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| Titel |
Sedimentary regimes at Potter Cove, King George Island, maritime Antarctica - from source to sink |
| VerfasserIn |
Donata Monien, Patrick Monien, Robert M. Brünjes, Tatjana Widmer, Bernhard Schnetger, Hans-Jürgen Brumsack |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078623
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| Zusammenfassung |
| Increased particle run-off due to recently retreated ice masses along the Antarctic margins
may play an important role in fertilizing the high-nutrient-low-chlorophyll regions of the
Southern Ocean. At Potter Cove, King George Island, maritime Antarctica, small melt water
streams at the south-eastern shoreline (Potter Peninsula) discharge up to 1,500Â mg L-1 (av.
110Â mg L-1) of suspended particle matter (SPM) per day into the coastal water body during
the summer seasons. Apart from potential light limitation of plankton growth by the
suspension load, the particle run-off affects benthic feeders, possibly changes the
depositional regime and the preservation of chemical proxies in the outlet zones, and
exports trace elements offshore. In Potter Cove’s water column, the average particle
size is low, and extreme turbidity events are restricted to the upper five to seven
meters. High particle loads are often associated with low salinities, most probably
induced by increased onshore precipitation. Sediment traps installed in the inner and
outer cove at 5 and 20Â m water depth suggest mass accumulation rates of 0.83 and
0.58 g cm-2 yr-1, and 0.13 and 0.11 g cm-2 yr-1 (considering 183 days of
sedimentation), respectively. 210Pb measurements of short sediment cores reveal
recent sediment accumulation rates of approximately 0.1 to 0.6 g cm-2 yr-1.
The SPM sampled in the melt water streams and plumes is chemically different to
surface sediments deposited in Potter Cove. Chemical characteristics suggest a
significant impact of particle sorting: SPM and outer cove sediments are more clayey,
whereas inner cove sediments contain more heavy minerals. Generally, sediment
deposits in Potter Cove exhibit coarser grain sizes and are mainly derived from Barton
Peninsula (northern shoreline), whereas the SPM consists of more fine-grained
material originating from Potter Peninsula eluviations. Sequential leaching of the
SPM by ascorbic acid showed that approximately 0.5 to 2% of the total iron (5.9
wt.% Fe) is easily dissolvable, which in turn can be translated into an additional
load of approximately 5 to 21 mmol L-1 dissolved Fe2+. In consequence, the
results of our three-summer study highlight that the major part of the particle load
from the melt water streams are exported to the Southern Ocean rather than being
deposited near shore in Potter Cove. These exported particles are rich in easily
leachable Fe acting as a natural fertilization to the Fe-limited Southern Ocean. |
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