Research Areas > Contaminants > Measurement, Fate & Bioavailability > Passive Sampling Applications > In situ Measurements of Toxic Organic Compounds in Sediment Porewater
Project: In-situ Measurements of Toxic Organic Compounds in Sediment Porewater
Background and Objective
The freely dissolved or “bioavailable” fraction of hydrophobic organic contaminants (HOCs) in sediment pore water is a direct measure of the contaminant pool that can impact biological organisms. However, direct quantification of this fraction with current technology is extremely difficult. Passive sampling technologies that measure freely dissolved HOCs offer clear advantages over traditional ex situ techniques. This technology would provide a proxy of direct HOC exposure for sediment dwelling organisms, improving the accuracy and relevance of sediment quality assessment and the efficacy of contaminated site remediation. The goal of this study is to develop and test an in situ sediment pore water sampler based on SCCWRP’s solid phase microextraction (SPME) water column sampler.
Status
This study was initiated in 2006 with anticipated completion in 2011.
Methods
• A prototype sampler was adapted from a previous water column design. Bench-scale SPME fiber calibration, kinetic and equilibrium experiments for regulated HOCs were carried out.
• SPME samplers and live benthic invertebrates were co-exposed for 28 days in aquaria containing spiked and field collected sediments (Figure 1).
• SPME samplers were deployed in the field for several weeks using simple, rugged fixtures (Figure 2)
Figure 1. Prototype solid phase microextraction (SPME) sampler (Left) can detect parts per trillion levels of hydrophobic organic compounds in sediment pore water (Right).
Figure 2. SCCWRP’s in situ deployment fixture for SPME samplers. The frame is composed of iron rebar and samplers are attached using stainless steel hose clamps.
Findings
The compact prototype (Figure 1) was capable of Method Detection Limits (MDLs) as low as 0.01 parts per trillion for equilibration times ranging from days to several weeks. Sampler measurements correlated well with tissue concentrations of co-exposed benthic invertebrates in spiked sediment 28-day bioassays and under field conditions (Figure 3), indicating its potential utility as a surrogate measurement for bulk chemistry in sediment quality assessments.
Figure 3. SPME porewater concentrations correlated well with body burdens (Cb) of DDTs for co-exposed bivalves (Macoma nasuta) and polychaetes (Nereis virens) (top), as well as for PCBs in native bivalves (Protothaca and Tagelus spp.) under field conditions at the Tijuana River National Estuarine Research Reserve (bottom).
Partners
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Tijuana River National Estuarine Research Reserve, U.S. Environmental Protection Agency, Texas A&M University, Space and Naval Warfare Command
Presentation
K Maruya, D Tsukada, W Lao, E Zeng, D Greenstein, and S Bay. February 2009. A SPME-based sampler for in situ assessment of sediment-associated organic contaminants: comparison with invertebrate body burdens. Presented at Fifth International Conference on Remediation of Contaminated Sediments, Jacksonville, FL.
Poster
K Maruya, W Lao, D Tsukada, D Greenstein, S Bay and E Zeng. November 2008. Correlation between SPME-measured sediment porewater and benthic invertebrate concentrations of hydrophobic organic contaminants (HOCs). Presented at Society of Environmental Toxicology and Chemistry (SETAC) 29th Annual Meeting.
This page was last updated on: 2/7/2011