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  • 1
    Publication Date: 2024-05-22
    Description: The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water column and altering the biogeochemistry, but also the subsistence economy of local people, and changes in climate because of the transformation of organic matter into greenhouse gases. Yet, the quantification of suspended sediment in Arctic coastal and nearshore waters remains unsatisfactory due to the absence of dedicated algorithms to resolve the high loads occurring in the close vicinity of the shoreline. In this study we present the Arctic Nearshore Turbidity Algorithm (ANTA), the first reflectance-turbidity relationship specifically targeted towards Arctic nearshore waters that is tuned with in-situ measurements from the nearshore waters of Herschel Island Qikiqtaruk in the western Canadian Arctic. A semi-empirical model was calibrated for several relevant sensors in ocean color remote sensing, including MODIS, Sentinel 3 (OLCI), Landsat 8 (OLI), and Sentinel 2 (MSI), as well as the older Landsat sensors TM and ETM+. The ANTA performed better with Landsat 8 than with Sentinel 2 and Sentinel 3. The application of the ANTA to Sentinel 2 imagery that matches in-situ turbidity samples taken in Adventfjorden, Svalbard, shows transferability to nearshore areas beyond Herschel Island Qikiqtaruk.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev , info:eu-repo/semantics/article
    Format: application/pdf
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  • 2
    Series available for loan
    Series available for loan
    Karlsruhe : Braun ; 1.1941(1940) - 59.1999(1997); 2000(1999) -
    Call number: S 91.0710 ; S 91.0710 (2020) ; S 91.0710 (2021) ; S 91.0710 (2022) ; S 91.0710 (2023)
    Type of Medium: Series available for loan
    ISSN: 0174-254X
    Location: Archive - must be ordered
    Location: Archive - must be ordered
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    Branch Library: GFZ Library
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  • 3
    Monograph available for loan
    Monograph available for loan
    Jakutsk : [Izdatel'stvo Instituta Merzlotovedenija SO RAN]
    Call number: AWI G3-24-95737
    Description / Table of Contents: Translation of abstract: The materials of the All-Russian Scientific Conference are devoted to the genesis, geography, diversity, ecology, protection and rational use of permafrost soils.
    Description / Table of Contents: Материалы Всероссийской научной конференции посвящены генезису, географии, разнообразию, экологию, охраны и рациональному использованию мерзлотных почв.
    Type of Medium: Monograph available for loan
    Pages: 182 Seiten , Illustrationen
    ISBN: 5-93254-061-3 , 5932540613
    Language: Russian
    Note: Оглавление Роль В.Г. Зольникова в изучении мерзлотных почв Зольников Василий Георгиевич (к столетию со дня рождения) / Л.Г. Еловская Роль В.Г. Зольникова в изучении почвенного покрова Якутии / Д.Д. Саввинов Роль Центрального музея почвоведения им. В.В. Докучаева в исследовании мерзлотных почв России / Б.Ф. Апарин Региональные проблемы изучения мерзлотных почв Микростроение органопрофиля мерзлотных почв криолитозоны Забайкалья / В.М. Корсунов, В.М. Чиркова Криогенные почвы юга Восточной Сибири и вопросы их картографирования / В.А. Кузьмин Микроструктура почвенного покрова северной части О.Большевик (архипелаг Северная Земля) / Б.Ф. Апарин, В.Б. Апарин О количественной оценке разнообразия почв / А.И. Куликов, Е.Д. Канаева, М.А. Куликов К вопросу о мерзлотных почвах Юго-Восточного Алтая / Е.Н. Смоленцева Формы серы в мерзлотных почвах притундровых лесов Енисейского Севера / Т.В. Пономарева Влияние растительного покрова и микрорельефа на азотный фонд почв бугорковой тундры Сибири / К. Биази, В. Ванек, О. Русалимова, К. Кайзер, Х. Мейер, П. Барсуков, А. Рихтер Состав гумуса мерзлотных почв мелкодолинных ландшафтов Лено-Амгинского междуречья / М.В. Оконешникова, Р.В. Десяткин Особенности микробных комплексов островных почв дельты р. Селенга как показатели мерзлотности, обусловленной влиянием оз. Байкал / Э.О. Макушкин, Н.Д. Сорокин, В.М. Корсунов, Е.Ю. Шахматова, Е.Н. Афанасова Проблемы эволюции мерзлотных почв Центральной Якутии / А.П. Чевычелов, В.