The influence of rare earth element fertilizer application on the distribution and bioaccumulation of rare earth elements in plants under field conditions

Abstract

This field study describes the distribution and bioaccumulation of rare earth elements (REEs) in wheat, rice and vegetables grown in Jiangxi, Anhui, Beijing and Heilongjiang provinces, located in southern and northern China after application of REE fertilizer at different levels. The results indicate that accumulation of REEs in different parts of plants follows the order: root>leaf>stem>grain. The concentrations of REEs in root, leaf and stem increase remarkably when the REE fertilizers were applied. However, no significant accumulation was observed in cereal grains except for those grown at the Jiangxi site. A significant accumulation of REEs in the edible parts of vegetables was observed, therefore, fertilizers containing REEs are not recommended. The exogenous REEs in the fertilized soil were extracted by a three-stage sequential extraction procedure into three fractions: (1) water soluble, exchangeable and carbonate bound (B1), (2) Fe–Mn oxide bound (B2) and (3) organic matter and sulfide bound (B3). The results demonstrated that all of the exogenous REEs were present in the fractions B1, B2 and B3 with ranges of 1.49–13.91%, 35.23–70.34% and 19.14–60.78% of total, respectively. No exogenous REEs entered the residual form within the field study period. However, the chemical forms of exogenous REEs in the fertilized soil and their bioavailability are dependent on the physicochemical properties of soil and plant species. It seems that REEs present in fraction B1 are more easily available to plants.