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| Titel |
Factors influencing the dissolved iron input by river water to the open ocean |
| VerfasserIn |
R. Krachler, F. Jirsa, S. Ayromlou |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 2, no. 4 ; Nr. 2, no. 4 (2005-11-07), S.311-315 |
| Datensatznummer |
250000632
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| Publikation (Nr.) |
 copernicus.org/bg-2-311-2005.pdf |
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| Zusammenfassung |
| The influence of natural metal chelators on the bio-available iron input to
the ocean by river water was studied. Ferrous and ferric ions present as
suspended colloidal particles maintaining the semblance of a dissolved load
are coagulated and settled as their freshwater carrier is mixed with
seawater at the continental boundary. However, we might argue that different
iron-binding colloids become sequentially destabilized in meeting
progressively increasing salinities. By use of a 59Fe tracer method,
the partitioning of the iron load from the suspended and dissolved mobile
fraction to storage in the sediments was measured with high accuracy in
mixtures of natural river water with artificial sea water. The results show
a characteristic sequence of sedimentation. Various colloids of different
stability are removed from a water of increasing salinity, such as it is the
case in the transition from a river water to the open sea. However, the iron
transport capacities of the investigated river waters differed greatly. A
mountainous river in the Austrian Alps would add only about 5% of its
dissolved Fe load, that is about 2.0 µg L-1 Fe, to coastal waters.
A small tributary draining a sphagnum peat-bog, which acts as a source of
refractory low-molecular-weight fulvic acids to the river water, would add
approximately 20% of its original Fe load, that is up to 480 µg L-1
Fe to the ocean's bio-available iron pool. This points to a natural
mechanism of ocean iron fertilization by terrigenous fulvic-iron complexes
originating from weathering processes occurring in the soils upstream. |
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