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[{"key": "dc.contributor.advisor", "value": "Kiljunen, Mikko", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.advisor", "value": "McCarthy, Mark", "language": null, "element": "contributor", "qualifier": "advisor", "schema": "dc"}, {"key": "dc.contributor.author", "value": "Heinonen, Miina", "language": "", "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2024-01-26T06:28:06Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2024-01-26T06:28:06Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2023", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/93066", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Boreal lakes experience fluctuations between ice cover and ice-off periods every year. The duration of ice cover plays a crucial role in understanding nitrogen cycling in these lakes. During the brief growing season, lakes experience rapid changes, in nitrogen cycle particularly during spring. Our current understanding of nitrogen cycling in lakes is limited to redox-driven chemical reactions in shallow, eutrophic lakes during ice free periods or in arctic unproductive lakes, rarely considering seasonal changes. The aim of this study was to investigate temporal changes in ammonium (NH4+) regeneration and potential uptake rates from ice cover period to the late autumn using stable isotope (15NH4+) enrichments and isotope dilution models. Water column NH4+ cycling data was collected from a small, humic lake in central Finland (Jyv\u00e4sj\u00e4rvi) during 2023 from the areas near a small river discharge and the central part of the western basin. Potential NH4+ uptake rates followed seasonal patterns and were higher close to a nutrient source (tributary input) and near the sediments compared to surface waters. Ammonium regeneration within the water column supported a larger proportion of community NH4+ uptake during low light conditions and colder temperatures. Ammonium regeneration rates in Jyv\u00e4sj\u00e4rvi were mainly affected by temperature, light, and availability of nutrients. Photoautotrophic production was observed under the ice, showing that some light penetrated the snow and ice layers. Further studies are required to understand the contributions of humic substances and bacterial activities in boreal lakes to overall nitrogen cycling dynamics during the winter period.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Boreaaliset j\u00e4rvet ovat ison osan vuodesta j\u00e4\u00e4n peitt\u00e4mi\u00e4 ja j\u00e4\u00e4peitteisen ajan kesto vaikuttaa merkitt\u00e4v\u00e4sti mm. typen kiertoon. Kasvukausi on puolestaan lyhyt ja sen aikaiset muutokset typen kierrossa ovat nopeita, etenkin kev\u00e4isin. Nykyinen ymm\u00e4rryksemme typen kierrosta rajoittuu p\u00e4\u00e4asiassa kes\u00e4ll\u00e4 tapahtuviin hapetus-pelkistysreaktioiden aiheuttamiin kemiallisiin muutoksiin matalissa runsasravinteisissa j\u00e4rviss\u00e4 tai arktisissa karuissa j\u00e4rviss\u00e4, eik\u00e4 vuodenaikaisia vaihteluita ole juurikaan otettu huomioon. T\u00e4ss\u00e4 tutkimuksessa k\u00e4ytettiin vakaitten isotooppien (15NH4+) rikastusmenetelm\u00e4\u00e4 ja isotooppien laimennusmallinnusta, joilla selvitettiin vuodenaikaista ammoniumin (NH4+) regeneraatiota (eli ravinteiden kierr\u00e4tyst\u00e4) ja takaisinsitoutumista humuspitoisessa Jyv\u00e4sj\u00e4rvess\u00e4. Aineisto ker\u00e4ttiin vuoden 2023 aikana Jyv\u00e4sj\u00e4rven l\u00e4ntisen altaan keskelt\u00e4 ja siihen laskevan K\u00f6yh\u00e4ojan suulta. NH4+ takaisinsitoutuminen oli riippuvainen mm. l\u00e4mp\u00f6tilan ajallisesta vaihtelusta ja oli suurempaa l\u00e4hemp\u00e4n\u00e4 ravinnekuormitusta ja sedimentti\u00e4 kuin pintavett\u00e4. Regeneraatio yll\u00e4piti suurempaa NH4+ sitoutumista takaisin tuottajille alhaisessa valossa ja kylmemmiss\u00e4 l\u00e4mp\u00f6tiloissa. Useista mitatuista parametreist\u00e4 l\u00e4mp\u00f6tila, valo ja ravinteiden saatavuus vaikuttivat eniten regeneraatioon. Valosta riippuvaista perustuotantoa havaittiin jo j\u00e4\u00e4n alla useita kuukausia ennen j\u00e4iden l\u00e4ht\u00f6\u00e4. Lis\u00e4tutkimuksia tarvitaan parantaaksemme ymm\u00e4rryst\u00e4 humusaineiden ja bakteerien vaikutuksesta yleiseen typen kiertodynamiikkaan talvikauden aikana boreaalisissa j\u00e4rviss\u00e4.