Iron oxidation kinetics in an acidic alpine lake
Four experiments were performed to assess the role of homogeneous, heterogeneous, biological and photochemical processes in the oxygenation of ferrous iron in aquatic ecosystems. Experiments were carried out at Lake Cristallina, Ticino, Switzerland, and in the laboratory. Rate constants are presente...
Saved in:
Published in | Water research (Oxford) Vol. 28; no. 2; pp. 323 - 333 |
---|---|
Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Elsevier Ltd
1994
Elsevier Science |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Four experiments were performed to assess the role of homogeneous, heterogeneous, biological and photochemical processes in the oxygenation of ferrous iron in aquatic ecosystems. Experiments were carried out at Lake Cristallina, Ticino, Switzerland, and in the laboratory. Rate constants are presented for homogeneous oxygenation in lakewater, for oxygenation by lake sediment under sterile and non-sterile conditions and for heterogeneous oxygenation in the presence of TiO
2, MnO
2, Fe
2O
3, Al
2O
3 and SiO
2. It was found that, on a surface area adjusted basis, TiO
2, MnO
2 and Fe
2O
3 were three orders of magnitude more effective in accelerating oxygenation than Al
2O
3 and SiO
2, suggesting that these minerals form strong, inner sphere complexes with Fe(II) in the pH range 4–6. Sterilization by gamma irradiation reduced oxygenation rate in the presence of lake sediment by two orders of magnitude on a surface area adjusted basis. Oxygenation in the presence of 0.44 μm filtered lakewater was not appreciably different from that in distilled water.
In situ experiments showed that oxygenation rate increased in the presence of sunlight. The heterogeneous rate constant for iron oxidation with lake sediment was 4.9 × 10
14 M
−2 atm
−1 s
−1 m
−2 and with pure minerals ranged from 1.8 × 10
10 to 5.3 × 10
13 M
−2 atm
−1 s
−1 m
−2. |
---|---|
Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0043-1354 1879-2448 |
DOI: | 10.1016/0043-1354(94)90270-4 |