Well-ventilated Conditions Research Articles

Enhancing low-temperature CO removal in complex flue gases: A study on La and Cu doped Co3O4 catalysts under real-world combustion environment

Designing CO oxidation catalysts for complex flue gases conditions is particularly challenging in fire scenarios. Traditional flue gas simulations use a few representative gases but often fail to adequately evaluate catalyst performance in real-world combustion conditions. In this study, we developed doping strategies using La and Cu to enhance the water resistance of Co3O4 catalysts. Catalyst 0.1La-Co3O4-CuO/CeO2 exhibits exceptional low-temperature catalytic activity, achieving 100% conversion at 130 °C. This enhancement is largely due to the introduction of La, which increases the active Co3+/Co2+ ratio and suppresses hydroxyl group formation on the Co3O4 surface. Cu doping also changes the Co3O4 lattice structure, forming Cu+ as active sites and enhancing the activity at low temperatures. For the first time, steady-state tube furnace and fixed bed were employed to evaluate the catalytic performance of CO in actual combustion atmosphere. Catalyst 0.1La-Co3O4-CuO/CeO2 maintains excellent catalytic efficiency (T100 = 120 °C) under well-ventilated conditions. However, its activity significantly decreases in poorly ventilated environments, due to the competitive adsorption of small molecules at active sites, such as acetone, commonly found in smoke. This study provides valuable insights for designing water-resistant, low-temperature, non-noble metal catalysts and offers a methodology for evaluating CO catalytic activity in real-world environments.

Benthic foraminiferal patchiness – revisited

Abstract. Many benthic organisms show aggregated distribution patterns due to the spatial heterogeneity of niches or food availability. In particular, high-abundance patches of benthic foraminifera have been reported that extend from centimetres to metres in diameter in salt marshes or shallow waters. The dimensions of spatial variations of shelf or deep-sea foraminiferal abundances have not yet been identified. Therefore, we studied the distribution of Globobulimina turgida dwelling in the 0–3 cm surface sediment at 118 m water depth in the Alsbäck Deep, Gullmar Fjord, Sweden. Standing stock data from 58 randomly replicated samples depicted a log-normal distribution of G. turgida with weak evidence for an aggregated distribution on a decimetre scale. A model simulation with different patch sizes, outlines, and impedances yielded no significant correlation with the observed variability of G. turgida standing stocks. Instead, a perfect match with a random log-normal distribution of population densities was obtained. The data–model comparison revealed that foraminiferal populations in the Gullmar Fjord were not moulded by any underlying spatial structure beyond 10 cm diameter. Log-normal population densities also characterise data from contiguous, gridded, or random sample replicates reported in the literature. Here, a centimetre-scale heterogeneity was found and interpreted to be a result of asexual reproduction events and restricted mobility of juveniles. Standing stocks of G. turgida from the Alsbäck Deep temporal data series from 1994 to 2021 showed two distinct cohorts of samples of either high or low densities. These cohorts are considered to represent two distinct ecological settings: hypoxic and well-ventilated conditions in the Gullmar Fjord. Environmental forcing is therefore considered to impact the population structure of benthic foraminifera rather than their reproduction dynamics.

Antioxidant Potentials of Pentaclethra macrophylla Seed (Ugba) on Mercury Toxicity Induced Hepatic, Renal and Testicular Oxidative Stress in Male Albino Rats

