Search

Simple cutting devices such as used in the printing industry allow precise and fine sectioning of frozen peats and sediments, thus enabling research with high temporal resolution. Large slices are useful in the collection of multiple synchronous subsamples for multidisciplinary research. This article describes the apparatus (called DAMOCLES) and its operation, and presents some examples from practice. These include combined microfossil, macrofossil and chemical analyses of the same sample with a sample resolution of 0.5 cm (temporal resolution c. 1 year): rapid changes occur that would have remained unnoticed with a coarser sampling distance. The final example presents a sample resolution of only 0.5 mm. These examples illustrate the possible uses of the DAMOCLES apparatus in palaeoecological research. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various articles within the issue on topics including organic soils, soil mechanics approaches to peat, and behavior of bentonite on mixed with sand or zeolite.

The published peat:coal compaction ratios range from 1.1:1 to 60:1 and from 1.1:1 to 11:1 for lignites. These probably represent realistic end-member values for the degree of compaction during the transformation of peat into lignite and then to coal. Hence, in many cases, the obtained values of the compaction ratio are under- or overestimated with reference to the entire coal seam. This study focuses on the changes of thickness between a peat bed and the resulting lignite seam. The fundamental question is how many times the thickness of the peat bed, prior to covering the mire by the overburden, was greater than the present-day thickness of the lignite seam. The majority of methods reported in this paper cannot be used directly to quantify the amount of compaction of the lignite seam. In this context, the only category of methods which allow a direct estimation of the peat:lignite compaction ratio are the so-called stratigraphic methods. Therefore, based on comparison of the initial peat bed thickness with lignite seam thickness, the most accurate peat:lignite compaction ratio ranges from 2:1 to 4:1. [ABSTRACT FROM AUTHOR]

This paper presents the creep behaviour of intact and remoulded specimens of fibrous peat obtained from a field site near Anzac, Alberta, Canada. The creep behaviour was investigated by means of long-term drained and undrained triaxial tests. The development of volumetric, axial, and undrained axial strain and strain rate during drained and undrained creep tests under variable stress conditions is presented. The stress-strain-strain rate (p′-εv-ε˙v) relationship is found to be unique for different stress and loading durations. The p′-εv-ε˙v relationship is analysed and represented by creep isotaches. The applicability of different creep models developed for normally consolidated clay is discussed and applied to define the development of creep strain in fibrous peat under varying isotropic and deviator stresses. The secondary consolidation coefficient for evaluating the volumetric strain rate of peat is found to be applicable with some limits. The drained creep behaviour of remoulded peat specimens differs from the behaviour shown by Shelby tube specimens, whereas the undrained creep behaviour in remoulded and Shelby tube specimens is similar. [ABSTRACT FROM AUTHOR]

ABSTRACT North Atlantic storminess can affect human settlements, infrastructure and transport links, all of which strongly impact local, national and global economies. An increase in storm frequency and intensity is predicted over the North-East Atlantic in the 21st century because of a northward shift in storm tracks and a persistently positive North Atlantic Oscillation (NAO), driven by recent atmospheric warming. Although documentary records of North Atlantic storminess exist, these are generally limited to the last c. 1000 years. This paper presents a continuous high-resolution proxy record of storminess spanning the last 8000 years from a 6 m-long core taken from a peat bog in northern Scotland. Bromine concentrations in the peat, derived from sea spray, are used to reconstruct storm frequency and storm intensity, and mire surface wetness is used as an indicator of longer-term climate shifts. The results suggest a relationship between positive phases of the NAO and increased North Atlantic storminess. However, subtle differences between bromine concentrations and mire surface wetness suggest that high-intensity but perhaps less frequent periods of storminess are not necessarily associated with a wetter climate. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present a review of peat landslide events in Ireland since 2003, when two significant events occurred. Since 2003, there have been at least 13 such events. Several of these events included more than one slide. It is also likely that there have been unrecorded slides. It seems that there is an increasing incidence of such events, but they seem to occur in clusters with intervening quiet periods. These clusters coincide with periods of intense rainfall. For many slides, at least two causal factors can be identified. Primarily these comprised intense rainfall but human activities such as road construction and peat cutting also contributed to the slides. Detailed geotechnical testing of the peat, including laboratory direct simple shear tests (DSS), is reported for two of the slides. Back-analysis of these two failures suggests that the mobilised strength of the material in the failure surface is similar to that measured in the DSS tests. However, conventional geotechnical analyses need to be treated with caution as they fail to account for the complex interactions in the sliding surface and in particular the lubricating role of water. [ABSTRACT FROM AUTHOR]

Because of the limited land area in Japan, many structures are built on peat and/or highly organic soft ground. These soils are well known for exhibiting large settlement and secondary compression during and after construction. Preloading is suitable for ground improvement of peat and highly organic soil, as well as clay. The author has performed a series of laboratory loading and/or unloading creep tests that simulate actual preloading method for peat and silty clay which samples collected in Japan. Previously, the author reported that the characteristics of long-term creep settlement after unloading (rebound ratio, rate of secondary compression and re-settlement point) are affected by the over consolidation ratio, preloading time and plasticity index [1], [2]. In this paper, the experimental data from loading and/or unloading creep tests and stress relaxation tests are used to further explore the behavior of highly organic soil. [ABSTRACT FROM AUTHOR]

