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Monitoring of Airborne and Waterborne Toxic Organic Contaminants by Use of Semipermeable Membrane Devices (SPMDs) D. A. Alvarez, J. D. Petty, J. N. Huckins, W. L. Cranor, J. A. Lebo, R. C. Clark, C. E. Orazio U. S. Geological Survey, Columbia Environmental Research Center, Columbia, MO G. L. Robertson U. S. EPA/National Exposure Research Lab, Las Vegas, NV R. E. Stewart Virginia Department of Environmental Quality, Richmond, VA H. F. Prest Agilent Technologies, Palo Alto, CA U. S. Department of the Interior U. S. Geological Survey
Semipermeable Membrane Devices (SPMDs) The SPMD, developed by scientists at the USGS-CERC, is the subject of two U. S. Government patents and is commercially available from Environmental Sampling Technologies, St. Joseph, MO. The SPMD was specifically designed to sequester hydrophobic (I. e. , lipophilic) chemicals from water and air. It is an abiotic mimetic of the bioconcentration process occurring in organisms exposed to lipophilic chemicals. SPMDs have been used worldwide to monitor the presence and potential impacts of lipophilic chemicals in a wide array of ecosystems.
Semipermeable Membrane Devices (SPMDs)
Semipermeable Membrane Devices (SPMDs) Sampling/Uptake – • passively samples chemical residues (log Kow>3) from the vapor or dissolved phase under nearly all environmental conditions. • Integrative sampling (I. e. , linear uptake) exists for most exposure scenarios. Models have been derived for all three phases of SPMD uptake (linear, curvilinear, and equilibrium). • Integrative sampling allows for detection of episodic contaminants releases and is reflective of a time weighted average (TWA) or cumulative dose of lipophilic chemicals.
Permeability/Performance Reference Compounds (PRCs) • analytically non-interfering organic compounds, such as perdeuterated phenanthrene, with moderate to high fugacity from SPMDs that are added to the lipid prior to deployment. • Determination of PRC losses allows for adjustment of calibration data to more accurately represent the exposure conditions. • Corrects for a wide range of environmental conditions (temperature, facial velocity of air/water, biofouling, etc. ) to increase the accuracy of ambient concentration estimates.
Chemical Analysis Exterior Cleaning Dialysate Dialytic Recovery Transport Sealed in can Enrichment and Fractionation Exposed SPMD Instrumental Chemical Analysis
Bioassays and Toxicity Testing Exterior Cleaning Dialysate Dialytic Recovery Sealed in can In vitro toxicity testing Transport Exposed SPMD Solubilize Acute Toxicity & Genotoxicity
Semipermeable Membrane Devices (SPMDs) Ruggedness – • Capable of surviving harsh environmental conditions Quality Control – • Level of QC incorporated is dependent on project goals • Addresses construction, deployment, retrieval, storage, processing, and analysis • Provide information on sample integrity and background interferences associated with the entire sampling and analytical process
Reproducibility Between Replicate SPMDs Rep. 1 Rep. 2 Rep. 3 Mean ± C. V. Fluoranthen e 1360 1450 1400 ± 3. 2% Pyrene 1130 1220 1180 ± 3. 8% Chlorpyrifos 5. 65 5. 35 5. 70 5. 57 ± 3. 4% Diazinon 6. 41 5. 93 6. 34 6. 23 ± 4. 2% t-Chlordane 4. 11 4. 15 3. 89 4. 05 ± 3. 5% o, p’-DDT 1. 29 1. 56 1. 13 1. 33 ± 16% p, p’-DDE 9. 03 7. 94 8. 46 8. 48 ± 6. 4% p, p’-DDD 8. 89 8. 93 8. 18 8. 67 ± 4. 9% Total PCBs 47. 9 39. 1 44. 4 43. 8 ± 10% Analyte concentrations reported as ng/g SPMD Data from SPMD sampling in the Elizabeth River, Virginia Unpublished Data Variation between SPMD replicates is generally <20%.
PAH and PCB Sampling in Antarctica SPMDs were deployed for 50 days at 5 sites at Mc. Murdo Station in Winter Quarter’s Bay, Antarctica. PAH patterns were similar to Diesel Fuel Arctic profiles. Water concentrations of PAHs were estimated up to 1. 5 µg/L. PCBs were present at levels up to 370 ng/SPMD. Patterns were similar to Aroclors 1254 and 1260.
