Further discussion on the intercomparison of the trace metal concentrations and particle size of fluvial sediment recovered from two centrifuge systems

A single large volume water sample taken at the mouth of the Upper Rhone River on Lake Geneva was processed directly in parallel through two continuous flow centrifuges, a Westphalia and an Alfa-Laval. Sediment was recovered from the Westphalia, and separately from the bowl and brass core of the Alfa-Laval. The three sediment samples were analyzed for particle size and the following elements: Zn, Cu, Mn, Cr, P, Co, B, V, Be, Sr, Na, Pb, Ni, Ba, Fe, Ca, and Mg. Results indicate that the particle size recovery of both machines is similar when sediment from the brass core and bowl of the Alfa-Laval are combined, and that the recovery for all elements other than Cu, V, B, and Pb are the same when the particle size differences are taken into account. Sediment from the Alfa-Laval brass core is clearly contaminated by Cu, B and is also elevated in V and Pb but not to a significant extent. The sediment recovered from the bowl of the Alfa-Laval is contaminated only with Cu, with a 10 ppm increase over the 52 ppm recovered in the Westphalia sediment. Operating procedures involve the discarding of the brass core sediment and the mixing of the Alfa-Laval bowl sediment with that from the Westphalia. The consequent increase in Cu is estimated at less than 5 ppm or within the confidence level of the analysis. These procedures are recommended to all operators of non modified Alfa-Laval units.     

Geochemical arguments for identifying second‐order sea‐level changes in hemipelagic carbonate ramp deposits

Second‐order transgressive–regressive (T–R) cycles, previously recognized using sedimentological criteria in Lower Jurassic hemipelagic deposits from northern Spain, are distinguishable based upon bulk‐rock organic geochemistry [total organic carbon (TOC) and hydrogen index (HI)] and the stable carbon isotope compositions from belemnite rostra. There is a coincidence between regressions and decreasing δ¹³C_bel, TOC and HI values, and between transgressions and increasing δ¹³C_bel, TOC and HI values. The δ¹⁸O and Mg/Ca records from the belemnite rostra are not always in phase with the T–R cycles. The δ¹⁸O_bel record reveals, however, a prominent excursion towards higher values within the spinatum Zone that correlates, according to our results, with a regression and with negative shifts in Mg/Ca, δ¹³C_bel and TOC. On the other hand, an excursion in the δ¹⁸O_bel towards lower values in the serpentinus Zone also correlates with a peak transgression and with positive shifts in Mg/Ca, δ¹³C_bel and TOC. These two excursions have been identified in other European regions as geochemical perturbations of the same characteristics. This suggests a link between second‐order relative sea‐level changes and variations in seawater geochemistry that may reflect local and regional palaeoceanographic perturbations in sea‐water temperature, salinity and water circulation during the Early Jurassic. Terra Nova, 18, 233–240, 2006     

流化冰对于鲣鱼的保鲜效果研究

以远洋鲣鱼为研究对象,以传统淡水碎冰保鲜为对照,研究流化冰处理对鲣鱼的理化性质及微生物特性的影响。结果表明:(1)–4°C冷藏18d后,流化冰保鲜鱼肉pH值、TVB-N、TBA、a*值和菌落总数依次为5.57、10.2mgN/100g、2.87mg/100g、8.92和2.61lgCFU/g,而淡水碎冰保鲜鱼肉各指标已达6.05、20.3mgN/100g、6.60mg/100g、7.16和3.02lgCFU/g,故可知流化冰保鲜处理效果明显优于碎冰保鲜。(2)在25±1°C室温条件下,将冰与鱼放入保温箱内保鲜8h后,流化冰保鲜鱼肉的a*值、pH值、TVB-N、TBA、菌落总数和汁液流失率均显著低于空白和淡水碎冰保鲜处理组(P0.05)。流化冰保鲜可显著减缓鱼体的腐败进程、延长产品货架期,进而满足冰鲜水产品的远洋及长距离运输要求。     

Extreme value modelling of daily areal rainfall over Mediterranean catchments in a changing climate

Heavy rainfall events during the fall season are causing extended damages in Mediterranean catchments. A peaks‐over‐threshold model is developed for the extreme daily areal rainfall occurrence and magnitude in fall over six catchments in Southern France. The main driver of the heavy rainfall events observed in this region is the humidity flux (FHUM) from the Mediterranean Sea. Reanalysis data are used to compute the daily FHUM during the period 1958–2008, to be included as a covariate in the model parameters. Results indicate that the introduction of FHUM as a covariate can improve the modelling of extreme areal precipitation. The seasonal average of FHUM can improve the modelling of the seasonal occurrences of heavy rainfall events, whereas daily FHUM values can improve the modelling of the events magnitudes. In addition, an ensemble of simulations produced by five different general circulation models are considered to compute FHUM in future climate with the emission scenario A1B and hence to evaluate the effect of climate change on the heavy rainfall distribution in the selected catchments. This ensemble of climate models allows the evaluation of the uncertainties in climate projections. By comparison to the reference period 1960–1990, all models project an amplification of the mean seasonal FHUM from the Mediterranean Sea for the projection period 2070–2099, on average by +22%. This increase in FHUM leads to an increase in the number of heavy rainfall events, from an average of 2.55 events during the fall season in present climate to 3.57 events projected for the period 2070–2099. However, the projected changes have limited effects on the magnitude of extreme events, with only a 5% increase in the median of the 100‐year quantiles. Copyright © 2011 John Wiley & Sons, Ltd.     

DEPENDENCE BETWEEN FUSION TEMPERATURES AND CHEMICAL COMPONENTS OF A CERTAIN TYPE OF COAL USING CLASSICAL,NON-PARAMETRIC AND BOOTSTRAP TECHNIQUES

A statistical study of the dependence between various critical fusion temperatures of a certain kind ofcoal and its chemical components is carried out.As well as using classical dependence techniques(multiple,stepwise and PLS regression,principal components,canonical correlation,etc.)together withthe corresponding inference on the parameters of interest,non-parametric regression and bootstrapinference are also performed.     

Triggering factors,behavior, and social impact of the January 2021 hail-debris flows at the Central Valley of Chile

Landslides - An extreme precipitation event produced catastrophic debris flows in central Chile during 29–31 January 2021 (austral summer). Our study focuses on the triggering factors and...