Deciphering the Distribution and Crystal-Chemical Environment of Arsenic, Lead, Silica, Phosphorus, Tin, and Zinc in a Porous Ferrihydrite Grain Using Transmission Electron Microscopy and Atom Probe Tomography

Abstract

The interaction of contaminants and nutrients with soil constituents is controlled by processes in intergranular and intragranular pore spaces of organic matter or/and common secondary minerals such as ferrihydrite, ∼Fe3+ 10O14(OH)2. This contribution shows that distribution and clustering of the contaminants As, P, Pb, Si, Sn, and Zn in a porous ferrihydrite grain is greatly affected by the heterogeneous size distribution and chemical composition of the pores as well as the ability of their polyhedra to polymerize with the same type of polyhedron. Transmission electron microscopy (TEM) and atom probe tomography (APT) studies are conducted on focused ion beam (FIB) sections extracted from a porous ferrihydrite grain from the smelter-impacted topsoil in Sudbury, Ontario, Canada. The ferrihydrite grain has pore spaces ranging in diameter from tens to hundreds of nanometers. TEM and scanning-TEM studies indicate that the surfaces of the pore walls are enriched in Si. APT data in conjunction with First Near Neighbor (1NN) analyses indicate different degrees of clustering of Pb, As, Sn, Zn, Si, and P within the sample and selected domains. Careful evaluations of 3D atomic plots and 1NN distances indicates the occurrence of polymerized arsenite-, silica-, Sn-, and Zn-polyhedra within pore spaces of the ferrihydrite. Deciphering adsorption, polymerization, and nucleation processes in porous Fe-(hydr)­oxides and other soil constituents requires multianalytical approaches and, in this regard, we discuss the advantages and disadvantages of the combination of TEM and APT for characterizing complex environmental samples at the atomic to nanometer scale.

Nanoscale characterization of the sequestration and transformation of silver and arsenic in soil organic matter using atom probe tomography and transmission electron microscopy

“…19 It occurs in both inorganic and organic forms such as arsenous acid (H 3 AsO 3 ), arsenic acid (H 3 AsO 4 ), monomethylarsenic acid, dimethylarsenic acid and in solids such as arsenides, arsenites, and arsenates. 19,34 Generally, inorganic As species and arsenite (As 3+ ) are more toxic in comparison with organic species and arsenate species, respectively. 35,36 Various studies addressed the effect of OM on the mobility of As adsorbed on different minerals.…”

Atom probe tomography and transmission electron microscopy: a powerful combination to characterize the speciation and distribution of Cu in organic matter

“…Although Cu-sulfides were deposited at this site via Cu-bearing particular matter (PM) emitted by the local smelter, 30 OM colloids and micrometer-size OM particles did not contain detectable abundances of Cu-sulfides (Fig. 1, Table 1), Schindler et al 31 investigated the occurrence of metal(loid)s in a porous Fe-(hydr)oxide soil grain from smelter-impacted soil in Sudbury, Ontario. The authors showed that the combination of transmission electron microscopy (TEM) and atom probe tomography (APT) allowed (1) textural, chemical and mineralogical features at the nano-scale (TEM) and (II) the clustering of metal(loid)s in pore spaces of the Fe-(hydr)oxide (APT) to be deciphered.…”

Virtual Special Issue of ACS Earth and Space Chemistry in Honor of Prof. Michael F. Hochella, Jr.

“…In addition, the three Hochella Symposium organizers were invited by Prof. Joel Blum, Editor-in-Chief of ACS Earth and Space Chemistry , to organize and serve as Guest Editors of a virtual special issue of this journal in honor of Mike Hochella. A total of 20 peer-reviewed manuscripts were accepted for publication in this virtual special issue (), with topics ranging from mineral/water interface chemistry and mineral/organic matter nanoparticles to organic matter/soil chemistry and microbial geochemistry studies. − These papers highlight the importance of nanogeoscience, mineral/aqueous solution interface chemistry, biogeochemistry, and organic matter/soil chemistry in understanding the Earth system.…”