Aim: This study aimed to evaluate the antioxidant potentials of Pentaclethra macrophylla seed (Ugba) on mercury-induced hepatic, renal and testicular oxidative stress in male Albino Rats.
 Study Design: This study is an experimental study.
 Place and Duration of Study: Department of Animal and Environmental Biology Animal House, Rivers State University, Port Harcourt, Nigeria, between January 2019 and January 2021.
 Methodology: Thirty-six (36) adult male albino rats weighing approximately 135±1.5g were purchased from the University of Port Harcourt, Rivers State, Nigeria. They were housed in plastic suspended cages, placed in well-ventilated conditions and provided with rat diet and water, and acclimatized for two weeks. Fresh matured seeds of Pentaclethra macrophylla (African oil bean seed) were sourced locally from markets in Imo state, Nigeria. The maceration technique was used to carry out an ethanolic extract of the plant seed. Mercury chloride salt was purchased from Port Harcourt. A standard dose of 3.0mg/kg body weight of mercury chloride obtained from acute toxicity study dose determination was administered to the rats for 30 days after they were divided into six groups of six rats per group. After 30 days, all the animals were weighed, anesthetized using chloroform. Tissue samples of liver, kidney, and testis were collected and homogenized in phosphate-buffered saline and stored at 40C for determination of oxidative stress assessment. Malondialdehyde, Reduced Glutathione (GSH), Catalase Activity, superoxide dismutase (SOD) activity, Glutathione Peroxidase Activity were analyzed using the homogenized sample. Data were expressed as mean ±SD, and the statistical analysis was performed with the SPSS statistics 23.0, and p values less than .05 were considered statistically significant.
 Results: The results showed that there were significant increases (P<.05) in the liver, kidney, and testicular MDA and significant decreases (p<.05) in SOD, CAT, GSH, and GPx activities in group 2 rats versus control. However, after treatment with different concentrations of Pentaclethra macrophylla, MDA activity significantly decreased (P<.05), while SOD, CAT, GPx, and GSH significantly increased (P<.05).
 Conclusion: The results obtained from the study showed that mercury chloride has the potential to cause liver, kidney, and testicular toxicity to adult male albino rats, and this toxicity was exerted majorly through oxidative stress and lipid peroxidation. However, treatment with Pentaclethra macrophylla seed extract ameliorated oxidative stress.

Experimental investigation and numerical simulation of the combustion of flexible polyurethane foam with larger geometries

Numerical modelling of the combustion of flexible polyurethane foam (FPUF) is challenging, as the structural collapse and shrinkage of the foam complicate its pyrolysis, and two fuel items are involved in the combustion. Two-layer pyrolysis models were established based on the bench-scale tests over the past decade, but the accuracy was limited when simulating the combustion of FPUF with larger geometries. To improve the accuracy of the numerical simulation, small-scale experiments were conducted to investigate the combustion of FPUF with a larger geometry. Firstly, numerical simulations using a two-layer pyrolysis model proposed in the most recent research were performed to simulate the combustion of FPUF in the small-scale experiments. It was found that the heat release rate (HRR) was over-predicted in the initial combustion stage. Subsequently, based on the analysis of the visual and measured data obtained from the small-scale experiments, a three-layer model was proposed to describe the pyrolysis of FPUF in flaming combustion. The three-layer model was validated with the comparison of the predicted and experimental data. The results indicate that the numerical simulation using the three-layer model has a better performance in replicating the combustion of FPUF under well-ventilated conditions. While, the capability of the three-layer model was limited when it was used to simulate the combustion of FPUF in under-ventilated conditions, as it is found that ventilation influences the HRR of FPUF to a significant extent.

Carbonaceous Aerosols Collected at the Observatory of Monte Curcio in the Southern Mediterranean Basin

This work provides the first continuous measurements of carbonaceous aerosol at the Global Atmosphere Watch (GAW) Monte Curcio regional station, within the southern Mediterranean basin. We specifically analyzed elemental carbon (EC) and organic carbon (OC) concentrations in particulate matter (PM) samples, collected from April to December during the two years of 2016 and 2017. The purpose of the study is to understand the behavior of both PM and carbonaceous species, in their fine and coarse size fraction, along with their seasonal variability. Based on 18 months of observations, we obtained a dataset that resulted in a vast range of variability. We found the maximum values in summer, mainly related to the enhanced formation of secondary pollutants owing to intense solar radiation, also due to the high frequency of wildfires in the surrounding areas, as well as to the reduced precipitation and aerosol-wet removal. We otherwise observed the lowest levels during fall, coinciding with well-ventilated conditions, low photochemical activity, higher precipitation amounts, and less frequency of Saharan dust episodes. We employed the HYSPLIT model to identify long-range transport from Saharan desert. We found that the Saharan dust events caused higher concentrations of PM and OC in the coarser size fraction whereas the wildfire events likely influenced the highest PM, OC, and EC concentrations we recorded for the finer fraction.

