J. Kaija - Academia.edu (original) (raw)

Papers by J. Kaija

Europace, 2002

The redox chemistry of a geochemically stable environment such as the Palmottu system has been in... more The redox chemistry of a geochemically stable environment such as the Palmottu system has been investigated based on extensive field measurements. The solid phases controlling uranium concentrations in groundwater, as well as the processes controlling its concentration in the redox transition zone have been studied. On-line redox measurements have been performed at Palmottu in order to ascertain the redox pairs able to control the redox state of this system. By comparing the characteristic reaction times of these redox processes with the residence times of these deep groundwaters we can assume that redox equilibrium is attained in this system. The thermodynamic modelling performed in this natural system indicates two zones with different redox controls: the Western area where the sulphide minerals seem to control the redox potential of this subsystem, and the Eastern area where the uranium mineralisation occurs. In this area the uranium minerals could play an important role as a red...

Uranium in the Aquatic Environment, 2002

Studies of uranium series geochemistry have made relatively little impact on performance assessme... more Studies of uranium series geochemistry have made relatively little impact on performance assessment where simplistic advection-dispersion models are still being used to derive dose and risk estimates. Supplementing the models with a scientifically sound representation of radionuclide migration would greatly enhance the rigour and transparency of the safety case. This paper outlines a methodology for employing natural geochemical fluxes as alternative indicators of repository safety by reference to case studies in Finland. The approach may be applied to any situation where a comparison between ambient exposure rates and increments received due to industrial activities is required.

ABSTRACT Nuclear science and technology EUR 18202

arkisto.gtk.fi

The management of nuclear waste from Finnish power companies is based on the final geological dis... more The management of nuclear waste from Finnish power companies is based on the final geological disposal of encapsulated spent fuel at a depth of several hundreds of metres in the crystalline bedrock. Permission for the licence requires that the safety of disposal is ...

Geofluids, 2003

The Palmottu hydrosystem is located in a granitic host rock in southern Finland. Along well-de®ne... more The Palmottu hydrosystem is located in a granitic host rock in southern Finland. Along well-de®ned pathways in the fractured crystalline rock, strontium isotopes are used to trace the degree of water±rock interaction (WRI) and mixing processes in groundwaters. The 87 Sr/ 86 Sr ratios range between 0.716910 and 0.735606 in the surface waters and between 0.719991 and 0.750787 in the groundwaters, but are between 0.720 and 0.735 in most of the samples. Moreover, the results show a lack of correlation between the water chemistries determining the classi®cation into different water-types (Na±Cl, Na±SO 4 , etc.) and the results of the strontium (Sr) contents and Sr isotopic ratios. From a WRI standpoint, this implies that the Sr behaviour is independent of the water chemistry; the occurrence of large 87 Sr/ 86 Sr variations is site speci®c and mainly dependent on the lithology. A model to determine the 87 Sr/ 86 Sr ratio of water after interaction with granite was developed. This model is based on the assumption that Sr was derived from three minerals: plagioclase, Kfeldspar and biotite. The results of the calculation indicate that around half of the water analysed within the Palmottu hydrosystem can be explained by the weathering of the granites. However, clearly lower 87 Sr/ 86 Sr are observed in waters when compared to the calculated 87 Sr/ 86 Sr and other sources of Sr, with low 87 Sr/ 86 Sr, rather than the calculated granite±water interaction, which may be suspected. When comparing the 87 Sr/ 86 Sr and ion ratios (Ca/Na, Mg/Na, Sr/Na, Cl/Na), the scattering of the data can be explained by the presence of four end-members: a brine component (low 87 Sr/ 86 Sr and Ca/Na ratios.. .), a deep granitic component (high 87 Sr/ 86 Sr ratios and low Ca/Na ratios.. .), a subsurface component (intermediate 87 Sr/ 86 Sr ratios associated with high Ca/Na ratios.. .) and a surface end-member:snow and river drainage (low 87 Sr/ 86 Sr and low Ca/Na ratios.. .). These extreme end-members de®ne a series of WRI-mixing line within a rather complex hydrosystem.

Geological survey of finland, special paper, 1991

Acid mine drainage from banked waste rocks (150 million m^3) and sulfide ore tailings of the Madn... more Acid mine drainage from banked waste rocks (150 million m^3) and sulfide ore tailings of the Madneuli Cu-Au open-pit mine have created major environmental pollution problem in Bolnisi district, Georgia. Intensive leaching of exposed rocks and direct discharge of mine waters to nearby watercourses have lead to strong heavy metal pollution of groundwater and Rivers Kazretula, Poladauri and Mashavera. Increased concentrations of Cu, Zn, Pb, Ni, Mn, Cr, Cd and Hg exceeding maximum permissible values by 3-2000 times, are registered almost everywhere. Polluted surface waters are used intensively for irrigation. Besides, contaminated groundwater is pumped for irrigation and drinking water supply in alluvial deposits along the rivers. Because the spread of contamination is a slow process, the adverse health effects may not yet have emerged in the investigation area. The transport modelling was used in the framework of risk assessment to estimate the direction, rate and extent of chemical mi...

EUR, 2002

The understanding of hydrogeochemical evolution is essential in order to assess the migration of ... more The understanding of hydrogeochemical evolution is essential in order to assess the migration of radionuclides at Palmottu. The objective of this study is to evaluate chemical interaction and mixing processes of groundwater evolution, and also to evaluate the residence time over ...

