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The effect of pH on iron and manganese uptake by a green alga
Author(s) -
Schenck R. C.,
Tessier A.,
Campbell P. G. C.
Publication year - 1988
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1988.33.4.0538
Subject(s) - manganese , metal , chemistry , adsorption , inorganic chemistry , chlamydomonas , ferric , nuclear chemistry , biochemistry , organic chemistry , mutant , gene
Experiments were conducted with 54 Mn and 59 Fe in buffered synthetic solutions to determine the short‐term uptake of manganese and iron by the green alga Chlamydomonas variabilis as a function of pH and metal concentration. Over the pH range 7 to 5, the adsorption of Fe(II) and Mn(II) onto the cell surface was independent of pH, but the fluxes of metals into the cells decreased 2–2.5 times for each unit decrease in pH. Thus increasing acidity decreased metal uptake and, by inference, the effects of the metal on the cell. We also compared the uptake of Fe(II) and Fe(III) at the same external concentration (0.1 µ M), under conditions where all the metal was dissolved (pH 5). The uptake rates were nearly identical, even though the ratio [Fe 2+ ]:[Fe 3+ ] was ∼10 6 . The measured fluxes of Fe(III) into an algal cell were l0 4 times greater than the calculated diffusive flux of Fe 3+ to the cell surface. The results indicate that the uptake of Fe(III) involves transport to the cell surface of hydroxy‐Fe(III) species that are in rapid protolytic equilibrium with each other and with the free hydrated ferric iron.