{"id":{"repo_id":"essex","oai_identifier":"oai:repository.essex.ac.uk:29855"},"canonical_url":"https://search.dev.ndltd.org/etd/essex/oai:repository.essex.ac.uk:29855","repository":{"repo_id":"essex","name":"University of Essex","base_url":"https://repository.essex.ac.uk/cgi/oai2"},"display":{"title":"Light hydrocarbon ratios as biosignatures of microbial activity","abstract":"The River Colne, UK, is a temperate estuary with large expanses of anoxic mudflats, referred to as a “microbial observatory”. Methane and ethane emissions were characterised over three sites spanning from the head of the estuary (Hythe), mid-estuary (Alresford) and the mouth (Mersea) which were sampled for dissolved hydrocarbons, in-situ fluxes, and hydrocarbon production from ex-situ sediment slurry incubations. Dissolved methane concentrations were highest at Mersea (85.88 ± 17.36 nM CH4) followed by Alresford (27.75 ± 14.29 nM CH4). Dissolved ethane concentrations at Hythe were highest with 631.05 ± 315.89 pM, followed by Mersea (605.69 ± 302.84 pM), with Alresford dipping to 0 pM. Methane fluxes were highest at Hythe for both the sediment-air (56.37 ± 12.40 nM min-1 cm-2) and water-air interfaces (134.73 nM min−1 cm−2). Sediment-air ethane fluxes at Hythe averaged 439.91 ± 19.98 pM min-1 cm-2, decreasing at Alresford (407.81 pM min−1 cm−2), while water-air at Hythe produced 892 pM min−1 cm−2, double that of Alresford (483.22 ± 388.71 pM min−1 cm−2) with no ethane fluxes at Mersea. Incubations from Hythe, Alresford and Mersea increased by 55.67 ± 72.094, 0.04 ± 0.158 and 0.69 ± 0.489 mM d-1 in headspace CH4 while mean ethane concentrations were 215.97 ± 12.373, 141.10 ± 59.839 and 182.86 ± 66.897 pM, respectively. Methane concentrations were significantly lower in slurries incubated with 2-bromoethanesulfonic acid (2-BES) or after autoclaving, while ethane concentrations were unaffected. These results, coupled with calculated methane – ethane ratios, can be used to inform future studies, particularly with regard to astrobiological research.","abstract_html":"The River Colne, UK, is a temperate estuary with large expanses of anoxic mudflats, referred to as a “microbial observatory”. Methane and ethane emissions were characterised over three sites spanning from the head of the estuary (Hythe), mid-estuary (Alresford) and the mouth (Mersea) which were sampled for dissolved hydrocarbons, in-situ fluxes, and hydrocarbon production from ex-situ sediment slurry incubations. Dissolved methane concentrations were highest at Mersea (85.88 ± 17.36 nM CH4) followed by Alresford (27.75 ± 14.29 nM CH4). Dissolved ethane concentrations at Hythe were highest with 631.05 ± 315.89 pM, followed by Mersea (605.69 ± 302.84 pM), with Alresford dipping to 0 pM. Methane fluxes were highest at Hythe for both the sediment-air (56.37 ± 12.40 nM min-1 cm-2) and water-air interfaces (134.73 nM min−1 cm−2). Sediment-air ethane fluxes at Hythe averaged 439.91 ± 19.98 pM min-1 cm-2, decreasing at Alresford (407.81 pM min−1 cm−2), while water-air at Hythe produced 892 pM min−1 cm−2, double that of Alresford (483.22 ± 388.71 pM min−1 cm−2) with no ethane fluxes at Mersea. Incubations from Hythe, Alresford and Mersea increased by 55.67 ± 72.094, 0.04 ± 0.158 and 0.69 ± 0.489 mM d-1 in headspace CH4 while mean ethane concentrations were 215.97 ± 12.373, 141.10 ± 59.839 and 182.86 ± 66.897 pM, respectively. Methane concentrations were significantly lower in slurries incubated with 2-bromoethanesulfonic acid (2-BES) or after autoclaving, while ethane concentrations were unaffected. These results, coupled with calculated methane – ethane ratios, can be used to inform future studies, particularly with regard to astrobiological research.","abstract_has_math":false,"creators":["Galstaun, Leslie I"],"institution":"University of Essex","degree_name":null,"degree_level":"masters","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-01","date_published":"2021-01","updated_at":"2026-07-24T02:18:40Z","subjects":["GE Environmental Sciences","QH301 Biology","QR Microbiology"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Galstaun, Leslie I"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2021-01"]},{"key":"dc:date.issued","label":"Date","values":["2021-01"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["School of Life Sciences"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Essex"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://repository.essex.ac.uk/29855/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["masters"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["GE Environmental Sciences","QH301 Biology","QR Microbiology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://repository.essex.ac.uk/29855/1/210218_LGALSTAUN_thesis.