Spéciation de radionucléides dans les suspensoides du Fleuve St. Laurent

Abstract About forty radionuclides, some naturally occurring, others artificially produced, have been detected in the St. Lawrence River at the heights of Québec City. Speciation studies of the radionuclides present in the suspended matter transported by the river were carried out from samples collected with a swimming pool type sand filter. Speciation was done with the reagents commonly used for similar studies for trace metals in sediments. Four fractions have been characterized; one associated with the carbonates, another with the iron and manganese oxides, the organics and the residue. The distribution of the radionuclides on these different fractions gives useful information on the type of interaction between the radioactive species and the solid phase. For instance, 7Be, 106Ru, 144Ce and 210Pb are weakly retained on the solid phase whereas naturally occurring radionuclides like 228Th, 238U, 226Ra, 40K and 137Cs are strongly retained on it. Airborne 210Pb following the decay of 222Ra in the air is the most likely source for this nuclide since most of it is not supported by 226Ra. In many respects, 210Pb seems to behave like the airborne 7Be.

Download Full-text

Fractionation of Selected Heavy Metals in Agricultural Soils / Frakcjonowanie Wybranych Metali Ciężkich W Glebach Uprawnych

Ecological Chemistry and Engineering S ◽

10.2478/eces-2013-0009 ◽

2013 ◽

Vol 20 (1) ◽

pp. 117-125 ◽

Cited By ~ 2

Author(s):

Szymon Różański

Keyword(s):

Organic Matter ◽

Significant Role ◽

Manganese Oxides ◽

Solid Phase ◽

Extraction Procedure ◽

Total Content ◽

Residual Fraction ◽

Geochemical Background ◽

Fraction Bound ◽

Iron And Manganese

Abstract The content of trace elements in soils varies widely and their mobility and availability depends not only on the total content but also on the form of in which these elements occur. The aim of this study was to determine the total content of nickel, lead, zinc and copper in soils used for agriculture, and assess the mobility and phytoavailability of these metals against a background of physical and chemical properties of these soils. In samples taken from three soil profiles (Phaeozem and 2 Fluvisols) the contents of Ni, Pb, Zn and Cu were determined using atomic absorption spectroscopy in the solutions obtained according to the protocol of modified BCR sequential extraction procedure supplemented with aqua regia digestion. The total content of the analyzed metals in most cases corresponded to the natural values, often not exceeding the geochemical background level. It was only in the one profile of the Fluvisols (Endogleyic Fluvisol) that a higher concentration of zinc and lead was noticed (especially in the surface horizon), slightly exceeding the legal limit. Among the studied metals the lowest phytoavailability was characterized by copper (exchangeable forms on average 4.73% of the total), and the highest by zinc (11.49%). Nickel was the most permanently bound with soil solid phase, and its content in the residual fraction reached 84.46% of the total. Approximately a half of the total lead content was determined as a fraction bound with iron and manganese oxides, while in the case of this metal a significant role in binding of this metal was playing organic matter (fraction bound with organic matter and sulphides - an average of 27.5%). Significant role in the binding of all investigated metals was credited to iron and manganese compounds.

Download Full-text

Trace element speciation in water and bottom sediments of the Pirogov water reservoir

Moscow University Bulletin. Series 4. Geology ◽

10.33623/0579-9406-2020-6-59-68 ◽

2020 ◽

pp. 59-68

Author(s):

O. A. Lipatnikova ◽

T. N. Lubkova ◽

N. A. Korobova

Keyword(s):

Trace Elements ◽

Surface Water ◽

Bottom Sediments ◽

Manganese Oxides ◽

Maximum Permissible Concentration ◽

Solid Phase ◽

Metal Speciation ◽

Water Reservoir ◽

Element Speciation ◽

Iron And Manganese

The composition and speciation of trace elements (Cu, Pb, Zn, Cd, Ni, Co, Mn, Fe, Ba, and Sr) in surface water and bottom sediments of the Pirogov water reservoir have been studied. It was found that the metal content in surface water does not exceed the maximum permissible concentration (MPC) for fishery water reservoir excluded Zn (2–9 MPC) and Cu (up to 2 MPC). According to results of thermodynamic calculations, the predominant metal speciation in water is the free ion (Sr, Ba, Zn, Ni, Co, Cd), fulvate (Cu) and carbonate (Pb) complex. The interstitial water is characterized by an increase in the content of sulfate complex of trace elements in loams, the solid phase of which is also characterized by slightly anomalous contents of Zn, Cd, Co, and Ni. According to data of sequential selective procedure, metals are predominantly immobilized in solid phase of bottom sediments in the crystal structure of silicates or bounded to iron and manganese oxides. Only for Cd and Mn exchangeable and bound to carbonates fractions are characterized by considerable relative contents.

