Lanthanide Soil Chemistry and Its Importance in Understanding Soil Pathways: Mobility, Plant Uptake, and Soil Health

Abstract

The lanthanide elements or rare earth elements (REEs) are an active soil science research area, given their usage as micro-fertilizers, documented cases of environmental impact attributed to industry/mining, and their ability to identify lithologic discontinuities and reveal active soil processes. To fully understand REEs requires an understanding of their chemical reactivity, both for the individual elements and their behavior as a group of elements. The elements of the lanthanide series, including La and Y, may have subtle to very perceptible chemical differences that when viewed collectively reveal information that gives emphasis to soil processes that clarify soil behavior or soil genesis. This chapter concentrates on lanthanide soil chemistry and shows how the soil chemistry of REEs may support soil science investigations. Lee [2], Henderson [3].CN6 is coordination number six and CN8 is coordination number eight. Table 1. Chemical properties of the trivalent rare earth elements, including La and Y. Lanthanides 50(nodules of Fe-and Mn-oxyhydroxides) and an abrupt increase in pH from an acidic to alkaline regime. Thus, oxidation-reduction and pH appear to be the controlling variables. Future research needsFuture research needs include; (i) understanding of the REE-microbiological interactions, especially in the rhizosphere, (ii) are the REE elements plant essential elements or growth promoting entities, (iii) more complex models (along with thermodynamic data) to better simulate the soil environment, and (iv) anticipate REE impacts to the soil environment because of increasing industrial REE utilization.

Tropical Soil Toposequence Characterization via pXRF Spectrometry

“…Conversely, in all the soils Y and Sr presented lower contents than the parent material. However, the ratios of Sr in soil vs. parent material and Y in soil vs. parent material were similar among the profiles, indicating somewhat stable forms of Sr‐ and Y‐bearing minerals in such soils (Capo et al, 1998; Aide, 2018).…”

“…Among all the trace elements, only Y and Sr did not present a statistical difference between the horizons of the studied soils. Sr is considered somewhat stable in soils and has been used to trace soil genesis (Capo et al, 1998), while Y may replace Zr in the zircon mineral, which is very resistant to weathering (Aide, 2018). Conversely, for Cu, differences between the contents in quartzite and in soil in the Typic Ustorthent were found, where the greatest content was observed in the A horizon.…”

Biological Function of Lanthanide in Plant-Symbiotic Bacteria: Lanthanide-Dependent Methanol Oxidation System

“…The Ln species have unique chemical and physical properties that set them apart from other elements, and they show relatively similar features each other. For example, each Ln has the similar ionic radius, although the ionic radius of the Ln decreases with increasing atomic number (Aide, 2019). This is called as "Ln Contraction".…”

“…The Ln is also defined as elements having partially to filled 4f orbital ground state electronic configurations, resulting from having three electrons removed from their d, s and f orbitals (Aide, 2019). The Ln species exhibit considerable ionic bonding character, and act as Lewis acids in the Ln +3 state (Lee, 1992;Aide, 2019). On the other hand, each Ln species also have subtle and distinct differences in electronic properties, i.e., magnetic, electrical or optical properties.…”

“…Ln species are also abundantly distributed in field soils and plants. In the soil, concentrations of Ln species having relatively smaller atomic weight, namely La 3+ , Ce 3+ , Pr 3+ , and Nd 3+ , are generally greater than those of the heavier Ln species (Aide, 2019). In this review, we defined these four elements as light-Ln (L-Ln), and among L-Ln species, Ce 3+ is the most abundant in the soil, with a concentration of over 60 mg/kg of soil (Aide, 2019).…”