Volcanic glass compositions and tephra layer age are critical for anchoring their sources and correlating among different sites; however, such work may be imprecise when the tephra has varied compositions. The ash from Changbaishan Millennium eruption (940s AD), a widely distributed tephra layer, has been detected in the far-east areas of Russia, the Korean Peninsula, Japan, and in Greenland ice cores. There are some debates on the presence of this tephra from sedimentary archives to the west of Changbaishan volcano, such as lake and peat sediments in the Longgang volcanic field. In this paper, major element compositions for clinopyroxene and Fe-Ti oxides were performed on proximal tephra from Changbaishan and the Millennium eruption ash record in Lake Sihailongwan. Clinopyroxene and Fe-Ti oxides microlites from Sihailongwan show augite- ferroaugite and titanmagnetite compositions, similar to those from dark pumice in Changbaishan proximal tephra, but different from the light grey pumice, which has ferrohedenbergite and ilmenite microlite compositions. This result implies that the tephra recorded in Sihailongwan was mainly from the trachytic eruptive phase of the Millennium eruption, and the rhyolitic eruptive phase made a relatively small contribution to this area. Analyzing clinopyroxene and Fe-Ti oxides microlites is a new method for correlating tephra layers from Changbaishan Millennium eruption. [ABSTRACT FROM AUTHOR]

Research into the medium-forming role of bogs is done in the confined space of bog sites. Various bog types with specific conditions react to global climate change in different ways. To extrapolate fairly the data of selective (to the scale of Western Siberia) researches, the information about bog cover structure of a large area is necessary. In the paper, we present the data concerning landscape structure of the Great Vasyugan Mire over the area of 5.5 mn ha, in accordance with 15 types of bog sites. Peat deposit structure features are given for different bog types. [ABSTRACT FROM PUBLISHER]

Peat deposits are comprised of high organic content substances primarily derived from dead plant vegetation. Peat itself is not inert but undergoes continuous biological decomposition that causes progressive destruction of the peat fabric, reductions in fibre and organic contents and biogas generation. Depending on the degree of decomposition, the organic solids can exist as fresh (intact) fibres, slightly decomposed or ultimately completely decomposed (amorphous) material. From a geotechnical perspective, an understanding of the relationship between degree of decomposition and engineering properties, including the level of compressibility, is important in dealing with such problematic deposits. However a review of the literature indicates that such relationships have not been sufficiently investigated. Moreover, potential impacts of uncontrolled or unexpected decomposition in-situ are regularly discounted in geotechnical practice. This paper reviews decomposition effects in peat and potentially significant knock-on effects in terms of the material’s physical properties and compressibility. Progressive reduction in solids volume and deterioration in the integrity of the organic structure due to on-going decomposition may cause significant additional settlement to occur over time. More decomposed peat generally undergoes lower primary consolidation and creep strains and is also less prone to future decomposition, compared with lesser decomposed peat. [ABSTRACT FROM AUTHOR]

Peat filters have been used to treat septic tank effluents from domestic and commercial sources, landfill leachate, and acid mine drainage. A better understanding of the hydraulics and impact of the organic loading on these types of systems will enhance the application of peat filter systems. This paper presents the results of a field study to evaluate the hydraulics of a peat filter used to treat the septic tank effluent from a public school west of Ottawa, Ontario, Canada. The filter was instrumented with tensiometers and transducers to monitor the pore-water pressures in response to a pulse of septic tank effluent. Samples of peat were collected to determine the dry density profile with depth. The soil moisture retention curve, effective porosity, and hydraulic conductivity as a function of dry density were determined in laboratory experiments. A one-dimensional unsaturated flow model was used to predict the pressure response due to a pulse. Two model scenarios were evaluated to demonstrate the impact of density variations on model simulations. Model simulations that accounted for dry density variations with depth measured in the field more accurately simulated the pressure responses measured in the field.Key words: unsaturated flow, peat, filters, septic, modelling, density.Des filtres de tourbe ont été utilisés pour traiter les effluents de fosses septiques de sources domestique et commerciale, les lixiviants des enfouissements sanitaires et le drainage acide minier. Une meilleure compréhension de l'hydraulique et de l'impact de la charge organique sur ces types de systèmes va bonifier l'application des systèmes de filtre de tourbe. Cet article présente les résultats d'une étude sur le terrain pour évaluer l'hydraulique d'un filtre de tourbe utilisé pour traiter l'effluent d'une fosse septique d'une école publique de l'ouest d'Ottawa, Canada. Le filtre a été instrumenté avec des tensiomètres et des capteurs pour mesurer les pressions interstitielles consécutives à une pulsation d'effluent de la fosse septique. Des échantillons de tourbe ont été prélevés pour déterminer le profil de densité sèche avec la profondeur. La courbe de rétention d'eau dans le sol, la porosité effective et la conductivité hydraulique en fonction de la densité sèche ont été déterminées au cours d'expériences en laboratoire. Un modèle d'écoulement non saturé unidimensionnel a été utilisé pour prédire la réaction de pression due à une pulsation. Deux scénarios de modèle ont été évalués pour démontrer l'impact des variations de densité sur les simulations du modèle. Les simulations du modèle qui tenaient compte des variations de densité sèche avec la profondeur mesurées sur le terrain ont simulé plus précisément les réactions de pression mesurées sur le terrain.Mots clés : écoulement non saturé, tourbe, filtres, septique, modélisation, densité.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Peat is a very variable but normally weak material. While engineering failures involving peat are common, the full diversity of engineering behaviours exhibited by peat has not been well classified due to its large range of possible compositions. This paper presents the behaviour of a fibrous peat which is a fill (made ground) originating from the most recent dredging of the West Lake, a site of cultural and historic importance in China. Given its relatively unique mechanism of deposition, the distinctive characteristics of this peat are presented in comparison to other peats reported in the literature highlighting its unique engineering behaviour. A laboratory study carried out on the peat at Jiangyangfan Eco-park, located in Hangzhou, China identifies that it has its special aspects when compared to other peats. The shearing behaviour of peat can be described using the framework of critical state theory. The most prominent characteristic of the West Lake Peat is that its undrained stress path bends towards the left at the very beginning of shearing which indicates that plastic deformation occurs at very small stress ratios. A constitutive model based on critical state theory for predicting the undrained shear behaviour of this type of peat from low stress to critical state levels is presented. This model also includes several elements of peat behaviour previously reported and it may therefore be applied to a wider range of peat soils. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a detailed survey of the activities of selected man-made radionuclides in peat deposits located in SW Spitsbergen. Peat cores from the High Arctic (SW Spitsbergen) were analyzed by gamma spectrometry (137Cs), alpha spectrometry (238Pu, 239,240Pu, 241Am activities) and by ICPMS (240Pu/239Pu atom ratios). Maximum activities evident in the peats correspond to the 1963/1964 global maximum fallout from atmospheric testing of nuclear weapons; some of the activity profiles have been altered post-deposition by water infiltration. Activity ratios of 238Pu/239+240Pu, 241Am/239+240Pu, 239+240Pu/137Cs and 240Pu/239Pu atom ratios indicate mixing between global (stratospheric) and regional (tropospheric) sources of these radionuclides in the Svalbard area. The 238Pu/239+240Pu activity ratios varied from 0.02±0.01 to 0.09±0.03, suggesting global fallout as the dominant source of Pu. The 239+240Pu/137Cs activity ratios varied from 0.01±0.01 to 0.42±0.11, which apparently arises from the post-depositional mobility of 137Cs. The 241Am/239+240Pu activity ratios ranged between 0.10±0.02 and 1.5±0.3 and exceed the published global fallout ratio for Svalbard of 0.37 due to the relatively higher geochemical mobility of Pu vs. Am and/or ingrowth of Am from the decay of 241Pu. The atom ratio 240Pu/239Pu ranged from 0.142±0.006 to 0.241±0.027; however, the vast majority of peat samples exhibited 240Pu/239Pu atom ratios similar to the stratospheric fallout (∼0.18). [Copyright &y& Elsevier]

