Uranyl Minerals from Abandoned Podgórze Mine (Sudetes Mountains, SW Poland) and Their REE Content

The Podgórze uranium deposit is located near Kowary in the Sudetes Mountains, SW Poland. The mine is located in the Karkonosze-Izera block, largely comprising Cambrian to Devonian metamorphic rocks intruded by the Variscan Karkonosze granite. Uranyl minerals from the Podgórze mine can be divided into three assemblages. The first one is associated with heavily ventilated mining galleries. The next assemblage is related to the outflow of water from fissures in the walls of the mine galleries. The last assemblage appears in the mine dump, where there is increased activity of other weathering products. The main purpose of this paper is to determine the mineralogical characteristics of uranyl minerals from the abandoned Podgórze uranium mine and reconstruct the physicochemical crystallization conditions based on the concentrations of rare earth elements (REEs) in these minerals. The results of thermodynamic modeling show that the aqueous species of uranyl ion in the mine water are represented by UO2HAsO4 (aq), UO2CO3(OH)3−, UO2CO3 (aq), and UO2OH+. The content of REEs and their distribution patterns were used to determine the crystallization conditions of uranyl minerals. Uranyl carbonates and arsenates have generally low concentrations of REEs compared to uranyl silicates, phosphates, and hydroxides, which have higher concentrations. The differences in REE concentration patterns may be related with the oxidizing nature of water circulating in the subsurface part of the deposit

Connectivity of edaphic and endolithic microbial niches in cold mountain desert of eastern pamir (Tajikistan)

Microbial communities found in arid environments are commonly represented by biologicalsoil crusts (BSCs) and endolithic assemblages. There is still limited knowledge concerning endolithsand BSCs occurring in the cold mountain desert of Pamir. The aim of the study was to investigate thecomposition and structure of endolithic bacterial communities in comparison to surrounding BSCs inthree subregions of the Eastern Pamir (Tajikistan). The endolithic and BSC communities were studiedusing culture-independent and culture dependent techniques. The structure of the endolithic bacte-rial communities can be characterized as Actinobacteria–Proteobacteria–Bacteroidetes–Chloroflexi–Cyanobacteria, while the BSCs’ can be described as Proteobacteria–Actinobacteria–Bacteroidetes–Cyanobacteria assemblages with low representation of other bacteria. The endolithic cyanobacterialcommunities were characterized by the high percentage of Chroococcidiopsaceae, Nodosilineaceae,Nostocaceae and Thermosynechococcaceae, while in the BSCs were dominated by Nodosilineaceae,Phormidiaceae and Nostocaceae. The analysis of 16S rRNA genes of the cyanobacterial culturesrevealed the presence of possibly novel species of Chroococcidiopsis,Gloeocapsopsis and Wilmottia.Despite the niches’ specificity, which is related to the influence of microenvironment factors onthe composition and structure of endolithic communities, our results illustrate the interrelationbetween the endoliths and the surrounding BSCs in some regions. The structure of cyanobacterialcommunities from BSC was the only one to demonstrate some subregional differences.This research was funded by the National Science Centre, grant number 2015/19/B/NZ9/00473 (I.J.), the Ministry of Science and Higher Education through the Faculty of Biology, University of Warsaw intramural grant number DSM501-D114-86-0117600-16 (N.K.), by the grant PID2019-105469RB-C22, AEI, MICINN (A.d.l.R.), and Integrated Development Programme (ZIP) of the University of Warsaw (N.K.).Peer reviewe

Uranyl Minerals from Abandoned Podgórze Mine (Sudetes Mountains, SW Poland) and Their REE Content

The Podgórze uranium deposit is located near Kowary in the Sudetes Mountains, SW Poland. The mine is located in the Karkonosze-Izera block, largely comprising Cambrian to Devonian metamorphic rocks intruded by the Variscan Karkonosze granite. Uranyl minerals from the Podgórze mine can be divided into three assemblages. The first one is associated with heavily ventilated mining galleries. The next assemblage is related to the outflow of water from fissures in the walls of the mine galleries. The last assemblage appears in the mine dump, where there is increased activity of other weathering products. The main purpose of this paper is to determine the mineralogical characteristics of uranyl minerals from the abandoned Podgórze uranium mine and reconstruct the physicochemical crystallization conditions based on the concentrations of rare earth elements (REEs) in these minerals. The results of thermodynamic modeling show that the aqueous species of uranyl ion in the mine water are represented by UO2HAsO4 (aq), UO2CO3(OH)3−, UO2CO3 (aq), and UO2OH+. The content of REEs and their distribution patterns were used to determine the crystallization conditions of uranyl minerals. Uranyl carbonates and arsenates have generally low concentrations of REEs compared to uranyl silicates, phosphates, and hydroxides, which have higher concentrations. The differences in REE concentration patterns may be related with the oxidizing nature of water circulating in the subsurface part of the deposit

A rusty carbon sink in estuarine sediments? Evaluation of an iron oxide burial experiment.

Iron oxides are known to play a key role in preserving organic carbon (OC) from mineralization, contributing to its burial, and consequently regulating CO2 and O2 atmospheric concentrations. Approximately 20% of OC in sediments is associated with iron minerals, the so-called “Rusty carbon sink”. Yet, the formation and stability of this organo-mineral association remain unclear, particularly in the natural environment.In this study, quartz grains, ferrihydrite-2-lines (FH2L) and 6-lines (FH6L) coated quartz grains were buried within 4 modified passive autosamplers (peepers) in a mudflat in the Scheldt (Appels, Belgium). Each peeper (~30 cm in length) comprises 3 columns of 12 traversing holes, each row filled with one of the minerals, separated from the sediments by a 63 µm pore size mesh. The peepers were collected after 3, 10, 18, and 23 months of exposure to the sediments. To date, this is the first in situ experiment aimed at following the dynamics of OC-Fe association in sediments over depth.A combination of different techniques, electron microscopic and spectroscopic (FIB, SEM, TEM, TEM-EELS, XPS), thermogravimetric (TGA-DTA coupled with mass spectrometry) and classical solid phase analyses were used to characterize the neo-formed organo-mineral associations. Over time, dissimilatory iron oxide reduction decreased the iron content of both 2L and 6L ferrihydrite, while OC accumulated over the residual iron. The OC pool consisted of thermo-labile (200-400°C), recalcitrant (400-550°C) and refractory carbon (550-650°C), identified via XPS as aromatic, alkene, and aliphatic compounds. FIB sections cut through the iron-coated grains showed the OC localized within the Fe-OC associations. This study sheds new insights onto the least-known processes regulating carbon burial in benthic environments, providing a broader perspective of the Fe-OC association that underlie the so-called 'rusty carbon sink'.info:eu-repo/semantics/publishe