A Simple and Fast Separation Method of Fe Employing Extraction Resin for Isotope Ratio Determination by Multicollector ICP-MS

A new, simple and fast separation method for Fe using an extraction chromatographic resin, Aliquat 336 (commercially available as TEVA resin) has been developed. A one milliliter column containing 0.33 mL TEVA resin on 0.67 mL CG-71C was used.Iron was adsorbed with 6mol·L-1 HCl + H2O2 on TEVA resin, and recovered with 2 mol·L-1HNO3. The recovery yield and total blank were 93.5 ± 6.5% and 6 ng, respectively. Theseparation method is simple, and takes < 2 hours. For evaluation of the Fe separation, Fe isotope ratios were measured by a double-spike method employing multicollector inductively coupled plasma source mass spectrometry (MC-ICP-MS) with repeatability of 0.06‰ (SD) for the standard solution and ~0.05‰ for the silicate samples. Therefore, the column chemistry developed in this study is a viable option for Fe isotope ratio measurement by MC-ICP-MS.

A Hybrid Statistical-Dynamical Downscaling of Air Temperature over Scandinavia Using the WRF Model

An accurate simulation of air temperature at local scales is crucial for the vast majority of weather and climate applications.In this work,a hybrid statistical–dynamical downscaling method and a high-resolution dynamical-only downscaling method are applied to daily mean,minimum and maximum air temperatures to investigate the quality of localscale estimates produced by downscaling.These two downscaling approaches are evaluated using station observation data obtained from the Finnish Meteorological Institute over a near-coastal region of western Finland.The dynamical downscaling is performed with the Weather Research and Forecasting(WRF)model,and the statistical downscaling method implemented is the Cumulative Distribution Function-transform(CDF-t).The CDF-t is trained using 20 years of WRF-downscaled Climate Forecast System Reanalysis data over the region at a 3-km spatial resolution for the central month of each season.The performance of the two methods is assessed qualitatively,by inspection of quantile-quantile plots,and quantitatively,through the Cramer-von Mises,mean absolute error,and root-mean-square error diagnostics.The hybrid approach is found to provide significantly more skillful forecasts of the observed daily mean and maximum air temperatures than those of the dynamical-only downscaling(for all seasons).The hybrid method proves to be less computationally expensive,and also to give more skillful temperature forecasts(at least for the Finnish near-coastal region).

Deep recycling of volatile elements in the mantle:Evidence from the heterogeneous B isotope in intra-plate basalts

Volatiles in the mantle are crucial for Earth’s geodynamic and geochemical evolution.Understanding the deep recycling of volatiles is key for grasping mantle chemical heterogeneity,plate tectonics,and long-term planetary evolution.While subduction transfers abundant volatile elements from the Earth’s surface into the mantle,the fate of hydrous portions within subducted slabs during intensive dehydration processes remains uncertain.Boron isotopes,only efficiently fractionating near the Earth’s surface,are valuable for tracing volatile recycling signals.In this study,we document a notably large variation inδ^(11)B values(−14.3‰to+8.2‰)in Cenozoic basalts from the South China Block.These basalts,associated with a high-velocity zone beneath East China,are suggested to originate from the mantle transition zone.While the majority exhibitδ^(11)B values(−10‰to−5‰)resembling the normal mantle,their enriched Sr-Nd-Pb isotope compositions and fluid-mobile elements imply hydrous components in their source,including altered oceanic crust and sediments.The normalδ^(11)B values are attributed to the dehydration processes.Remarkably highδ^(11)B values in the basalts indicate the presence of subducted serpentinites in their mantle source.A small subset of samples with lowδ^(11)B values and radiogenic isotope enrichments suggests a contribution from recycled detrital sediments,though retaining minimal volatile elements after extensive dehydration.These findings provide compelling evidence that serpentinites within subducted slabs predominantly maintain their hydrous nature during dehydration processes in subduction zones.They may transport a considerable amount of water into deep mantle reservoirs,such as the mantle transition zone.