Abstract: The paper presents a new prototype cell, which has been realized for simultaneous monitoring of the electrical and geo-mechanical properties of peat. The apparatus is a modified hydraulic oedometer implemented with pore-pressure control, back-pressure facility and two electrode porous plates for multi-frequency complex conductivity measurements during compression of the sample. Technical issues are addressed and solutions are reported together with the calibration of both the electrical and mechanical system. A combined consolidation–conductivity test on a peat sample is presented. The complex conductivity response can be interpreted in terms of a change in soil properties (such as porosity and structure of the sample) during the consolidation. Preliminary results make this apparatus a suitable tool to improve the characterization of peat deposits in terms of hydraulic and mechanical properties. [Copyright &y& Elsevier]

The paper presents the effect of alkali on tropical peat stabilized with ordinary portland cement (OPC), fly ash (FA) and different chemicals e.g., accelerator (a combination of 2.0% sodium sulfate, 0.5% sodium chloride and 0.1% triethanolamine); 2.6% aluminum sulfate; and 2.6% calcium sulfate. Various physical and engineering properties tests were conducted on original peat, FA and stabilized peat samples to check the effect of alkali and chemicals. Unconfined Compressive Strength (UCS) tests were carried out on treated (i.e., peat treated with 2% NaOH to reduce its acidity) and untreated stabilized peat samples with OPC, FA, and different chemicals for various curing periods. The results show that UCS value increases with curing periods and treated peat samples show better results than untreated peat for both OPC and FA stabilized peat samples. The highest UCS value was found on treated stabilized peat where calcium sulfate and OPC were used as stabilizers for 120 days curing period. In addition, specific gravity (Gs), pH, loss on ignition (N), Organic Content (OC) and Scanning Electron Microscope (SEM) studies were also carried out on stabilized peat samples to investigate the stabilized behavior and micro-structure of the peat. [ABSTRACT FROM AUTHOR]

Abstract: Peat bogs generally exhibit significantly lower Hg accumulation rates during the pre-industrial (pre-1800 AD) period than lake sediments. Organic matter (OM) humification and losses of associated Hg from the deeper sections of peat profiles were recently proposed as an explanation for this widely-observed discrepancy. Here, this hypothesis is tested by examining the state of OM preservation and Hg accumulation rates in a dated, 165cm (6270yr) long permafrost peat core from northern Canada. Pyrolytic speciation of organic carbon using RockEval 6 analysis, and organic petrology of the OM, showed that OM throughout most of the core was better preserved than is typical of many peat deposits, although below ∼120cm depth the initial stages of humification resulted in losses of labile organic compounds and increases in the proportion of refractory carbon. However, through most of the core there was little evidence of significant humification which could have caused large OM mass losses. Mercury flux averaged 0.82±0.36µg/m2/yr over the six millennia of peat accumulation, well within the range previously reported from other peat bogs. Thus, this paper adds to other studies, using a variety of humification indicators, which found no relationship between OM preservation/humification and pre-industrial Hg flux rates in peat bogs. Other explanations must be sought to account for the observed differences between pre-industrial peat and lake sediment Hg histories. [Copyright &y& Elsevier]

