The multi-component Hekla Ö Tephra,Iceland: a complex widespread mid-Holocene tephra layer     

Daníel Freyr Jónsson  Esther Ruth Gudmundsdóttir  Gudrún Larsen  Bergrún Arna Óladóttir  Egill Erlendsson  Sigrún Dögg Eddudóttir  Olgeir Sigmarsson 《第四纪科学杂志》2020,35(3):410-421

Large Plinian eruptions from Hekla volcano, Iceland, produce compositionally zoned tephra used as key markers in tephrochronology. However, spatial variations in chemical composition of a tephra layer may complicate its identification. An example is the 5950–6180 cal a bp Hekla Ö tephra layer, which shows compositional spread from rhyolite, dacite and andesite to basalt. In soil sections north of Hekla, the SiO₂ content of the tephra glass reaches 76 wt% in the lowest unit of the Hekla Ö deposit and decreases to 62–63 wt% in the uppermost unit. Intermingled within the whole deposit are basalt tephra grains having 46–47 wt% SiO₂. The composition of the basalt glass includes primitive basalt and a more evolved basalt (MgO >6 and <6 wt%, respectively). Together with literature data, the Hekla Ö tephra and the so-called T-Tephra/Hekla-T are most likely from contemporaneous eruptions of different vents on the Hekla volcanic system, forming a single important marker tephra (Hekla ÖT) deposited over 80% of Iceland. Identification is complicated by its spatial compositional heterogeneity, such as systematic decrease in SiO₂ content from the east to the west of Hekla volcano. Consequently, an individual tephra layer from a large explosive eruption can have different composition at different locations. © 2020 John Wiley & Sons, Ltd.  相似文献   

A Holocene high-resolution record of aquatic productivity,seasonal anoxia and meromixis from varved sediments of Lake Łazduny,North-Eastern Poland: insight from a novel multi-proxy approach     

Andrea Sanchini  Sönke Szidat  Wojciech Tylmann  Hendrik Vogel  Agnieszka Wacnik  Martin Grosjean 《第四纪科学杂志》2020,35(8):1070-1080

Anthropogenic eutrophication and spreading anoxia in freshwater systems is a global concern. Little is known about anoxia in earlier historic times under weaker human impact, or under prehistoric natural conditions with different trophic, land cover and climatic regimes. We use a novel approach that combines high-resolution hyperspectral imaging with µ-XRF and HPLC-pigment data, which allows us to assess chloropigments (productivity) and bacteriopigments (anoxia) at seasonal subvarve-scale resolution. Our ~9700 cal a bp varved sediment record from NE Poland suggests that productivity increased stepwise from oligotrophic Early Holocene conditions (until ~9200 cal a bp ) to mesotrophic conditions in the Mid- and Late Holocene. Natural eutrophication was mainly a function of progressing landscape evolution with intense weathering under dense forest and warm-moist climatic conditions. Generally, anoxia increased with increasing productivity. Seasonal anoxia and some multi-decadal periods of meromixis were the common mixing patterns throughout the Holocene except for a period of persisting meromixis between ~5200 and 2000 cal a bp. Anthropogenic deforestation around 400 cal a bp resulted in substantially better lake oxygenation despite high productivity. In this small lake, aquatic productivity and lakeshore forest cover (wind shield) were more important factors controlling oxic/anoxic conditions than Holocene temperature variability.  相似文献   

Erratum to: Forest–water dynamics within a mountainous catchment in Austria     

Elisabeth Pötzelsberger  Hubert Hasenauer 《Natural Hazards》2015,77(3):2145-2145

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Potential of SAR intensity tracking technique to estimate displacement rate in a landslide-prone area in Haridwar region,India     

Atanu Bhattacharya  Kriti Mukherjee  Manoj Kuri  Malte Vöge  M. L. Sharma  M. K. Arora  Rejinder K. Bhasin 《Natural Hazards》2015,79(3):2101-2121

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Water resources sustainability in a globalizing world: who uses the water?          下载免费PDF全文

Megan Konar  Tom P. Evans  Morgan Levy  Christopher A. Scott  Tara J. Troy  Charles J. Vörösmarty  Murugesu Sivapalan 《水文研究》2016,30(18):3330-3336

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Rain on snow induced urban floods in cold maritime climate: Risk,indicators and trends     

Hrund Ólöf Andradóttir  Anna Rut Arnardóttir  Tarek Zaqout 《水文研究》2021,35(9):e14298

Urban floods pose a societal and economical risk. This study evaluated the risk and hydro-meteorological conditions that cause pluvial flooding in coastal cities in a cold climate. Twenty years of insurance claims data and up to 97 years of meteorological data were analysed for Reykjavík, Iceland (64.15°N; <100 m above sea level). One third of the city's wastewater collection system is combined, and pipe grades vary from 0.5% to 10%. Results highlight semi-intensive rain (<7 mm/h; ≤3 year return period) in conjunction with snow and frozen ground as the main cause for urban flood risk in a climate which undergoes frequent snow and frost cycles (avg. 13 and 19 per season, respectively). Floods in winter were more common, more severe and affected a greater number of neighbourhoods than during summer. High runoff volumes together with debris remobilized with high winds challenged the capacity of wastewater systems regardless of their age or type (combined vs. separate). The two key determinants for the number of insurance claims were antecedent frost depth and total precipitation volume per event. Two pluvial regimes were particularly problematic: long duration (13–25 h), late peaking rain on snow (RoS), where snowmelt enhanced the runoff intensity, elongated and connected independent rainfall into a singular, more voluminous (20–76 mm) event; shorter duration (7–9 h), more intensive precipitation that evolved from snow to rain. Closely timed RoS and cooling were believed to trigger frost formation. A positive trend was detected in the average seasonal snow depth and volume of rain and snowmelt during RoS events. More emphasis, therefore, needs to be placed on designing and operating urban drainage infrastructure with regard to RoS co-acting with frozen ground. Furthermore, more detailed, routine monitoring of snow and soil conditions is important to predict RoS flood events.  相似文献   

The prediction of surface temperature in the new seasonal prediction system based on the MPI-ESM coupled climate model     

J. Baehr  K. Fröhlich  M. Botzet  D. I. V. Domeisen  L. Kornblueh  D. Notz  R. Piontek  H. Pohlmann  S. Tietsche  W. A. Müller 《Climate Dynamics》2015,44(9-10):2723-2735

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Improving Properties of Sealing Layers Made of Till by Adding Green Liquor Dregs to Reduce Oxidation of Sulfidic Mine Waste     

Maria Mäkitalo  Josef Mácsik  Christian Maurice  Björn Öhlander 《Geotechnical and Geological Engineering》2015,33(4):1047-1054

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Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone,Iceland     

Deborah E. Eason  John M. Sinton  Karl Grönvold  Mark D. Kurz 《Bulletin of Volcanology》2015,77(6):1-27

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Lagged response of nutrient leaching to reduced surpluses at the field and catchment scales          下载免费PDF全文

Barbro Ulén  Göran Johansson  Katarina Kyllmar  Lovisa Stjernman Forsberg  Gunnar Torstensson 《水文研究》2015,29(13):3020-3037

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