A passive sampler based on solid-phase microextraction for quantifying hydrophobic organic contaminants in sediment...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Ecotoxicology

Background:

• Sediment quality assessment struggles with discrepancies between chemical and biological data.
• Bulk sediment toxicant concentrations often fail to represent bioavailable levels, especially for hydrophobic organic compounds (HOCs).
• Accurate measurement of bioavailable HOCs is crucial for reliable sediment impact assessments.

Purpose of the Study:

• To develop and validate a novel pore-water sampler utilizing solid-phase microextraction (SPME).
• To directly measure freely dissolved (bioavailable) HOC concentrations in sediment pore water.
• To enhance the accuracy of sediment quality assessments.

Main Methods:

• Development of a compact SPME pore-water sampler with polydimethylsiloxane (PDMS)-coated fibers.
• Calibration of SPME fibers for 12 model HOCs across varying coating thicknesses.
• Laboratory microcosm experiments exposing spiked estuarine sediment to the developed samplers.
• Determination of time to equilibrium and equilibrium concentrations of HOCs.

Main Results:

• The SPME pore-water sampler effectively measured freely dissolved HOC concentrations.
• Time to equilibrium ranged from 14 to 110 days, with 30 days sufficient for over half of the target HOCs.
• Equilibrium SPME measurements showed high correlation with, but were generally lower than, independent liquid-liquid extraction results.

Conclusions:

• The developed SPME pore-water sampler shows significant promise for directly measuring bioavailable HOCs in sediment.
• This method addresses a critical gap in measuring difficult-to-quantify parameters in contaminated sediments.
• Improved measurement of bioavailable HOCs will lead to more accurate sediment impact assessments.