П. Скрыбыкина, А.А. Перк Особенности распространения доминирующих типов мерзлотных почв бассейна р. Биллях / Я.Р. Герасимов, Г.Н. Саввинов Биохимические и геохимические особенности почв урбанизированных территорий (на примере г. Мирный, Западная Якутия) / М.В. Щелчкова, Я.Б.Легостаева Экология мерзлотных почв Метанообразование в мерзлых почвах / А. Брушков, М. Фукуда Методические проблемы почвенно-геохимических исследований в экологии / Б.С. Ягнышев Криотурбации мерзлотных почв Севера при глобальном изменении климата (разнообразие, экология) / П.П. Гаврильев, Р.Н. Иванова Динамика гидротермических поясов / А.И. Дмитриев Влияние температурного режима почвы на радиальный прирост стволов лиственницы в Центральной Якутии / А.Н. Николаев, П.П. Федоров Сезонная динамика теплофизических свойств аласных почв / В.С. Макаров Изменение пространственной структуры растительного покрова аласа как показатель динамики почвенных условий / М.Х. Николаева, А.Р. Десяткин Агрофизические свойства мерзлотных палевых осолоделых почв Центральной Якутии / А.П. Пестерев Связь радиального прироста лиственницы Каяндера с температурным режимом почв / П.П. Федоров, А.Н. Николаев Естественные радионуклиды и радиоцезий в почвах тундровой и таежной зон Якутии / П.И. Собакин, А.П. Чевычелов Средняя годовая температура почвогрунтов на подошве деятельного слоя Западной Якутии и ее зависимость от средней годовой температуры воздуха / И.С. Васильев Баланс органогенного углерода в мерзлотных лесных экосистемах / Т.Х. Максимов, Б.И. Иванов, А.Й. Долман, Е.Й. Муре, А.П. Максимов, А.В. Кононов, Т. Ота, М. Хейманп Исследования динамики промерзания мерзлотных таежных почв около г. Якутска / П.Я. Константинов Охрана и рациональное использование мерзлотных почв Мерзлотно-экологическое районирование агроземель на примере Мегино-Кангаласского улуса / П.В. Ефремов Классификация геокриологических и почвенных процессов по степени опасности и безопасности для сельскохозяйственного освоения / П.П. Гаврильев Влияние погодных условий на солевой режим и продуктивность аласных дерново-луговых почв / А.Р. Десяткин, М.Х. Николаева Ритмика обводнения аласных почв Лено-Амгинского междуречья / Н.П. Босиков Урожайность зерновых в зависимости от варианта обработки и водно-физических свойств мерзлотной палевой осолоделой почвы / С.И. Баишев Почвенный покров и его деградация в окрестностях города Мирный / П.П. Данилов, Г.Н. Саввинов Особенности почвенного покрова территории месторождения "Таборное" / В.Г. Тарабукина, В.С. Макаров, В.С. Боескоров , English translation of Table of contents The role of V.G. Zolnikov in the study of permafrost soils Zolnikov Vasily Georgievich (on the occasion of the centenary of his birth) / L.G. Elovskaya The role of V.G. Zolnikov in the study of the soil cover of Yakutia / D.D. Savvinov The role of the Central Museum of Soil Science named after. V.V. Dokuchaev in the study of permafrost soils in Russia / B.F. Aparin Regional problems of studying permafrost soils Microstructure of the organoprofile of permafrost soils in the permafrost zone of Transbaikalia / V.M. Korsunov, V.M. Chirkova Cryogenic soils of the south of Eastern Siberia and issues of their mapping / V.A. Kuzmin Microstructure of the soil cover in the northern part of O. Bolshevik (Severnaya Zemlya archipelago) / B.F. Aparin, V.B. Aparin On the quantitative assessment of soil diversity / A.I. Kulikov, E.D. Kanaeva, M.A. Kulikov On the issue of frozen soils in South-Eastern Altai / E.N. Smolentseva Forms of sulfur in frozen soils of tundra forests of the Yenisei North / T.V. Ponomareva The influence of vegetation cover and microrelief on the nitrogen pool of soils in the hummock tundra of Siberia / K. Biasi, V. Vanek, O. Rusalimova, K. Kaiser, H. Meyer, P. Barsukov, A. Richter Composition of humus in permafrost soils in shallow valley landscapes of the Lena-Amga interfluve / M.V. Okoneshnikova, R.V. Desyatkin Features of microbial complexes of island soils of the river delta Selenga as indicators of permafrost caused by the influence of the lake. Baikal / E.O. Makushkin, N.D. Sorokin, V.M. Korsunov, E.Yu. Shakhmatova, E.N. Afanasova Problems of evolution of permafrost soils in Central Yakutia / A.P. Chevychelov, V.P. Skrybykina, A.A. Perk Features of the distribution of the dominant types