Workreport 2017-2



Geochemical and Physical properties and in Situ distribution Coefficients of the Deep Soil Pits OL-KK25 and OL-KK26 at Olkiluoto


Kuusisto, J.



Page count:



In this working report the geochemical and physical properties together with in situ distribution coefficients, Kd values of the deep soil pits (OL-KK25 & OL-KK26) were analyzed. The in situ Kd values are used to estimate the mobility of radionuclides in different environments. In this research the focus was in the indigenous key elements (Ag, Cl, Cs, I, Mo, Nb, Ni, Pb, Se, Sn and Sr). These elements are the most important elements in safety assessment because they are analogues to the highest doses
contributing radionuclides from the repositories.

The Kd values were calculated from the total and bioavailable element concentrations. The bioavailable concentrations were analysed with NH4Ac (pH 4,5) extraction and total concentrations with HNO3-HF (trace) extraction or LiBO2 fusion. In addition to the Kd values for the deep soil layers, grain size distribution, organic matter content (LOI), pH, organic and inorganic carbon, main anions of the pore water and mineralogy were analysed. The cation exchange capacity (CEC) and base saturation (BS) were calculated using the the results of NH4Ac (pH 4.5) extraction. Finally, all the soil parameters and Kd values were taken into correlation analysis to find out the most important parameters that have influence on the mobility of elements.

According to the earlier and this study at Olkiluoto, heterogeneity is more common than homogeneity. The soil types among other properties varies significantly between the soil pits and vertically within the pits. Due the high variability on soil properties, also the concentrations and Kd values varied widely. According to this study, significant factors that effect on Kd values are mineralogy, clay content, grain size, organic matter content and pH. The environmental factors influence on the speciation of elements which after all determines the behavior of elements at the geo-biosphere interface. The results of this study improves understanding the dependency of element mobility with soil parameters which enables to assess the radionuclide transportation from repositories to surface environment with more accurate site specific soil parameters. The soil type-classification functions also as a basis for overburden modelling, biotope classification and forecasts of future environment developments by determining the vegetation succession and available habitats for fauna.


Deep soil pits, soil profiles, geochemical properties, distribution coefficients (Kd values) and Olkiluoto.


Geochemical and Physical Properties and in Situ Distribution Coefficients of the Deep Soil Pits OL-KK25 and OL-KK26 at Olkiluoto (pdf) (4.5 MB)


Share article:
This website stores cookies on your computer. These cookies are used to improve our website and provide more personalised services to you.


To make this site work properly, we sometimes place small data files called cookies on your device. Most big websites do this too.

1. What are cookies?

A cookie is a small text file that a website saves on your computer or mobile device when you visit the site. It enables the website to remember your actions and preferences (such as login, language, font size and other display preferences) over a period of time, so you don’t have to keep re-entering them whenever you come back to the site or browse from one page to another.

2. How do we use cookies?

A number of our pages use cookies to remember your actions and preferences (such as login, language, font size and other display preferences.)

Also, some videos embedded in our pages use a cookie to anonymously gather statistics on how you got there and what videos you visited.

Enabling these cookies is not strictly necessary for the website to work but it will provide you with a better browsing experience. You can delete or block these cookies, but if you do that some features of this site may not work as intended.

The cookie-related information is not used to identify you personally and the pattern data is fully under our control. These cookies are not used for any purpose other than those described here.

3. How to control cookies

You can control and/or delete cookies as you wish – for details, see You can delete all cookies that are already on your computer and you can set most browsers to prevent them from being placed. If you do this, however, you may have to manually adjust some preferences every time you visit a site and some services and functionalities may not work.