scholarly journals Linking environmental observations and solid solution thermodynamic modeling: the case of Ba- and Sr-rich micropearls in Lake Geneva

2017 ◽  
Vol 89 (5) ◽  
pp. 645-652 ◽  
Author(s):  
Bruno Thien ◽  
Agathe Martignier ◽  
Jean-Michel Jaquet ◽  
Montserrat Filella
Keyword(s):  
Solid Solution ◽  
Trace Elements ◽  
Thermodynamic Modeling ◽  
Lake Geneva ◽  
Calcium Carbonates ◽  
Lake Waters ◽  
Non Equilibrium

AbstractIntracellular inclusions of amorphous Ba- and Sr-rich calcium carbonates – referred to as “micropearls”– have recently been detected in Lake Geneva. These micropearls are formed under conditions of pronounced Ba and Sr undersaturation in the lake waters. Their formation can be explained by the ability of certain microorganisms to preconcentrate these trace elements in tandem with a non-equilibrium solid-solution growing mechanism.

scholarly journals First Observation of Unicellular Organisms Concentrating Arsenic in ACC Intracellular Inclusions in Lake Waters

Geosciences ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 32
Author(s):  
Agathe Martignier ◽  
Montserrat Filella ◽  
Jean-Michel Jaquet ◽  
Mathieu Coster ◽  
Daniel Ariztegui
Keyword(s):  
Lake Geneva ◽  
Amorphous Calcium Carbonate ◽  
Lake Titicaca ◽  
Calcium Carbonates ◽  
Unicellular Eukaryotes ◽  
Biomineralization Process ◽  
Sr:Ca Ratios ◽  
Unicellular Organisms ◽  
Lake Waters ◽  
Chemical Groups

In unicellular organisms, intracellular inclusions of amorphous calcium carbonate (ACC) were initially described in cyanobacteria and, later, in unicellular eukaryotes from Lake Geneva (Switzerland/France). Inclusions in unicellular eukaryotes, named micropearls, consist of hydrated ACCs, frequently enriched in Sr or Ba, and displaying internal oscillatory zonations, due to variations in the Ba:Ca or Sr:Ca ratios. An analysis of our database, consisting of 1597 micropearl analyses from Lake Geneva and 34 from Lake Titicaca (Bolivia/Peru), showed that a certain number of Sr- and Ba-enriched micropearls from these lakes contain As in amounts measurable by EDXS. A Q-mode statistical analysis confirmed the existence of five chemically distinct morpho-chemical groups of As-bearing micropearls, among which was a new category identified in Lake Geneva, where As is often associated with Mg. This new type of micropearl is possibly produced in a small (7–12 μm size) bi-flagellated organism. Micropearls from Lake Titicaca, which contain Sr, were found in an organism very similar to Tetraselmis cordiformis, which was observed earlier in Lake Geneva. Lake Titicaca micropearls contain larger As amounts, which can be explained by the high As concentration in the water of this lake. The ubiquity of this observed biomineralization process points to the need for a better understanding of the role of amorphous or crystalline calcium carbonates in As cycling in surface waters.

Rare Earth Phosphates in the Kerch Caviar Ironstones

2021 ◽  
Author(s):  
A.V. Nekipelova ◽  
E.V. Sokol ◽  
S.N. Kokh ◽  
P.V. Khvorov
Keyword(s):  
Solid Solution ◽  
Trace Elements ◽  
Rare Earth ◽  
Major And Trace Elements ◽  
Environmental Risks ◽  
Solid Solution Series ◽  
Unconventional Resources ◽  
Total Budget ◽  
Low Costs ◽  
Clay Type

Abstract —The mineralogy and contents of major and trace elements (including REE+Y) in bulk samples and separate size fractions of caviar-like ironstones from the Kamysh-Burun deposit (Kerch iron province) are studied to estimate the contributions of different REE+Y species to the total budget. The analyzed ore samples contain MREE adsorbed on Fe3+-(oxy)hydroxides, as well as LREE authigenic phosphates. The predominant rhabdophane-type (Ce(PO4)⋅nH2O) phases are enriched in La, Pr, Nd, and Ca, depleted in Ce, and free from Th. The REE carriers belong to solid solution series of two main types: LREE(PO4)·nH2O – (Ca,Ce,Th)(PO4)·H2O (rhabdophane-like phase and brockite) or LREE(PO4)·nH2O – (Ca,U,Fe3+)((PO4),(SO4))·2H2O (rhabdophane-like phase and tristramite). REE phosphates occur most often in the ≤ 0.25 mm fractions of ironstones, where average and maximum ΣREE contents (Xav = 606–1954 ppm; Xmax = 769–3011 ppm) are comparable with the respective amounts in the Chinese industrial clay-type REE deposits. The Kerch ores are commercially attractive unconventional resources of highly demanded Pr and Nd: they can be extracted at relatively low costs, due to high Pr/Ce and Nd/Ce ratios, while low Th and U reduce the environmental risks from stockpiled wastes.

