Late Holocene environmental conditions in Coronation Gulf,southwestern Canadian Arctic Archipelago: evidence from dinoflagellate cysts,other non‐pollen palynomorphs,and pollen     

Anna J. Pieńkowski  Peta J. Mudie  John H. England  John N. Smith  Mark F. A. Furze 《第四纪科学杂志》2011,26(8):839-853

Boxcore 99LSSL‐001 (68.095° N, 114.186° W; 211 m water depth) from Coronation Gulf represents the first decadal‐scale marine palynology and late Holocene sediment record for the southwestern part of the Northwest Passage. The record was studied for organic‐walled microfossils (dinoflagellate cysts, non‐pollen palynomorphs), pollen, terrestrial spores, and sediment characteristics. ²¹⁰Pb, ¹³⁷Cs, and three accelerator mass spectrometry ¹⁴C dates constrain the chronology. Three prominent palaeoenvironmental zones were identified. During the interval AD 1470–1680 (Zone I), the climate was warmer and wetter than at present, and environmental conditions were more favourable to biological activity and northward boreal forest migration, with reduced sea‐ice and a longer open‐water (growing) season. The interval AD 1680–1940 (Zone II) records sea‐ice increase, and generally cool, polar conditions during the Little Ice Age. During AD 1940–2000 (Zone III), organic microfossils indicate an extended open‐water season and decreased sea‐ice, with suggested amelioration surpassing that of Zone I. Although more marine studies are needed to place this record into an appropriate context, the succession from ameliorated (Zone I) to cooler, sea‐ice influenced conditions (Zone II) and finally to 20th‐century warming (Zone III) corresponds well with several terrestrial climatic records from the neighbouring mainland and Victoria Island, and with lower‐resolution marine records to the west. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

A reconstruction of the palaeohydrological conditions of a flood‐plain: a multi‐proxy study from the Grabia River valley mire,central Poland          下载免费PDF全文

Dominik Pawłowski  Grzegorz Kowalewski  Krystyna Milecka  Mateusz Płóciennik  Michał Woszczyk  Tomasz Zieliński  Daniel Okupny  Wojciech Włodarski  Jacek Forysiak 《Boreas: An International Journal of Quaternary Research》2015,44(3):543-562

This study investigated the Grabia River valley mire in central Poland to reconstruct its palaeoenvironmental conditions from the Younger Dryas to the present. We analysed sedimentological, biological and geochemical data from the palaeo‐oxbow lake and valley mire to identify the principal hydrological trends, especially episodes of high water level. During the Lateglacial and Holocene, the Grabia River had a meandering channel, and its hydraulic parameters and the channel dimensions changed in response to climatic oscillations and vegetation development. We identified phases of high flood intensity and high groundwater level that correlate with regional and supraregional climatic events. The frequency and timing of palaeohydroclimatic oscillations show strong similarities to records from other sites in Poland and the rest of Europe. We show that various analytical methods, namely, pollen, plant macrofossils, Cladocera, Chironomidae, sedimentological, geochemical and radiocarbon data, can be effective tools for reconstructing past hydroclimatic changes in palaeo‐oxbow lakes and investigating the effects of past climate changes on river environments. The high sensitivity of the biota, especially Cladocera, to changes in water level permits the reconstruction of palaeoecological changes, especially flood episodes that occurred in the river valley. In particular, the increase in the proportion of sediment‐associated Cladocera and pelagic taxa was closely correlated with floods. Through comparisons with the palaeobiological data, geochemical data allowed the identification of humid phases within the fen associated with a rising groundwater table, direct fluvial activity (floods) and alluvial deposition. We also discuss the limitations of palaeohydrological reconstructions based on these proxies, especially on fossil aquatic invertebrates.  相似文献   

Diffusive mass exchange of non‐reactive substances in dual‐porosity porous systems – column experiments under saturated conditions          下载免费PDF全文

Bastian Knorr  Piotr Maloszewski  Florian Krämer  Christine Stumpp 《水文研究》2016,30(6):914-926

