Soil Geochemical Baselines and Risks

Introduction

In this project, the geochemical geochemical baseline concentrations of soil in actively used Finnish land areas and the risks associated with acid sulphate soils are surveyed and studied. Data is produced on the elemental concentrations of the most common mineral soils from the surrounding soil of growth centres, mining areas and selected production areas. The data is distributed for public use through the national geochemical baseline concentration database (TAPIR) maintained by GTK, as well as other channels. Information on the probability of the occurrence of acidic sulphate soils and on metal concentrations is also added to GTK’s databases.

The project consists of three work packages:
WP1 = urban soil geochemical baselines
WP2 = soil geochemical baseline concentration in mining environments,
WP3 = study of acid sulphate soils.

The Ministry of the Environment has renewed the guidelines for the assessment and remediation of contaminated soil, in which the geochemical baseline concentration database is an integral part of the assessment of soil contamination and the need for remediation. Information on geochemical baseline concentrations is also needed in depositing excavated soils (upcoming government decree on the recovery of soil waste); in connection to changes in land use; in land use planning and the preparation of municipal building codes as initial information for water management solutions in high geochemical baseline concentrations, for example; in baseline studies of areas with mineral potential and industrial areas; and in the extraction of rock materials in areas with high arsenic and metal concentrations. Information on geochemical baseline concentrations is also an integral part of the EIA and permit processes.

The geochemical baseline concentration of the soil in the vicinity of mines is investigated by surveying the geochemical baseline concentrations of the mining areas. The environmental survey of production areas will be started as a pilot study in one active production area and extended during the project to cover all of the planned areas based on the results of the pilot study.

The project supplements existing survey data on acid sulphate soils in line with the objectives of the national strategy for mitigating the adverse effects of acid sulphate soils (Ministry of Agriculture and Forestry, 2011) and Finland’s water resource management plans 2016–2021. The work surveys the prevalence, depth and quality of acid sulphate soil, as well as soil types, acidity and sulphur concentration and the concentrations of 30 other elements. A research report will be prepared on the surveyed acid sulphate soils that describes the principles and methods of the survey. The results of the surveys of acid sulphate soils are presented as maps showing the likelihood of occurrence of acid sulphate soils. The results and background information of the observation points are also displayed on the map. The material is publicly available through GTK’s map service. The data can be used in water protection, land use planning, implementation and remediation. In cooperation with others, we will investigate the formation and occurrence of acid sands, acid tills and acid peat in Finland, as well as their connection to the occurrence of black shales. In the project, the occurrence and properties of acid sulphate soils are studied by modelling. The models will enable us to produce spatial data sets of different scales for customers quickly and reliably.

In addition to data collection, the project investigates the use of soil geochemical baseline concentration data in the risk assessment of population centres, production areas and mining areas. Bioavailability of soil metals is central to risk assessments. Therefore, information, for example, on the solubility and mobility of metals under different conditions (pH, organic matter percentage, clay percentage, oxidation of sulphides, cation exchange capacity, natural geochemical baseline concentration versus anthropogenic concentrations, climate change) is required to support them. In population centres particularly, risk assessments are essentially linked to the identification of different exposure routes (e.g. soil ingestion, urban farming) in high geochemical baseline concentration areas. The solubility of high geochemical baseline concentrations and the absorption of dissolved harmful substances from seepage water into soil and their transfer to groundwater are also studied in the project.

GTK’s self-financed project.

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