Abstract: Construction of a 16-m deep, 55-m wide, almost square, underground structure through 8-m of soft soils and 8-m of sandstone and siltstone led to the development of widespread settlements. The affected area extended to distances of over 200 m from the perimeter of the structure. The floor slab of the underground structure was not designed for water pressure. Thus, operation of the structure requires continuous pumping of seepage water collected at a sump located at the lowermost elevation within the structure. Subsurface investigation and monitoring data obtained over 5.75-year period following the construction of the structure indicated that the settlement resulted from consolidation of soft soils due to depressurization of an aquifer within the underlying bedrock caused by continuous dewatering needed for the operation of the structure. An analytical study was undertaken to project the long term settlement. A simple analytical model could be used to simulate the complex hydrogeological problem reasonably. The details of hydrogeologic setting, subsurface investigation and monitoring activities, and the analytical model for projecting long-term settlements are presented in this paper. [Copyright &y& Elsevier]

Abstract: This paper presents geochemical profiles of a tephra-bearing minerotrophic peat column from NE-Iceland obtained using various elemental analyses of the solid phase and the pore water. The influence of tephra grain size, thickness and composition of each tephra on the peat geochemistry was investigated. Interpretations are supported by a statistical approach, in particular by autocorrelation, and by microscopy observations. Minerotrophic peat geochemistry may be strongly dependent upon post-depositional mobilization and possible leaching of elements as demonstrated by Fe and trace metal concentration profiles. Chemical elements, and more specifically potentially harmful metals, can be slowly leached out of volcanic falls during their weathering and re-accumulate downwards. It is emphasised that a tephra deposit can act as an active geochemical barrier, blocking downward elemental movements and leading to the formation of enriched layers. In this study, the formation of poorly amorphous Fe phases above the Hekla 3 tephra is shown. These poorly crystalline Fe phases scavenged Ni. [Copyright &y& Elsevier]

The article focuses on the study of the chemical elements of rain in the peat area near the Moor House National Nature Reserve in Great Britain to determine its degree of ombrogeny. The study measured the nutrient elements brought rain in the peat area for years, and assessed the effects of birds, smoke, and other pollution. The results of the conducted research found six elements from the rain, including inorganic nitrogen, phosphorus, and magnesium. The results were also compared with independent measurements, and chemical inventories of peat bogs.

Study of climatic evolution in the source area of the Yellow River (SAYR) and its mechanisms is of significance for understanding and predicting the climate and environmental changes and permafrost evolution on the northeastern Tibetan Plateau (TP). This study reconstructed the Asian monsoon and climatic evolution in SAYR since 6.1 cal (cal = the calendar year, as below) ka BP in the mid-late Holocene using geochemical parameters (i.e., SiO2/[RO+R2O], SiO2/Al2O3, SiO2/TiO2, SiO2/[Al2O3 + Fe2O3], chemical index of alteration (Al2O3/[Al2O3 + CaO* + Na2O + K2O]), chemical index of weathering (Al2O3/[Al2O3 + CaO* + Na2O]), [CaO + K2O + Na2O]/Al2O3 and K/Na ratios) of peat deposits and AMS 14C chronology. The climate was warm and humid between 6.1 and 5.4 cal ka BP, with weak winter monsoon intensity and strong summer monsoon intensity, and accompanied by strong chemical weathering and leaching. From 5.4 to 1.5 cal ka BP, the climate was relatively cold and dry with enhanced winter monsoon and weakened summer monsoon intensities. During 1.5 and 0.8 cal ka BP, with the winter and summer monsoon changing rapidly, lower winter monsoon intensity, higher summer monsoon intensity, and higher chemical weathering and leaching since 6.1 cal ka BP indicated a warm and humid regional climate. It has been relatively cold and dry as a whole, with a trend of being warm and wet, since 0.8 cal ka BP, accompanied by gradually weakened winter monsoon intensity, gradually enhanced summer monsoon intensity, and gradually enhanced chemical weathering and leaching. The Asian monsoon and climatic evolution process in SAYR is highly unstable and has undergone centennial-millennial scale oscillations since 6.1 cal ka BP. Also, six phases at 6.1-5.9, 4.5-4.2, 2.7-2.4, 1.9-1.7, 1.5-1.4, and 0.6-0.4 cal ka BP correspond with cold events recorded by peat and lacustrine deposits and ice cores on the northeastern and eastern TP and with deep-sea sediments in high-latitude regions in the Northern Hemisphere. The results show that climate change in SAYR on the northeastern TP has been consistent with global climate change since the mid-late Holocene. [ABSTRACT FROM AUTHOR]

The article presents information on the peat sessions held during the INQUA Congress in Nagoya, Japan in July 2015, which featured the "Carbon in Peat on Earth Through Time" meeting which focused on the controls on formation, persistence and disappearance of peats in different climates.

