Last interglacial (MIS 5e) sea-level determined from a tectonically stable,far-field location,Eyre Peninsula,southern Australia

The last interglacial maximum (Marine Isotope Substage 5e [MIS 5e], 128–116 ka) is a distinctive event in recent Earth history. Shoreline successions of this age are important for calibrating climate models and defining the overall behaviour of the crust–mantle system to fluctuating ice and ocean-water volumes. In a global context, the recently intensified interest in last interglacial shoreline successions has revealed considerable variability in the magnitude of sea-level rise during this time interval and highlighted the need to examine paleosea-level evidence from tectonically stable, far-field settings. Situated in the far-field of continental ice sheets and on the tectonically stable Gawler Craton, the 300 km coastal sector of western Eyre Peninsula between Fowlers Bay and Lake Newland in southern Australia represents an important region for defining the glacio-eustatic (ice-equivalent) sea-level attained during the last interglacial maximum based on the relative sea-level observations from this region. Low-energy, shoaling upward, peritidal bioclastic carbonate successions of the last interglacial (locally termed Glanville Formation) formed within back-barrier, estuarine–lagoonal environments in the lee of eolianite barrier complexes (locally termed Bridgewater Formation) along this coastline. The well-preserved shelly successions (coquinas) contain diverse molluscan fossil assemblages including species no longer living in the coastal waters of South Australia (e.g. the Sydney cockle Anadara trapezia and the benthic foraminifer Marginopora vertebralis). The extent of amino acid racemisation (a measure of fossil age based on increasing d/l value) in a range of species, and in particular A. trapezia and Katelysia sp., confirms the time equivalence of the isolated embayment-fill successions, correlated with the informal type section of the Glanville Formation at Dry Creek, north of Adelaide. Preliminary U-series analyses on A. trapezia also suggest a correlation with the last interglacial maximum, but further highlight the complexity in dating fossil molluscs by the U-series method in view of their open-system behaviour. The shelly successions of the Glanville Formation occur at elevations higher than attained by sea-level in the current, Holocene interglacial. A higher sea-level of between 2.1 ± 0.5 and 4 ± 0.5 m above present sea-level is inferred for the last interglacial maximum (MIS 5e) along this coastline based on the elevation of sedimentary successions host to the shallow subtidal–intertidal fossil molluscs Katelysia sp., and Anadara trapezia. The paleosea-level observations place a lower limit on the sea-level attained during the last interglacial maximum and suggest that caution be exercised in the definition of the upper limit of sea-level during this interglacial.     

Sorption and diffusion studies with low molecular weight organic compounds in cementitious systems

The uptake of methanol, ethanol, formaldehyde, acetaldehyde, formic acid and acetic acid by cement paste was determined in hydrating cement after 1 h, 28 d and 390 d hydration. The sorption values determined for formate and acetate were critically assessed by investigating through- and out-diffusion of these compounds in fully hydrated cement paste and their uptake by individual cement phases. Diffusion studies included inverse modelling of four data sets for each compound and an uncertainty analysis based on a Latin hypercube sampling procedure. Solid–liquid distribution ratios determined from the hydration experiments are on the order of 10⁻⁴ m³ kg⁻¹ in the case of alcohols and aldehydes indicating non-specific (very weak) bonding onto the surface of the cement phases, e.g. through hydrogen bonding. Hydration and diffusion studies reveal slightly higher distribution ratios and reversible uptake by cement paste and cement phases in the case of acetate indicating specific adsorption (electrostatic interaction) onto partially positively charged surface sites of the cement phases. Selective binding of a small fraction of formate is evidenced from both sorption and out-diffusion experiments suggesting the presence of sorption sites capable of strongly bonding the anion, presumably by SO₄²⁻/HCOO⁻ replacement in the ettringite structure.     

盐度对鲈鱼稚、幼鱼发育阶段氨基酸的影响

为揭示鲈鱼(Lateolabrax japonicus)稚、幼鱼在淡化过程中氨基酸的组成及含量的变化规律,本实验在15.00、7.50及0.00共3个盐度梯度下,用氨基酸全自动分析仪对鲈鱼稚、幼鱼氨基酸的组成及含量进行了测定和分析。结果表明,实验中,3个盐度组的总氨基酸含量均逐渐增加,且它们之间没有显著性差异;实验中15.00盐度的必需氨基酸总量略呈下降趋势,而7.50盐度组和0.00盐度组均呈上升趋势,3个盐度之间存在显著性差异(P0.05);除脯氨酸外,3个盐度组中其他的非必需氨基酸含量及总的非必需氨基酸含量也均无显著差异。     

Reed litter Si content affects microbial community structure and the lipid composition of an invertebrate shredder during aquatic decomposition

The decomposition of plant litter is an important mechanism in regard to energy and nutrient dynamics of ecosystems. Silicon concentration of plant tissue can affect these processes by changing litter quality, i.e. nutrient stoichiometry and cellulose and phenols content. To determine which group of microbial decomposers benefits from high Si content in plants and how this impacts on animal decomposers, a batch experiment was conducted with reed leaf litter (Phragmites australis) differing in Si content in the presence/absence of invertebrate shredders (Gammarus pulex). Lipid concentration of G. pulex, in reed litter and fine particulate matter (FPOM) were examined. High Si concentration in reed resulted in a decline of gram positive bacteria in the heterotrophic biofilm and of gram negative bacteria in FPOM. The lipid composition in the next trophic level, the decomposer G. pulex, changed too, indicating a diet shift in favor of bacteria and algae with increasing litter Si concentration. Thus, basal decomposers were affected by the Si availability in plant resources, and these effects likely persist along the food chain, as FPOM is a dominant food supply for other groups, e.g. collectors. This impact of Si content on plant substrate quality for decomposer food webs may have global relevance, due to related modifications in carbon and nutrient cycling during litter decomposition.     

