Chemical speciation and bioavailability of rare earth elements (REEs) in the ecosystem: a review

Abstract

Rare earths (RE), chemically uniform group of elements due to similar physicochemical behavior, are termed as lanthanides. Natural occurrence depends on the geological circumstances and has been of long interest for geologist as tools for further scientific research into the region of ores, rocks, and oceanic water. The review paper mainly focuses to provide scientific literature about rare earth elements (REEs) with potential environmental and health effects in understanding the research. This is the initial review of RE speciation and bioavailability with current initiative toward development needs and research perceptive. In this paper, we have also discussed mineralogy, extraction, geochemistry, analytical methods of rare earth elements. In this study, REEs with their transformation and vertical distribution in different environments such as fresh and seawater, sediments, soil, weathering, transport, and solubility have been reported with most recent literature along key methods of findings. Speciation and bioavailability have been discussed in detail with special emphasis on soil, plant, and aquatic ecosystems and their impacts on the environment. This review shows that REE gained more importance in last few years due to their detrimental effects on living organisms, so their speciation, bioavailability, and composition are much more important to evaluate their health risks and are discussed thoroughly as well.

Underutilized biogeochemical tracers distinguish invertebrate populations in a complex river system

“…For example, Dy, Er, and Nd concentrations in sediment were significantly different between sediment from each catchment, but concentrations were low and consistent between shrimp populations. Ce, La, and Sm are “light” REE and are considered more mobile than the other heavier lanthanides in this study (Khan et al ). Differences in atomic weight may affect both the bioavailability and integration of different REE into tissue (Yang et al ; Bosco‐Santos et al ; Khan et al ).…”

“…Ce, La, and Sm are “light” REE and are considered more mobile than the other heavier lanthanides in this study (Khan et al ). Differences in atomic weight may affect both the bioavailability and integration of different REE into tissue (Yang et al ; Bosco‐Santos et al ; Khan et al ). However, Y is typically considered a heavy REE (Zepf ), thus other factors likely effect REE uptake.…”

“…Ce, Sm, and La are REE, and although Y is not a REE, it is commonly grouped as such given it has similar chemical properties and is typically found in lanthanide containing minerals (Connelly ; Migaszewski and Gałuszka ). REEs have low solubility, therefore sediment and fine suspended particles are the primary sinks or reservoirs for REE in aquatic environments (Khan et al ). These properties, in combination with their predictable and consistent cycling patterns, mean REE are excellent geochemical tracers and are regularly used to identify sources of eroded sediment (Zhang et al , Stevens and Quinton ).…”

Mineral-leaching chemical transport with runoff and sediment from severely eroded rare-earth tailings in southern China

“…The term "rare-earth element" (REE) refers to 17 elements containing lanthanide series along with scandium and yttrium (Khan et al, 2016). China is the dominant rare-earth element provider and accounts for over 95 % of the world production (Tse, 2011).…”

“…As a large quantity of ammonium sulfate and ammonium bicarbonate were added in the production process, NH + 4 and SO 2− 4 still remain in the REE mining region. It is estimated that the process has generated about 20-25 000 t of wastewater and 300-500 mg L −1 total ammonia nitrogen concentration up until 2005 (Khan et al, 2016). NH + 4 tends to adsorb onto soil, and excess NH + 4 would accelerate soil acidification, reduce soil mineral element content, change soil solution ion composition, and aggravate the soil contamination (Zhou et al, 2014).…”