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The River Colne, UK, is a temperate estuary with large expanses of anoxic mudflats, referred to as a “microbial observatory”. Methane and ethane emissions were characterised over three sites spanning from the head of the estuary (Hythe), mid-estuary (Alresford) and the mouth (Mersea) which were sampled for dissolved hydrocarbons, in-situ fluxes, and hydrocarbon production from ex-situ sediment slurry incubations. Dissolved methane concentrations were highest at Mersea (85.88 ± 17.36 nM CH4) followed by Alresford (27.75 ± 14.29 nM CH4). Dissolved ethane concentrations at Hythe were highest with 631.05 ± 315.89 pM, followed by Mersea (605.69 ± 302.84 pM), with Alresford dipping to 0 pM. Methane fluxes were highest at Hythe for both the sediment-air (56.37 ± 12.40 nM min-1 cm-2) and water-air interfaces (134.73 nM min−1 cm−2). Sediment-air ethane fluxes at Hythe averaged 439.91 ± 19.98 pM min-1 cm-2, decreasing at Alresford (407.81 pM min−1 cm−2), while water-air at Hythe produced 892 pM min−1 cm−2, double that of Alresford (483.22 ± 388.71 pM min−1 cm−2) with no ethane fluxes at Mersea. Incubations from Hythe, Alresford and Mersea increased by 55.67 ± 72.094, 0.04 ± 0.158 and 0.69 ± 0.489 mM d-1 in headspace CH4 while mean ethane concentrations were 215.97 ± 12.373, 141.10 ± 59.839 and 182.86 ± 66.897 pM, respectively. Methane concentrations were significantly lower in slurries incubated with 2-bromoethanesulfonic acid (2-BES) or after autoclaving, while ethane concentrations were unaffected. These results, coupled with calculated methane – ethane ratios, can be used to inform future studies, particularly with regard to astrobiological research."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Light hydrocarbon ratios as biosignatures of microbial activity"]}]}],"canonical_facts":{"dc:creator":["Galstaun, Leslie I"],"dc:date":["2021-01"],"dc:date.issued":["2021-01"],"dc:description.abstract":["The River Colne, UK, is a temperate estuary with large expanses of anoxic mudflats, referred to as a “microbial observatory”. Methane and ethane emissions were characterised over three sites spanning from the head of the estuary (Hythe), mid-estuary (Alresford) and the mouth (Mersea) which were sampled for dissolved hydrocarbons, in-situ fluxes, and hydrocarbon production from ex-situ sediment slurry incubations. Dissolved methane concentrations were highest at Mersea (85.88 ± 17.36 nM CH4) followed by Alresford (27.75 ± 14.29 nM CH4). Dissolved ethane concentrations at Hythe were highest with 631.05 ± 315.89 pM, followed by Mersea (605.69 ± 302.84 pM), with Alresford dipping to 0 pM. Methane fluxes were highest at Hythe for both the sediment-air (56.37 ± 12.40 nM min-1 cm-2) and water-air interfaces (134.73 nM min−1 cm−2). Sediment-air ethane fluxes at Hythe averaged 439.91 ± 19.98 pM min-1 cm-2, decreasing at Alresford (407.81 pM min−1 cm−2), while water-air at Hythe produced 892 pM min−1 cm−2, double that of Alresford (483.22 ± 388.71 pM min−1 cm−2) with no ethane fluxes at Mersea. Incubations from Hythe, Alresford and Mersea increased by 55.67 ± 72.094, 0.04 ± 0.158 and 0.69 ± 0.489 mM d-1 in headspace CH4 while mean ethane concentrations were 215.97 ± 12.373, 141.10 ± 59.839 and 182.86 ± 66.897 pM, respectively. Methane concentrations were significantly lower in slurries incubated with 2-bromoethanesulfonic acid (2-BES) or after autoclaving, while ethane concentrations were unaffected. These results, coupled with calculated methane – ethane ratios, can be used to inform future studies, particularly with regard to astrobiological research."],"dc:format":["text"],"dc:identifier.uri":["https://repository.essex.ac.uk/29855/1/210218_LGALSTAUN_thesis.pdf"],"dc:language":["en"],"dc:publisher.department":["School of Life Sciences"],"dc:publisher.institution":["University of Essex"],"dc:relation.isreferencedby":["https://repository.essex.ac.uk/29855/"],"dc:subject":["GE Environmental Sciences","QH301 Biology","QR Microbiology"],"dc:title":["Light hydrocarbon ratios as biosignatures of microbial activity"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["masters"]},"updated_at":"2026-07-24T02:18:40Z"}