of permafrost soils in the river basin. Billyakh / Ya.R. Gerasimov, G.N. Savvinov Biochemical and geochemical features of soils in urbanized areas (on the example of the city of Mirny, Western Yakutia) / M.V. Shchelchkova, Ya.B.Legostaeva Ecology of frozen soils Methane formation in frozen soils / A. Brushkov, M. Fukuda Methodological problems of soil-geochemical research in ecology / B.S. Yagnyshev Cryoturbation of permafrost soils of the North under global climate change (diversity, ecology) / P.P. Gavrilyev, R.N. Ivanova Dynamics of hydrothermal belts / A.I. Dmitriev The influence of soil temperature on the radial growth of larch trunks in Central Yakutia / A.N. Nikolaev, P.P. Fedorov Seasonal dynamics of thermophysical properties of alass soils / V.S. Makarov Changes in the spatial structure of the alas plant cover as an indicator of the dynamics of soil conditions / M.Kh. Nikolaeva, A.R. Desyatkin Agrophysical properties of frozen pale yellow solodized soils of Central Yakutia / A.P. Pesterev Relationship between the radial growth of Cajander larch and the temperature regime of soils / P.P. Fedorov, A.N. Nikolaev Natural radionuclides and radiocesium in soils of the tundra and taiga zones of Yakutia / P.I. Sobakin, A.P. Chevychelov Average annual soil temperature at the base of the active layer of Western Yakutia and its dependence on the average annual air temperature / I.S. Vasiliev Organogenic carbon balance in permafrost forest ecosystems / T.Kh. Maksimov, B.I. Ivanov, A.Y. Dolman, E.Y. Mure, A.P. Maksimov, A.V. Kononov, T. Ota, M. Heymanp Study of the dynamics of freezing of frozen taiga soils near the city of Yakutsk / P.Ya. Konstantinov Protection and rational use of permafrost soils Permafrost-ecological zoning of agricultural lands using the example of the Megino-Kangalassky ulus / P.V. Efremov Classification of geocryological and soil processes according to the degree of danger and safety for agricultural development / P.P. Gavriliev The influence of weather conditions on the salt regime and productivity of alas sod-meadow soils / A.R. Desyatkin, M.Kh. Nikolaev Rhythm of watering of alass soils of the Lena-Amga interfluve / N.P. Bosikov Grain yield depending on the treatment option and water-physical properties of frozen pale-yellow soil / S.I. Baishev Soil cover and its degradation in the vicinity of the city of Mirny / P.P. Danilov, G.N. Savvinov Features of the soil cover of the territory of the Tabornoe deposit / V.G. Tarabukina, V.S. Makarov, V.S. Fighters , In kyrillischer Schrift
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  • 4
    Call number: AWI Bio-24-95736
    Description / Table of Contents: Moss-microbe associations are often characterised by syntrophic interactions between the microorganisms and their hosts, but the structure of the microbial consortia and their role in peatland development remain unknown. In order to study microbial communities of dominant peatland mosses, Sphagnum and brown mosses, and the respective environmental drivers, four study sites representing different successional stages of natural northern peatlands were chosen on a large geographical scale: two brown moss-dominated, circumneutral peatlands from the Arctic and two Sphagnum-dominated, acidic peat bogs from subarctic and temperate zones. The family Acetobacteraceae represented the dominant bacterial taxon of Sphagnum mosses from various geographical origins and displayed an integral part of the moss core community. This core community was shared among all investigated bryophytes and consisted of few but highly abundant prokaryotes, of which many appear as endophytes of Sphagnum mosses. Moreover, brown mosses and Sphagnum mosses represent habitats for archaea which were not studied in association with peatland mosses so far. Euryarchaeota that are capable of methane production (methanogens) displayed the majority of the moss-associated archaeal communities. Moss-associated methanogenesis was detected for the first time, but it was mostly negligible under laboratory conditions. Contrarily, substantial moss-associated methane oxidation was measured on both, brown mosses and Sphagnum mosses, supporting that methanotrophic bacteria as part of the moss microbiome may contribute to the reduction