Speciation of rare earth elements in soil and accumulation by wheat with rare earth fertilizer application

Abstract

apsule'': Rare earth elements increased wheat yields and accumulated in plants in relation to concentrations in fertilizers. AbstractA greenhouse study was conducted to investigate the accumulation of rare earth elements (REEs), La, Ce, Pr and Nd, in winter wheat (Triticum aestivum L.), and the speciation of these elements in soil following the application of REE-based fertilizers. Improved crop yield was con®rmed by the experiment. The accumulation behavior of La, Ce, Pr and Nd in wheat varied depending on the concentration of REE fertilizer application, i.e. increased with increasing REE concentration at low fertilization application, constant over the medium REE range, and decreased with increasing REE concentration at high fertilizer application. Signi®cant negative correlation was obtained between REE contents in roots and soil pH (r=À0.5787 to À0.8442 for La). REEs in both the fertilized and unfertilized soils were fractionated by a three-stage sequential extraction procedure into three chemically distinct fractions: water soluble, exchangeable and carbonate bound (B1), Fe±Mn oxide bound (B2), and organic and sul®de bound (B3). REEs in fertilized soils were found mainly in the B2 and B3 fractions, with only a small amount in the B1 fraction. REEs in B1 and B2 fractions were negatively correlated with soil pH (r=À0.6892 to À0.8927 and À0.7462 to À0.9482). Signi®cant correlation was obtained between REEs in B1 fraction and REE contents in root. The correlation coecients ranged from 0.6159 to 0.7410 when fertilizer application was lower than 20.0 mg/kg soil. No acceptable relationship was observed between REE contents in shoot and any of the extractable fractions in soils. #

Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils

“…It also can be seen from Table 6 that the concentrations in fraction B1 have significant correlation with the root uptake. This is in good accordance with our previous findings (Li et al, 1998;Zhang and Shan, 2001). The reason for different correlationship between the shoots and roots and soil fractions may be due to the short culture period of plant.…”

Geochemistry of rare earth elements in soils under different land uses in a typical karst area, Guizhou Province, Southwest China

“…Because yttrium exhibits similar properties to the lanthanide family, it is also considered as one of this group of elements (Liu and Byrne, 1995;Tyler, 2004). Recently, the usage of REE has been increasing rapidly in industrial and agricultural applications (Wang and Liang, 2015;Zhang and Shan, 2001). Therefore, the biogeochemical cycles of REE and their ecological and environmental effects are greatly concerned by many researchers (Liu et al, 2016;Martin-Garcia et al, 2016).…”

“…Agricultural activity is one of the most important human inputs of potentially hazardous REE in this area. Since agricultural soil has both direct and indirect influences on public health via food production, it is of great importance to have a decent understanding of the accumulation and the spatial variability of REE in soils (Nakamaru et al, 2006;Wang et al, 2015;Zhang and Shan, 2001). …”

Effect of earthworms (Eisenia fetida) on the fractionation and bioavailability of rare earth elements in nine Chinese soils

“…Many efforts have been made to understand the chemical behavior and bioavailability of REEs in the environment (Wyttenbach et al, 1998;Li et al, 1998;Zhang and Shan, 2001;Lu et al, 2003). It is well established that the physico-chemical properties of soils are the main factors controlling the mobility, transformation, and bioavailability of REEs in soils .…”