Coal and Deodorizer Residues in Marine Sediments—contaminants or Pollutants?

Self Cite

Abstract-A Sediment Quality Triad study involving synoptic measures of polycyclic aromatic hydrocarbon (PAH) contamination, toxicity, and resident community (benthic infauna, crab) alteration was conducted to assess impacts from an aluminum smelter discharge. No sediment toxicity was observed, despite extensive testing since 1988 on four test species. Evidence of effects on resident communities was minimal. Effects were not expected in areas Ͼ1 km from the smelter, because PAH concentrations have decreased with recent effluent improvements to below levels associated with effects in other studies. However, concentrations within 1 km of the smelter were high (maximum concentration was 10,000 mg/kg total PAH, although most were Ͻ150 mg/kg). Based on the literature, those concentrations should have had significant effects on toxicity test responses and benthic communities. Because they did not, we conclude that availability of sediment PAH was limited. Concentrations of parent PAH and metabolites in Dungeness crab (Cancer magister) were also low, supporting the hypothesis of limited bioavailability. Bioavailability may be limited because much of the PAH is present as pitch or coal particles. This study indicates that high contaminant concentrations may not be associated with effects, if availability is limited.

Section: Discussionmentioning

confidence: 88%

Limited bioavailability of sediment pah near an aluminum smelter: Contamination does not equal effects

Paine

Chapman²,

Allard³

et al. 1996

Self Cite

“…For example, 1,4‐dichlorobenzene originating from urinal deodorizers was identified as a significant indicator of minor adverse effects (reduced growth of the polychaete Neanthes arenaceodentata , elevated larval abnormalities in the blue mussel Mytilus edulis , and increased abundance and decreased diversity of benthic species) associated with sediments adjacent to a major, relatively untreated marine sewage discharge [36]. However, the mean 1,4‐dichlorobenzene concentration at the outfall was only 0.4 mg/kg 1%OC , and the contribution of 1,4‐dichlorobenzene to the observed effects could not be separated from effects of several metals and/or organic enrichment [37]. Similarly, in toxicity tests of sediment samples collected from a river in Ohio, USA, the sediment sample containing the highest reported concentration of total chlorinated benzenes (toxic index value of 0.2) produced toxicity in the midge Chironomus tentans and the amphipod Hyalella azteca (P.C.…”

Section: Discussionmentioning

confidence: 99%

A model to predict threshold concentrations for toxic effects of chlorinated benzenes in sediment

Fuchsman

Duda

Barber

1999

Abstract-A probabilistic model was developed to predict effects threshold concentrations for chlorinated benzenes in sediment. Based on published quantitative structure-activity relationships relating the toxicity of chlorinated benzenes to the degree of chlorination, congeners with the same number of chlorine substitutions were considered toxicologically equivalent. Hexachlorobenzene was excluded from the assessment based on a lack of aquatic toxicity at the water solubility limit. The equilibrium partitioning approach was applied in a probabilistic analysis to derive predicted effects thresholds (PETs) for each chlorinated benzene group, with model input distributions defined by published log K ow values and aquatic toxicity data (LC50s and acute to chronic ratios) extracted from the published literature. The probabilistic distributions of PETs generally increased with chlorination, with 20th percentile values ranging from 3.2 mg/kg 1%OC for chlorobenzene to 67 mg/kg 1%OC for tetrachlorobenzene congeners. The toxicity of total chlorinated benzenes in sediment can be assessed by applying the PETs in a toxic index model, based on the assumption that multiple chlorinated benzene congeners will show approximately additive toxicity, as characteristic of nonpolar narcotic toxicants. The 20th percentile PET values are one to two orders of magnitude higher than published screening-level guidelines, suggesting that the screening-level guidelines will provide overly conservative assessments in most cases. Relevant spiked sediment toxicity data are very limited but seem consistent with the probabilistic model; additional testing could be conducted to confirm the model's predictions.

“…Unburned coal can be a significant source of total PAHs in marine coastal sediments [41][42][43]. The weak digestive fluids of suspension feeders like Crassostrea virginica and Mytilus edulis and even the stronger fluids of the deposit feeders A. marina, Rhepoxynius abronis, and Neanthes arenaceodentata, seemingly cannot desorb PAHs from coal particles ( [16,17] this study). Polycyclic aromatic hydrocarbons sorbed to coal particles have high desorption activation energies [44] that inhibit dissolution into water and digestive fluids.…”

Section: Geochemical Aspects Of Bioavailabilitymentioning

confidence: 94%

Digestive bioavailability to a deposit feeder (Arenicola marina) of polycyclic aromatic hydrocarbons associated with anthropogenic particles

Voparil

Burgess

Mayer

et al. 2004

Marine sediments around urban areas serve as catch basins for anthropogenic particles containing polycyclic aromatic hydrocarbons (PAHs). Using incubations with gut fluids extracted from a deposit-feeding polychaete (Arenicola marina), we determined the digestive bioavailability of PAHs from fly ashes, coal dusts, diesel soots, tire tread materials, and urban particulates. We found that gut fluids solubilize significant concentrations of PAHs from two tire treads, two diesel soots, and the urban particulates. However, PAHs in fly ashes and coal dusts were not available to the digestive agents in gut fluid. Potential digestive exposure to PAHs is much greater than that predicted to be available from these materials using equilibrium partitioning theory (EqP). Amending an already-contaminated sediment with fly ash decreased phenanthrene solubilization by gut fluid. In contrast, addition of tire tread to the sediment resulted in increased solubilization of four PAHs by gut fluid. Therefore, addition of certain types of anthropogenic particles to sediments may result in an increase in bioavailable PAHs rather than a net decrease, as predicted by EqP. Difficulty in predicting the amount of change due to amendment may be due to interactions occurring among the mixture of compounds solubilized by gut fluid.