Comparisons To Biomonitoring Organisms • SPMDs sample only the bioavailable dissolved phase, uptake by organisms occurs via respiration (dissolved phase) and feeding (dissolved and suspended) • Reproducible with very low background • Not affected by most water quality parameters or contamination. For some environmental contamination scenarios, the use of SPMDs and organisms are complementary. • Organisms undergo rapid depuration of gut contents and potential biotransformation and excretion of metabolites
Passive Sampling of Water and Coastal Air via SPMDs Water (ng L-1) Air (pg m-3) 49 260 -BHC 0. 89 860 -BHC 0. 21 530 o, p’-DDT ND 340 p, p’-DDT 29 460 p, p’-DDE 33 6300 cis-Chlordane 1. 9 460 trans-Chlordane 6. 8 420 trans-Nonachlor 4. 6 420 HCB A 28 day exposure of SPMDs was performed at Younger Lagoon near Santa Cruz, CA. SPMD uptake is phenomenologicially similar for both air and water allowing estimation of contaminant concentrations using established models. Prest, H. F. ; Jacobson, L. A. ; Huckins, J. N. Chemosphere 1995, 30, 1351 -1361.
Comparison of Active Hi. Vol Samplers and SPMDs for Airborne PCBs Hi. Vol (pg m-3) SPMD (pg m-3) Congener 28 18 12 Congener 52 6. 7 8. 0 Congener 101 4. 2 4. 3 Congener 118 1. 9 1. 6 Congener 138 2. 1 1. 4 Congener 153 3. 1 2. 0 Congener 180 0. 7 0. 5 Total PCBs 93 92 A two month study comparing active Hi. Vol samplers to passive SPMDs was performed by scientists from the Lancaster University in the U. K. PCBs Time required to reach equilibrium between atmospheric and SPMD associated PCBs was estimated to be at least 2. 4 years, thereby allowing extended deployments for the determination of TWA concentrations of PCBs. Ockenden, W. A. ; Prest, H. F. ; Thomas, G. O. ; Sweetman, A. ; Jones, K. C. Environ. Sci. Technol. 1998, 32, 15381543.
Air Sampling along the U. S. /Mexico border SPMDs were deployed at 57 sites within residential areas along the border between Arizona and Mexico as part of an integrated assessment of selected airborne organic contaminants. Analysis of the SPMDs focused on residues of PAHs, OCs, PCBs, and selected current use pesticides (diazinon, chlorpyrifos, endosulfan, permethrin, and trifluralin). In the three cases where SPMDs were deployed inside and outside of the same house, observed levels of contaminants were generally elevated by a factor of 4 or greater within the house.
Az Air Estimated Airborne Concentrations (ng/m 3) Site 2 Site 43 Site 46 Total PAHs 590 3, 200 960 Total PCBs 23 16 12 Chlordanes 1. 4 3. 7 1. 5 Endosulfans 1. 7 1. 4 1. 0 Diazinon 240 130 7. 6 Chlorpyrifos 650 390 0. 4 Permethrins 10 0. 21 1. 1 o, p’-DDT 33 0. 50 0. 95 o, p’-DDE 6. 0 0. 25 0. 18 o, p’-DDD 1. 2
Conclusions SPMDs provide a means of estimating TWA concentrations of lipophilic airborne and waterborne chemicals. Uptake models have been derived to estimate ambient concentrations of selected chemicals based on laboratory calibration data and analyte physicochemical properties. SPMDs can and have been used under most environmental conditions. PRCs increase the accuracy of analyte concentration estimates by correcting for site specific variability of environmental conditions.
Conclusions Complex chemical mixtures sequestered by SPMDs can be subjected to various bioassay tests to determine the potential additive or synergistic effects on organism/human health. SPMDs provide data on a wider range of chemicals from harsher environments than can be achieved by biomonitoring organisms. Additional information available at: http: //wwwaux. cerc. cr. usgs. gov/SPMD/index. ht m
Acknowledgements M. O’Rourke and S. Rogan University of Arizona W. A. Ockenden Lancaster University, United Kingdom Partial Funding for SPMD research provided by U. S. EPA, State of Virginia, U. S. Department of Defense, American Petroleum Institute, and the National Science Foundation.