{"title":"A simple, safe method for preserving dissolved methane in freshwater samples using benzalkonium chloride","authors":"Ken'ichi Osaka, Reina Nagata, Moegi Inoue, Masayuki Itoh, Shoko Hosoi-Tanabe, Hiroki Iwata","doi":"10.1002/lom3.10632","DOIUrl":null,"url":null,"abstract":"<p>Methane (CH<sub>4</sub>) dissolved in water is readily consumed by CH<sub>4</sub>-oxidizing bacteria, so the possibility of the dissolved CH<sub>4</sub> concentration (dCH<sub>4</sub>) in sampled water changing before analysis is a concern. To determine the accurate in situ dCH<sub>4</sub> level, mercury chloride (HgCl<sub>2</sub>) or sodium azide (NaN<sub>3</sub>) is traditionally used for sample preservation. However, these preservatives are very toxic and great care must be taken when adding them to samples. Benzalkonium chloride (BAC), a quaternary ammonium salt cationic surfactant, is a readily available disinfectant that is less harmful to the human body than HgCl<sub>2</sub>, NaN<sub>3</sub>, and other preservatives. In this study, we investigated the usefulness of BAC in preserving dCH<sub>4</sub> in swamp water, which is a critical terrestrial source of CH<sub>4</sub>. The dCH<sub>4</sub> in samples without BAC decreased immediately after sample collection, whereas the dCH<sub>4</sub> in the samples with added BAC did not change significantly for at least 15 d. In addition, when BAC was added to 18 water samples with different water chemistries, the dCH<sub>4</sub> did not change significantly from immediately after sampling to 1 week after sampling (average difference: 3%). Thus, in the water samples used in this study, BAC effectively preserved dCH<sub>4</sub> in the samples for at least 1 week. Further testing of the effect of BAC on the preservation of dCH<sub>4</sub> in different types of water samples worldwide will help to establish a more complete, simple, and safe method.</p>","PeriodicalId":18145,"journal":{"name":"Limnology and Oceanography: Methods","volume":null,"pages":null},"PeriodicalIF":2.1000,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Limnology and Oceanography: Methods","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/lom3.10632","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"LIMNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Methane (CH4) dissolved in water is readily consumed by CH4-oxidizing bacteria, so the possibility of the dissolved CH4 concentration (dCH4) in sampled water changing before analysis is a concern. To determine the accurate in situ dCH4 level, mercury chloride (HgCl2) or sodium azide (NaN3) is traditionally used for sample preservation. However, these preservatives are very toxic and great care must be taken when adding them to samples. Benzalkonium chloride (BAC), a quaternary ammonium salt cationic surfactant, is a readily available disinfectant that is less harmful to the human body than HgCl2, NaN3, and other preservatives. In this study, we investigated the usefulness of BAC in preserving dCH4 in swamp water, which is a critical terrestrial source of CH4. The dCH4 in samples without BAC decreased immediately after sample collection, whereas the dCH4 in the samples with added BAC did not change significantly for at least 15 d. In addition, when BAC was added to 18 water samples with different water chemistries, the dCH4 did not change significantly from immediately after sampling to 1 week after sampling (average difference: 3%). Thus, in the water samples used in this study, BAC effectively preserved dCH4 in the samples for at least 1 week. Further testing of the effect of BAC on the preservation of dCH4 in different types of water samples worldwide will help to establish a more complete, simple, and safe method.
期刊介绍:
Limnology and Oceanography: Methods (ISSN 1541-5856) is a companion to ASLO''s top-rated journal Limnology and Oceanography, and articles are held to the same high standards. In order to provide the most rapid publication consistent with high standards, Limnology and Oceanography: Methods appears in electronic format only, and the entire submission and review system is online. Articles are posted as soon as they are accepted and formatted for publication.
Limnology and Oceanography: Methods will consider manuscripts whose primary focus is methodological, and that deal with problems in the aquatic sciences. Manuscripts may present new measurement equipment, techniques for analyzing observations or samples, methods for understanding and interpreting information, analyses of metadata to examine the effectiveness of approaches, invited and contributed reviews and syntheses, and techniques for communicating and teaching in the aquatic sciences.