Diffusive mass exchange into immobile water regions within heterogeneous porous aquifers influences the fate of solutes. The percentage of immobile water is often unidentified in natural aquifers though. Hence, the mathematical prediction of solute transport in such heterogeneous aquifers remains challenging. The objective of this study was to find a simple analytical model approach that allows quantifying properties of mobile and immobile water regions and the portion of immobile water in a porous system. Therefore, the Single Fissure Dispersion Model (SFDM), which takes into account diffusive mass exchange between mobile and immobile water zones, was applied to model transport in well‐defined saturated dual‐porosity column experiments. Direct and indirect model validation was performed by running experiments at different flow velocities and using conservative tracer with different molecular diffusion coefficients. In another column setup, immobile water regions were randomly distributed to test the model applicability and to determine the portion of immobile water. In all setups, the tracer concentration curves showed differences in normalized maximum peak concentration, tailing and mass recovery according to their diffusion coefficients. These findings were more pronounced at lower flow rates (larger flow times) indicating the dependency of diffusive mass exchange into immobile water regions on tracers' molecular diffusion coefficients. The SFDM simulated all data with high model efficiency. Successful model validation supported the physical meaning of fitted model parameters. This study showed that the SFDM, developed for fissured aquifers, is applicable in porous media and can be used to determine porosity and volume of regions with immobile water. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Root‐related rhodochrosite and concretionary siderite formation in oxygen‐deficient conditions induced by a ground‐water table rise          下载免费PDF全文

Maciej J. Bojanowski  Elżbieta Jaroszewicz  Adrijan Košir  Maciej Łoziński  Leszek Marynowski  Anna Wysocka  Arkadiusz Derkowski 《Sedimentology》2016,63(3):523-551

Sedimentological, mineralogical, stable carbon and oxygen isotope determinations and biomarker analyses were performed on siderite concretions occurring in terrestrial silts to understand their formation and to characterize the sedimentary and diagenetic conditions favouring their growth. High δ¹³C values (6·4‰ on average) indicate that siderite precipitated in an anoxic environment where bacterial methanogenesis operated. The development of anoxic conditions during shallow burial was induced by a change in sedimentary environment from flood plain to swamp, related to a rise of the ground‐water table. Large amounts of decaying plant debris led to efficient oxygen consumption within the pore‐water in the peat. Oxygen depletion, in combination with a decrease in sedimentation rate, promoted anoxic diagenetic conditions under the swamp and favoured abundant siderite precipitation. This shows how a change in sedimentary conditions can have a profound impact on the early‐diagenetic environment and carbonate authigenesis. The concretions contain numerous rhizoliths; they are cemented with calcium‐rhodochrosite, a feature which has not been reported before. The rhodochrosite cement has negative δ¹³C values (?16·5‰ on average) and precipitated in suboxic conditions due to microbial degradation of roots coupled to manganese reduction. The exceptional preservation of the epidermis/exodermis and xylem vessels of former root tissues indicates that the rhodochrosite formed shortly after the death of a root in water‐logged sediments. Rhodochrosite precipitated during the initial stages of concretionary growth in suboxic microenvironments within roots, while siderite cementation occurred simultaneously around them in anoxic conditions. These suboxic microenvironments developed because oxygen was transported from the overlying oxygenated soil into sediments saturated with anoxic water via roots acting as permeable conduits. This model explains how separate generations of carbonate cements having different mineralogy and isotopic compositions, which would conventionally be regarded as cements precipitated sequentially in different diagenetic zones during gradual burial, can form simultaneously in shallow burial settings where strong redox gradients exist around vertically oriented permeable root structures.  相似文献   

Spontaneous self-combustion of organic-rich lateglacial lake sediments after freeze-drying     

Nadine Dräger  Achim Brauer  Brian Brademann  Rik Tjallingii  Michał Słowiński  Mirosław Błaszkiewicz  Norbert Schlaak 《Journal of Paleolimnology》2016,55(2):185-194

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Biosorption optimization and equilibrium isotherm of industrial dye compounds in novel strains of microscopic fungi     

K.?Rybczyńska-TkaczykEmail author  T.?Korni??owicz-Kowalska 《International Journal of Environmental Science and Technology》2016,13(12):2837-2846