Abstract: Fluvial systems in which peat formation occurs are typified by autogenic processes such as river meandering, crevasse splaying and channel avulsion. Nevertheless, autogenic processes cannot satisfactorily explain the repetitive nature and lateral continuity of many coal seams (compacted peats). The fluvial lower Palaeocene Tullock Member of the Fort Union Formation (Western Interior Williston Basin; Montana, USA) contains lignite rank coal seams that are traceable over distances of several kilometres. This sequence is used to test the hypothesis that peat formation in the fluvial system was controlled by orbitally forced climate change interacting with autogenic processes. Major successions are documented with an average thickness of 6·8 m consisting of ca 6 m thick intervals of channel and overbank deposits overlain by ca 1 m thick coal seam units. These major coal seams locally split and merge. Time‐stratigraphic correlation, using a Cretaceous–Palaeogene boundary event horizon, several distinctive volcanic ash‐fall layers, and the C29r/C29n magnetic polarity reversal, shows consistent lateral recurrence of seven successive major successions along a 10 km wide fence panel perpendicular to east/south‐east palaeo‐flow. The stratigraphic pattern, complemented by stratigraphic age control and cyclostratigraphic tests, suggests that the major peat‐forming phases, resulting in major coal seams, were driven by 100 kyr eccentricity‐related climate cycles. Two distinct conceptual models were developed, both based on the hypothesis that the major peat‐forming phases ended when enhanced seasonal contrast, at times of minimum precession during increasing eccentricity, intensified mire degradation and flooding. In model 1, orbitally forced climate change controls the timing of peat compaction, leading to enhancement of autogenic channel avulsions. In model 2, orbitally forced climate change controls upstream sediment supply and clastic influx determining the persistence of peat‐forming conditions. At the scale of the major successions, model 2 is supported because interfingering channel sandstones do not interrupt lateral continuity of major coal seams. [ABSTRACT FROM AUTHOR]

Poly-β-hydroxyalkanoate (PHA) is a prokaryotic energy reserve material that has been used as an indicator of environmental stress in aquatic bacteria. The following technique has been used to quantify PHA in peatland microorganisms. Peat samples were dried, digested in sulphuric acid to convert PHA into crotonic acid, and the resulting acid determined using organic acid high performance liquid chromatography (HPLC) and ultraviolet (UV) detection at 214 nm. This technique is suggested to have potential value as an indicator of environmental stress on peatland microorganisms, such as that caused by summer drought, or changes in soil nutrient availability, which are predicted consequences of climatic change. [ABSTRACT FROM PUBLISHER]

Glen Docherty has a long history of debris flow activity along the glen’s north east slope, but in early August 2015 a peaty-debris flow was triggered on the glen’s south west slope, involving an initial slide volume of 190 m3 debris/peat, of which 89 m3 consisted of peat. The flow merited study due to (a) its unusual location relative to debris flow activity affecting the rest of the glen, (b) the volume of peat involved and its effect on flow behaviour, (c) the role of immediate post-debris flow fluvial activity and (d) later responses to the event including subsequent weathering, fluvial activity and the potential for debris flow reactivation. [ABSTRACT FROM AUTHOR]

Changes in the vegetation and climatic conditions on the eastern slope of the Subpolar Urals over the past 10000 years have been reconstructed on the basis of integrated palynological, botanical, and radiocarbon analysis of material from two sections of peat deposits in the floodplains of the Lyapin and Man'ya rivers (the Severnaya Sos'va basin). The dynamics of regional vegetation have been traced: from the herb-shrub tundra in the late postglacial time to the spruce-larch forest-tundra and sparse larch-birch-spruce stands in the Early Holocene, to birch-pine-spruce forests with an admixture of fir in the Middle Holocene, and to northern taiga forests with dominance of Scots pine and Siberian stone pine (similar to present-day forests) in the Late Holocene. The results show that the northern taiga zone of the study region in the period between approximately 5500 and 2500 years BP was occupied by forests of middle and southern taiga facies, as the climate was significantly warmer than it is today. [ABSTRACT FROM AUTHOR]

A calendar of events is presented including the VII Geochemistry Symposium in Turkey from March 16-18, 2016, Water Resources Management 2017 in Czech Republic from June 18-20, 2017 and the 16th International Peat Congress in Estonia in June 2020.

ABSTRACT Ombrotrophic peatlands often lack any substantial local mineral component and therefore present exceptional opportunities for the extraction and identification of tephra horizons. Following concerns of shard geochemistry alteration during isolation using acid digestion, an alternative methodology using heavy liquids has been proposed. However, harsh basic and acidic digestions are rarely required in organic-rich, ombrotrophic peatlands. Consequently, this study tested for geochemical differences between tephra shards from a known rhyolitic eruption, isolated from the same stratigraphic depth of a peat sequence using density separation and an acid digestion methodology typically applied to ombrotrophic peat samples and analysed using electron probe microanalysis. Findings suggest that the two samples could not be geochemically distinguished using visual and statistical methods and that, in the context of rhyolitic tephras in ombrotrophic peats, acid digestion can be used without significant effects on the interpretation of results. Density separation may still be required in peatlands with high mineral input and further work is required to examine the effect of the acid digestion technique on tephra of non-rhyolitic compositions. [ABSTRACT FROM AUTHOR]

The effect of land-reclamation on the surface and subsurface runoff is studied in Ust'-Selenga depression has been analyzed. Drainage and irrigation activities intensified peat oxidation destruction, resulting in a more intense input of peat decomposition products (i.e., ammonium, nitrite and nitrate ions, as well as soluble organics). Surface and subsurface water draining the bog are favorable for the intense migration of iron and manganese ions in solution. These elements are found in concentrations exceeding the values of MAC for water bodies used for fishery. [ABSTRACT FROM AUTHOR]

