Silicon and aluminum in Bulgarian coals

The presence and distribution of Si and Al in 19 Bulgarian coal basins and deposits, belonging to 8 coal provinces, were studied. Coals are of different rank (lignite to anthracite) and age (Late Carboniferous to Pliocene). The presence of both studied major elements depends strongly on: i) their concentration within the basin’s provenance; ii) the extent of terrigenous supply; iii) environmental acidity during peat formation; and iv) the presence and composition of epigenetic mineralization within the coal seams. Because of the presumed abundant terrigenous supply, the concentrations of both Si and Al are higher than the world average for most of the studied coals. Exceptions are the Maritsa-West, Burgas, Staniantsi, Oranovo, Chukurovo and Pernik Basins, for which reduced terrigenous supply can be suggested. For most of the basins, both Si and Al demonstrate good positive correlation with the ash yields, thus arguing for predominant inorganic affinity. Relatively low Si/Al ratios (typically <2) and good positive correlation between Si and Al (ro>0.6) imply the predominant role of the clay mineral assemblages as the main source of the elements in coal. Quartz is presumed to have dominant role only in Maritsa-West Basin. Poorer or negative correlations with the ash yields in part of the studied basins (i.e. Svoge, Maritsa-West, Sofia, Burgas and Dobrudzha Basins) suggest either mixed or predominantly organic affinity of the elements. Release of Si and Al from the clay minerals during the peat formation/diagenesis and subsequent formation of organo-metallic complexes is considered to responsible for such affinity.

Bituminous coals on emergent surfaces in an Asbian, lower Carboniferous (Mississippian) limestone succession on the North Wales carbonate platform, UK, and implications for palaeoclimate

Emergent surfaces in the Mississippian (Asbian to Brigantian) carbonate platform succession of North Wales record periods of plant colonisation and peat formation that led ultimately to the local development of coals. Examination of bituminous coals on three emergent surfaces within Cefn Mawr Quarry reveals information on palaeoclimate that is not available from study of the limestones alone. Three coal seams in the Asbian Loggerheads Limestone Formation were identified and the lowest one studied in detail. Vitrinite reflectance data from alternating bands of vitrite and duroclarite microlithotypes, the distribution of pyrite within them, and the sharp contacts between them, suggest that there were abrupt changes in marine influence during the development of the peats that formed the coals. It is inferred that local palaeoclimate alternated between periods of high and low rainfall, the amount of rainfall influencing the extent to which seawater encroached into the peats, with higher rainfall suppressing the ingress of saline waters into groundwater. On the basis of modern peat growth rates, the timescale of the alternation indicated by each duroclarite-vitrite couplet is suggestive of an annual cycle, such as would arise in a monsoonal climate. The low proportion of ash in the three coals, the preservation of internal lamination, the low diversity of spore species in the lowest coal compared with the over- and underlying mudrock, and the presence of rhizoconcretions in palaeokarstic limestone beneath the lowest and highest coals, demonstrate that the peat swamps were isolated from the hinterland and autochthonous. This study demonstrates that a wider application of palynology and coal petrology is an important contribution to the study of marine carbonate successions of any age where terrestrial organic matter, formed during emergence, has been preserved.

Paleoclimatic and Redox Condition Changes during Early-Middle Jurassic in the Yili Basin, Northwest China

The Jurassic was mainly a “greenhouse” period characterized by global warming and by significant peat accumulations in some continental basins. However, studies of Jurassic climate and environments have mainly focused on marine records and only a few on terrestrial sediments. Yili Basin, a mid-latitude terrestrial basin in present Northwest China, included accumulation of the important recoverable coal seams. In this study, geological data, clay mineral analysis, and palynological assemblages were employed on fine-grained samples from the Su’asugou section in southern Yili Basin. The factors (paleoclimate, depositional conditions, and paleo-vegetation) impacting peat accumulation were investigated. The results suggest that the siliciclastics may have been derived from exposed Carboniferous rocks in a continental arc environment. A warm and humid paleoclimate in the Yili basin dominated during the early-Early Jurassic deposition of the Badaowan Formation and the Middle Jurassic deposition of the Xishanyao Formation. This climate contributed to high sedimentary rates and to a high productivity of peat-forming paleo-vegetation that was preserved under dysoxic conditions. In contrast, during the late-Early Jurassic between these two formations, the Sangonghe Formation was an interval of relatively aridity that included red beds preserved under more hypoxic sedimentary conditions, and with an interruption in peat formation and preservation.

Diversity of Testate Amoebae as an Indicator of the Conservation Status of Peatlands in Southwest Europe

Testate amoebae are one of the most studied groups of microorganisms in Sphagnum peatland ecosystems and, therefore, one of the most reliable bioindicators of their ecological status. Peatland ecosystems are supported by a delicate biogeochemical balance that leads to the formation of peat, one of the main sinks of C, as a result of soil–atmosphere interaction, but currently they are one of the most threatened wetland types at their southern distribution limit. In the European continent, where climatic conditions limit peat formation, they have endured significant anthropic pressure for centuries, and the risk of loss of biodiversity linked to these ecosystems is critical. In addition, peatlands are poorly known ecosystems in the Iberian Peninsula compared with other wetlands; therefore, we have studied the chemical parameters of water and the diversity patterns of testate amoebae in the western Iberian Peninsula to better understand the current status of these ecosystems. The analysis of testate amoeba communities showed an inverse relationship between the diversity and conservation status of these peatlands, both in relation to chemical parameters (i.e., pH, electrical conductivity, phosphates) and to the proportion of anthropized area, with a marked geographical pattern in the degree of anthropogenic disturbance.

