CICEET Progress Report for the period 9/16/06 Through 3/15/07

Project Title: An in situ sediment porewater sampler for organic micropollutants based on solid phase microextraction (SPME) technology
Principal Investigator(s): Keith A. Maruya, Eddy Y. Zeng and Steven M. Bay
Project Start Date: 9/1/05 (anticipated); 11/14/05 (actual)

Figures

Figure 1a

Figure 1b

Figure 2

Figure 3

Tables

Table 1

Table 2

Tasks to meet objectives
(1) Design of long term time series experiment completed and experiment initiated.
(2) Experiments using radiolabled analogs designed and initiated.
(3) Incorporate reverse sorption analytes into SPME fibers for evaluation in long term day time series experiments.
(4) Collect, process and analyze estuarine sediments with low background contamination. Spike with various concentrations (50-1000ppb each analyte) and age for 60d minimum in accordance with protocols optimized in Year 1.
(5) Complete and submit articles (1) predicting sampler performance via modeling; and (2) detailing the use of radiolabeled analogs in assessing the mass balance and compartmental distribution associated with SPME fiber calibration experiments.

Progress on Tasks
Tasks 2 and 5 have been completed. Tasks 1 and 3 are underway and are scheduled for completion (as planned) by 5/07. Task 4 was delayed by facility move and is now scheduled for completion by 6/07.

Project Objectives for Next Reporting Period

Work plan to Meet Objectives
(1) Complete spiking and aging of estuarine sediments for Year 2 bioaccumulation experiments
(2) Design and initiate Year 2 bioaccumulation experiments
(3) Complete data analyses for Year 1 60 d equilibrium and time series experiments

Anticipated Success in Meeting Project Objectives
(1) Sediments collected 12/06; processing and analysis of sediment scheduled for completion 4/1/07; spiking to commence on 4/1/07; aging completed by 6/1/07.
(2) Initial planning meeting held 2/07; preliminary experiments scheduled for 3/07-6/07; initiate bioaccumulation experiment #1 on 6/15/07, complete by 8/1/07; initiate bioaccumulation experiment #2 on 9/15/07, complete by 11/1/07.
(3) Data analysis of Year 1 data to be completed by 5/1/07

Overall Project Timeline Update
See Table 2

Summary of Results
Time to equilibrium in spiked test sediments. A long-term (240 day) time series experiment was initiated to determine the time needed to establish equilibrium between the porewater sampler fitted with a 100 _m PDMS-coated SPME fiber and estuarine sediments spiked with 12 representative target analytes. Replicate samplers were placed under static conditions in sediment spiked at ~ 300 ng/g (each analyte) and aged for a period exceeding 4 months. Target compound masses associated with the SPME fibers (Nf) generally stabilized by day 30 (e.g. for PCB-52) and did not increase after 60 d for PCB-180, the most hydrophobic compound tested (Figure 1a and Figure 1b). Under static (i.e. worst case) conditions for this combination of analytes and sampler configuration, it was concluded that maximum equilibration times are as long as 2 months.

Assessment of SPME calibration parameters using radiolabled HOC analogs. PDMS-water distribution coefficients (Kfs) from the literature vary in some cases over several orders of magnitude for the same target HOC. To determine which published values are most applicable, a procedure to measure Kfs using commercially available 14C-labeled HOC analogs was developed. Briefly, the radioactivities associated with the spiked aqueous phase, the experimental system surfaces (glassware and stir bar) and the SPME fiber were accurately determined using liquid scintillation counting. For three model analytes (PCB-52, PCB-153 and benzo[a]pyrene), essentially all radioactive material was recovered in the three measured compartments, with the aqueous phase containing a small percentage of the initial radiolabel added (Figure 2). Kfs determined by this technique agreed well with selected previously published values (Table 1), underscoring the need for careful determination and selection of calibration parameters prior to sampler deployment.

Reducing sampler exposure times in situ. In some, but not all instances, a more rapid in situ deployment period for the SPME-based sampler may be desirable. To determine if HOC uptake by the sampler can be predicted using kinetic models, 100 mm SPME fibers were pre-loaded with perdeuterated PAH analogs prior to installation in the sampler and exposure to spiked estuarine sediments in the long-term time series experiment. Although sampling and data analyses are incomplete, preliminary data for some analytes suggest the use of reverse sorption first order sorption/desorption kinetics may be sufficient to predict HOC masses sorbed by SPME fibers prior to reaching equilibrium with the surrounding sediment porewater (Figure 3). This would allow the sampler to be useful under non-equilibrium conditions (i.e. shorter exposure times).

Dissemination
Publications:
(1) Yang ZY, Zeng EY, Maruya KA, Mai BX, Ran Y. 2007. Predicting organic contaminant concentrations in sediment porewater using solid phase microextraction. Chemosphere 66:1408-1414.