两种氨基酸衍生化方法的比较研究

氨基酸的衍生化过程是气相色谱-燃烧-同位素比值质谱法(GC/C/IRMS)测定单体氨基酸碳稳定同位素组成方法中的关键步骤之一。采用了2种氨基酸衍生化方法分别对17种标准氨基酸进行衍生化处理：一种是氨基酸N-乙酰基正丙酯(NAP)法,另一种是氨基酸N-三氟乙酰基异丙酯(TFAIP)法。通过测量17种氨基酸衍生化前后的稳定碳同位素组成,比较了每种方法的重复性及衍生化过程中的同位素分馏作用的大小。结果说明氨基酸N-三氟乙酰基异丙酯(TFAIP)法是一种较为理想的氨基酸衍生化方法。     

Simulations of accidental coal immersion

Coal is currently becoming an increasingly interesting fossil energy resource and that is the reason why its maritime transport, and hence the risk of collier accidents, increase. In this work, the environmental impact of an accidental coal immersion at sea is studied: the physicochemical effects are estimated using innovative experimental setups – a laboratory seawater canal called “polludrome” is used to evaluate the behaviour of coal particles submitted to a seawater flow, and a specifically designed tub is used to study the physicochemical consequences induced when coal is introduced into continuously renewed seawater. When coal is introduced into seawater, the most easily visible consequences are physical: fine coal particles reduce the daylight penetration up to 100% and move along with the flow, and coal chunks accumulate on the floor. Chemical effects are also measured: humic matters are dissolved from coal into seawater (up to 2 mg L⁻¹), but no release of polycyclic aromatic hydrocarbons is evidenced. Some inorganic compounds are dissolved, among which manganese, whose concentrations can reach 1 μg L⁻¹. Fortunately, the results show that the environmental impact of this type of accident would remain limited.     

On the metal content and metal ion uptake of botanically specific peats and the derived humic acids

With respect to ten metals (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga) which are continguous in the Periodic Table the natural metal content and the ability to take up metal ions has been determined for three peats of defined botanical origin, each peat being sampled at three different levels. A correlation is found between the natural metal content and botanical origin. Apart from aluminium, the concentration of individual metals increased in the series Sphagnum < fen sedge < reed, the increase being statistically significant (P = 0.001) for V, Mn, Co, Ni, and Ga and for the sum of the metal ions measured.No clear correlation emerged between botanical origin and metal uptake. The metal uptake by the humic acid derived from each peat sample was also determined, and correlated with the metal uptake of the source peat itself.In all the humic acid and peat metal-uptake experiments the selectivities were very similar. V, Cr, Cu, Ga were readily taken up while Mn, Co and Zn were consistently less preferred.     

Differential transport and degradation of bulk organic carbon and specific terrestrial biomarkers in the surface waters of a sub-arctic brackish bay mixing zone

Detailed organic geochemical analyses were performed on surface water particulate samples of the lower Kalix River and northern Bothnian Bay collected during the spring flood of 2005. Both bulk geochemical and molecular biomarker analyses indicated a predominance of terrestrially-derived particulate organic matter (POM), both of higher plant and Sphagnum origin in the low salinity zone (LSZ) of the Kalix River estuary, with an increasing contribution of marine-derived POM in the offshore Bothnian Bay basin.Two-dimensional box modeling of the mixed surface layer in the LSZ indicated that 65% of the particulate organic carbon (POC) and between 73 and 93% of the terrestrial biomarker classes analyzed (high molecular weight n-alkanes, n-alkanoic acids and n-alkanols as well as sitosterol) were degraded in the course of their weeklong transit through the inner LSZ during the spring flood. This corresponds to field-based degradation rate constants for the biomarkers of 0.5 and 2.5 day^− 1, which are similar to results reported from mesocosm experiments for related compounds. The degradation rate constant for terrestrial POC of 0.38 day^− 1 was about 20 times larger than for DOC and suggests that POC mineralization stands for 44% of the total mineralization, which is much larger than previously considered.This sub-arctic river-export regime has a geochemistry resembling that of neighboring western Russian Arctic Rivers, suggesting that a large part of the OM coastally exported from northernmost Eurasian soils may be degraded within the vicinity of the river mouths and putatively be released as carbon dioxide. The 65% degradation of terrestrial POC in the coastal surface water of this sub-arctic recipient is substantially larger than a global-average of 35% used in recent budget estimates of the fate of terrestrially-exported POC on the pan-arctic shelves. Considering ongoing and predicted changes in the Arctic Region due to global warming a more efficient degradation of river-exported terrestrial POC may have far-reaching consequences for the large-scale biogeochemical cycling of carbon in the pan-arctic region and beyond.     

温度对四种海洋微藻脂肪酸组成的影响

对在不同温度下培养的4种海洋微藻脂肪酸的气相色谱分析表明，不同微藻的脂肪酸组成及其不饱和程度受温度影响的差别较大。在本实验条件下，随着温度升高，球等革命金藻、盐生杜氏藻、三角褐指藻的总多不饱和脂肪酸（TPUFA）百分含量及脂肪酸平均双键数（MDB）均呈下降趋势，其总单不饱和脂肪酸（TMUFA)和总饱和脂肪酸（TSFA）百分含量则呈增加趋势；随着温度提高小球藻TPUFA百分含量和脂肪酸平均双键数先降低后增加，在20℃时出现最小值。