Projects / Programmes
CO2 FIXATION IN RIVER CARBONATES: MASS BALANCE, HYDROLOGICAL, GEOCHEMICAL AND BIOCHEMICAL CONTROLS
| Code |
Science |
Field |
Subfield |
| 1.06.04 |
Natural sciences and mathematics |
Geology |
Geochemistry |
| Code |
Science |
Field |
| P420 |
Natural sciences and mathematics |
Petrology, mineralogy, geochemistry |
carbonate, tufa, CO2, mass balance, stable isotope, biomarkers, river
Researchers (11)
Organisations (3)
Abstract
The aim of the proposed research is to investigate the tufa formation in the Krka River (Slovenia) based on geochemical and stable isotope analyses of the river water and authigenic river carbonate precipitates. We plan to (1) construct the mass balance of carbon on the course of the tufa precipitating stream and to estimate the contribution of river carbonate precipitation to the overall carbon mass balance on the level of the watershed, (2) to investigate the conditions and rate of tufa formation in stream sections characterised by different temperature and hydrochemical conditions, (3) to estimate the variation in carbonate precipitation rate, mechanisms of precipitation, geochemical and isotope composition of tufas during last decades, related to the anthropogenic influences and global warming, where biomarkers will be used as indicators of variations in biological production, and (4) to estimate the potential of tufas as palaeoenvironmental archives on different time scales. For the first time in Slovenia, we will analyse the molecular and carbon isotopic composition of lipids and fatty acids as biomarkers to elucidate the difference between microenvironments within the barriers. Based upon the obtained results, we will elaborate the guidelines for protection of tufa precipitating springs and streams, which are recognised as valuable natural environmental archives and sensitive habitats requiring special protection, following the UNESCO »Convention Concerning the Protection of the World Cultural and Natural Heritage«, EEC Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora 92/43 and Natura 2000 protection programme.
Significance for science
Since the project represented a basic research, its main ambition was contribution to the Science. As most relevant contributions we consider:
- Methodology for quantification of standard uncertainty of tufas as palaeoclimate indicators; the publication in Chemical Geology (2009) is, to our knowledge, the first one which quantified the standard uncertainty of the Mg geochemical thermometer and contributions of individual considered parameters to the overall uncertainty. Although the geochemical and isotopic (?18O) palaeothermometers in carbonates give similar results, their uncertainty remains large (up to 10oC), depending upon the complexity of hydrological situation and lithological composition of the watershed in karstified areas. The anthropogenic influences can completely mask the chemical and isotopic palaeotemperature signal.
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The identification of limitations of tufas as palaeotemperature archives in areas, where in the hinterland or in the direct proximity dolomite aquifers occur; if the detrital carbonate (marine limestone and dolomite) component occurs in tufa, both Mg geochemical and ?18O isotopic thermometer may become questionable
- Identification of limitations in areas with complicated hydrological situations, where hydrochemical composition of water and geochemical precipitation of precipitates are influenced by an interplay of many different interconnected or independent factors, including the anthropogenic effluents of organic and inorganic contaminants; anthropogenic signal may completely cover the natural geochemical and temperature signal
- Estimation of mass balance of carbon in a tufa precipitating stream showed, that rivers effectively remove fixed C as carbonate from the area. At present climate conditions in the investigated area, the contribution of the CO2 fixation to the overall CO2 balance is virtually negligible compared to the discharge of dissolved inorganic carbon from the area. Emanation of CO2 through degassing into the atmosphere is about an order of magnitude higher than CO2 fixation, however, still small compared to the discharge of dissolved inorganic C (? 0.5 %). We emphasise, however, that the situation in the Krka river is very specific compared to other rivers in Slovenia, (such as Sava), mainly because of the high degree of karstification of entire Krka river catchment and watershed and continuous diffuse river recharge, contributing fresh dissolved CO2 to the river water on its entire course.
Significance for the country
The results of the project can contribute to the expert groundwork for the Natura 2000 areas management, which partly extend also over Krka river valley. Tufa is one of typical phenomena of karstified areas and Slovenia, as a classical karst country, where the karst research and terminology were born, paid surprisingly little attention to their research. To our knowledge, this was the first research project which was dedicated to a systematical research of tufa precipitation. Following the definition of United Nations, tufa is considered as natural heritage. Nevertheless, in Slovenia not even an inventarisation of tufa springs and waterfalls was made. As one of the key geomorphological and landscape features of the Krka river valley, the river and its waterfalls are exploited for tourism. Rafting, kayaking, fishing, camping at river banks, aquaculture, illegal and uncontrolled exploitation of tufa as building and ornamental stone, anthropogenic effluents to the river etc., they all may affect the precipitation and sustainability of tufa barriers, although – to this moment and as concluded from the results of our study – the existence of the barriers is not yet in jeopardy.
Publications deriving from the project – most of them are still in preparation – have been cited in the best scientific journals. They will all contribute to the affirmation of Slovene palaeoclimatology and hydrochemistry.
During the course of the project, we connected to the leading tufa research groups in the world. In particular, we got involved into cooperation with the research group lead by Prof. Concepcion Arenas Abad from the University in Zaragoza, which is definitely one of the leading groups in the area of mineralogical and geochemical analysis of recent tufa in Europe. In 2010, we joined the project CGL2009-09216 "Significado ambiental (climatico e hidrologico) de registros tobaceos de la Cordillera Iberica monitorizados entre 1999 y 2009. Comparacion con otros registros recientes y antiguos", coordinated by prof. Arenas Abad, as a EU team member. The project is funded by CSIC (Spanish Superior Council of Scientific Research). This cooperation was preceded by contacts established with the Autonomous University of Madrid, Department of Geography, and Spanish Geological Survey (IGME).
Most important scientific results
Annual report
2008,
2009,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2008,
2009,
final report,
complete report on dLib.si
