Assessing Soil Functions for Sustainable Remediation of Contaminated Sites

Doctoral thesis, 2014

Soil contamination is a worldwide problem. Soil remediation is often carried out to reduce the risks posed by contaminants in the soil to human health and environment. Contaminant concentration is typically the only soil quality aspect maintained in remediation projects. However, emerging regulatory requirements on soil protection has introduced the soil function concept and demand that other chemical as well as physical and biological soil quality indicators are considered in soil management projects. Some remediation technologies may adversely impact soil functions, e.g. lead to compaction, nutrient deficiencies, and decreased water storage capacity. Others may lead to improvement of soil functions. Hence, it is important to evaluate the effects of remediation alternatives on soil functions when assessing the overall sustainability of decision options. A generic approach to soil function assessment in sustainability assessments is presented, conceptualizing linkages between soil functions, soil ecosystem services and the environmental, social and economic sustainability domains. A minimum set of soil quality indicators is identified and a scoring method for soil function assessment is developed, taking uncertainties of input data into consideration. The scoring method is further operationalized with the SF Box tool and integrated into SCORE (Sustainable Choice Of REmediation) for sustainability assessment of remediation alternatives. The developed soil function assessment method is applied on four case studies in Sweden. The results show that contaminated soil may have a good nutrient status and a good water storage capacity providing potentially favorable conditions for functioning, while reduction of the risks posed by contaminants to the environment does not necessarily lead to restoration of soil functions. To ensure proper soil functioning, special care needs to be taken with regard to physical, chemical and biological properties of the remediated soil in the top layer within future green areas.