Temperature dependence of chemical exchange during seafloor weathering: Insights from the Troodos ophiolite

Chemical fluxes associated with low-temperature, off-axis, alteration of the upper oceanic crust (seafloor weathering) may play an important role in controlling the composition of the ocean and the long-term carbon cycle. However, it is challenging to quantify these fluxes and how they change with changing bottom water temperature over geological timescales. Here we study the exchange of major elements associated with seafloor weathering in the exceptionally preserved Cretaceous Troodos ophiolite and compare them to less well constrained data from drill cores from the modern ocean basins. Calcite O-isotope thermometry from four traverses through the lavas reveals a well-ventilated region at the top of the lava pile where alteration occurred at near-constant temperatures similar to that of bottom water. The lithological makeup of the crust appears to control the thickness of this region, with increased abundance of sheet flows marking the base of this zone. Maintaining low-temperatures in the well-ventilated region requires large fluid fluxes facilitated by the high permeability of the pillow lavas. Large-scale addition of CO2 to the crust only occurs in this well-ventilated region indicating that the alkalinity producing reactions required for calcite precipitation occurred at temperatures sensitive to bottom water temperature. Comparison of whole rock geochemical data for samples from the well-ventilated zone with volcanic glass compositions shows that the changes in rock compositions due to seafloor weathering are large (roughly −4 wt% SiO2, +0.5 to 1 wt% MgO, −5 wt% CaO, −0.5 wt% Na2O, +3.5 wt% K2O and +2.5 wt% CO2). Comparison to data from drill cores from modern oceanic crust that was also altered under well-ventilated conditions suggests that bottom water temperature plays a major role in controlling the chemical exchange between the ocean and lavas; parameterizations for the associated fluxes are provided. Because elemental exchange between the ocean and oceanic crust globally depends strongly on bottom water temperature, fixed values for these fluxes cannot be used in models of the evolution of seawater chemistry or subduction fluxes.

Analysis of experimental hydrocarbon localised fires with and without engulfed steel members

Localised fires can represent an important hazard to structural safety of buildings where a fully generalised fire cannot develop or when it is at its early stage. Plume correlations given in the codes are valid for undisturbed plume and it is not known whether the presence of a structural element engulfed into the localised fire can affect the validity of such correlations. In structural design, this may lead to highly conservative assumptions or, even, to possible misuses of the correlations. In order to provide insight into this issue, a comprehensive experimental programme aimed at providing data on hydrocarbon localised fires with and without engulfed vertical steel members was performed. In detail, a series of 22 tests of circular hydrocarbon pool fires in well-ventilated conditions of diameters ranging from 0.6 m to 2.2 m were performed with diesel and heptane. The particular aspect of these tests is that they were performed by means of a system that controlled the fuel flow and thus the rate of heat release (RHR) of the fire. The flame length and the temperatures of the fire plume measured experimentally were compared with existing plume correlations, data in the literature and the Eurocode correlations. The results show that: the presence of the column contributed to “straighten” the flame; although pool fires with same diameters were characterised by the same RHR, the flame length was different depending on the fuel type; experimental gas temperatures were lower than the temperature correlation given in the Eurocodes. In sum, the correlations included in the Eurocodes provided reasonable predictions in terms of flame length and of fire plume temperature rise around a steel vertical element located along the centreline of the localised fire.