of methane emissions from pristine and rewetted peatlands of the northern hemisphere. Among the investigated abiotic and biotic environmental parameters, the peatland type and the host moss taxon were identified to have a major impact on the structure of moss-associated bacterial communities, contrarily to archaeal communities whose structures were similar among the investigated bryophytes. For the first time it was shown that different bog development stages harbour distinct bacterial communities, while at the same time a small core community is shared among all investigated bryophytes independent of geography and peatland type. The present thesis displays the first large-scale, systematic assessment of bacterial and archaeal communities associated both with brown mosses and Sphagnum mosses. It suggests that some host-specific moss taxa have the potential to play a key role in host moss establishment and peatland development.
    Description / Table of Contents: Während die Beziehungen zwischen Moosen und den mit ihnen assoziierten Mikroorganismen oft durch syntrophische Wechselwirkungen charakterisiert sind, ist die Struktur der Moos-assoziierten mikrobiellen Gemeinschaften sowie deren Rolle bei der Entstehung von Mooren weitgehend unbekannt. Die vorliegende Arbeit befasst sich mit mikrobiellen Gemeinschaften, die mit Moosen nördlicher, naturnaher Moore assoziiert sind, sowie mit den Umweltfaktoren, die sie beeinflussen. Entlang eines groß angelegten geographischen Gradienten, der von der Hocharktis bis zur gemäßigten Klimazone reicht, wurden vier naturbelassene Moore als Probenstandorte ausgesucht, die stellvertretend für verschiedene Stadien der Moorentwicklung stehen: zwei Braunmoos-dominierte Niedermoore mit nahezu neutralem pH-Wert sowie zwei Sphagnum-dominierte Torfmoore mit saurem pH-Wert. Die Ergebnisse der vorliegenden Arbeit machen deutlich, dass die zu den Bakterien zählenden Acetobacteraceae das vorherrschende mikrobielle Taxon der Sphagnum-Moose gleich welchen geographischen Ursprungs darstellen und insbesondere innerhalb des Wirtsmoosgewebes dominieren. Gleichzeitig gehörten die Acetobacteraceae zum wesentlichen Bestandteil der mikrobiellen Kerngemeinschaft aller untersuchten Moose, die sich aus einigen wenigen Arten, dafür zahlreich vorkommenden Prokaryoten zusammensetzt. Die vorliegende Arbeit zeigt zudem erstmals, dass sowohl Braunmoose als auch Torfmoose ein Habitat für Archaeen darstellen. Die Mehrheit der Moos-assoziierten Archaeen gehörte dabei zu den methanbildenden Gruppen, wenngleich die metabolischen Aktivitätsraten unter Laborbedingungen meistens kaum messbar waren. Im Gegensatz hierzu konnte die Bakterien-vermittelte Methanoxidation sowohl an Braunmoosen als auch an Sphagnum-Moosen gemessen werden. Dies zeigt eindrucksvoll, dass Moos-assoziierte Bakterien potenziell zur Minderung von Methanemissionen aus nördlichen, aber auch wiedervernässten Mooren beitragen können. Ein weiteres wichtiges Resultat der vorliegenden Arbeit ist die Bedeutung des Moortyps (Niedermoor oder Torfmoor), aber auch der Wirtsmoosart selbst für die Struktur der Moos-assoziierten Bakteriengemeinschaften, während die archaeellen Gemeinschaftsstrukturen weder vom Moortyp noch von der Wirtsmoosart beeinflusst wurden und sich insgesamt deutlich ähnlicher waren als die der Bakterien. Darüber hinaus konnte erstmalig gezeigt werden, dass sich die bakteriellen Gemeinschaften innerhalb der unterschiedlichen Moorsukzessionsstadien zwar ganz erheblich voneinander unterscheiden, ein kleiner Teil der Bakterien dennoch Kerngemeinschaften bilden, die mit allen untersuchten Moosarten assoziiert waren. Bei der hier präsentierten Arbeit handelt es sich um die erste systematische Studie, die sich auf einer großen geographischen Skala mit den bakteriellen und archaeellen Gemeinschaften von Braunmoosen und Torfmoosen aus naturbelassenen nördlichen Mooren befasst. Die vorliegenden Ergebnisse machen deutlich, dass die untersuchten Moose ein ganz spezifisches mikrobielles Konsortium beherbergen, welches mutmaßlich eine Schlüsselrolle bei der Etablierung der Wirtspflanzen am Anfang der Moorentwicklung spielt und darüber hinaus das Potential hat, die charakteristischen Eigenschaften von Mooren sowie deren weitere Entwicklung zu prägen.
