Interpreting Results from Field Deployments of Semipermeable Membrane Devices

Abstract

Three canisters of semipermeable membrane devices (SPMDs), each containing five SPMDs, were deployed at three different locations on a transect across a small river removed from the impact of near-field point sources. Following a 62-day deployment, the masses of various polynuclear aromatic hydrocarbons (PAH) sequestered by each SPMD in each canister were determined. The compound-specific mean residues (ng/SPMD) obtained for the PAHs with pK(ow) values >4.4 showed statistically significant (alpha = 0.10) differences between the three deployment locations (canisters) ranging from approximately 10 to 160 ng/SPMD, corresponding to relative percent differences (RPDs) ranging from 10% to 54%. There were no statistically significant differences between the same three locations for the single PAH with a pK(ow) <4.4. A detailed discussion of how different (uncontrollable) environmental variables may have impacted the experimental results is provided to illustrate the uncertainties associated with interpreting the results from SPMD field deployments and highlight the need for some means of correcting for these impacts. The results from this work also illustrate the need to account for spatial variability in water column concentrations (i.e., sample heterogeneity) as part of any interpretation.

Overview and comparison of lipid‐containing semipermeable membrane devices and oysters (Crassostrea gigas) for assessing organic chemical exposure

“…Based on previous SPMD studies [30,31,33,58], differences in environmental conditions of exposure sites are unlikely to affect SPMD sampling rates by more than one order of magnitude. When SPMDs are deployed in an apparatus that baffles flow‐turbulence differences (i.e., the major factor affecting sampling rate of high‐ K ow compounds) among sites [71], variations in the sampling rates of individual compounds are expected to be less. Furthermore, the use of PRCs in SPMDs appears to reduce the uncertainty associated with water concentration estimates across sites to less than twofold [33].…”

Field testing of equilibrium passive samplers to determine freely dissolved native polycyclic aromatic hydrocarbon concentrations

“…Field deployment is a necessity for measuring freely dissolved concentrations in surface water ( C SW,free ) of hydrophobic compounds in the overlying surface water column. Semipermeable membrane devices often have been used, mostly in a nonequilibrium mode [17,18]. Either diffusion calculations [17,18] or isotopically labeled internal standards (performance reference compounds) [10,18] are used to derive C SW,free .…”

“…Semipermeable membrane devices often have been used, mostly in a nonequilibrium mode [17,18]. Either diffusion calculations [17,18] or isotopically labeled internal standards (performance reference compounds) [10,18] are used to derive C SW,free . Semipermeable membrane devices render time‐integrated aqueous concentrations.…”

Development of a Solid-Phase Microextraction-Based Method for Sampling of Persistent Chlorinated Hydrocarbons in an Urbanized Coastal Environment

“…In recent years, an integrative passive sampling technique based on semipermeable membrane devices (SPMD) has been developed (19). SPMDs appear to have overcome many of the drawbacks of the large-volume sampling approaches, but calibration, sample processing, and data interpretation are still involved (19)(20)(21)(22)(23).…”