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| Titel |
Influence of global temperature change on the geochemical processes in the Plitvice Lakes waters - a case study |
| VerfasserIn |
Andreja Sironić, Jadranka Baresic, Nada Horvatincic, Andrijana Brozinčević, Maja Vurnek, Sanja Kapelj |
| 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 |
250132725
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| Publikation (Nr.) |
 EGU/EGU2016-13259.pdf |
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| Zusammenfassung |
| One of the major reasons for the global air temperature increase, recorded as the highest in
the last decade, is considered to be the increase of the atmospheric CO2 concentration.
However, in calculation of the global carbon budget a certain unknown carbon sink is
identified, and karst relief is considered to be an important candidate for it, as well as being a
source of carbon. Aquatic systems on karst enable carbon exchange between karst and
atmosphere, often through groundwater geochemical carbonate rock dissolution
(carbon sink) and in form of secondary calcium carbonate precipitation (carbon
source).
Protected area of the Plitvice Lakes National Park, settled in the karst area of Croatia, was
chosen as a case study of karst geochemical processes. The Lakes are also specific
for its tufa precipitation in form of tufa barriers. Physical and chemical data of
water collected on 8 locations (2 springs and 6 lakes) in the last 30 years were
studied.
The data records were not systematic for all 30 years, so first the seasonal periodicity of all
data was assessed and temporal change was investigated in each calendar month, and
then the change was studied by comparing two distinct periods: 1981-1986 and
2010-2014.
On all selected locations we observed temporal increase of air and water temperature, Ca2+
and HCO3− concentrations, calcite saturation index (SIcalc) and of calcite dissolution ionic
ratio (IRcalc,) and a decrease in Mg/Ca ratio, though the intensity of this changes differ
locally. No statistically significant change was observed for pH and CO2(aq) and Mg2+
concentrations. Discharge rates did not show significant change in the last 30 years; however
there is a change in their seasonal distribution and more extreme values were recorded in
recent period.
Comparison of mean monthly air and water temperature for two periods implies more
influence of groundwater inflow at all locations in recent period, which is probably a result of
seasonal change in water discharge rates.
Significant increase in Ca2+ and HCO3− concentrations at lake locations were caused by
their increase in springs. With Mg2+ concentration simultaneously being stagnant, this is an
indication of stronger calcite than dolomite dissolution. One of the reasons for this could be
increased air/soil temperature resulting in higher CO2 soil production primarily dissolving
calcite.
A temporal and spatial change in SIcalc and IRcalc values on surface waters were explained
as being under influence of change in water temperature. |
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