Rare Earth Elements in the Soil Environment

Abstract

Rare earth elements (REE) are a homogenous group of 17 chemical elements in the periodic table that are key to many modern industries including chemicals, consumer electronics, clean energy, transportation, health care, aviation, and defense. Moreover, in recent years, they have been used in agriculture. One of the consequences of their worldwide use is the possible increase of their levels in various environmental compartments. This review addresses major topics concerning the study of REE in the soil environment, with special attention to the latest research findings. The main sources of REE to soils, the contents of REE in soils worldwide, and relevant information on the effects of REE to plants were explored. Ecological and human health risk issues related to the presence of REE in soils were also discussed. Although several findings reported positive effects of REE on plant growth, many questions about their biological role remain unanswered. Therefore, studies concerning the actual mechanism of action of these elements on cellular and physiological processes should be further refined. Even more urgent is to unveil their chemical behavior in soils and the ecological and human health risks that might be associated with the widespread use of REE in our modern society.

Rare earth elements concentration in mushroom cultivation substrates affects the production process and fruit‐bodies content of Pleurotus ostreatus and Cyclocybe cylindracea

“…In those particular studies, measurements of REEs were performed on P. ostreatus and C. cylindracea mushrooms derived from substrates consisting of wheat‐straw and sawdust from Poland and China respectively. Especially as regards China, i.e, the country with the largest REE reserves and the biggest producer in the world, REEs are used to enrich fertilizers, which are then widely applied in agriculture in continuously increasing amounts . This expanding use of REEs in various fields of human activity could progressively affect their occurrence in living organisms with unknown long‐term repercussions.…”

“…Especially as regards China, i.e, the country with the largest REE reserves and the biggest producer in the world, REEs are used to enrich fertilizers, which are then widely applied in agriculture in continuously increasing amounts. 38 This expanding use of REEs in various fields of human activity could progressively affect their occurrence in living organisms with unknown long-term repercussions. On the other hand, it is noteworthy that REE concentration values found in C. cylindracea and P. ostreatus mushrooms (in this study) are quite similar to those previously reported from measurements on wild mushrooms, [12][13][14]39 and differ only when compared to samples collected alongside a heavily trafficked road in Poland (where much higher values were observed for most elements).…”

Cerium negatively impacts the nutritional status in rapeseed

“…Cerium and other rare earths (REs) have the potential to accumulate progressively in soil due to their increased use in a variety of modern industries and in the last 30 years their wide use as fertilizers in Chinese agriculture (Hu et al, 2004;Tyler, 2004;El-Ramady, 2010;Emsley, 2011;Ramos et al, 2016). Due to elevated concentrations of REs in phosphate fertilizers, Ce can accumulate in agricultural soils outside China too (Kanazawa and Kamitani, 2006;Ramos et al, 2016). For example, it has been estimated that in Brazilian soils 12,000 t of Ce were added through phosphate fertilizers in 2014 (Ramos et al, 2016).…”

“…Due to elevated concentrations of REs in phosphate fertilizers, Ce can accumulate in agricultural soils outside China too (Kanazawa and Kamitani, 2006;Ramos et al, 2016). For example, it has been estimated that in Brazilian soils 12,000 t of Ce were added through phosphate fertilizers in 2014 (Ramos et al, 2016). However, the increase of REs in soil is usually small and large amounts are easily washed away Science of the Total Environment 593-594 (2017) [735][736][737][738][739][740][741][742][743][744] from upper soil horizons through rain of watering (Tyler, 2004).…”

Analysis of water leached from soil treated with leachate from plant biomass ash

“…The presence of nutrients in ash has the potential to fertilize and to correct soil acidity (Melese et al, 2015). In this context, studies are needed to understand the composition of the ash, and to determine the proper quantities and the effects of ash applied to the soil, subsoil, plants, feasibility of use (Ramos et al, 2016), and effects on water in the subsoil. On the other hand, indiscriminate or excessive use of the ash may cause problems (Quirantes et al, 2016).…”