title: Efficiency of sediment quality guidelines for predicting toxicity: the case of the St. Lawrence River.
abstract: Multitiered frameworks that are designed for risk assessment of contaminated sediment rely on sediment quality guidelines (SQGs) at the first tier or screening level. In the case of contamination by multiple pollutants, results can be aggregated under indices such as the mean quotient. A decision is then reached (e.g., to dispose of dredged materials in open water) without further investigation, provided that the SQGs or the specific values of indices or quotients derived from the SQGs are not exceeded. In this way, SQGs and quotients play a critical role in environmental protection. As part of the development of a tiered framework to assess the environmental risk of materials dredged from the St. Lawrence River, we evaluated various quotients based on SQGs available for this river with a data set that matches chemistry and toxicity test endpoints. The overall efficiency of all tested quotients was rather low, and we then examined factors such as sediment grain size, nutrients, metal-binding phases (e.g., Al, Fe), and dissolved organic carbon to explain misclassified samples. This examination led to the design of a modified tier 1 framework in which SQGs are used in combination with decision rules based on certain explanatory factors.
authors.affiliation: Cemagref UR MALY, 3bis quai Chauveau CP 220, 69336 Lyon Cedex 9, France. melanie.desrosiers@mddep.gouv.qc.ca
authors.forename: Mélanie
authors.initials: M
authors.lastname: Desrosiers
authors.forename: Marc P
authors.initials: MP
authors.lastname: Babut
authors.forename: Magella
authors.initials: M
authors.lastname: Pelletier
authors.forename: Caroll
authors.initials: C
authors.lastname: Bélanger
authors.forename: Suzie
authors.initials: S
authors.lastname: Thibodeau
authors.forename: Louis
authors.initials: L
authors.lastname: Martel
mesh_terms: D000818:Animals; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity*; D019015:Geologic Sediments / Q000737:chemistry*; D017408:Guidelines as Topic; D008670:Metals / Q000032:analysis / Q000633:toxicity; D009656:North America; D009930:Organic Chemicals / Q000032:analysis / Q000633:toxicity; D018570:Risk Assessment; D045483:Rivers / Q000737:chemistry*; D018675:Toxicity Tests; D014865:Waste Disposal, Fluid
chemical_list: D004785:Environmental Pollutants; D008670:Metals; D009930:Organic Chemicals