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Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis

Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis
Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis
This study describes a method to quantify the chemical composition of deep30 sea hydrothermal deposits in situ using laser-induced breakdown spectroscopy (LIBS). Partial least squares (PLS) regression analysis is applied to spectra obtained using a long laser pulse with a duration of 150 ns. The number of measurements needed to address the spatial heterogeneity of samples is determined through high-resolution mapping of the elemental distribution in rock samples. PLS applied to laboratory measured seawater-submerged samples achieved an average relative error (RE) of 25 % for Cu, Pb, and Zn compared to benchmark concentration values in cross-validation and validation studies, where both the benchmark concentration values and LIBS spectral data are made available with this publication. The PLS model was applied to LIBS signals obtained in situ from hydrothermal deposits at 1000 m depth in the ocean. The results show that target inhomogeneity limits the accuracy of the surface LIBS measurements compared to benchmark values from bulk analysis of samples. Making multiple measurements with small position offsets at each location improves the accuracy of estimates compared to an equivalent number of measurements at a single position. Maps of element distribution generated using quantified in situ data demonstrates how chemical survey outputs can be generated by combining LIBS with multivariate analysis. This enables real-time chemical feedback during deep-sea operations and chemical surveys in situations or with platforms where sample recovery is not possible.
0967-0637
Takahashi, Tomoko
937057f6-8e83-4a7f-b11f-b549c94afdf6
Thornton, Blair
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Yoshino, Soichi
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Sakka, Tetsuo
fd41ffee-1abd-46cb-99dc-94bb96aecc38
Ohki, Koichi
0591f5f7-dcf3-45b0-a6ee-9b026b7b82a6
Ohki, Toshihiko
e8962f22-9e79-46b8-8b97-8a99c3dc47d4
Nozaki, Tatsuo
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Takaya, Yutaro
5d136173-0577-4dfe-9d9e-6e20a64606c0
Takahashi, Tomoko
937057f6-8e83-4a7f-b11f-b549c94afdf6
Thornton, Blair
8293beb5-c083-47e3-b5f0-d9c3cee14be9
Yoshino, Soichi
4da2ce3b-a3f1-498f-b940-90b39580e99c
Sakka, Tetsuo
fd41ffee-1abd-46cb-99dc-94bb96aecc38
Ohki, Koichi
0591f5f7-dcf3-45b0-a6ee-9b026b7b82a6
Ohki, Toshihiko
e8962f22-9e79-46b8-8b97-8a99c3dc47d4
Nozaki, Tatsuo
72088ad3-6a8e-44b5-8192-968b3530a545
Takaya, Yutaro
5d136173-0577-4dfe-9d9e-6e20a64606c0

Takahashi, Tomoko, Thornton, Blair, Yoshino, Soichi, Sakka, Tetsuo, Ohki, Koichi, Ohki, Toshihiko, Nozaki, Tatsuo and Takaya, Yutaro (2020) Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis. Deep Sea Research Part I: Oceanographic Research Papers. (doi:10.1016/j.dsr.2020.103232).

Record type: Article

Abstract

This study describes a method to quantify the chemical composition of deep30 sea hydrothermal deposits in situ using laser-induced breakdown spectroscopy (LIBS). Partial least squares (PLS) regression analysis is applied to spectra obtained using a long laser pulse with a duration of 150 ns. The number of measurements needed to address the spatial heterogeneity of samples is determined through high-resolution mapping of the elemental distribution in rock samples. PLS applied to laboratory measured seawater-submerged samples achieved an average relative error (RE) of 25 % for Cu, Pb, and Zn compared to benchmark concentration values in cross-validation and validation studies, where both the benchmark concentration values and LIBS spectral data are made available with this publication. The PLS model was applied to LIBS signals obtained in situ from hydrothermal deposits at 1000 m depth in the ocean. The results show that target inhomogeneity limits the accuracy of the surface LIBS measurements compared to benchmark values from bulk analysis of samples. Making multiple measurements with small position offsets at each location improves the accuracy of estimates compared to an equivalent number of measurements at a single position. Maps of element distribution generated using quantified in situ data demonstrates how chemical survey outputs can be generated by combining LIBS with multivariate analysis. This enables real-time chemical feedback during deep-sea operations and chemical surveys in situations or with platforms where sample recovery is not possible.

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Takahashi_DSR_2020 - Accepted Manuscript
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More information

Submitted date: 21 January 2020
Accepted/In Press date: 25 January 2020
e-pub ahead of print date: 27 February 2020

Identifiers

Local EPrints ID: 437906
URI: http://eprints.soton.ac.uk/id/eprint/437906
ISSN: 0967-0637
PURE UUID: 6b1a37f8-6835-4ff3-8950-42e72c4e6c7e

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Date deposited: 24 Feb 2020 17:30
Last modified: 06 Oct 2020 20:08

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