9 research outputs found
Sources and behavior of perchlorate in a shallow Chalk aquifer under military (World War I) and agricultural influences
International audienc
Interâlaboratory Characterisation of Apatite Reference Materials for Chlorine Isotope Analysis
Here we report on a set of six apatite reference materials (chlorapatites MGMH#133648, TUBAF#38 and fluorapatites MGMH#128441A, TUBAF#37, 40, 50) which we have characterised for their chlorine isotope ratios; these RMs span a range of Cl mass fractions within the apatite Ca10(PO4)6(F,Cl,OH)2 solid solution series. Numerous apatite specimens, obtained from mineralogical collections, were initially screened for 37Cl/35Cl homogeneity using SIMS followed by ÎŽ37Cl characterisation by gas source mass spectrometry using both dualâinlet and continuousâflow modes. We also report major and key trace element compositions as determined by EPMA. The repeatability of our SIMS results was better than ± 0.10% (1s) for the five samples with > 0.5% m/m Cl and ± 0.19% (1s) for the low Cl abundance material (0.27% m/m). We also observed a small, but significant crystal orientation effect of 0.38% between the mean 37Cl/35Cl ratios measured on three oriented apatite fragments. Furthermore, the results of GSâIRMS analyses show small but systematic offset of ÎŽ37ClSMOC values between the three laboratories. Nonetheless, all studied samples have comparable chlorine isotope compositions, with mean 103ÎŽ37ClSMOC values between +0.09 and +0.42 and in all cases with 1s â€Â ± 0.25.Key Points:
Six apatite reference materials having various Cl mass fractions were characterised for chlorine isotope ratios by SIMS and three GSâIRMS laboratories.
A small, but significant, crystal orientation effect was recorded by SIMS analyses.
Correlation of instrumental mass fractionation factor with Cl mass fraction is visible along the apatite solid solution series.Narodowe Centrum NaukiDeutscher Akademischer AustauschdienstHelmholtz Recruiting InitiativeInstitute of Geological Sciences, Polish Academy of Science
The impact of biogenic carbon emissions on aerosol absorption inMexico City The impact of biogenic carbon emissions on aerosol absorption in Mexico City
Abstract In order to determine the wavelength dependence of atmospheric aerosol absorption in the Mexico City area, the absorption Ă
ngstrom exponents (AAEs) were calculated from aerosol absorption measurements at seven wavelengths obtained with a sevenchannel aethalometer during two field campaigns, the Mexico City Metropolitan Are