    Type of Medium: Dissertations
    Pages: XX, 139, liv Seiten , Illustrationen, Diagramme
    Language: English
    Note: Dissertation, Universität Potsdam, 2024 , Content Preface Acknowledgements Summary Zusammenfassung Abbreviations 1. Introduction 1.1. Peatlands 1.1.1. Peatland development and peat bog succession 1.1.2. Characteristic peatlands of the northern hemisphere 1.1.3. Anthropogenic threats of northern peatlands 1.1.4. Peat bog restoration 1.2. Peatland bryophytes 1.2.1. Brown mosses 1.2.2. Sphagnum mosses 1.3. Moss microbiota 1.3.1. Moss-associated bacteria 1.3.2. Moss-associated archaea 1.3.3. Endophytic prokaryotic communities 1.4. Biotic and abiotic influences on moss-associated microorganisms 1.5. Objectives 1.6. Study sites 1.6.1. High Arctic peatlands of Svalbard (SV) 1.6.2. Polygonal Tundra of Samoylov (SA) 1.6.3. Palsa Bogs of Neiden (NEI) 1.6.4. Kettle Bog Peatlands of Mueritz National Park (MUE) 2. Material and Methods 2.1. Sampling scheme overview 2.2. Sampling of pore water 2.3. Sampling of moss plantlets 2.4. Analysis of pore water chemistry 2.5. Cell wall analysis 2.5.1. Cation exchange capacity (CEC) 2.5.2. Holocellulose (HC) 2.5.3. Lignin and Lignin-like polymers (LLP) 2.5.4. Bulk moss litter analysis 2.6. Moss surface sterilisation and separation of putative epiphytic and endophytic microbial communities 2.7. DNA extraction and sequencing 2.8. Sequence analyses and bioinformatics 2.9. Statistical analyses 2.10. Potential methane production and oxidation assays 2.10.1. Surface sterilisation prior to activity tests 2.10.2. Methane production 2.10.3. Methane oxidation 3. Results 3.1. Peatland bulk and pore water characteristics 3.2. Diversity and structure of natural peatland microbial communities 3.3. Environmental drivers of moss-associated microbial communities 3.4. Microbial taxa associated with brown mosses and Sphagnum mosses 3.4.1. Moss-associated bacteria 3.4.2. Moss-associated archaea 3.4.3. Bacterial and archaeal core communities 3.4.4. Acetobacteraceae as dominant taxon of the bacterial core community 3.5. Sphagnum bacteriomes of disturbed, rewetted and pristine temperate kettle bog 3.6. Potential moss-associated methane production and methane oxidation rates 3.6.1. Moss-associated methane production 3.6.2. Moss-associated methane oxidation 4. Discussion 4.1. Environmental influences on moss-associated bacterial communities 4.2. Moss-associated archaeal communities and their environmental drivers 4.3. Distinct patterns of endophytic bacteria 4.4. The core microbiota and their possible role for peatland succession 4.5. The potential role of Acetobacteraceae for Sphagnum host mosses and bog ecosystems 4.6. Moss-associated microbial communities of the methane cycle and their potential metabolic activity 4.7. Diversity and structure of Sphagnum bacteriomes from pristine, disturbed and rewetted kettle bogs 5. Conclusion 6. Critical remarks and outlook 6.1. Critical remarks 6.2. Outlook Bibliography Supplementary
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  • 5
    Call number: S 92.0195 ; 3 / S 92.0195 (2021) ; 3 / S 92.0195(2022) ; 3 / S 92.0195(2023)
    Type of Medium: Series available for loan
    ISSN: 0340-4366
    Classification:
    E.7.
