Research project Mobility and Bioaccumulation of Toxic Metals in Contaminates Soils (ToxMet)
In Sweden, about 86,000 areas are either contaminated or potentially contaminated, often with Cadmium, Lead, or Mercury. Prioritizing their remediation is challenging. This project aims to develop methods to enhance the interpretation of current studies and streamline risk assessment.
Cadmium (Cd), lead (Pb), and mercury (Hg) are all metals classified as particularly hazardous by the Swedish Chemicals Agency. Although we have reduced our direct emissions of these substances today, for example, by no longer using lead additives in gasoline, there are still many contaminated sites in Sweden. For instance, soils around shooting ranges may contain high levels of lead due to the use of lead ammunition, and glassworks have resulted in pollution of both lead, cadmium, and other metals. The extent of risk these areas pose to human health and the environment depends on various factors: the levels present in the soil, whether the metals spread to lakes, streams, and other aquatic systems, how sensitive these areas are to further contamination by pollutants, and how the contaminated areas are utilized. In this project, we aim to enhance risk assessment tools for metal contamination and gain a better understanding of the mobility of toxic metals in polluted soils.
Project description
Risk assessment of contaminated sites in Sweden is based on the Swedish Method for Inventories of Contaminated Sites (MIFO). Today, out of Sweden's 86,000 registered sites identified as potentially or confirmed contaminated, approximately 1,300 are assessed to pose very great risks to human health or the environment. However, a recent analysis comparing Sweden's qualitative risk assessment method with the qualitative approach employed in Germany indicates that we may be underestimating the number of sites that represent a potential risk (Wanner et al. 2023). Better tools for risk assessment of contaminated sites in Sweden is needed, in particular when it comes to assessing the risk of contaminant release and exposure.
Contaminated soils consist of various natural materials, including various inorganic and organic particles and microorganisms, and a mixture of toxic metals and organic contaminants. To what extent these pollutants are transported with the mobile phase (e.g., groundwater) depends on the type of contaminant and the nature of the particulate matter, microbial activity, and chemistry of the surrounding pore water. Thus, the total concentration of a specific contaminant, often used in risk assessments, is not a very informative parameter for contaminant mobility. To better characterize this risk, standardized leaching and percolation tests are recommended (most common SS-EN-12457-3 and SIS C EN/TS 14405). While these tests offer valuable insights, the assessment and extrapolation of the data they produce pose a significant challenge, as indicated by concerns raised in a report commissioned by SEPA. These concerns encompass the accuracy of these tests in replicating natural conditions, such as pH, redox conditions, and water chemistry. Additionally, the underestimation of contaminant mobility was highlighted, as equilibrium is not always reached in these time-constrained tests, primarily due to slow desorption kinetics.
In this project, we aim to enhance risk assessment tools for metal contamination and gain a better understanding of the mobility of toxic metals in polluted soils.
Specifically, we aim to:
• Describe adsorption/desorption kinetics and quantify mobile and refractory pools of C d, Pb, and Hg in contaminated soils using novel approaches based on isotopically enriched tracers
• Identify environmental conditions and soil characteristics (biotic and abiotic) that enhance metal mobility and bioavailability
• Link toxic metal mobility to their chemical speciation and then to bioavailability for humans and aquatic organisms
• Develop new recommendations on the application of standardized leaching and percolation tests in risk assessment to overcome the limitations of these methods.
Get involved!
We are now working to identify 5-7 contaminated sites to include in our study. These sites should be accessible for sampling and of interest for stakeholders.
More information on our Swedish webpage.
Project members
Project managers
Sofi Jonsson
Associate Professor/Unit manager
Members
Hanna Karlsson
Ulf Skyllberg
Justyna Hampel
Research engineer
Elena Gorokhova
Professor
Ann-Kristin Eriksson Wiklund
Director of Studies/Reseracher