Download Full-text

Natural Radionuclides in the St. Lawrence River

Water Quality Research Journal ◽

10.2166/wqrj.1984.020 ◽

1984 ◽

Vol 19 (2) ◽

pp. 120-128 ◽

Cited By ~ 3

Author(s):

D. Grondin ◽

M.D. Lupien

Keyword(s):

Sampling Method ◽

Natural Radionuclides ◽

Suspended Material ◽

Naturally Occurring ◽

Naturally Occurring Radionuclides ◽

Solid Phases ◽

Liquid And Solid Phases ◽

St Lawrence River

Abstract The alum floc sampling method has proven to be a rapid and efficient means for studying radioactivity in freshwater, allowing the preconcentration of not only soluble nuclides but also those attached to the suspended material in rivers. This paper contains an assessment of the distribution of naturally occurring radionuclides between the liquid and solid phases present in the St. Lawrence River. It also describes the distribution of these natural radionuclides on the various fractions of the suspended material. A radioactivity profile observed at St. Foy, Québec, reveals the contribution of each tributary to the solid and liquid fluxes of the St. Lawrence River.

Download Full-text

Quebec City - St. Lawrence River

10.31096/wua121_box13_tray2box4_nos_120 ◽

2019 ◽

Keyword(s):

Quebec City ◽

St Lawrence River

Download Full-text

Optimization of the selection of analysis methods for the determination of naturally occurring radionuclides

Kerntechnik ◽

10.3139/124.100547 ◽

2008 ◽

Vol 73 (3) ◽

pp. 118-121

Author(s):

T. Heinrich ◽

L. Funke ◽

M. Köhler ◽

U.-K. Schkade ◽

F. Ullrich ◽

...

Keyword(s):

Naturally Occurring ◽

Analysis Methods ◽

Naturally Occurring Radionuclides ◽

Selection Of

Download Full-text

Distribution of Naturally Occurring Radionuclides in Taiwanese Rocks

Radiation Protection Dosimetry ◽

10.1093/rpd/45.1-4.281 ◽

1992 ◽

Vol 45 (1-4) ◽

pp. 281-283 ◽

Cited By ~ 2

Author(s):

T.-C. Chu ◽

P.-S. Weng ◽

Y.-M. Lin

Keyword(s):

Naturally Occurring ◽

Naturally Occurring Radionuclides

Download Full-text

Ultrasound-Assisted Citric Acid Extraction of Zinc in Plateau Red Soil and Tessier Speciation Study

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.726-731.4464 ◽

2013 ◽

Vol 726-731 ◽

pp. 4464-4467

Author(s):

Wei Wei ◽

Xue Jin Zhou ◽

Yun Tao Gao

Keyword(s):

Heavy Metal ◽

Citric Acid ◽

Manganese Oxides ◽

Red Soil ◽

Extraction Rate ◽

Acid Extraction ◽

Speciation Study ◽

Ultrasonic Assisted ◽

Ultrasound Assisted ◽

Iron And Manganese

Taking plateau red soil as research object, using the ultrasonic-assisted organic acid extraction the heavy metal zinc in it, and analyze the form of zinc. Results showed that the extraction rate can reach 68%, with the increase of time, the extraction effect of zinc is obviously enhanced in this method. Ultrasonic-assisted citric acid extraction soil can increase the extraction rate of exchangeable, bound to carbonates and bound to iron and manganese oxides relatively.

Download Full-text

Strategies for EELS Data Analysis. Introducing UMAP and HDBSCAN for Dimensionality Reduction and Clustering

Microscopy and Microanalysis ◽

10.1017/s1431927621013696 ◽

2021 ◽

pp. 1-14

Author(s):

Javier Blanco-Portals ◽

Francesca Peiró ◽

Sònia Estradé

Keyword(s):

Dimensionality Reduction ◽

Clustering Analysis ◽

Manganese Oxides ◽

Spatial Clustering ◽

State Of The Art ◽

Core Loss ◽

Nonnegative Matrix ◽

Case Scenario ◽

Electron Energy Loss ◽

Iron And Manganese

Hierarchical density-based spatial clustering of applications with noise (HDBSCAN) and uniform manifold approximation and projection (UMAP), two new state-of-the-art algorithms for clustering analysis, and dimensionality reduction, respectively, are proposed for the segmentation of core-loss electron energy loss spectroscopy (EELS) spectrum images. The performances of UMAP and HDBSCAN are systematically compared to the other clustering analysis approaches used in EELS in the literature using a known synthetic dataset. Better results are found for these new approaches. Furthermore, UMAP and HDBSCAN are showcased in a real experimental dataset from a core–shell nanoparticle of iron and manganese oxides, as well as the triple combination nonnegative matrix factorization–UMAP–HDBSCAN. The results obtained indicate how the complementary use of different combinations may be beneficial in a real-case scenario to attain a complete picture, as different algorithms highlight different aspects of the dataset studied.

Download Full-text