PAH effects on meio- and microbial benthic communities strongly depend on bioavailability

Area of Science:

• Environmental Science
• Ecotoxicology
• Marine Biology

Background:

• Anthropogenic pollutants' effects differ based on habitat and bioavailability, which remains poorly understood.
• Assessing environmental impacts of polycyclic aromatic hydrocarbons (PAHs) requires understanding if total concentration measurements suffice or if bioavailability must be considered.

Purpose of the Study:

• To evaluate if total polycyclic aromatic hydrocarbon (PAH) concentrations in sediments adequately indicate environmental effects or if bioavailability measurements are necessary.
• To assess the impact of PAH addition on meiofaunal and microbial communities in different marine sediments over 60 days.

Main Methods:

• A 60-day experiment involving the addition of nominal PAH concentrations (1,300 μg/kg) to three distinct marine sediments.
• Analysis of meiofaunal and microbial community responses, including potential nitrification and denitrification rates.
• Measurement of PAH bioavailability in sediments at 0 and 60 days.

Main Results:

• PAH bioavailability varied significantly across the three sediment types, with lower bioavailability observed in muddy sediments.
• Despite bioavailability differences, PAH addition caused significant negative effects on all tested sediments.
• Microbial nitrogen cycle measurements showed a stronger correlation with bioavailable alkylated PAHs, indicating their utility as stress indicators.

Conclusions:

• Sediment characteristics significantly influence PAH bioavailability and subsequent environmental effects.
• Bioavailability measurements of PAHs provide a more accurate assessment of ecological risk than total PAH concentrations.
• Incorporating sediment characteristics and bioavailability data is essential for accurate risk analysis of petroleum-contaminated marine environments.