Proposals for Quality Criteria for Sediments
Sediment quality criteria (SQC) can be used for sediment quality assessment by comparing environmental concentrations of the target substances with the corresponding quality criteria.is largely based on the EU Technical Guidance for Deriving Environmental Quality Standards (TGD). For most substances, the protection objective is to prevent benthic communities from deterioration, i.e. the SQC are derived using ecotoxicological effect data and represent threshold concentrations for risk in benthic organisms above which adverse effects cannot be ruled out. For some substances that tend to bioaccumulate and biomagnify, the protection objective of secondary poisoning in organisms higher in the food chain (e.g. fish, birds, mammals) has been taken into consideration in the derivation process.
The SQC refer to whole sediment (< 2 mm grain size) and, where stated, to 1 % Total Organic Carbon (TOC). Normalisation for the TOC content of the sediment being assessed is recommended. Exceeding the SQC does not necessarily signal impairment of the biological community or certify toxicity, but it can no longer be excluded that organisms are not affected. Indeed, differences in the bioavailability and hence the toxicity of contaminants in different sediment types are likely to occur. Thus, it is recommended that SQC be employed as screening tools. Under most circumstances, exceedance of the criteria should trigger additional investigations to refine the risk assessment or verify the potential risk associated with the exceedance. The generic tiered assessment framework proposed for sediment quality assessment in which SQC are used in a first screening step can be found here (see). The derivation dossiers are already linked in the table or can be obtained from the Ecotox Centre.
(a) SQC are classified as preliminary (P) if not enough effect data are available for their derivation (more information).
(b) Derived for 1 % Total Organic Carbon (TOC). Normalisation for the TOC content recommended before comparison
(c) Added Risk Approach. The SQC can be adapted to the local situation by adding to the background concentration 17.9 mg/kg for Zn and 0.016 mg/kg d.w. for Hg.
(d) Protects from all planar PCBs.
(e) Substance potentially bioaccumulated and biomagnified. The SQC is intended to protect top predators from secondary poisoning.