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by Paivi Vuorio (paelvuor@jyu.fi) on 2024-01-26T06:28:06Z\nNo. of bitstreams: 0", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2024-01-26T06:28:06Z (GMT). No. of bitstreams: 0\n Previous issue date: 2023", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.format.extent", "value": "32", "language": "", "element": "format", "qualifier": "extent", "schema": "dc"}, {"key": "dc.language.iso", "value": "eng", "language": null, "element": "language", "qualifier": "iso", "schema": "dc"}, {"key": "dc.rights", "value": "In Copyright", "language": "en", "element": "rights", "qualifier": null, "schema": "dc"}, {"key": "dc.subject.other", "value": "fototrofinen tuotanto", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "heterotrofinen tuotanto", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.subject.other", "value": "typen kierto", "language": "", "element": "subject", "qualifier": "other", "schema": "dc"}, {"key": "dc.title", "value": "Seasonal changes in ammonium regeneration and potential uptake rates in boreal lake Jyv\u00e4sj\u00e4rvi", "language": "", "element": "title", "qualifier": null, "schema": "dc"}, {"key": "dc.type", "value": "master thesis", "language": null, "element": "type", "qualifier": null, "schema": "dc"}, {"key": "dc.identifier.urn", "value": "URN:NBN:fi:jyu-202401261554", "language": null, "element": "identifier", "qualifier": "urn", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Master\u2019s thesis", "language": "en", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.type.ontasot", "value": "Pro gradu -tutkielma", "language": "fi", "element": "type", "qualifier": "ontasot", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Faculty of Sciences", "language": "en", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Matemaattis-luonnontieteellinen tiedekunta", "language": "fi", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Department of Biological and Environmental Science", "language": "en", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.department", "value": "Bio- ja ymp\u00e4rist\u00f6tieteiden laitos", "language": "fi", "element": "contributor", "qualifier": "department", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "University of Jyv\u00e4skyl\u00e4", "language": "en", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "Jyv\u00e4skyl\u00e4n yliopisto", "language": "fi", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Aquatic sciences", "language": "en", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "dc.subject.discipline", "value": "Akvaattiset tieteet", "language": "fi", "element": "subject", "qualifier": "discipline", "schema": "dc"}, {"key": "yvv.contractresearch.funding", "value": "0", "language": "", "element": "contractresearch", "qualifier": "funding", "schema": "yvv"}, {"key": "dc.type.coar", "value": "http://purl.org/coar/resource_type/c_bdcc", "language": null, "element": "type", "qualifier": "coar", "schema": "dc"}, {"key": "dc.rights.copyright", "value": "\u00a9 The Author(s)", "language": null, "element": "rights", "qualifier": "copyright", "schema": "dc"}, {"key": "dc.rights.accesslevel", "value": "restrictedAccess", "language": null, "element": "rights", "qualifier": "accesslevel", "schema": "dc"}, {"key": "dc.type.publication", "value": "masterThesis", "language": null, "element": "type", "qualifier": "publication", "schema": "dc"}, {"key": "dc.subject.oppiainekoodi", "value": "4012", "language": null, "element": "subject", "qualifier": "oppiainekoodi", "schema": "dc"}, {"key": "dc.subject.yso", "value": "j\u00e4rvet", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "typpi", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "j\u00e4\u00e4peite", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "ravinnekierto", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "typensidonta", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "lakes", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "nitrogen", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "ice cover", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "nutrient cycle", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.subject.yso", "value": "nitrogen fixation", "language": null, "element": "subject", "qualifier": "yso", "schema": "dc"}, {"key": "dc.rights.url", "value": "https://rightsstatements.org/page/InC/1.0/", "language": null, "element": "rights", "qualifier": "url", "schema": "dc"}, {"key": "dc.rights.accessrights", "value": "The author has not given permission to make the work publicly available electronically. Therefore the material can be read only at the archival workstation at Jyv\u00e4skyl\u00e4 University Library (https://kirjasto.jyu.fi/en/workspaces/facilities/facilities#autotoc-item-autotoc-2).", "language": "en", "element": "rights", "qualifier": "accessrights", "schema": "dc"}, {"key": "dc.rights.accessrights", "value": "Tekij\u00e4 ei ole antanut lupaa avoimeen julkaisuun, joten aineisto on luettavissa vain Jyv\u00e4skyl\u00e4n yliopiston kirjaston arkistoty\u00f6semalta. Ks. https://kirjasto.jyu.fi/fi/tyoskentelytilat/laitteet-ja-tilat#autotoc-item-autotoc-2.", "language": "fi", "element": "rights", "qualifier": "accessrights", "schema": "dc"}]
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