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  • 6
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    Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais.
    Publication Date: 2024-05-21
    Description: Streams are ecosystems closely dependent to their adjacent ecotones, representing important water recharge sources for drainage networks and playing a central role in global nutrient cycling. The primary source of energy in streams comes from allochthonous material originating from riparian vegetation, which becomes available through processing performed by aquatic organisms. Modifications in the composition of the adjacent vegetation, which can be natural or due to land use and occupation, may alter the ecosystem functioning. Despite their critical role in preserving biodiversity, riparian ecosystems face continuous alteration or even removal. Anthropogenic activities, such as excessive use of pesticides and fertilizers in rural areas, and catchment imperviousness in urban areas, for example, negatively affect water quality, leading to contamination and disruptions in the food chain. Studies predominantly focus on densely forested riparian zones, composed mainly of trees, but natural riparian zones with herbaceous or shrubby vegetation have effects less explored when compared to woody vegetation. These include differences in channel stability and morphology, because woody vegetation is more suitable for stabilization of stream banks than herbaceous vegetation. These differences are particularly relevant for organisms like aquatic insects, that play a fundamental role in energy transfer to higher trophic levels and are widely used as bioindicators, given their sensitivity to environmental changes. Metrics such as richness and abundance are commonly used to estimate levels of biodiversity, but for a comprehensive understanding of the role of such species in ecosystem functioning, it is essential to also consider functional diversity. In this context, the following aspects were assessed: i) the effect of sub-basin riparian vegetation stratum (tree x shrub) on the composition and beta-diversity of aquatic insects in tropical streams and ii) the relationship between different levels of anthropogenic intensification and taxonomic and functional indices of aquatic insects, as well as their relationship with environmental variables. The study concluded that functional diversity was more sensitive than taxonomic diversity to changes related to land use and cover in riparian vegetation. Vegetation stratum (tree and shrub) significantly altered total functional diversity, while anthropogenic intensification significantly reduced all functional indices analysed and only one taxonomic index. The results obtained and analysed contributed to an analytical understanding of the functioning of tropical aquatic ecosystems. Furthermore, the study provides valuable parameters and insights for future predictions and mitigation strategies in environments affected by human activities.
    Description: Riachos são ecossistemas estritamente dependentes dos seus ecótonos adjacentes, representando importantes fontes de recarga de água para redes de drenagem e desempenhando um papel central no ciclo global de nutrientes. A principal fonte de energia dos riachos é proveniente do material alóctone da vegetação ripária, que se torna disponível através do processamento pelos organismos aquáticos. Modificações na composição da vegetação adjacente, que podem ser naturais ou decorrentes do uso e cobertura da terra, podem alterar as funções ecossistêmicas. Apesar do seu papel fundamental na preservação da biodiversidade, os riachos são continuamente alterados ou até mesmo removidos. As atividades antrópicas, como o uso excessivo de pesticidas e fertilizantes nas zonas rurais, e a impermeabilização do solo em áreas urbanas, por exemplo, possuem um impacto negativo na qualidade da água, levando à contaminação e a perturbações na cadeia alimentar. Os estudos são predominantemente realizados nas zonas ripárias altamente florestadas, compostas principalmente por árvores de grande porte, mas as zonas ripárias naturais com vegetação herbácea ou arbustiva têm efeitos menos explorados quando comparadas com a vegetação arbórea. Entre os efeitos, incluem diferenças na estabilidade e morfologia do canal, porque a vegetação arbórea é mais adequada para a estabilização das margens do que a vegetação herbácea. Estas diferenças são particularmente relevantes para organismos como os insetos aquáticos, que desempenham um papel fundamental na transferência de energia para níveis tróficos superiores e são amplamente utilizados como bioindicadores, dada a sua sensibilidade às alterações ambientais. Métricas como riqueza e abundância são comumente utilizadas para estimar níveis de biodiversidade, mas para uma compreensão abrangente do papel dessas espécies no funcionamento do ecossistema, é essencial considerar também a diversidade funcional. Neste contexto, avaliou-se os seguintes aspectos: i) o efeito do estrato de vegetação ripária (arbóreo x arbustivo) da sub-bacia sobre a composição e diversidade beta de insetos aquáticos em riachos tropicais e ii) a relação entre a intensificação antrópica e as variáveis ambientais com índices taxonômicos e funcionais de insetos aquáticos. O estudo constatou que a diversidade funcional foi mais sensível às mudanças relacionadas com o uso e cobertura da terra na vegetação ripária. O estrato da vegetação (arbóreo e arbustivo) alterou significativamente a diversidade funcional total, enquanto a intensificação antrópica reduziu significativamente todos os índices funcionais analisados e apenas um taxonômico. Os resultados obtidos e analisados contribuíram para uma compreensão analítica do funcionamento dos ecossistemas aquáticos tropicais, destacando os efeitos do uso e cobertura da terra na diversidade funcional dos insetos aquáticos, em dois hotspots da biodiversidade. Outrossim, o estudo indica parâmetros e informações valiosas para futuras previsões e estratégias de mitigação em ambientes afetados por atividades humanas.
