The {Sigma}PAH model estimates the probability of toxicity of PAH-contaminated sediments using a combination of equilibrium partitioning, WSAR, toxic unit, additivity, and concentration-response models. The sediment concentration of organic carbon and 13 PAH (polynuclear aromatic hydrocarbon) compounds were measured. Interstitial water concentrations (PAH{sub iw}) of the 13 compounds were predicted by equilibrium partitioning. The 10-d LC50 of each compound in interstitial water (10-d LC50{sub iw}) was predicted by a QSAR regression of 10-d LC50{sub iw} (From spiked sediment tests) to K{sub ow}. Toxic unit concentrations of individual compounds (TU{sub i}) were predicted as PAH{sub iw}/10-d LC50{sub iw}. The total number of toxic units of the 13 compounds ({Sigma}TU{sub i}) was calculated assuming the additivity of toxic effects of PAHs. {Sigma}TU{sub i} was used to predict the probability of toxicity to marine and estuarine amphipods using a concentration-response model derived from spiked sediment toxicity tests. The {Sigma}PAH model was verified by comparing predicted and observed toxicity in field-collected sediment samples. There was 86.6% correspondence and no significant difference between predicted and observed toxicity at PAH-contaminated sites. Ecological-effect levels predicted by the {Sigma}PAH model correspond with several sediment-quality guidelines.

ΣPAH: A Model to predict the toxicity of polynuclear aromatic hydrocarbon mixtures in field‐collected sediments

Sediment quality guidelines (SQGs) for polycyclic aromatic hydrocarbons (PAHs) have been derived from a variety of laboratory, field, and theoretical foundations. They include the screening level concentration, effects ranges—low and—median, equilibrium partitioning concentrations, apparent effects threshold, ΣPAH model, and threshold and probable effects levels. The resolution of controversial differences among the PAH SQGs lies in an understanding of the effects of mixtures. Polycyclic aromatic hydrocarbons virtually always occur in field-collected sediment as a complex mixture of covarying compounds. When expressed as a mixture concentration, that is, total PAH (TPAH), the guidelines form three clusters that were intended in their original derivations to represent threshold (TEC = 290 μg/g organic carbon [OC]), median (MEC = 1,800 μg/g OC), and extreme (EEC = 10,000 μg/g OC) effects concentrations. The TEC/MEC/EEC consensus guidelines provide a unifying synthesis of other SQGs, reflect causal rather than correlative effects, account for mixtures, and predict sediment toxicity and benthic community perturbations at sites of PAH contamination. The TEC offers the most useful SQG because PAH mixtures are unlikely to cause adverse effects on benthic ecosystems below the TEC.

Consensus sediment quality guidelines for polycyclic aromatic hydrocarbon mixtures

Sediment toxicity testing: a bioassay approach using the amphipod Corophium volutator and the polychaete Arenicola marina

Toxicity and heavy metal contamination of surficial sediments from the Bay of Thessaloniki (Northwestern Aegean Sea) Greece.

Characterisation and management of incinerator wastes

Halifax Harbour sediments contain heavy metals and organic contaminants To assess the biological effects of these compounds in the sediment, seven sites spanning a range of known sediment types, water depths, metal levels, and organic contaminant levels were chosen for assessment by a series of tests Sediment toxicity was measured by the reduction of microbial luminescence (Photobacterium phosphoreum) in three Microtoxr tests (pore water, solvent extract, and solid phase), by the percentages of survival and reburial in two amphipod species (Rhepoxynius abronius and Corophium volutator), and by the survival and change in biomass of juvenile polychaete (Neanthes sp) Uptake of contaminants from sediment was assessed by a bioaccumulation test, using a bivalve mollusc (Macoma balthica) The chronic effects of the sediment on bottom-dwelling fish were assessed by histopathological studies on winter flounder (Pseudopleuronectes americanus) collected from the harbor The results of this study showed detectable biological effects of the Halifax sediments on two (Photobacterium phosphoreum and Rhepoxynius abronius) of the four species of tested organisms These effects were associated with high concentrations of polynuclear aromatic hydrocarbons (PAHs) in the harbor sediments The order of sensitivity for the various sediment toxicity tests was Microtox solvent extract = Microtox solid phase > Rhepoxynius abronius > Microtox pore water > Corophium volutator = Neanthes sp Mortality in Macoma was increased, although no significant uptake of contaminants was detected in the bioaccumulation test Hepatic lesions were observed in winter flounder collected from the harbor, suggesting a chronic effect of the contaminated harbor sediment

Rita E. Berrigan

Papers

Sediment bioassessment in Halifax Harbour