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| Titel |
Sulfur (34SSO4) and oxygen (18OSO4) isotopic investigation of origin of dissolved sulfate at the Lake Acıgöl, Turkey |
| VerfasserIn |
Muhittin Karaman, Murat Budakoğlu, Suat Taşdelen |
| 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 |
250132748
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| Publikation (Nr.) |
 EGU/EGU2016-13283.pdf |
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| Zusammenfassung |
| A dual isotope method containing the sulfur (34SSO4) and oxygen (18OSO4) isotopic
composition of dissolved sulfate (SO4) was used for surveying SO4 sources from lake water
and springs from the Acı göl Basin. Lake Acı göl is a Na-Cl-SO4-typehypersaline lake that is
bordered by sulfate-rich springs to the south. The concentration of the dissolved sulfate of the
springs ranges between 34 and 1100 mg L−1, and the lake water contains an average of
22635 mg L−1dissolved sulfate. The measured dissolved sulfate value of rain during the
sampling season is 36 mg L−1. The type of spring waters bordering the lake is
Na-Ca-SO4-Cl-HCO3, and the others are Mg-Ca-HCO3 and Mg-Ca-Na-SO4-HCO3. The
34SSO4 and 18OSO4 isotopic compositions were checked in 19 aqueous samples. The results
showed that δ34SSO4 values of the springs varied from -4.6 to +24.1‰ and δ18OSO4values
from +1.8 to +13.1‰Ṡulfate rich springs feeding the lake have sulfur isotopes that range
between +22.1 and +24.1‰Ṡprings at the north side of the lake contain the lowest
sulfur and oxygen isotope values (δ34SSO4= -4.6‰ δ18OSO4=+1.8). The maximum
δ34SSO4values are collected from borehole drilled in the western/dry part of lake area
(δ34SSO4=+32.6). The variations in δ34SSO4and δ18OSO4measuredvalues of lake
water were less than 2.5‰Ṫhe δ18OSO4 values of the lake range from +16.6‰ to
+18.1‰ (mean = +17.4), while the δ34SSO4 values are between +25.3 and +27.5‰ (mean =
+26.6). The slope of the 18OSO4 vs. 34SSO4linear relationship (R2=0.91, n=10) of
the springs is 0.4, which indicates the sulfur isotopes increase rapidly relative to
the oxygen isotopes. The linear relationship (R2=0.64, n=9) between 18OSO4 and
34SSO4has a negative slope value (-0.67) for lake water. This indicates the sulfur isotopes
decreases rapidly relative to the oxygen isotopes. Sulfate reduction and re-oxidation
control the 18OSO4 vs. 34SSO4ratio in spring and lake water. The dual isotopes of
the δ34SSO4 and δ18OSO4 values of dissolved sulfate discriminate that springs
have three major sources of sulfate: (a) sulfate derived from only dissolution of
evaporate minerals, (b) sulfate derived from combination of atmospheric deposition
and dissolution of evaporate minerals, and (c) sulfate derived from oxidation of
sulphide minerals. The source of the dissolved sulfate of lake water is dissolution of
evaporates.
Keywords: Hypersaline Lakes, Sulfur (34SSO4) and oxygen (18OSO4) isotope,
dissolved sulfate |
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