    Description: PhD
    Keywords: Insetos aquáticos de água doce ; Ecologia de riachos ; Diversidade funcional e taxonômica ; Bioindicadores ambientais ; Uso e cobertura da terra ; Vegetação ripária ; Ações naturais e antrópicas ; ASFA_2015::F::Freshwater ecology ; ASFA_2015::I::Insects (aquatic) ; ASFA_2015::S::Streams ; ASFA_2015::E::Ecology ; ASFA_2015::B::Biodiversity ; ASFA_2015::B::Bioindicators ; ASFA_2015::L::Land use ; ASFA_2015::R::Riparian vegetation ; ASFA_2015::H::Human impact
    Repository Name: AquaDocs
    Type: Thesis/Dissertation
    Format: 79pp.
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  • 7
    Publication Date: 2024-05-21
    Description: The Dome Fuji (DF) region in Antarctica is a potential site for an ice core with a record of over 1 Myr. Here, we combine large-scale internal airborne radar stratigraphy with a 1-D model to estimate the age of basal ice in the DF region. The radar data used in the study were collected in a survey during the 2016-2017 Antarctic season. We transfer the latest age-depth scales from the DF ice core to isochrones traced in radargrams in the surrounding 500 km × 550 km region. At each point of the survey the 1-D model uses the ages of isochrones to construct the age-depth scale at depths where dated isochrones do not exist, the surface accumulation rate and the basal thermal condition, including melt rate and the thickness of stagnant ice. Our resulting age distribution and age density suggest that several promising sites with ice older than 1.5 Myr in the DF region might exist. The deduced melt rates and presence of stagnant ice provide more constraints for locating sites with a cold base. The accumulation rates range from 0.015 to 0.038 m a-1 ice equivalent. Based on sensitivity studies we find that the number and depth of picked isochrones and the timescale of the ice core severely affect the model results. Our study demonstrates that constraints from deep radar isochrones and a trustworthy timescale could improve the model estimation to find old ice in the DF region.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 8
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    Copernicus Publications
    In:  EPIC3The Cryosphere, Copernicus Publications, 17(11), pp. 4903-4916, ISSN: 1994-0416
    Publication Date: 2024-05-21
    Description: Reliable in situ surface mass balance (SMB) estimates in polar regions are scarce due to limited spatial and temporal data availability. This study aims at deriving automated and continuous specific SMB time series for fast-moving parts of ice sheets and shelves (flow velocityg10a-1) by developing a combined global navigation satellite system (GNSS) reflectometry and refractometry (GNSS-RR) method. In situ snow density, snow water equivalent (SWE), and snow deposition or erosion are estimated simultaneously as an average over an area of several square meters and independently on weather conditions. The combined GNSS-RR method is validated and investigated regarding its applicability to a moving, high-latitude ice shelf. A combined GNSS-RR system was therefore installed in November 2021 on the Ekström ice shelf (flow velocityĝ€¯≈ĝ€¯150a-1) in Dronning Maud Land, Antarctica. The reflected and refracted GNSS observations from the site are post-processed to obtain snow accumulation (deposition and erosion), SWE, and snow density estimates with a 15ĝ€¯min temporal resolution. The results of the first 16 months of data show a high level of agreement with manual and automated reference observations from the same site. Snow accumulation, SWE, and density are derived with uncertainties of around 9ĝ€¯cm, 40m-2ĝ€¯a-1, and 72m-3, respectively. This pilot study forms the basis for extending observational networks with GNSS-RR capabilities, particularly in polar regions. Regional climate models, local snow modeling, and extensive remote sensing data products will profit from calibration and validation based on such in situ time series, especially if many such sensors will be deployed over larger regional scales.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 9
    Publication Date: 2024-05-21