Postglacial floodings of the Marmara Sea: molluscs and sediments tell the story

The early Holocene marine flooding of the Black Sea has been the subject of intense scientific debate since the “Noah’s Flood” hypothesis was proposed in the late 1990s. The chronology of the flooding is not straightforward because the connection between the Black Sea and the Mediterranean Sea involves the intermediate Marmara Sea Basin via two sills (Dardanelles and Bosphorus). This study explores the chronology of late Pleistocene–Holocene flooding by examining sedimentary facies and molluscs from 24 gravity cores spanning shelf to slope settings in the southern Marmara Sea Basin. A late Pleistocene Ponto-Caspian (Neoeuxinian) mollusc association is found in 12 of the cores, comprising 14 mollusc species and dominated by brackish (oligohaline–lower mesohaline) endemic taxa (dreissenids, hydrobiids). The Neoeuxinian association is replaced by a Turritella–Corbula association at the onset of the Holocene. The latter is dominated by marine species, several of which are known to thrive under dysoxic conditions in muddy bottoms. This association is common in early Holocene intervals as well as sapropel intervals in younger Holocene strata. It is an indicator of low-salinity outflows from the Black Sea into the Marmara Sea that drive stratification. A marine Mediterranean association (87 species) represents both soft bottom and hard substrate faunas that lived in well-ventilated conditions and upper mesohaline–polyhaline salinities (ca. 25 psu). Shallower areas were occupied by hard substrate taxa and phytopdetritic communities, whereas deeper areas had soft bottom faunas. The middle shelf part of the northern Gemlik Gulf has intervals with irregular and discontinuous sedimentary structures admixed with worn Neoeuxinian and euryhaline Mediterranean faunas. These intervals represent reworking events (slumping) likely related to seismic activity rooted in the North Anatolian Fault system. The core data and faunas indicate an oscillating postglacial sea-level rise and phases of increased/decreased ventilation in the Marmara Sea during the Holocene, as well as palaeobiogeographic reorganisations of Ponto-Caspian and Mediterranean water bodies since the latest Pleistocene (<30 ka). The findings contribute to arguments against a single catastrophic flooding of the Black Sea at about 7.5 ka (Noah’s Flood).

Particle and volatile organic emissions from the combustion of a range of building and furnishing materials using a cone calorimeter

A series of experimental small-scale fire tests using a cone calorimeter were conducted. The objective of the tests was to provide a comparative assessment of particle and volatile organic compound emissions from the combustion of 10 commonly used types of building and furnishing materials relative to radiata pine, a dominant construction material. The materials tested included wood-based products (particle board, particle board with melamine surface finishes, medium-density fibreboard, painted pine), wool/nylon carpet, polyester insulation, two types of polyurethane (PUR) foams, high density polystyrene with cladding material and plasterboard. Tests were run at two irradiance levels, 25kWm−2 and 50kWm−2 under well-ventilated conditions. Samples were collected for analysis of gravimetric mass, particulate organic and elemental carbon, polycyclic aromatic hydrocarbons (PAHs), carbonyls and volatile organic compounds along with continuous measurements of carbon monoxide (CO), carbon dioxide (CO2) and fine particles (PM2.5).Under the tested conditions of flaming combustion of 11 materials, the highest pollutant concentrations per mass of specimen burnt resulted from the combustion of polyester insulation, polystyrene with cladding material, PUR foam and a wool/nylon carpet. Among wood-based materials, medium-density fibreboard and particle board with melamine surface ranked highest in emissions, with pine ranking lowest. However, wood-based products make up the majority of mass in building structures so that emissions from wood-based products may contribute more significantly to total emissions and hence to exposures than emissions from the polymeric materials.

Fire behavior of carbonates-based electrolytes used in Li-ion rechargeable batteries with a focus on the role of the LiPF6 and LiFSI salts

A detailed investigation of the combustion behavior of LiPF6 or LiFSI-based carbonate electrolytes was conducted with the objective of getting better knowledge of lithium-ion battery system fire induced thermal and chemical threats. The well–controlled experimental conditions provided by the Tewarson calorimeter have enabled the accurate evaluation of fire hazard rating parameters such as heat release rate and effective heat of combustion and the quantification of toxic effluents (HF, SO2, NOx…). Results have shown that all the electrolytes tested burn in phases depending on the flammability nature of their mixture constituents. The first stage of combustion is solely governed by the more volatile solvent (linear carbonate) and the influence of adding salt comes into effect predominantly in the second stage. It has been also shown that combustion enthalpy of electrolytes lies in the solvent mixture, irrespective of the salt added. The fire induced toxicity in well-ventilated conditions is found to be mainly dictated by the salt and its chemical structure, showing very limited concerns that emanate from the organic solvents.

