A comparative study of thermolysis characteristics and kinetics of seaweeds and fir wood

Thermal analysis and thermolysis kinetics of three kinds of seaweeds and fir wood (M. glyptostriboides Huet Cheng), a kind of typical land plant, had been conducted. The results showed that thermal stability follows the order of Grateloupia filicina < Ulva lactuca < Dictyopteris divaricata < fir wood. A notable difference on heat flow between seaweeds and fir wood during thermolysis was that the former were mainly connected with exothermic processes at relatively lower temperature regimes. while the latter was connected with an apparent endotherm at a relatively higher temperature regime followed by a maximum exothermic peak. This suggested that the heat coupling might be realized if co-thermolysis of seaweeds and fir wood were carried out. The main devolatilization phase of each seaweed could be described by Avrami-Erofeev equation, which indicated that thermolysis of seaweeds follows the mechanism of random nucleation and nuclei growth, whereas that of fir wood by Z-L-T equation and its thermolysis mechanism was three-dimensional diffusion. The activation energies calculated for both seaweeds and fir wood increase as conversion increases. However, those for the former have wider distribution. (c) 2006 Elsevier Ltd. All rights reserved.

Lack of latitudinal trends in wood anatomy of Dodonaea viscosa (Sapindaceae), a species with a worldwide distribution

Latitudinal or altitudinal variation in several anatomical characters of wood is common for woody dicotyledonous genera with a wide distribution, but whether such variation exists at the species level is disputed. Latitudinal and altitudinal trends in wood anatomy of Dodonaea viscosa were studied, using 102 samples collected between 41.2degrees S and 33.3degrees N latitude and 7-2750 in altitude. We studied variation in four quantitative features: vessel element length, fiber length, vessel frequency, and tangential vessel diameter. Ontogenetic trends were minimal with a slight decrease or increase in the innermost stem and were negligible among the studied specimens. Throughout the distributional range of the species, no latitudinal trends were detected in either the Northern or Southern Hemispheres, Altitudinal trends were also nonexistent, except for two features in specimens from China and Japan. Absence of latitudinal or altitudinal trends in this widely distributed species suggests that in some species the species-level variation in wood anatomy is not controlled by ecological gradients.

西南极南设得兰群岛中新生代火山岩基底沉积学及其大地构造制约

Livingston Island, the second island of South Shetland Island, constains Mesozoic-Cenozoic basement, Mesozoic-Cenozoic volcanic sequences, plutonic intrusions and post-subduction volcanic rocks, which document the history and evolution of an important part of the South Shetland Islands magmatic arc. The sedimentary sequence is named the Miers Bluff Formation (MBF) and is interpreted as turbidite since the first geological study on South Shetland Islands, and is interpreted as turbidite. It base and top are not exposed, but a thickness of more than 3000m has been suggested and seems plausible. The turbidite is overlain by Mid - Cretaceous volcanic rocks and intruded by Eocene tonalites. The age of the Miers Bluff Formation is poorly constrained Late Carboniferous -Early Triassic. Sedimentary Environment, tectonic setting and forming age of sedimentary rocks of the Miers Bluff Formation were discussed by means of the methods of sedimentology, petrography and geochemistry, combinig with the study of trace fossils and microfossil plants. The following conclusions are obstained. A sedimentary geological section of Johnsons Dock is made by outside measuring and watching, and then according the section, the geological map near the Spanish Antarctic station was mapped. Four pebbly mudstone layers are first distinguished, which thickness is about 10m. The pebbly mudstone is the typical rock of debris flow, and the depostional environment of pebbly mudstone may be the channel of mid fan of submarine fan. The sedimentsry structural characteristics and size analysis of sandstones show the typical sedimentary feature of turbidity flow and the Miers Bluff Formation is a deep-water turbidite (include some gravity-flow sediments). The materials of palaeocurrents suggest the continental slope dip to southeast, and indicate the provenance of turbidity sediment in the northwest area. By facies analysis, six main facies which include seven subfacies were recognized, which are formed in mid-fan and lower-fan of submarine, meanwhile, the sedimentary features of each facies and subfacies are summarized. The study of clastic composition, major elements, trace elements and rare earth elements indicates the forming setting of the Miers Bluff Formaton is active continental margin and continental island arc and the provenance is dissected magmatic arc which main composition is felsic gneiss. Many trace fossils of the whole succession were found in the turbidites of the Miers Bluff Formation. All these trace fossils are deep sea ichnofossils. There are fifteen ichnogenus, sixteen ichnospecies. Moreover, a new trace fossil was found and a new ichnogenus and new ichnospecies was proposed - Paleaichnus antarctics ichnogen, et ichnosp, nov.. Except the new ichnogenus and ichnospecies, others had been found in deep-sea flysch turbidites. Some are in mudstone and are preserved in the cast convex of overlying sandstone sole, they formed before turbidity flows occurred and belong to the high-different Graphoglyptida of fiysch mudstone. Others as Fucusopsis and Neonereites are preserved in sandstones and stand for trace assemblages after turbidity sedimentation. These trace fossils are typical members of abyssal "Nereites" ichnofacies, and provide for the depositional environment of the Miers Bluff Formation. Fairly diverse microfossil plants have been recovered from the Miers Bluff Formation, Livingston Island, including spores, pollen, acritarchs, wood fragments and cuticles. Containing a total of about 45 species (forms) of miospores, the palynofiora is quantitatively characterized by the dominance of non-striate bisaccate pollen, but spores of pteridophytes and pollen of gymnosperms are proportionate in diversity. It is somewhat comparable to the subzone C+D of the Alisporites zone of Antarctica, and the upper Craterisporites rotundus zone and the lower Polycingulatisporites crenulatus zone of Australia, suggesting a Late Triassic (possibly Norian-Rhaetian) age, as also evidenced by the sporadic occurrence of Aratrisporites and probable Classopollis as well as the complete absence of bisaccate Striatiti. The parent vegetation and paleoclimate are preliminarily deduced. At last, the paper prooses the provenance of sedimentary rocks of the Miers Bluff Formation locates in the east part to the southern Chile(or Southern South American). In the Triassic period, contrasting with New Zealand, Australia and South American of the Pacific margin of Gondwanaland, the Miers Bluff Formation is deposited in the fore-arc basin or back-arc basin of magmatic arc.

