Guidelines on remediation of contaminated sites
Appendix 6.2
Eco-toxicological risk assessment
An eco-toxicological risk assessment of contaminated sites is carried out in steps, so that the initial assessment is based on existing data or a comparatively simple screening. If a risk is identified, the investigations can then be extended in one or more steps. However, special information on non-sensitive area use may render further assessment obsolete.
Stage 1
The results from chemical analyses are compared with eco-toxicological criteria of soil quality /1,2/. The contamination is unproblematic as regards the soil environment if the criteria for all substances are met, and high concentrations of substances for which no criteria exist are not identified at the site in question.
Stage 2
If a correlation of chemical analyses and eco-toxicological soil-quality criteria pose a risk to the terrestrial environment (plants, soil-dwelling animal life, or micro-organisms), the assessment is supplemented by biological investigations of the uppermost soil strata at the site. If the contaminated area is situated in an urban environment, the investigations at stage 2 may be omitted. If the contamination consists of few substances, or of mixtures of related substances in concentrations which must be deemed high in terms of environmental impact, it is sufficient to examine the effects on the most sensitive group of organisms, if this group is identifiable.
The following test methods are recommended:
Micro-organisms
 | Soil respiration (a general parameter for carbon decomposition in soil: OECD draft or ISO 14240). |
| Inhibition of ammonium-oxidising micro-organisms (a specific parameter for the nitrogen cycle; OECD draft or ISO 14238). |
Plants
The OECD standard test for plants (OECD No. 308 or ISO/CD 11269).
Soil-dwelling animal life:
| OECD earthworm test (acute toxicity, OECD 207 or ISO 11268-1 (DS/ISO)). |
| Collembolan test (reproduction test; ISO/CD 11267). |
If other internationally recognised methods or method suggestions are used, the reasons for this should be stated in the reports.
Stage 3
If one or more tests at stage 2 show effects, it is recommended to carry out a charting of the species composition of plants and/or soil-dwelling animal life at the site with a view to assessing effects on the site.
Stage 4
If, on the basis of the laboratory tests at stage 2 and/or the field investigations at stage 3, the risk assessment displays significant impact on flora, fauna, or micro-organisms, an assessment of the acceptable risk can be carried out. With consideration being given to future area use, proposals can then be prepared for special measures to protect flora, fauna, and micro-organisms, if such protection has not already been achieved by means of measures to protect human health, groundwater, or the surface recipients.
References
| /1/ | Økotoksikologiske jordkvalitetskriterier (‘Eco-toxicological
soil-quality criteria’). Working report from the Environmental Protection Agency. No.
82, 1997. [Tilbage] |
| /2/ | Økotoksikologiske jordkvalitetskriterier (‘Eco-toxicological
soil-quality criteria’). Project on soil and groundwater from the Environmental
Protection Agency. Report No. 13, 1995. [Tilbage] |