Samples of early Miocene Muara Wahau coal from three drill cores were investigated with respect to maceral composition. Huminite macerals are dominant in the coal, ranging from 73.3 to 88.0% (vol.) with an average value of 77.4% (vol.). Liptinite macerals account for lower amount, from 0.7 to 6.7 with an average value of 1.8% (vol.). Inertinite macerals vary from 4.3 to 34.0% (vol.), averaging at 15.3% (vol.). Some paleoenvironmental indices based on the maceral composition were determined. Groundwater index (GWI) and vegetation index (VI) were considered as indicators for hydrological regime and type of peat vegetation. Tissue preservation index (TPI) and gelification index (GI) were determined to indicate the degree of preservation and relative wetness of the peat forming conditions. The VI-GWI diagram suggest that the coal was developed from herbaceous plants in ombrotrophic type of peat. TPI-GI diagram shows that the preservation was low and the peat was relatively wet or limnic. However, ombrotrophic peat type have commonly been related to relatively drier or telmatic environments. It is therefore, interpreted that the limnic condition could occur in ombrotrophic peat type, as the water level was rising up during the development of a high moor peat. [ABSTRACT FROM AUTHOR]

Tephra layers can form useful age-equivalent stratigraphic markers for correlating palaeoenvironmental sequences and they provide information about the spatio-temporal nature of past volcanic ash fall events. The use of microscopic ‘cryptotephra’ layers has both increased the stratigraphic resolution of tephra sequences in proximal areas and extended the distal application of tephrochronology to regions of the world situated far from volcanoes. Effective tephrochronology requires the discrimination between in situ tephra deposited directly from volcanic plumes and tephras that have been remobilised since their initial deposition. We present tephrostratigraphic and glass chemistry data from two proximal peat profiles (one lowland, one upland) from the Shetland Islands, UK. Both profiles contain the Hekla-Selsund tephra (deposited c. 1800–1750 cal. bc), whilst the Hekla 4 ash (c. 2395–2279 cal. bc) is present in the upland record. Overlying the Hekla-Selsund tephra are a number of distinct peaks in tephra shard abundance. The geochemistry of these layers shows that they represent re-working of the Hekla 4 and Hekla-Selsund layers rather than primary air-fall deposits. Pollen analysis of the peat sequences illustrates that these re-deposited tephra layers are coincident with a rise in heather-dominated vegetation communities (heath and/or moorland) and a subsequent intensification of burning in the landscape. We suggest that burning caused increased erosion of peats resulting in the remobilisation of tephra shards. The study demonstrates both the need for caution and the opportunities created when applying tephrochronologies in regions heavily affected by past human activity that contain both reworked tephra layers and in situ fallout. [ABSTRACT FROM PUBLISHER]

The spatial and temporal variability of a low-centred polygon on the eastern floodplain area of the lower Anabar River (72.070°N, 113.921° E; northern Yakutia, Siberia) has been investigated using a multi-method approach. The present-day vegetation in each square metre was analysed, revealing a community of Larix, shrubby Betula, and Salix on the polygon rim, a dominance of Carex and Andromeda polifolia in the rim-to-pond transition zone, and a predominantly monospecific Scorpidium scorpioides coverage within the pond. The total organic carbon (TOC) content, TOC/TN (total nitrogen) ratio, grain size, vascular plant macrofossils, moss remains, diatoms, and pollen were analysed for two vertical sections and a sediment core from a transect across the polygon. Radiocarbon dating indicates that the formation of the polygon started at least 1500 yr ago; the general positions of the pond and rim have not changed since that time. Two types of pond vegetation were identified, indicating two contrasting development stages of the polygon. The first was a well-established moss association, dominated by submerged or floating Scorpidium scorpioides and/or Drepanocladus spp. and overgrown by epiphytic diatoms such as Tabellaria flocculosa and Eunotia taxa. This stage coincides temporally with a period in which the polygon was only drained by lateral subsurface water flow, as indicated by mixed grain sizes. A different moss association occurred during times of repeated river flooding (indicated by homogeneous medium-grained sand that probably accumulated during the annual spring snowmelt), characterized by an abundance of Meesia triquetra and a dominance of benthic diatoms (e.g. Navicula vulpina), indicative of a relatively high pH and a high tolerance of disturbance. A comparison of the local polygon vegetation (inferred from moss and macrofossil spectra) with the regional vegetation (inferred from pollen spectra) indicated that the moss association with Scorpidium scorpioides became established during relatively favourable climatic conditions, while the association dominated by Meesia triquetra occurred during periods of harsh climatic conditions. Our study revealed a strong riverine influence (in addition to climatic influences) on polygon development and the type of peat accumulated. [ABSTRACT FROM AUTHOR]

Previous sedimentological studies on peat sequences from the eastern Tibetan Plateau showed that there have been eolian dust inputs to the wetlands on the eastern Tibetan Plateau, thereby providing an opportunity to reconstruct the history of the Asian winter monsoon at a higher temporal resolution. Here the dust flux and the content of trace metallic elements (Ti, Ni, and V) in a peat sequence from the Hongyuan Swamp (32°46.7′N, 102°31.0′E) are used to reconstruct variations in the intensity of the Asian winter monsoon during the Holocene. This record, when compared with the summer monsoon proxy, can help elucidate the phase relationship between these two systems. Our proxy-based reconstructions show different patterns of changes in the Asian winter and summer monsoons before and after 5.5 cal. ka BP. Generally, the two monsoons varied reciprocally before 5.5 cal. ka BP; however, after 5.5 cal. ka BP, these two systems exhibit synchronous changes. Moreover, both the frequency and amplitude of the variations in these two monsoons are different before and after 5.5 cal. ka BP. The rate of changes in the solar insolation during the Holocene matches well with these monsoon records, implying that the mid-Holocene climate transition may have resulted from orbital forcing. [ABSTRACT FROM PUBLISHER]