ABSTRACT Nuclear science and technology EUR 18202

Europace, 2002

The redox chemistry of a geochemically stable environment such as the Palmottu system has been in... more The redox chemistry of a geochemically stable environment such as the Palmottu system has been investigated based on extensive field measurements. The solid phases controlling uranium concentrations in groundwater, as well as the processes controlling its concentration in the redox transition zone have been studied. On-line redox measurements have been performed at Palmottu in order to ascertain the redox pairs able to control the redox state of this system. By comparing the characteristic reaction times of these redox processes with the residence times of these deep groundwaters we can assume that redox equilibrium is attained in this system. The thermodynamic modelling performed in this natural system indicates two zones with different redox controls: the Western area where the sulphide minerals seem to control the redox potential of this subsystem, and the Eastern area where the uranium mineralisation occurs. In this area the uranium minerals could play an important role as a red...

Uranium in the Aquatic Environment, 2002

Studies of uranium series geochemistry have made relatively little impact on performance assessme... more Studies of uranium series geochemistry have made relatively little impact on performance assessment where simplistic advection-dispersion models are still being used to derive dose and risk estimates. Supplementing the models with a scientifically sound representation of radionuclide migration would greatly enhance the rigour and transparency of the safety case. This paper outlines a methodology for employing natural geochemical fluxes as alternative indicators of repository safety by reference to case studies in Finland. The approach may be applied to any situation where a comparison between ambient exposure rates and increments received due to industrial activities is required.

ABSTRACT Nuclear science and technology EUR 18202

arkisto.gtk.fi

The management of nuclear waste from Finnish power companies is based on the final geological dis... more The management of nuclear waste from Finnish power companies is based on the final geological disposal of encapsulated spent fuel at a depth of several hundreds of metres in the crystalline bedrock. Permission for the licence requires that the safety of disposal is ...

Geofluids, 2003

The Palmottu hydrosystem is located in a granitic host rock in southern Finland. Along well-de®ne... more The Palmottu hydrosystem is located in a granitic host rock in southern Finland. Along well-de®ned pathways in the fractured crystalline rock, strontium isotopes are used to trace the degree of water±rock interaction (WRI) and mixing processes in groundwaters. The 87 Sr/ 86 Sr ratios range between 0.716910 and 0.735606 in the surface waters and between 0.719991 and 0.750787 in the groundwaters, but are between 0.720 and 0.735 in most of the samples. Moreover, the results show a lack of correlation between the water chemistries determining the classi®cation into different water-types (Na±Cl, Na±SO 4 , etc.) and the results of the strontium (Sr) contents and Sr isotopic ratios. From a WRI standpoint, this implies that the Sr behaviour is independent of the water chemistry; the occurrence of large 87 Sr/ 86 Sr variations is site speci®c and mainly dependent on the lithology. A model to determine the 87 Sr/ 86 Sr ratio of water after interaction with granite was developed. This model is based on the assumption that Sr was derived from three minerals: plagioclase, Kfeldspar and biotite. The results of the calculation indicate that around half of the water analysed within the Palmottu hydrosystem can be explained by the weathering of the granites. However, clearly lower 87 Sr/ 86 Sr are observed in waters when compared to the calculated 87 Sr/ 86 Sr and other sources of Sr, with low 87 Sr/ 86 Sr, rather than the calculated granite±water interaction, which may be suspected. When comparing the 87 Sr/ 86 Sr and ion ratios (Ca/Na, Mg/Na, Sr/Na, Cl/Na), the scattering of the data can be explained by the presence of four end-members: a brine component (low 87 Sr/ 86 Sr and Ca/Na ratios.. .), a deep granitic component (high 87 Sr/ 86 Sr ratios and low Ca/Na ratios.. .), a subsurface component (intermediate 87 Sr/ 86 Sr ratios associated with high Ca/Na ratios.. .) and a surface end-member:snow and river drainage (low 87 Sr/ 86 Sr and low Ca/Na ratios.. .). These extreme end-members de®ne a series of WRI-mixing line within a rather complex hydrosystem.

Geological survey of finland, special paper, 1991

Acid mine drainage from banked waste rocks (150 million m^3) and sulfide ore tailings of the Madn... more Acid mine drainage from banked waste rocks (150 million m^3) and sulfide ore tailings of the Madneuli Cu-Au open-pit mine have created major environmental pollution problem in Bolnisi district, Georgia. Intensive leaching of exposed rocks and direct discharge of mine waters to nearby watercourses have lead to strong heavy metal pollution of groundwater and Rivers Kazretula, Poladauri and Mashavera. Increased concentrations of Cu, Zn, Pb, Ni, Mn, Cr, Cd and Hg exceeding maximum permissible values by 3-2000 times, are registered almost everywhere. Polluted surface waters are used intensively for irrigation. Besides, contaminated groundwater is pumped for irrigation and drinking water supply in alluvial deposits along the rivers. Because the spread of contamination is a slow process, the adverse health effects may not yet have emerged in the investigation area. The transport modelling was used in the framework of risk assessment to estimate the direction, rate and extent of chemical mi...

EUR, 2002

The understanding of hydrogeochemical evolution is essential in order to assess the migration of ... more The understanding of hydrogeochemical evolution is essential in order to assess the migration of radionuclides at Palmottu. The objective of this study is to evaluate chemical interaction and mixing processes of groundwater evolution, and also to evaluate the residence time over ...

ABSTRACT Nuclear science and technology EUR 18202