Anthropogenic Rare Earth Elements: Gadolinium in a Small Catchment in Guizhou Province, Southwest China.

Jue Zhang,Zhuhong Wang,Huipeng Jia,Qixin Wu,Yuanyi Shen,Yanling An

doi:10.3390/ijerph16204052

Abstract

Rare earth elements (REEs), known as “industrial vitamins”, are widely used in medical treatment, industry, agriculture, etc. However, with the increasing demand for REEs, excess REEs, such as gadolinium (Gd), are considered micropollutants in the environment. In this paper, the distributions of dissolved REEs were analyzed in three small streams, in order to determine the extent and occurrence of Gd anomalies. The shale-normalized REE patterns in the three streams were less smooth with heavy REEs higher than light REEs, for a weak reaction of the heavy REE complexes. A negative Ce (cerium) anomaly and positive samarium (Sm) and europium (Eu) anomalies were observed in the three streams and the negative Ce anomaly was affected by the pH of the alkaline rivers. However, a positive Gd anomaly was found in only a typical urban small stream, Jinzhong. With a population of approximately 60,000, Jinzhong runs by a hospital and through wastewater treatment plants (WWTPs). The concentrations of Gd in Jinzhong ranged from 1.54 to 86.65 ng/L with high anthropogenic Gd proportions (63.64%–98.07%). Anthropogenic Gd showed significant seasonal variations and distinct spatial disparities from upstream to downstream, and it was associated with certain ions such as Cl−. Anthropogenic Gd could be attributed to gadopentetic acid (Gd-DTPA), which is used in magnetic resonance imaging (MRI) in hospitals. This type of Gd was shown to be correlated with municipal wastewater. Due to the high stability and low particulate reactivity in water, anthropogenic Gd has great potential to serve as a tracer to prove the presence of medical wastewater.

Highlights

Consisting of 16 critical elements, rare earth elements (REEs) could be divided into three groups:(1) Light rare earth elements (LREE, from lanthanum to neodymium); (2) Middle rare earth elements (MREE, from praseodymium to holmium); (3) Heavy rare earth elements (HREE, from erbium to lutetium, including yttrium)
With the high- concentration of Gd in Jinzhong, the ΣREE were less than 150 ng/L
Dissolved REEs leached from the labile REE-bearing minerals inherit the REE characteristics from the rocks [36]

Summary

Introduction

Consisting of 16 critical elements, rare earth elements (REEs) could be divided into three groups:(1) Light rare earth elements (LREE, from lanthanum to neodymium); (2) Middle rare earth elements (MREE, from praseodymium to holmium); (3) Heavy rare earth elements (HREE, from erbium to lutetium, including yttrium). Consisting of 16 critical elements, rare earth elements (REEs) could be divided into three groups:. As good tracers in rivers, REEs in a dissolved load play a significant role in sediments sources [1], groundwater mixing [2], and some geochemical processes in water systems [3,4]. With unique physical and chemical properties, REEs are widely applied in industry and agriculture (e.g., cell phones, glass additives, catalytic converters, fiber optics, rechargeable batteries, electric cars, and fertilizers) [5,6,7]. With the explosive demand for REEs, the enrichment of REEs in the environment and their possible health risks to humans have resulted in substantial concerns [8,9,10]. Public Health 2019, 16, 4052; doi:10.3390/ijerph16204052 www.mdpi.com/journal/ijerph

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