Tobacco dust induced genotoxicity as an occupational hazard in workers of bidi making cottage industry of central India.

Context:To explore genotoxicity in bidi rollers occupationally exposed to bidi tobacco dust.Aims:To assess the extent of genotoxicity of tobacco dust to bidi rollers of Jabalpur, Madhya Pradesh, India and cytotoxicity of bidi tobacco extract.Settings and Design:Blood samples from 31 bidi rollers and 30 controls taken after written informed consent were analyzed for chromosome aberrations (CA) and comet assay.Materials and Methods:Genotoxicity was studied by CA in cultured peripheral blood lymphocytes of bidi rollers and the deoxyribonucleic acid (DNA) damage studies were done by comet assay of their blood. The toxicity of bidi tobacco extract to normal human lymphocytes was studied by MMT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay as drop in viability.Statistical Analysis Used:Student's t-test and DMRT.Results:There is a general trend of increase in CA% of both in exposed and control groups with age, but in every group the bidi rollers have a significantly higher CA% than the controls. The CA % is also directly related to exposure. The comet assay findings reveal that the mean comet length and tail length increases with exposure time. The toxicity of bidi tobacco extract (TE) to normal human lymphocytes was tested in vitro by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay at 2 h of incubation. The trend of drop in viability with increasing concentrations of TE was clearly evident from the data from four donors in spite of their individual differences in viability.Conclusions:The results obtained in this investigation indicate that bidi rollers seem to be facing the occupational hazard of genotoxicity due to handling bidi tobacco and inhalation of tobacco dust. They should be advised to work under well-ventilated conditions.

Estimation of chemical heat release rate in rack storage fires based on flame volume

Quantification of heat release rate is crucial to many fire research works. Under certain conditions, such as very large fires and fire tests with sprinklers, measurements of fire heat release rate can be a challenging problem. This study attempted to develop a methodology of estimating chemical heat release rate using flame volume. This method is based on the theory that heat release rate per unit flame volume is relatively invariant, as long as the combustion is controlled by diffusion in buoyant fires under well-ventilated conditions. Test data were examined from a variety of fire experimental conditions to evaluate the proposed method. The results demonstrate that the flame-volume based method can provide reasonable estimation of heat release rate compared to oxygen-consumption based method.

High-density polyethylene thermal degradation and gaseous compound evolution in a cone calorimeter

In this paper, the thermal degradation of pure high-density polyethylene (HDPE) has been studied in a cone calorimeter (CC) under well-ventilated conditions with a piloted ignition. Ten CC irradiance levels (from 15 to 80kWm−2) have been applied to HDPE sample to characterize their influence on the thermal degradation parameters (ignition time (tig), critical heat flux (CHF), mass loss rate (MLR) and specific mass loss rate (SMLR)) as well as on the concentrations of exhaust gases emitted during the combustion process. During our experiments, gaseous compound mole fractions have been quantified simultaneously by a Fourier transformed infrared (FTIR) spectrometer and another gas analyzer. Thus, several main species (CO, CO2, H2O, NOx, lightweight hydrocarbons and O2) with concentrations and emission yields of high or non-negligible consistency have been encountered, regardless of the external heat flux considered. Furthermore, using the oxygen consumption method, heat release rate (HRR), total heat release (THR) and effective heat of combustion (EHC) have been calculated for each irradiance level. Therefore, these different results (thermal properties, emission yields, HRR, THR and EHC) are in quite good accordance (same order of magnitude) with those found in previous studies.

