A review of peeper passive sampling approaches to measure the availability of inorganics in sediment porewater

Florent F Risacher; Haley Schneider; Ilektra Drygiannaki; Jason Conder; Brent G Pautler; Andrew W Jackson

doi:10.1016/j.envpol.2023.121581

A review of peeper passive sampling approaches to measure the availability of inorganics in sediment porewater

Environ Pollut. 2023 Jul 1:328:121581. doi: 10.1016/j.envpol.2023.121581. Epub 2023 Apr 11.

Authors

Florent F Risacher¹, Haley Schneider², Ilektra Drygiannaki³, Jason Conder⁴, Brent G Pautler⁵, Andrew W Jackson⁶

Affiliations

¹ Geosyntec Consultants, 135 Laurier Avenue West, Ottawa, Ontario, K1P 5J2, Canada. Electronic address: frisacher@geosyntec.com.
² Geosyntec Consultants, 924 Anacapa St Ste 4A, Santa Barbara, CA, 93101, USA.
³ Geosyntec Consultants, 134 N La Salle St Ste 300, Chicago, IL, 60602, USA.
⁴ Geosyntec Consultants, 3530 Hyland Ave, Suite 100, Costa Mesa, CA, 92626, USA.
⁵ SiREM, 130 Stone Rd. West, Guelph, Ontario, Canada, N1G 3Z2, Canada.
⁶ Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA.

PMID: 37054866
DOI: 10.1016/j.envpol.2023.121581

Abstract

Sediment porewater dialysis passive samplers, also known as "peepers," are inert containers with a small volume of water (usually 1-100 mL) capped with a semi-permeable membrane. When exposed to sediment over a period of days to weeks, chemicals (typically inorganics) in sediment porewater diffuse through the membrane into the water. Subsequent analysis of chemicals in the peeper water sample can provide a value that represents the concentrations of freely-dissolved chemicals in sediment, a useful measurement for understanding fate and risk. Despite more than 45 years of peeper uses in peer-reviewed research, there are no standardized methods available, which limits the application of peepers for more routine regulatory-driven decision making at sediment sites. In hopes of taking a step towards standardizing peeper methods for measuring inorganics in sediment porewater, over 85 research documents on peepers were reviewed to identify example applications, key methodological aspects, and potential uncertainties. The review found that peepers could be improved by optimizing volume and membrane geometry to decrease the necessary deployment time, decrease detection limits, and provide sufficient sample volumes needed for commercial analytical laboratories using standardized analytical methods. Several methodological uncertainties related to the potential impact of oxygen presence in peeper water prior to deployment and oxygen accumulation in peepers after retrieval from sediment were noted, especially for redox-sensitive metals. Additional areas that need further development include establishing the impact of deionized water in peeper cells when used in marine sediment and use of pre-equilibration sampling methods with reverse tracers allowing shorter deployment periods. Overall, it is expected that highlighting these technical aspects and research needs will encourage work to address critical methodological challenges, aiding in the standardization of peeper methods for measuring porewater concentrations at contaminated regulatory-driven sediment sites.

Keywords: Inorganic; Metals; Passive sampling; Peepers; Porewater; Sediment.

Publication types

Review

MeSH terms

Environmental Monitoring* / methods
Geologic Sediments / analysis
Metals / analysis
Water / analysis
Water Pollutants, Chemical* / analysis

Substances

Metals
Water
Water Pollutants, Chemical