The aim of this study was to evaluate the biosorption capacity of selected strains of microscopic fungi. We optimized the biosorption process and used the Freundlich isotherm for three strains: H. haematococca BwIII43, K37 and T. harzianum BsIII33 to describe the biosorption equilibrium of anthraquinone dye, Alizarin Blue Black B (ABBB) and alkali lignin (AL). In optimal conditions (1 g of mycelium biomass, pH = 7.0, 28 °C) for ABBB and AL sorption, the live biomass of H. haematococca BwIII43 was characterized by a higher sorption capacity, amounting to 247.47 and 161.00 mg g^?1, respectively. The highest sorption properties toward anthraquinone dye (K _F = 19.96 mg g^?1) were shown for the biomass of H. haematococca K37. In the presence of alkali lignin, the highest sorption capacity and bond strength exhibited the biomass of H. haematococca BwIII43 (K _F = 28.20 mg g^?1, n = 3.46). Effective decolorization of ABBB and AL by the selected strains of microscopic fungi indicated that the biosorption process additionally enhanced the removal of color compounds from the solution.  相似文献   

Spring water chemistry in a formerly glaciated area of western Poland: the contribution of natural and anthropogenic factors     

Anna Szczucińska 《Environmental Earth Sciences》2016,75(8):712

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Efficiency of methane fermentation of waste microalgae biomass (WMAB) collected in processes of reclamation of eutrophicated water reservoirs     

Marcin Dębowski  Marcin Zieliński  Marta Kisielewska  Mirosław Krzemieniewski 《Environmental Earth Sciences》2016,75(6):525

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Non-woven polypropylene fabric modified with carbon nanotubes and decorated with nanoakaganeite for arsenite removal     

J. Tomaszewska  P. Smektała  I. Zgłobicka  J. Michalski  K. J. Kurzydłowski  P. Krzemiński  C. Escudero-Oñate 《International Journal of Environmental Science and Technology》2018,15(9):1831-1842

Due to its harmful impact on human health, the presence of heavy metals, metalloids and other toxic pollutants in drinking or irrigation water is a major concern. Recent studies have proved that nanosized adsorbents are significantly more effective than their microsized counterparts. Particular attention has been given to nanocomposites with nanoadsorbents embedded in matrixes that could provide stability to the material and contribute to eliminating problems that may appear when using conventional granular systems. This study presents the preparation of a novel hybrid filter from a commercially available polypropylene (PP) non-woven fabric matrix modified with multiwall carbon nanotubes (MWCNT) and iron oxy(hydroxide) nanoparticles, and its use in the removal of As(III). A Box–Behnken statistical experimental design has been chosen to explore relevant variables affecting the filter performance: (1) As(III) concentration, (2) pH and (3) sorbent dose. From an As(III) concentration of 10 mg L^?1, at pH 6.5 and with a sorbent dose of 5 g L^?1, the PP filter modified with MWCNT removes 10% of the initial metalloid concentration, reaching a capacity of 0.27 mg g^?1. After modification with iron oxy(hydroxide), the performance of the material is largely enhanced. The filter, under the same conditions, removes 90% of the initial As(III) concentration, reaching a capacity almost tenfold higher (2.54 mg g^?1). This work demonstrates that the developed hybrid filter is effective toward the removal of As(III) in a wide range of pHs. A cubic regression model to compute the removal of the filter as a function of pH and sorbent dose is provided.  相似文献   

Mg-enriched erythrite from Bou Azzer,Anti-Atlas Mountains,Morocco: geochemical and spectroscopic characteristics     

Dumańska-Słowik  Magdalena  Pieczka  Adam  Natkaniec-Nowak  Lucyna  Kunecki  Piotr  Gaweł  Adam  Heflik  Wiesław  Smoliński  Wojciech  Kozub-Budzyń  Gabriela 《Mineralogy and Petrology》2018,112(3):381-392

Mineralogy and Petrology - Supergene Mg-enriched erythrite, with an average composition (Co2.25Mg0.58Ni0.14Fe0.04Mn0.02 Zn0.02) (As1.97P<0.01O8)·8H2O, accompanied by skutterudite,...  相似文献