A field-deployable method for measuring picomolar mercury levels in natural waters
11 affiliations
- 1Scripps Institution of Oceanography
- 2University of California San Diego
- 3University of San Diego
- 4Department of Marine and Fisheries Sciences
- 5University of Ghana
- 6Graduate School of Oceanography
- 7University of Rhode Island
- 8Department of Earth and Environmental Sciences
- 9University of Michigan
- 10Ocean Sciences Department
- 11University of California
Abstract
Measurements of mercury (Hg) at sub- to picomolar concentrations in natural waters often rely on cold vapor atomic fluorescence spectrometry (CVAFS), which provides the sensitivity required for trace detection. However, CVAFS instruments are not well suited for routine field deployment and require compressed high-purity argon or helium gas to operate, limiting their use in remote regions and locations without established analytical infrastructure. Cold-vapor atomic absorption spectrometry (CVAAS) offers a robust alternative but generally lacks the sensitivity required for low-level natural waters. Here, we optimized and tested the Nippon Instruments EMP Gold+, a purge-and-trap preconcentration system coupled to a portable CVAAS detector, to address this analytical challenge. We developed protocols for total Hg (THg) and dissolved gaseous Hg (DGM) and evaluated their performance in seawater during field deployments in Monterey Bay, California, USA and the Gulf of Guinea, Ghana. The optimized methods achieved detection limits of 0.97 pM for THg and 0.25 pM for DGM. THg measured in the Gulf of Guinea agreed closely with laboratory CVAFS measurements (R 2 = 0.953, slope = 1.11), with field matrix-spike recoveries of 90.6-96.2%. In Monterey Bay, portable DGM measurements reproduced the vertical structure observed independently for dimethylmercury using gas chromatography coupled to CVAFS. We demonstrate that this new approach can support direct measurements in regions where compressed gases and specialized analytical infrastructure are unavailable and provide rapid screening to guide subsequent sampling for more detailed Hg speciation.
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BibTeX
@misc{ovbiebo2026fielddeployable,
title = {{A field-deployable method for measuring picomolar mercury levels in natural waters}},
author = {Roland P. Ovbiebo and Johannes West and Abril Hernandez and Hannah M. Adams and Ziheng Kuang and Gabriella A. Yeboah and Edem Mahu and Melissa Omand and Brian K. Arbic and Carl Lamborg and Amina T. Schartup},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15009893/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009893/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - A field-deployable method for measuring picomolar mercury levels in natural waters
AU - Roland P. Ovbiebo
AU - Johannes West
AU - Abril Hernandez
AU - Hannah M. Adams
AU - Ziheng Kuang
AU - Gabriella A. Yeboah
AU - Edem Mahu
AU - Melissa Omand
AU - Brian K. Arbic
AU - Carl Lamborg
AU - Amina T. Schartup
PY - 2026
DA - 2026/10/05
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009893/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009893/v1
AB - Measurements of mercury (Hg) at sub- to picomolar concentrations in natural waters often rely on cold vapor atomic fluorescence spectrometry (CVAFS), which provides the sensitivity required for trace detection. However, CVAFS instruments are not well suited for routine field deployment and require compressed high-purity argon or helium gas to operate, limiting their use in remote regions and locations without established analytical infrastructure. Cold-vapor atomic absorption spectrometry (CVAAS) offers a robust alternative but generally lacks the sensitivity required for low-level natural waters. Here, we optimized and tested the Nippon Instruments EMP Gold+, a purge-and-trap preconcentration system coupled to a portable CVAAS detector, to address this analytical challenge. We developed protocols for total Hg (THg) and dissolved gaseous Hg (DGM) and evaluated their performance in seawater during field deployments in Monterey Bay, California, USA and the Gulf of Guinea, Ghana. The optimized methods achieved detection limits of 0.97 pM for THg and 0.25 pM for DGM. THg measured in the Gulf of Guinea agreed closely with laboratory CVAFS measurements (R 2 = 0.953, slope = 1.11), with field matrix-spike recoveries of 90.6-96.2%. In Monterey Bay, portable DGM measurements reproduced the vertical structure observed independently for dimethylmercury using gas chromatography coupled to CVAFS. We demonstrate that this new approach can support direct measurements in regions where compressed gases and specialized analytical infrastructure are unavailable and provide rapid screening to guide subsequent sampling for more detailed Hg speciation.
ER -