Calorimetric study of Wood alloy

The heat capacities of Wood alloy have been measured with an automatic adiabatic calorimeter over the temperature range of 80 similar to 360 K. The thermodynamic data of solid-liquid phase transition have been obtained from the heat capacity measurements. The melting temperature, enthalpy and entropy of fusion of the substance are 345.662 K, 18.47 J.g(-1) and 0.05343 J.g(-1).K-1, respectively. The necessary thermal data are provided for the low temperature thermodynamic study of the alloy.

The Effect of Wood Burial and Submersion on Decomposition: Implications for Reducing Carbon Emissions

Gemstone Team Carbon Sinks

Prehistoric Pinus woodland dynamics in an upland landscape in northern Scotland: the roles of climate change and human impact

Pollen, microscopic charcoal, palaeohydrological and dendrochronological analyses are applied to a radiocarbon and tephrochronologically dated mid Holocene (ca. 8500–3000 cal B.P.) peat sequence with abundant fossil Pinus (pine) wood. The Pinus populations on peat fluctuated considerably over the period in question. Colonisation by Pinus from ca. 7900–7600 cal B.P. appears to have had no specific environmental trigger; it was probably determined by the rate of migration from particular populations. The second phase, at ca. 5000–4400 cal B.P., was facilitated by anthropogenic interference that reduced competition from other trees. The pollen record shows two Pinus declines. The first at ca. 6200–5500 cal B.P. was caused by a series of rapid and frequent climatic shifts. The second, the so-called pine decline, was very gradual (ca. 4200–3300 cal B.P.) at Loch Farlary and may not have been related to climate change as is often supposed. Low intensity but sustained grazing pressures were more important. Throughout the mid Holocene, the frequency and intensity of burning in these open Pinus–Calluna woods were probably highly sensitive to hydrological (climatic) change. Axe marks on several trees are related to the mid to late Bronze Age, i.e., long after the trees had died.

Chaetopterid tubes from vent and seep sites: Implications for fossil record and evolutionary history of vent and seep annelids

Vestimentiferan tube worms living at deep-sea hydrothermal vents and cold seeps have been considered as a clade with a long and continuing evolutionary history in these ecosystems. Whereas the fossil record appears to support this view, molecular age estimates do not. The two main features that are used to identify vestimentiferan tubes in the fossil record are longitudinal ridges on the tube's surface and a tube wall constructed of multiple layers. It is shown here that chaetopterid tubes from modern vents and seeps—as well as a number of fossil tubes from shallow-water environments—also show these two features. This calls for a more cautious interpretation of tubular fossils from ancient vent and seep deposits. We suggest that: current estimates for a relatively young evolutionary age based on molecular clock methods may be more reliable than the inferences of ancient “vestimentiferans” based on putative fossils of these worms; not all of these putative fossils actually belong to this group; and that tubes from fossil seeps should be investigated for chitinous remains to substantiate claims of their potential siboglinid affinities.