(2) Yang ZY, Greenstein D, Zeng EY, Maruya KA. Determination of poly(dimethyl)siloxane-water partition coefficients for selected hydrophobic organic chemicals using 14C-labeled analogs. J Chromatogr A (in press)

Workshops attended: None

Conferences:
(1) PI Maruya gave a presentation titled “Passive in situ sampling technologies for measuring ultratrace aqueous concentrations of organic contaminants” at the SETAC Asia/Pacific 2006 Conference, Beijing, China, Sept. 18-21, 2006. (~400 participants)

(2) PI Maruya gave a presentation titled “A solid phase microextraction (SPME)-based sampler for bioavailable organic contaminants in sediment porewater” at the Fourth International Conference on Remediation of Contaminated Sediments, Savannah, Georgia, Jan. 22­25, 2007. (~800 participants)

Manuals, Protocols: None

Outreach Activities:
(1) Invited seminar “Can we regulate persistent organic pollutants (POPs) in urbanized coastal environments? Department of Civil and Environmental Engineering, California State University Fullerton, November 28, 2006. (~30 participants)

(2) Invited seminar “Passive sampling techniques for organic contaminants in aquatic systems, Environmental Toxicology Departmental Symposium, University of California, Riverside, December 6, 2006. (~50 participants)

Contact with End Users:
A presentation on the development and application of this technology was given to SCCWRP’s Technical Advisory Group at their quarterly meeting on 2/14/07 by PI Maruya (~30 participants). Advisors present at this meeting represented the regulatory (State of California Water Boards, USEPA Region 9), discharger (City and Counties of Los Angeles and San Diego, Orange and Ventura Counties) and resource management (California Coastal Commission) communities. Mr. Chris Beegan, project manager for the development of sediment quality objectives (SQOs) for the State of California and End User Advisor for this project, participated in the discussion on the potential utility of this tool relative to SQO development and implementation. Sidebar discussions with Messrs. T. Fleming (USEPA) and D. Gregorio (California State Water Resources Control Board) on potential applications of the SPME sampler were held. These stakeholders are routinely involved with the regulation and management of organic pollutants in contaminated sediments.

This project is also incorporated into the 2007-08 SCCWRP Draft Research Plan, which is approved by SCCWRP Member Agencies, including those listed in the previous paragraph.

Patent, Copyright, Invention Disclosure Activity: None

Expenditures
A total of $162,878 has been encumbered by SCCWRP since project inception (11/14/05) to 12/31/06 (Expenditures for the period 01/01/07 to 03/1/07 were not available at time of press). Because of the nearly 3-month delay in the original contract start date, the expenditures to date are in the range anticipated for the work accomplished in this reporting period. We anticipate an increased rate of encumbrance over the next reporting period in support of the multiple tasks planned.

End User Advisor Feedback
Name: Chris Beegan
Organization: State Water Resources Control Board, California
Location: Sacramento, CA
Phone number: 916 341 5577
E-mail: cbeegan@waterboards.ca.gov

1) At this stage, what are the potential applications for this research? Please discuss how you and others could potentially use the technology.
This technology would provide a direct measure of the potential bioavailability of sediment-associated organic pollutants, which could be incorporated into sediment quality objectives under development for the State of California. The primary drawback associated with bulk sediment chemistry, a widely used assessment tool, is that it provides no information on the bioavailable fraction. In the future, SPME could actually provide greater utility and performance in quantifying the bioavailable fraction of pollutants within any aqueous media. If this is demonstrated, measurements from this sampler could potentially replace sediment chemistry in the multiple line of evidence (MLOE) approach proposed by the State for assessing sediment quality.

2) What, if anything, has changed about this project's potential applicability since the last reporting period (not applicable to the first Progress Report)?
The experimental results described herein further validate previously adopted procedures used to calibrate the SPME fibers and suggest that flexibility in deployment times is possible. While the State Water Board is moving forward with a sediment quality control plan for bays and estuaries, sediment managers are still hampered by the lack of tools that provide an accurate measure of bioavailability. These results suggest that SPME may significantly improve our ability to determine which chemicals could potentially harm aquatic life. Staff at the State Water Board believes that developing sound and reproducible measures of bioavailability is critical to the long-term success of sediment quality management and restoration.

3) Do you see any key challenges that the researchers may want to address or keep in mind?
The next key challenge is to demonstrate the correlation between sampler measurements and bioavailability (e.g. bioaccumulation by benthic invertebrates), scheduled to commence during the next reporting period.

4) Does this report offer you enough information to adequately address the above questions? Yes

5) Other feedback? These most recent findings are very encouraging.