scholarly journals Distribution of Arsenic Inclusions in Rare Earth Steel Ingots

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 146 ◽  
Author(s):  
Hongpo Wang ◽  
Silu Jiang ◽  
Peng Yu ◽  
Bin Bai ◽  
Lifeng Sun ◽  
...  
Keyword(s):  
Solid Solution ◽  
Trace Elements ◽  
Rare Earth ◽  
Single Phase ◽  
Arsenic Concentration ◽  
Distribution Characteristic ◽  
Dramatic Decrease ◽  
Full Profile ◽  
Steel Ingots ◽  
Peeling Off

Trace element arsenic is detrimental to the quality and properties of steel products. We used lanthanum to modify the distribution of arsenic by the formation of arsenic rare earth inclusions and investigated all inclusions on the full profile of the ingots prepared in the laboratory. The results show that the addition of lanthanum has dramatically influenced the distribution of arsenic in the ingots by the formation of arsenic inclusions. The arsenic inclusions turn out to be mainly the cluster-shaped La-S-As, as well as its composite inclusions combined with LaS and La-As. La-S-As can be considered a solid solution of LaS and LaAs. They distribute mainly at the top surface of the ingots within 3 mm, at the side and bottom surfaces within 1.5 mm, leading to a dramatic decrease of arsenic concentration at the inner part of the ingots. This distribution characteristic of La-S-As can be used to manufacture steel ingots with very low arsenic concentration by peeling off these (La-S-As)-containing layers. On the contrary, the distribution of composite inclusions (La-S-As)-(La-As) and single-phase La-As, is uniform. Except for the reaction with arsenic, lanthanum can also react with phosphorous and antimony to modify the existing state of these trace elements.

Non-equilibrium solid solution and nanocrystal structure of Fe–Cu alloy after plastic deformation under pressure

1993 ◽  
Vol 68 (6) ◽  
pp. 877-881 ◽  
Author(s):  
V. A. Teplov ◽  
V. P. Pilugin ◽  
V. S. Gaviko ◽  
E. G. Chernyshov
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Cu Alloy ◽  
Non Equilibrium

Nucleation in Solid Solution Stimulated by Non-Equilibrium Electrons. II. Electronic Model

1970 ◽  
Vol 41 (1) ◽  
pp. 395-404 ◽  
Author(s):  
S. Stoyanov ◽  
D. Kashchiev ◽  
M. Geoegiev
Keyword(s):  
Solid Solution ◽  
Electronic Model ◽  
Non Equilibrium

Mercury and Selected Trace Elements from a Remote (Gosainkunda) and an Urban (Phewa) Lake Waters of Nepal

2015 ◽  
Vol 226 (2) ◽  
Author(s):  
Chhatra Mani Sharma ◽  
Shichang Kang ◽  
Mika Sillanpää ◽  
Qing Li ◽  
Qianggong Zhang ◽  
...  
Keyword(s):  
Trace Elements ◽  
Lake Waters

scholarly journals Detecting trends in freshwater trace element concentrations: methodological issues and data treatment

2018 ◽  
Vol 1 (2) ◽  
pp. 87-98 ◽  
Author(s):  
Juan Carlos Rodríguez-Murillo ◽  
Pascale Nirel ◽  
Montserrat Filella
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Statistical Significance ◽  
Temporal Trends ◽  
Monitoring Program ◽  
Data Treatment ◽  
Wide Range ◽  
Lake Waters ◽  
Program Data ◽  
Difficult Issue

Abstract Despite the fact that the increased use of elements linked to the Anthropocene is frequently assumed to lead to an increase in the concentrations of the elements in surface waters, temporal trends of trace element (TE) concentrations have rarely been checked. A temporally extended, traceable dataset of TE concentrations in the waters of Lake Geneva, Switzerland (1996–2015) has been used here to explore methodological and data treatment issues that arise when attempting to rigorously determine temporal trends in freshwater TE concentrations. The trace elements studied (Cd, Co, Gd, Mo, Pb, Sb, Sr) have been chosen to cover a wide range of chemical and utilisation conditions. We show that detecting temporal trends from monitoring program data is feasible, even when trends are weak, provided that rigorous data treatment methods are applied. Aspects related to the effect of data quality are discussed in detail. However, ascertaining the statistical significance of any trends calculated remains a difficult issue. With the exception of Co and Sr, that show no significant changes, and Pb, that shows a general decrease, concentrations in lake waters of the trace elements considered have increased significantly, particularly between 2006 and 2015.

Sign in / Sign up

Export Citation Format

Share Document