Impacts of the Wetland Environment on Demographic Development During the Neolithic in the Lower Yangtze Region—Based on Peat and Archaeological Dates

Wetlands were important resources for the hunting–gathering and early farming communities in coastal areas in the Neolithic. However, the relationship between the development of the wetland environment and the human population remains unclear due to the lack of successive wetland environmental changes throughout the Holocene in coastal areas. Here, the summed probability distributions (SPD) of radiocarbon dates of peat were used as an indicator and combined with archaeological radiocarbon dates to reconstruct the wetland environmental and demographic changes during the Neolithic in the lower Yangtze region. The results showed that the shifts in demographic centers and population development were related to wetland environment with peat formation. The first shift of the demographic center was from the hilly regions to the coastal plain and occurred during ca. 8,300–8,000 cal yr BP, which might be caused by the attractiveness of survival resources offered by the coastal wetland environment and the 8.2 ka event. The second shift occurred from the Ningshao Plain to the Taihu region and might be attributed to the widespread waterlogged environment in the Ningshao Plain. The peak of demographic development coincided with the peak of peat formation during the middle Holocene in the lower Yangtze region, indicating that the wetland environment facilitated changes in human societies. The formation of peat might be related to the sea-level and El Niño-Southern Oscillation events; however, further studies are required for deep comprehension. The present study is an attempt at identifying the past impacts of the wetland environment on demographic development and can form the basis for a more comprehensive understanding of the interactions between the humans and their living environment.

Depth-dependent decomposition of root litter in drained and rewetted fen ecosystems

&lt;p&gt;Peatlands cover only 3% of the lands surface, but store roughly a third of the global soil carbon due to inhibited decomposition rates. Over a third of the peatland area in Europe are fens, in which the peat is primarily formed by roots and rhizomes of vascular plants. These fens have been subjected to widespread drainage and conversion into agricultural areas. As a result, they continuously emit large amount of greenhouse gases. One strategy of mitigating the emissions, and ideally restoring the original sink function, is to rewet fen peatlands. However, it remains uncertain how rewetting changes decomposition rates compared to the drained state, and what the underlying biogeochemical processes and organic matter transformations during litter decomposition and peat formation are. We here present decomposition rates of root material in different depth, over 6 months, a year, and two years in different drained and rewetted fen ecosystems (percolation fen, coastal fen, alder forest). In addition to mass loss, we also assessed the composition of carbon compounds over time.&lt;/p&gt;

THE ECOLOGICAL BACKGROUND OF EARLY NEOLITHIC INNOVATIONS IN THE NORTH OF WESTERN SIBERIA

In the mid-7th — early 6th millennium BC at the Mesolithic–Neolithic transition, a number of innovations appeared in the lifeways of people in the West Siberian taiga, including the first appearance of pottery (the defining criterion for the onset of the Neolithic), the intensification of the subsistence economy with an increasing role of aquatic resources, and the transition to a less mobile lifestyle. These innovations were reflected in the construction of long-term open and few fortified settlements, including circular layouts and the construction of ritual mounds (kholmy). These improvements attest to significant changes in subsistence economy as well as worldviews of the hunter-fisher-gatherers of the taiga zone of West Siberia. The emergence of these innovations chronologically coincides with the most prominent global climatic cooling event of the Holocene, which took place around 6.2 thousand years cal BC (the so-called 8.2 ka BP event) and had a substantial impact on the ancient societies of Europe and Southwest Asia. To reconstruct the paleoclimate of northern West Siberia, the most informative source to date are peatbogs, which contain, as a rule, complete sedimentation sequences of all Holocene periods, allowing a greater degree of reliability in using scientific methods in paleogeographical reconstructions. This article reviews current evidence on features and age of the peat formation process and additional information on the Early Holocene paleoclimatic developments in northern West Siberia. The preliminary data indicate that favourable climatic conditions led to balanced and probably abundant environmental resources in the early Atlantic period. At the same time, the sparsely populated territory might have seen the arrival of new population groups into the region, which might have introduced or triggered a number of socio-economic innovations such as the construction of fortified settlements with complex layouts and the tradition of clay pottery manufacture.

Coal petrology analysis and implications in depositional environments from Upper Cretaceous to Miocene: a study case in the Eastern Cordillera of Colombia

Coal petrological characteristics along the Piedemonte Llanero and the reconstruction of the deposit environment were obtained from macerals and micro-lithotypes analysis since these data provide information about the processes and prevalent conditions during the peat formation. We analyzed seams from Cenomanian to Miocene geological units (Chipaque Formation, Palmichal Group, Arcillas del Limbo Formation, and San Fernando Formation). Coal range decreases gradually from high-volatile C bituminous (HVCB) in the Chipaque Formation to sub-bituminous C in the San Fernando Formation. The coals are enriched in macerals of vitrinite, whereas the liptinite and inertinite concentrations vary according to the stratigraphic position. The micro-lithotypes are bi-maceral and tri-macerals, being the highest concentrations of clarite and vitrinertoliptite. The results of the facies analysis show that the peat in which the coals developed is mainly of arboreal and herbaceous affinity (rich in lignin and cellulose). Peats are ombrotrophic (rainfed) to mesotrophic (transitional or mixed mires) with variations in the flooding surface and influxes of brackish water. Good tissue preservation is inferred from the wet conditions in forest swamps with few humification and gelation. According to the micro-lithotypes composition, the peat environment was deduced as estuarine system, evolving to lacustrine environment of the deltaic system, both restricted by changes in sea level, which are evidenced by oxic and anoxic periods in the analyzed sequence.