    Description: In order to complement the picture of the atmospheric water cycle in the Southern Ocean, we have continuously monitored water vapor isotopes since January 2020 on Amsterdam Island in the Indian Ocean. We present here the first 2-year long water vapor isotopic record at this site. We show that the water vapor isotopic composition largely follows the water vapor mixing ratio, as expected in marine boundary layers. However, we detect 11 periods of a few days where there is a strong loss of correlation between water vapor δ18O and water vapor mixing ratio as well as abrupt negative excursions of water vapor δ18O. These excursions often occur toward the end of precipitation events. Six of these events show a decrease in gaseous elemental mercury, suggesting subsidence of air from a higher altitude. Our study aims to further explore the mechanism driving these negative excursions in water vapor δ18O. We used two different models to provide a data–model comparison over this 2-year period. While the European Centre Hamburg model (ECHAM6-wiso) at 0.9° was able to reproduce most of the sharp negative water vapor δ18O excursions, hence validating the physics process and isotopic implementation in this model, the Laboratoire de Météorologie Dynamique Zoom model (LMDZ-iso) at 2° (3°) resolution was only able to reproduce seven (one) of the negative excursions, highlighting the possible influence of the model resolution for the study of such abrupt isotopic events. Based on our detailed model–data comparison, we conclude that the most plausible explanations for such isotopic excursions are rain–vapor interactions associated with subsidence at the rear of a precipitation event.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 10
    Publication Date: 2024-05-21
    Description: In a context of global warming and sea level rise acceleration, it is key to estimate the evolution of the atmo- spheric hydrological cycle and temperature in polar regions, which directly influence the surface mass balance of the Arc- tic and Antarctic ice sheets. Direct observations are available from satellite data for the last 40 years and a few weather data since the 1950s in Antarctica. One of the best ways to access longer records is to use climate proxies in firn or ice cores. The water isotopic composition in these cores is widely used to reconstruct past temperature variations. We need to progress in our understanding of the influence of the atmospheric hydrological cycle on the water isotopic composition of ice cores. First, we present a 2-year-long time series of vapor and precipitation isotopic composition mea- surement at Dumont d’Urville Station, in Adélie Land. We characterize diurnal variations of meteorological parameters (temperature, atmospheric water mixing ratio (hereafter hu- midity) and δ18O) for the different seasons and determine the evolution of key relationships (δ18O versus temperature or humidity) throughout the year: we find that the temper- ature vs. δ18O relationship is dependent on synoptic events dynamics in winter contrary to summer. Then, this data set is used to evaluate the atmospheric general circulation model ECHAM6-wiso (model version with embedded water stable isotopes) in a coastal region of Adélie Land where local con- ditions are controlled by strong katabatic winds which directly impact the isotopic signal. We show that a combina- tion of continental (79 %) and oceanic (21 %) grid cells leads model outputs (temperature, humidity and δ18O) to nicely fit the observations, at different timescales (i.e., seasonal to syn- optic). Therefore we demonstrate the added value of long- term water vapor isotopic composition records for model evaluation. Then, as a clear link is found between the isotopic compo- sition of water vapor and precipitation, we assess how iso- topic models can help interpret short firn cores. In fact, a virtual firn core built from ECHAM-wiso outputs explains much more of the variability observed in S1C1 isotopic record than a virtual firn core built from temperature only. Yet, deposition and post-deposition effects strongly affect the firn isotopic signal and probably account for most of the re- maining misfits between archived firn signal and virtual firn core based on atmospheric modeling.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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