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Manganese oxidation in pH and O 2 microenvironments produced by phytoplankton 1, 2
Author(s) -
Richardson Laurie L.,
Aguilar Carmen,
Nealson Kenneth H.
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.1988.33.3.0352
Subject(s) - manganese , photosynthesis , photosystem ii , cyanobacteria , chemistry , algae , dcmu , environmental chemistry , birnessite , extracellular polymeric substance , inorganic chemistry , botany , biology , biochemistry , biofilm , manganese oxide , organic chemistry , bacteria , genetics
Pure cultures of Chlorella sp. catalyzed the oxidation of soluble Mn(II) to particulate, extracellular, manganic oxides. Manganese oxidation was dependent on photosynthetic activity: no oxidation was observed in the dark when cells were grown heterotrophically on glucose, or in the light when photosystem II was inhibited by the addition of DCMU. Manganates were not formed when media were buffered below pH 8.0, suggesting that an important driving force for manganese oxidation was the high pH resulting from photosynthesis. Field studies with minielectrodes in Oneida Lake, New York, demonstrated steep gradients of O 2 and pH and the presence of particulate manganic oxides associated with pelagic aggregates of the cyanobacterium Microcystis sp. The manganese oxidation reaction apparently occurs only when photosynthesizing algae are present as dense populations that can generate microenvironments of high (>9.0) pH, either as aggregates in the pelagic zone or concentrated cell cultures in the laboratory. A large‐scale transition from soluble to particulate manganese was measured in the surface waters of Oneida Lake throughout summer 1986. Removal of Mn(II) was correlated with the presence of aggregate‐forming cyanobacteria that oxidize Mn(II) by the mechanism described above.