The provenance of the Pompeii cooking wares: Insights from LA–ICP-MS trace element analyses

Distribution character of localized iron microniche in lake sediment microzone revealed by chemical image

DGT (diffusive gradients in thin films) technique and LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) for heterogeneous distribution of the soluble labile iron (Fe) at submillimeter resolution in lake sediment porewater are reported. The soluble labile Fe species include ion and labile organic complexes. The chemical images in two dimensions (2D) for DGT concentration of Fe (C_DGT(Fe)) are investigated for Fe remobilization character. There are 902 C_DGT(Fe) values between 1000 and 2000 μg L^-1, 463 values between 2000 and 3000 μg L^-1, and 112 values over 3000 μg L^-1 in all chemical maps. Based on the linear correlation relationships between C_DGT (Fe) and total Fe (TFe), total organic carbon (TOC), acid-volatile sulfide (AVS), Eh, concentrations of the soluble reactive phosphorus (P) (SRP), and soluble labile trace metals (Zn, Cu, Pb, and Zn) in a vertical 1D profile of sediment or porewater, Fe release mechanisms are mainly due to the reductive Fe release from iron oxyhydroxides and the decomposition of organic matter in algae biomass and deep sediment layer. It can be used to explain the formation mechanisms of Fe microniches in chemical maps with heterogeneous character to a great extent. C_DGT(Fe) peak flux in the center of Fe microniche and the low C_DGT (Fe) at the edge of a microniche are due to the formation of the insoluble iron sulfide and the abundant acid-volatile sulfide (AVS) in sediment. The verified co-remobilization of the soluble labile Fe and trace metals or SRP in sediment porewater can be used to predict their simultaneous release from Fe microniches with the large C_DGT (Fe) peaks. The different kinds of Fe microniche zones and hot spots from sediment/water interface (SWI) to deep sediment correspond to the formation mechanisms of microniches mentioned above. Moreover, some narrow Fe microniche zones with the large C_DGT (Fe) across chemical maps are due to the desorption of Fe(II) from the freshly formed oxide on Myriophyllum verticiilatur roots, which are located at sites of microniche zones.

Lanthanoides in Glass and Glass Ceramics

Many types of glass contain lanthanoides; among them, special glass for optical applications is the one with the highest content of lanthanoides. The precise determination of the lanthanoides’ concentration is performed by inductively coupled plasma-optical emission spectrometry (ICP-OES). However, up to now, there are no established standard processes guaranteeing a uniform approach to the lanthanoide analysis. The knowledge of the lanthanoides’ concentrations is necessary on the microscale in some cases, especially if a suitable separation and recycling procedure is to be applied. Here, the analysis is performed by energy-dispersive X-ray (EDX) or wavelength-dispersive X-ray (WDX) analytics in the scanning electron microscope.