Spraying Ozonated Water under Well-Ventilated Conditions Does Not Cause Any Visible Injury to Fruit-Vegetable Seedlings

To determine whether horticultural plants are visibly injured by being sprayed with ozonated water (OW) for airborne-disease control, we sprayed OW with a dissolved ozone concentration (DOC) of 4.0 or 8.0 mg L−1 or distilled water (DW) on melon (Cucumis melo L. ‘Andes’), tomato (Lycopersicon esculentum M. ‘Momotaro-York’), watermelon (Citrullus lanatus M. ‘Fujikou’), cucumber (Cucumis sativus L. ‘Sharp’), green pepper (Capsicum annuum L. ‘Kyounami’), and eggplant (Solanum melongena L. ‘Senryo-nigou’) seedlings under well-ventilated conditions. The OW and DW were sprayed on the seedlings at 10 a.m. and 2 p.m. on 3 successive days. No yellowing, chlorosis, necrosis, or malformation was observed for any of the seedlings during this period and also 1 day after the last OW spraying. These results indicate that intensive spraying of OW with a high DOC, for airborne-disease control, does not cause any visible injury to the fruit-vegetable seedlings used as long as the spraying is carried out under well-ventilated conditions.

Carbon Monoxide Generation in Fires: Effect of Temperature on Halogenated and Aromatic Fuels

Carbon monoxide is widely regarded as the major toxicant in fire effluents. It is produced as a result of incomplete combustion, by low temperatures, flame quenching, or under-ventilation. Polymers containing halogens and aromatic rings give higher carbon monoxide yields in well-ventilated conditions, when burnt in the steady state tube furnace (ISO 19700) at a furnace temperature of 650°C. This is believed to result from flame quenching by hydrogen halides or the enhanced stability of aromatic rings in flames, respectively. This work investigates the effect of ventilation condition and furnace temperature on the yield of carbon monoxide from burning mixtures of polyvinyl chloride and polyethylene, polyamide 6 containing a brominated flame retardant and an antimony synergist, and polystyrene. In each case, the high carbon monoxide yields in well-ventilated burning reduced at higher furnace temperatures, showing a diminution of both flame retardancy and fire toxicity above 850°C.

Smoke and hydrocarbon yields from fire retarded polymer nanocomposites

Polypropylene (PP) and Polyamide 6 (PA6) samples, with and without fire retardants (FR) (ammonium polyphosphate in PP, and a mixture of organic aluminium phosphinate and melamine polyphosphate (OP 1311) in PA 6) and nanofillers (NC) were burned under different fire conditions in order to compare their toxic product yields. Fire effluents (CO, smoke and hydrocarbons) were generated using a steady state tube furnace (BS 7900, ISO TS 19700) for the separate materials and fire retarded and nanocomposite modifications of these materials under flaming conditions. Under well-ventilated conditions yields of carbon monoxide (CO) for all PP samples are similar, whereas for PA6 samples much higher yields of CO for PA6 + FR and PA6 + NC are observed. The highest yields of CO occur for both pure polymers in under-ventilated fire conditions when fire retardant and nanoclay are combined together. For PP the smoke is fairly independent of fire condition, but the PP + FR + NC shows less agglomeration. For PA6 the sample containing OP 1311 shows consistently higher smoke yields. For hydrocarbon yields similar effects are observed for both PP and PA6 polymers; the highest yields are for PA6 + NC, except under-ventilated fires where PA6 + FR produce the most; for PA6 + FR + NC samples the lowest yields are observed, compared to either NC or FR formulations.

Effects of vitiation on the heat release rate in mechanically-ventilated compartment fires

The prediction of the heat release rate in compartment fires is still a challenging question due to the feedback of the environmental variables on the burning rate. A set of large-scale, mechanically-ventilated pool fire experiments supports the present analysis. Most of these tests yielded a quasi steady-state with limited pyrolysis compared to well-ventilated conditions. From a well-stirred reactor approach, the effect of vitiation on the steady-state pyrolysis rate is discussed. The Global Equivalence Ratio concept, expressed as 0 2 " / f c O ? = A m ?H q Y ?H ? ? ?? , is introduced to classify the experiments. It also appears to be the main factor in determining the under-ventilated pyrolysis rate whenever the airflow inlet is situated high in the fire room. Whenever the inlet position is low, however, the oxygen concentrations tend to be stratified and the well-stirred reactor approach fails to predict the pyrolysis rate. In both cases, a zone modelling approach including the dependency of pyrolysis on the oxygen content near the flame provides a better estimation of the fuel mass loss rate and hence of the heat release rate.