The groundwater flow models currently used in the western part of The Netherlands and in other similar peaty areas are thought to be a too simplified representation of the hydrological reality. One of the reasons is that, due to the schematization of the subsoil, its heterogeneity cannot be represented adequately. Moreover, the applicability of Darcy's law in these types of soils has been questioned, but this law forms the basis of most groundwater flow models. With the purpose of assessing the typical heterogeneity of the subsoil and to verify the applicability of Darcy's law, geohydrological fieldwork was completed at an experimental field within a research area in the western part of The Netherlands. The assessments were carried out for the so-called Complex Confining Layer (CCL), which is the Holocene peaty to clayey layer overlying Pleistocene sandy deposits. Borehole drilling through the CCL with a hand auger was completed and revealed the typical heterogeneous character of this layer, showing a dominance of muddy, humified peat which is alternated with fresher peat and clay. Slug tests were carried out to study the applicability of Darcy's law, given that previous studies suggested its nonvalidity for humified peat soils due to a variable horizontal hydraulic conductivity Kh with head differences. For higher humification degrees, the experiments indeed suggested a variable Kh, but this appeared to be the result of the inappropriate use of steady-state formulae for transient experiments in peaty environments. The muddy peat sampled has a rather plastic nature, and the high compressibility of this material leads to transient behavior. However, using transient formulae, the slug tests conducted for different initial groundwater heads showed that there was hardly any evidence of a variation of the hydraulic conductivity with the applied head differences. Therefore, Darcy's law can be used for typical peat soils present in The Netherlands. The heterogeneity of the subsoil and the apparent applicability of Darcy's law were taken into account for the detailed heterogeneous model that was prepared for the research area. A MODFLOW model consisting of 13 layers in which 4 layers represent the heterogeneous CCL was set up for an average year, assuming steady-state conditions; and for the winter of 2009 to 2010, adopting transient conditions. The transient model was extended to simulate for longer periods with the objective of visualizing the flow paths through the CCL. The results from these models were compared with a 10 layer model, whereby the CCL is represented by a single layer assuming homogeneity. From the comparison of the two model types, the conclusion could be drawn that a single layer schematization of the CCL produces flowpath patterns which are not the same but still quite similar to a 4 layer representation of the CCL. However, the single layer schematization results in a considerable underestimation of the flow velocity, and subsequently a longer travel time, through the CCL. Therefore, a single layer model of the CCL seems quite appropriate to represent the general flow behavior of the shallow groundwater system, but would be inappropriate for transport modeling through the CCL. [ABSTRACT FROM AUTHOR]

Late-Holocene peat stratigraphy of a Canadian boreal peat bog was examined to evaluate the potential of Sphagnum δ13C values as surface moisture proxy indicators. Isotopic measurements were compared to testate amoebae-inferred water-table depth reconstructions, plant macrofossil assemblages and past decomposition levels inferred by colorimetric humification. AMS radiocarbon dates were coupled with 210Pb dates to establish peat chronology. Although the mechanisms underlying carbon fractionation processes in peatlands are not well understood, we demonstrate that Sphagnum δ13C values have potential for palaeohydrological reconstructions, since variations presented by the isotopic values can generally be correlated with the other proxy records, especially during drier episodes. [ABSTRACT FROM AUTHOR]

Little is known about the medieval use of peat as fuel. Until now, most research has focused on different aspects of peat extraction but not on its consumption. However, the discovery and analysis of several fragments of peat bricks from an archaeological deposit dating around 1200 AD from the abbey of Ename (located along the upper part of the river Scheldt, near Oudenaarde, Flanders, Belgium) provided a first opportunity to gather information on the trade and use of peat in late medieval times in Flanders. Analysis of pollen and botanical macroremains from the peat bricks has shown that their composition is dominated by heather (Calluna vulgaris L. Hull and Erica tetralix L.) and peat moss (Sphagnum sp.), thus representing oligotrophic conditions. In the Ename region, only eutrophic peat is present. The nearest occurrence of oligotrophic peat has to be sought in the coastal area and the Scheldt estuary, two rather distant regions, which are known for (commercial) peat production in late medieval times. The Ename peat bricks not only illustrate the existence of long distance peat transport around 1200 AD, but also suggest the need for the import of fuel into the rural region of Oudenaarde. Indeed, from historical sources it is known that the extent of woodland in this part of Flanders showed a minimum in the late 13th century, presumably forcing people to look for alternative sources of fuel. [ABSTRACT FROM AUTHOR]

