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

Abstract

The ΣPAH model estimates the probability of toxicity of PAH‐contaminated sediments using a combination of equilibrium partitioning, QSAR, 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 (PAH1W) of the 13 compounds were predicted by equilibrium partitioning. The 10‐d LC50 of each compound in interstitial water (10‐d LC501W) was predicted by a QSAR regression of 10‐d LC501W (from spiked sediment tests) to Kow. Toxic unit concentrations of individual compounds (TU1) were predicted as PAH1w/10‐d LC501w. The total number of toxic units of the 13 compounds (ΣTU1) was calculated assuming the additivity of toxic effects of PAHs. ΣTU1 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 ΣPAH 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 theΣPAH model correspond with several sediment‐quality guidelines.

Characterizing ecological risk for polycyclic aromatic hydrocarbons in water from Lake Taihu, China

“…As shown in Fig. 2 (Swartz et al 1995). This may be attributed to subtle differences in exposure levels and aquatic ecosystem structure and functions in different study areas, as well as regional water quality parameters such as pH, dissolved organic matter (DOM), and hardness.…”

Sedimentary loadings and ecological significance of polycyclic aromatic hydrocarbons in a typical mariculture zone of South China

“…1,[42][43][44][45][46][47][48] At the same time, there is also considerable controversy over the effectiveness of these sediment guidelines in assessing ecological risks caused by PAHs. 49,50 However, Swartz 51 has noted that these sediment quality guidelines are more similar than dissimilar, and has proposed consensus guidelines for PAHs, i.e., threshold, median and extreme effects concentration (TEC, MEC and EEC).…”

Comparison of porewater and elutriate bivalve larval development toxicity testing in a sediment quality triad framework

“…Values for log LC were available from Swartz et al (1995) and are summarized in Table 10. PAHsCdiment and foc values were available for the three samples from chemical analyses conducted as part of the SQT.…”

“…These physical sediment characteristics also influence the bioavailability of COPCs, and make predictions of adverse biological effects based on bulk sediment concentrations unreliable. As a result, equilibrium partitioning models and toxicity testing based on porewater exposures have been used for derive sediment quality criteria for metals (Ankley et al, 1996), nonionic organic compounds (Di Toro et al, 1991), PAHs (Di Toro and McGrath, 2000) and PAH mixtures (Swartz et al, 1995) based on observed correlations between porewater concentrations and adverse biological effects in different benthic organisms. The SQGs are estimated from an acceptable porewater concentration and mathematical formula intended to represent the relationship between porewater and bulk sediment COPC concentrations.…”