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| Titel |
Temporal evolution of anthropogenic pollution and environmental changes in a marine inlet: the example of Gemlik Gulf, Marmara Sea |
| VerfasserIn |
Gülüm Albut, M. Namik Çağatay, Nurdan Gungor, Emin Gungor, Dursun Acar, Nuray Balkis |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088959
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| Publikation (Nr.) |
 EGU/EGU2014-3139.pdf |
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| Zusammenfassung |
| Marginal marine basins are particularly prone to anthropogenic pollution because of
restricted water circulation and commonly high population density in their drainage basin.
Gemlik Gulf is such a semi-enclosed inlet with maximum depth of 113 m in the eastern part
of the Sea of Marmara, which is separated from the rest of the Marmara shelf by a -50 m deep
sill. It is under anthropogenic risk from different industrial and municipal pollution
sources in its drainage basin.Moreover, Gemlik Gulf, located on the middle branch
of the North Anatolian fault (NAF), is under a future earthquake risk with a high
possibility of pollution from disruption to industrial plants and municipal infrastucture,
similar to the the one that occurred in the Ä°zmit Gulf during the 1999 Mw 7.4 Ä°zmit
earthquake.
In this study, we investigated the extent and temporal evolution of the heavy metal and
organic pollution using a wide range of analyses of a 84 cm sediment/water interface long
core from the central part of the basin, involving μ-XRF Core Scanner, Inductively Coupled
Plasma-Mass Spectrometry (ICP-MS), Total Organic (TOC) and Inorganic Carbon (TIC), and
mass spectrometric stable C and N isotopic and C and N elemental analyses. The chronology
of the core was determined using radionuclide (210Pb and 137Cs) and AMS radiocarbon
analysis.
The core covers about last 800 years. The upper part of the core, representing the last 155
years, is gray mud grading into very dark grey mud in the top 84 cm. The 5-8 cm
interval below sea floor (bsf) (AD 1985-1995) includes 3 white laminae consisting of
coccolithophore Emiliania huxleyi and another carbonate rich layer deposited during AD
1855-1950. TOC values are commonly between 1.5 and 2.5 % below 12.5 cmbsf (AD
1965), but increases up to 4.25 % towards the core top. The core includes a mass
flow unit, which is most probably triggered by the AD 1855 earthquake, and is
characterized by high contents of Fe, Zr, low contents of Ca, Nb, La U, Th, Zn and Pb,
Cu.
Enrichment factor (EF) of Mo, obtained with respect to the average metal values of
uncontaminated substratum in the core and normalisation to Al, increase sharply
upwards starting from 15 cmbsf (AD 1955) to a maximum EF of 23. Such a dramatic
Mo increase, together with a Mn depletion, indicates the establishment of bottom
water anoxia in the Gulf at least since AD 1970. At around the same time increases
started to be observed in concentrations of most metals and semi-metals such as
Cd, Zn, Cu, Pb, U, S, Sb, with a maximum EF of 5.7, 2.1, 1.6, 1.6, 1.3, 3.2, 2.2,
respectively.
C/N ratio and δ13C reveals the cylicity in origin of organic matter changing
from bottom to top of the core respectively as: terrestrial, a mixture of marine and
terrestrial, terrestrial in the mass flow unit, mixed, marine and terrestrial in most
recent sediments of last about 15 years. The organic matter of terrestrial origin as
well as pollutants were transported by Kocadere and Karsak Creeks and Kocasu
river.
δ15N values range between 4 and 4.5 oduring AD 1230-1540 and 2.5 and 3.1
oduring AD 1540-1740 and between 3.7 and 5.6 osince AD 1855 to present.
Assessment of δ15N data together with the TOC and TIC data suggest that denitrification
process has been effective especially during the last 150 years, and least effective
during AD 1540-1740 which includes the Late Maunder Minimum cold period. |
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