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| Titel |
Sedimentological and geochemical record of submarine mine tailing footprint
in Repparfjorden (Northern Norway) |
| VerfasserIn |
Beata Sternal, Juho Junttila, Kristine Bondo Pedersen, Kari Skirbekk, Matthias Forwick, JoLynn Carroll |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131427
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| Publikation (Nr.) |
 EGU/EGU2016-11834.pdf |
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| Zusammenfassung |
| The knowledge on understanding the physical, chemical and biological processes dominating
in marine system affected by submarine tailings disposal (STD) remains limited and further
knowledge to make reliable long-term predictions of future environmental impacts is needed.
One way of contributing to this is by investigation of marine environments already affected
by the tailings discharge in the past.
We present preliminary results from a multidisciplinary study of marine sediments from
Repparfjorden in northern Norway, a fjord that was influenced by the deposition of tailings
from a copper mine during the 1970’s. The study is a part of the competence cluster
Environmental Waste Management (EWMA) that as one of its important aims has
advancing the knowledge of spreading of mine-tailing related contaminants. Here
we give particular attention to the reconstruction of sedimentation style, rate of
sediment accumulation, as well as potential sediment transport paths (contaminants
dispersion).
Seventeen short cores (up to 21 cm long) were retrieved from sites covering the entire
area of Repparfjorden. The cores were sliced into 1-cm intervals that are and will be analysed
for grain-size, concentration of heavy metals and total organic carbon content of bulk
sediment. Sediment chronologies are and will be derived using 210Pb and 137Cs dating
techniques.
An approximately 7-cm thick interval which is different from present fjord sedimentation
was observed below c. 10 cm depth in three of the cores retrieved from the area of tailings
deposition in the 1970’s. Sediments of this discrete depth interval are mainly composed of
mud or sandy mud with bimodal grain-size distribution (first mode: medium silt fraction;
second mode: very coarse silt). They are characterised by very high Cu concentrations (>250
mg/kg). Preliminary measurements of the 210Pb activity indicate an increase in sediment
accumulation rate during the deposition of this interval. Therefore, we interpret it to be
mainly composed of mine tailing sediments. As this sediment interval was only observed in 3
of 17 cores, we suggest that the lateral extent of the tailings is restricted to a relatively
small area of the fjord. However, elevated concentrations of Cu (40-80 mg/kg)
were also detected in a discrete sediment interval (3-10 cm) in one core ∼3 km
beyond the tailing deposition site. In addition, high Cu concentrations (60-190
mg/kg) in sediments between the seafloor and the tailing deposit, as well as some
centimetres below the deposit (in all cores from the old tailing deposition site) suggest
possible dispersion of Cu to the immediate surrounding sediments in the cores. |
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