsmentioning

confidence: 99%

Long-term trends in pH in Japanese coastal waters

Ishizu¹,

Miyazawa²,

Tsunoda³

et al. 2019

Preprint

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Abstract. In recent decades, acidification of the open ocean has shown consistent increases. However, analysis of long-term data in coastal waters shows that the pH is highly variable because of coastal processes and anthropogenic carbon inputs. It is therefore important to understand how anthropogenic carbon inputs and other natural or anthropogenic factors influence the temporal trends in pH in coastal waters. Using water quality data collected at 1481 monitoring sites as part of the Water Pollution Control Program, we determined the long-term trends in pH in Japanese coastal waters at ambient temperature from 1978 to 2009. We found that pH decreased (i.e., acidification) at between 70&#8201;% and 75&#8201;% of the sites and increased (i.e., basification) at between 25&#8201;% and 30&#8201;% of the sites. The rate of decrease varied seasonally and was, on average, &#8722;0.0014&#8201;yr&#8722;1 in summer and &#8722;0.0024&#8201;yr&#8722;1 in winter, but with relatively large deviations from these average values. While the overall trends reflect acidification, watershed processes might also have contributed to the large variations in pH in coastal waters. The seasonal variation in the average pH trends reflects variability in warming trends, while regional differences in pH trends are partly related to heterotrophic water processes induced by nutrient loadings.

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“…(2), we estimated the pH values normalized to 25 • C (pH 25 ), assuming that the minimum (maximum) pH insitu and highest (lowest) temperature and other parameters were measured at the same time. By assuming the other parameters that affected the pH calculation in the CO2sys (Lewis and Wallace 1998, csys.m), such as salinity, DIC, and alkalinity, did not change (these parameters are not measured as part of the WPCL program), we used the method of Lui and Chen (2017) to calculate the pH 25 , as follows:…”

Section: Global Effects On Ph Insitu Trendsmentioning

confidence: 99%

“…7 but showing the pH 25 trends at 289 sites (selected by quality control step 3). The value of pH 25 was estimated using the method of Lui and Chen (2017).…”

Section: Global Effects On Ph Insitu Trendsmentioning

confidence: 99%

Long-term trends in pH in Japanese coastal seawater

et al. 2019

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Abstract. In recent decades, acidification of the open ocean has shown a consistent increase. However, analysis of long-term data in coastal seawater shows that the pH is highly variable because of coastal processes and anthropogenic carbon inputs. It is therefore important to understand how anthropogenic carbon inputs and other natural or anthropogenic factors influence the temporal trends in pH in coastal seawater. Using water quality data collected at 289 monitoring sites as part of the Water Pollution Control Program, we evaluated the long-term trends of the pHinsitu in Japanese coastal seawater at ambient temperature from 1978 to 2009. We found that the annual maximum pHinsitu, which generally represents the pH of surface waters in winter, had decreased at 75 % of the sites but had increased at the remaining sites. The temporal trend in the annual minimum pHinsitu, which generally represents the pH of subsurface water in summer, also showed a similar distribution, although it was relatively difficult to interpret the trends of annual minimum pHinsitu because the sampling depths differed between the stations. The annual maximum pHinsitu decreased at an average rate of −0.0024 yr−1, with relatively large deviations (0.0042 yr−1) from the average value. Detailed analysis suggested that the decrease in pH was caused partly by warming of winter surface waters in Japanese coastal seawater. The pH, when normalized to 25 ∘C, however, showed decreasing trends, suggesting that dissolved inorganic carbon from anthropogenic sources is increasing in Japanese coastal seawater.

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Reconciliation of pH₂₅ and pH_insitu acidification rates of the surface oceans: A simple conversion using only in situ temperature

Cited by 18 publications

References 33 publications

Internal consistency of the inorganic carbon system in the Arctic Ocean

Internal consistency of the inorganic carbon system in the Arctic Ocean

Long-term trends in pH in Japanese coastal waters

Long-term trends in pH in Japanese coastal seawater

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