Rare earth elements in environment and effects on plants: A review scientific paper

Abstract

Rare earth elements (REEs) are widely distributed in low concentrations in all parts of the biosphere. REEs are not at all rare, their concentration in the earth?s crust is close to 0.015%. REEs include the elements scandium, yttrium and the lanthanides from lanthanum to lutetium. REEs show similar physical and chemical properties. Today REEs are applied in industries and technologies, in agriculture as microfertilizers and feed additives and they are also used in medicine. REEs are dispersed especially as accessory minerals in pegmatites, granites and associated metamorphic volcanic rocks. Out of more than 250 kinds of minerals containing REEs, only bastnaesite and monazite are of economic importance. Their concentration in the soil varies widely and depends on their presence in parental materials, soil texture, organic matter content, pedogenetic processes and anthropogenic activities. REEs are found in small concentrations in surface stagnant and flowing waters as well as in underground waters. They are found in water in both suspended and dissolved form. REEs enter the atmosphere from various sources, largely owing to human activities. The majority of REEs in the atmosphere are carried by microscopic particles. The uptake and consequently accumulation of REEs in plants are affected by numerous biotic factors, such as plant species and genotype, and abiotic factors such as their concentration in the soil and some chemical and physical soil characteristics. They can enter plants via both root and foliage tissues. There are plant species called hyperaccumulators that are able to accumulate significant amounts of REEs without adverse consequences. RREs are not biogenic for higher plants or for other living organisms, but can influence their life processes. Experi?ments show that REEs can be beneficial for growth, yield and biochemical composition of cultivated plants. They can also alleviate some ecological stress in plants. It is not clear enough how they affect human and animal health. The wide-spread application of REEs in different industries as well as in agriculture lead to a constant increase of the concentrations of these elements in the environment. Therefore, studies on the uptake, accumulation, dis?tribution of REEs in cultivated plant species and their entrance into the food chain as well as their stimulating or toxic effect on living organisms, can be very significant in the future.