A calorimetric study of wildland fuels

The burning of two species of pine needles: Pinus halepensis and Pinus pinaster, was studied to characterize the behavior of the forest floor in wildland fires. These fuels are representative of the Mediterranean ecosystem and have very different shapes and surface-to-volume ratios. Calorimetry was performed using the FM-global fire propagation apparatus (FPA). To better understand the effects of transport in the fuel beds, the standard sample holder was replaced by a holder that allowed for the porous properties of the fuel to be studied in a systematic manner. These holders were designed with holes on the surface to allow for different air flow rates to pass through the holder and into the fuel sample. These characteristics created different internal fuel bed conditions and were the first such tests that could be identified that examined transport on this level in these types of wildland fuels. Tests were conducted under natural convection and forced flow. The test series results were analyzed with respect to the direct values of the measured variables and calculated values of heat release rate. Discrete variables of time to ignition, duration of flaming combustion and peak heat release rate were compared using an analysis of variance method. As the experiments were conducted under well-ventilated conditions, the heat release rate calculated by calorimetry was compared to mass loss rate and heat of combustion. CO concentration in time proved to be a good indicator of the combustion dynamics in the fuel bed. Heat release rate, time to ignition and time to reach peak heat release rate indicated a strong dependence on flow conditions and on fuel specie. It was shown that the transport processes in the fuel beds had a significant effect on the burning characteristics.

Abrupt climate warming in East Antarctica during the early Holocene

We report a centennial-scale warming event between 8600 and 8400 cal BP from Amery Oasis, East Antarctica, that is documented by the geochemical record in a lacustrine sediment sequence. The organic carbon content, the C/S ratio, and the sedimentation rate in this core have distinctly elevated values around 8500 y ago reflecting relatively warm and ice-free conditions that led to well-ventilated conditions in the lake and considerable sedimentation of both autochthonous and allochthonous organic matter on the lake bottom. This abrupt warming event occurred concurrently with reported warm climatic conditions in the Southern Ocean while the climate in central East Antarctic remained cold. The comparison of the spatial and temporal variability of warm climatic periods documented in various terrestrial, marine, and glacial archives from East Antarctica elucidates the uniqueness of the centennial-scale warming event in the Amery Oasis. We also discuss a possible correlation of the Amery warming event with the abrupt climatic deterioration around 8200 cal BP on the Northern Hemisphere.

Deep-sea ecosystem variability of the Aegean Sea during the past 22 kyr as revealed by Benthic Foraminifera

Specific responses of the regional deep-sea ecosystems to climatic and oceanographic processes during the last 22 kyr are revealed by benthic foraminiferal faunas from two cores in the northern and southern Aegean Sea. Under glacial boundary conditions, high-diversity benthic foraminiferal faunas and elevated benthic foraminiferal numbers indicate enhanced organic matter availability and well-ventilated deep-water masses in the whole Aegean Sea. The glacial termination is accompanied by significant fluctuations in productivity and deep-water ventilation. In the northern Aegean Sea, meltwater inflow from mountain glaciers during the Bølling/Allerød warm period resulted in a restriction of local deep-water formation, as mirrored by a dominance of bolivinids. During the deposition of sapropel S1, drops in benthic foraminiferal number and diversity are more significant in the southern Aegean Sea when compared to the north. This suggests the persistence of local deep-water formation in the northern Aegean Sea during S1 deposition. In addition, faunal fluctuations within S1 at both sites suggest the repeated influence of short-term cooling events on the re-ventilation and re-colonization of Aegean deep-sea ecosystems. During the middle and late Holocene, benthic foraminiferal faunas document the establishment of oligotrophic and well-ventilated conditions in the southern Aegean Sea. The corresponding faunas from the northern Aegean Sea reflect generally mesotrophic conditions and variable deep-water oxygenation. During the entire Holocene, the deep-sea ecosystems of this region responded very sensitively to short-term changes in humidity and temperature. These abrupt climate changes controlled the inflow of nutrients from rivers and the Black Sea and the formation of local deep-water masses.