Event Title

Testing the effectiveness of metal uptake by SLMD passive samplers in waters of varying hardnesses

Research Mentor(s)

Ruth Sofield

Description

Stabilized liquid membrane devices (SLMDs) are passive samplers designed to uptake metals in surface waters. They accumulate ionic metals in aqueous sampling media over approximately month-long periods of deployment, giving a time-averaged concentration of bioavailable metal ions. Despite their usefulness in assessing the amounts of metal toxicants in the aqueous environment, the effectiveness of SLMDs remains understudied. One factor influencing their ability to effectively take up metal ions is water hardness. The chelating agent inside the device is mobilized by the complexing of oleic acid with Ca2+, possibly making waters with lower Ca2+ concentrations less amenable to SLMD sampling. Our work was designed to assess the functionality of SLMDs in waters of varying hardness. To do this, we built and deployed SLMDs in 230 mL test chambers with three hardness treatments. Replicates of very soft, moderately hard, and very hard waters were each spiked with one of four metals (Al3+, Cu2+, Ag+, or Zn2+) to a concentration of 200 ppm or a mixture of all three to a total ion concentration of 200 ppm. SLMDs were left in each spiked water over a period of one month, and then were digested for analysis with ICP-MS. Because Ca2+ plays a critical role in mobilizing the chelating agent to the water column, we expect to see less metal on SLMDs placed in spiked soft water than on those placed in spiked hard water.

Document Type

Event

Start Date

May 2018

End Date

May 2018

Location

Environmental Sciences

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Language

English

Format

application/pdf

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May 17th, 12:00 PM May 17th, 3:00 PM

Testing the effectiveness of metal uptake by SLMD passive samplers in waters of varying hardnesses

Environmental Sciences

Stabilized liquid membrane devices (SLMDs) are passive samplers designed to uptake metals in surface waters. They accumulate ionic metals in aqueous sampling media over approximately month-long periods of deployment, giving a time-averaged concentration of bioavailable metal ions. Despite their usefulness in assessing the amounts of metal toxicants in the aqueous environment, the effectiveness of SLMDs remains understudied. One factor influencing their ability to effectively take up metal ions is water hardness. The chelating agent inside the device is mobilized by the complexing of oleic acid with Ca2+, possibly making waters with lower Ca2+ concentrations less amenable to SLMD sampling. Our work was designed to assess the functionality of SLMDs in waters of varying hardness. To do this, we built and deployed SLMDs in 230 mL test chambers with three hardness treatments. Replicates of very soft, moderately hard, and very hard waters were each spiked with one of four metals (Al3+, Cu2+, Ag+, or Zn2+) to a concentration of 200 ppm or a mixture of all three to a total ion concentration of 200 ppm. SLMDs were left in each spiked water over a period of one month, and then were digested for analysis with ICP-MS. Because Ca2+ plays a critical role in mobilizing the chelating agent to the water column, we expect to see less metal on SLMDs placed in spiked soft water than on those placed in spiked hard water.