Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed Measurements
Gases dissolved in the deep water of lakes can pose a hazard when extreme concentrations are reached. A sudden release of large amounts of gas can cost the lives of humans living in the neighbourhood, as happened at Lake Nyos in 1986. Since 2001, the gas risk at Lake Nyos has been mitigated by induc...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2021-07-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2021.645011/full |
| _version_ | 1819135381370568704 |
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| author | Bertram Boehrer Kazuto Saiki Takeshi Ohba Greg Tanyileke Dmitri Rouwet Minoru Kusakabe |
| author_facet | Bertram Boehrer Kazuto Saiki Takeshi Ohba Greg Tanyileke Dmitri Rouwet Minoru Kusakabe |
| author_sort | Bertram Boehrer |
| collection | DOAJ |
| description | Gases dissolved in the deep water of lakes can pose a hazard when extreme concentrations are reached. A sudden release of large amounts of gas can cost the lives of humans living in the neighbourhood, as happened at Lake Nyos in 1986. Since 2001, the gas risk at Lake Nyos has been mitigated by induced degassing, but the lake continues to be supplied by CO2, and a regular survey needs to be implemented to guarantee safe conditions. Frequent sampling of this remote lake requires an enormous effort, and many analytical techniques are very difficult to run at the lake site. In this contribution, we combined a commercially available sound speed sensor with a CTD (electrical conductivity, temperature, depth) probe to obtain an indirect but quantitative estimate of carbon dioxide concentrations with fine depth resolution (decimetre scale). Dissolved carbon dioxide increases sound speed but does not contribute to electrical conductivity. Hence the difference between measured and calculated (on the base of electrical conductivity, temperature and pressure) sound speed gives a quantitative indication of dissolved carbon dioxide. We infer the vertical distribution of dissolved CO2 and hence continue the survey of the progress of the intended degassing. In conclusion, we present an easy to implement method for very high CO2 concentrations in deep lakes, and we highly recommend the implementation of the sound speed-CTD probe combination at Lake Nyos and at other gas-laden volcanic lakes, as such an approach could safeguard the people living in the area with acceptable cost and effort for the operators. In this manner, alarming CO2 concentrations in deep parts of lakes can be detected in a timely fashion. |
| first_indexed | 2024-12-22T10:18:11Z |
| format | Article |
| id | doaj.art-6c973486647f453f8da4d082b402b91a |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-22T10:18:11Z |
| publishDate | 2021-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-6c973486647f453f8da4d082b402b91a2022-12-21T18:29:42ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632021-07-01910.3389/feart.2021.645011645011Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed MeasurementsBertram Boehrer0Kazuto Saiki1Takeshi Ohba2Greg Tanyileke3Dmitri Rouwet4Minoru Kusakabe5Helmholtz-Centre for Environmental Research – UFZ, Magdeburg, GermanyGraduate School of Science, Osaka University, Osaka, JapanSchool of Science, Tokai University, Hiratsuka, JapanInstitute for Geological and Mining Res. (IRGM), Yaounde, CameroonIstituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Bologna, ItalyUniversity of Toyama, Toyama, JapanGases dissolved in the deep water of lakes can pose a hazard when extreme concentrations are reached. A sudden release of large amounts of gas can cost the lives of humans living in the neighbourhood, as happened at Lake Nyos in 1986. Since 2001, the gas risk at Lake Nyos has been mitigated by induced degassing, but the lake continues to be supplied by CO2, and a regular survey needs to be implemented to guarantee safe conditions. Frequent sampling of this remote lake requires an enormous effort, and many analytical techniques are very difficult to run at the lake site. In this contribution, we combined a commercially available sound speed sensor with a CTD (electrical conductivity, temperature, depth) probe to obtain an indirect but quantitative estimate of carbon dioxide concentrations with fine depth resolution (decimetre scale). Dissolved carbon dioxide increases sound speed but does not contribute to electrical conductivity. Hence the difference between measured and calculated (on the base of electrical conductivity, temperature and pressure) sound speed gives a quantitative indication of dissolved carbon dioxide. We infer the vertical distribution of dissolved CO2 and hence continue the survey of the progress of the intended degassing. In conclusion, we present an easy to implement method for very high CO2 concentrations in deep lakes, and we highly recommend the implementation of the sound speed-CTD probe combination at Lake Nyos and at other gas-laden volcanic lakes, as such an approach could safeguard the people living in the area with acceptable cost and effort for the operators. In this manner, alarming CO2 concentrations in deep parts of lakes can be detected in a timely fashion.https://www.frontiersin.org/articles/10.3389/feart.2021.645011/fullgasgas pressurelake Nyoslimnic eruptionremediationsound speed |
| spellingShingle | Bertram Boehrer Kazuto Saiki Takeshi Ohba Greg Tanyileke Dmitri Rouwet Minoru Kusakabe Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed Measurements Frontiers in Earth Science gas gas pressure lake Nyos limnic eruption remediation sound speed |
| title | Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed Measurements |
| title_full | Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed Measurements |
| title_fullStr | Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed Measurements |
| title_full_unstemmed | Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed Measurements |
| title_short | Carbon Dioxide in Lake Nyos, Cameroon, Estimated Quantitatively From Sound Speed Measurements |
| title_sort | carbon dioxide in lake nyos cameroon estimated quantitatively from sound speed measurements |
| topic | gas gas pressure lake Nyos limnic eruption remediation sound speed |
| url | https://www.frontiersin.org/articles/10.3389/feart.2021.645011/full |
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