Figure 5: Experimentally determined B/Ca partition coefficient as a function of hydrogen ion concentration. | Nature Communications

Figure 5: Experimentally determined B/Ca partition coefficient as a function of hydrogen ion concentration.

From: Coral calcification in a changing World and the interactive dynamics of pH and DIC upregulation

Figure 5

Measured B/Ca partition coefficient (KD) as defined by equation (4) from the data of Holcomb et al.19 The line represents a best-fit exponential curve to the data with KDB/Ca=KD,0 exp([H+]T), where KD,0=2.97±0.17 × 10−3 (±95% CI), =0.0202±0.042, r2=0.64 and n=63. The range for pHcf of upregulating calcifiers (that is, Porites spp.) is between 8 and 9 (shaded); equivalent to [H+]T of between 1 and 10 nmol kg−1 giving a range in KDB/Ca (× 10−3) of 2.6–2.8, and therefore relatively in-sensitive to changes in coral pHcf. Importantly, our experimentally determined KDB/Ca value is an order of magnitude higher than the previous estimate by Allison et al.,20 (open diamond) and consistent with the substitution of B(OH)4 with CO32−.

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