A new sea-level curve (MHW, mean high water level) for the southern North Sea is presented, spanning the last 10 000 years and based on new data recently obtained along the German coast. The 118 dates were selected from basal as well as intercalated peats of the Holocene sequence and archaeological dates from the last 3000 years. Because of different MHW levels along the German North Sea coast, all data were corrected to the standard tide gauge at Wilhelmshaven to make them comparable. Special advantages of this area for sea-level reconstructions are negligible tectonic and isostatic subsidence and the absence of coastal barrier systems that might have mitigated or masked sea-level changes. Changes of water level had therefore immediate consequences for the facies and could be dated exactly. The chronostratigraphic Calais–Dunkirk system has been improved and adapted to the new data. Altogether seven regressions (R 1–R 7) have been identified, each of them characterized by a distinct decline in sea level. These fluctuations are in accord with the evidence from other parts of the North Sea region. A draft of former North Sea shorelines is presented on the basis of this sea-level curve. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Detailed investigations of peaty earth hummocks called pounus were carried out in northernmost Finnish Lapland in the vicinity of the Kevo Subarctic Research Station. Pounus are complex, often vegetated, cryogenic mounds formed partly of peat. Some have a core of mineral soil or several large stones, or just one frost-heaved boulder covered by peat. They belong to the same group of earth hummocks as thufur and nonsorted circles. The typology of pounus is described and compared with other types of cryogenic earth hummocks. Stratigraphical study of pounus shows how cryoturbation has deformed the previous soil horizons of typical Arctic podzols and has been followed by intense peat growth and later frost reactivation. Microstructures in pounus confirm the frost activity and several phases of peat growth during their formation. Alternating warmer and dryer conditions with water-table rise and renewed peat formation could be inferred. The present stage of development is frost reactivation and peat growth. Pounus are relatively young features. The maximum age for pounu development corresponds with the age of peat formation. Peat of a boulder pounu yielded a data of 330 ± 70 BP and a minerogenic pounu gave an age of 710 ± 50 BP. The Sphagnum peat formation on peat pounus started intensively about 1000 BP. They are random surficial forms with variable control by frost heave and vegetation growth, independent of the presence or absence of permafrost. They are related to a dynamic snowcover in areas of open birch stands or tundra and their development is polygenetic with alternating frost disturbance and phases of humification or podzolization. Pounus act thermally as a biological refuge in the autumn and spring. At present, perennial frozen cores seem to be common, especially in large peat pounus. Pounu development, as with other earth hummocks, occurs after the main phase of interglacial pedogenesis and can be considered as an indicator of a general cooling trend, developing mostly during the second half of the Holocene. Pounus' relation to climatic change is discussed. Pounus can be considered as an indication of a general cooling trend associated with progressive depletion of summer insolation. Hummock extent is coherent and parallel with trends in permafrost growth, but not directly linked to it. [ABSTRACT FROM AUTHOR]

The Upper Weichselian and Holocene layers of the 190 m thick peat sequence in the Philippi basin (NE Greece) are studied by means of their mineralogical and geochemical features. The ash contents range between 11.4 and 53.4% and inorganic carbon contents range between 0.5 and 5.7%. X-ray diffraction (XRD) analysis revealed that Mg-calcite, quartz, clay minerals, K-feldspars, plagioclases, and chlorites are the dominant minerals in the peat. Lime, pyrite, siderite, apatite, iron-oxides, weddellite, and basaluminite occur subordinately. During Upper Pleniglacial and Late Glacial times, clastic sedimentation prevailed in the palaeomire. Peat was enriched in Fe, K, Ti, As, Cr, Cu, Ni, Rb, Th, Y, Zn, and Zr. In Early Holocene, authigenic sedimentation of Ca-rich material dominated. Peat became enriched in As, Br, Se, Sr, and U. In Middle Holocene, fluctuations of the water table in the mire resulted in the deposition of both authigenic and clastic minerals. The Late Holocene peat is intensely damaged due to drainage and cultivation. The mineral matter features of the Upper Weichselian peat are identical to the features of many Greek lignites. [ABSTRACT FROM AUTHOR]

(1) Chemical analyses of peat samples from a grid of ninety-seven sample points in wetheath vegetation at Aylesbeare Common, Devon, show trends significant at the 1% level in third-order trend-surfaces for pH and extractable Ca, Mg, K, Mn, P and NH[SUB4]-N. Ca, Mg and pH are closely correlated (and K and Mn moderately so) with one another and with the first component of a principal-component analysis of the measured peat variables. (2) The major vegetation contrast between species-poor wet heath and acid Sphagnum carpet communities on the one hand, and species-rich wet heath and Molinietum on the other, correlates closely with the distribution of Ca, Mg and pH. Molinia performs best in areas with higher pH, Ca, Mg and K, and where there is active water movement. (3) Leaf (or green shoot) material of eight species -- Molinia caerulea. Ulex gallii, Trichophorwn cespitosum, Eriophorum angustifolium, Narthecium ossifragum, Cirsium dissetium, Succisa pratensis and Serratula tinetoria -- from points on the sampling grid was analysed for Ca, Mg, K, Na, Mn, Fe, N and P. (4) In mean percentage chemical composition, Cirsium, Succisa and Serratula are relatively high in Ca, Mg and K, Cirsium and Succisa in Na, Molinia and Ulex in Fe, Molinia, Narthecium and Serratula in Mn, Molinia and (especially) Ulex in N, and Ulex, Cirsium, Succisa and Serratula in P. Narthecium contains higher levels of most elements than the other monocotyledons. (5) The concentration of an element in a plant species is best predicted by the concentration of the same element in the peat in only a few instances: Ca in Cirsium Succisa and Serratula; Mg in Trichophorum; K in Molinia; Fe in Ulex, Eriophorum and Succisa; Mn in Ulex, Trichophorum, Eriopharum and Cirsium. More commonly the uptake of one element is most strongly related to the concentration of another dement in the peat. Thus K in Trichophorum and Succisa is positively correlated with peat Ca; Ulex Mg and K, and Cirshum Mg... [ABSTRACT FROM AUTHOR]

The article presents a study that investigates on the role of bryophytes in the formation of calcareous fens in Oxford, England. The study was conducted by assessing the different types of water accumulated in calcareous peat wherein its essence depend on the content level of oxygen and nitrate. The study reveals that bryophytes assume an essential role in the succession of open water carried though the calcareous fens in the district as well as the formation of phanerogamic seedlings in different stages of soil. It also discusses the zonation characteristics of tussocks and the procedure in the establishment of fens.