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. 2002 Mar 12;99(6):3394–3399. doi: 10.1073/pnas.062478699

Figure 4.

Figure 4

Lability of Al (527 μg/liter) at pH 7.36 within 1 min (A), 6 h (B), 24 h (C), and 48 h (D) of its addition to UHP water containing 5 mM Mops buffer alone (control, ▪), Mops buffer plus 46 μg/liter Si (○), and Mops buffer plus 5.5 mg/liter Si (▴). Aluminum lability was determined by measuring its rate of complexation with DMHP at 274 nm as a function of time. Free (i.e., unbound) DMHP absorbs strongly at 274 nm, which is distinct to Al-bound DMHP that absorbs strongly at 289 nm. A lower absorbance represents Al binding (i.e., quantity of Al bound), whereas the pattern of absorbance with time is dictated by the lability of different Al species in the water column. The pattern of Al binding is identical in the presence or absence of 46 μg/liter Si.