Occurrence, accumulation, and risk assessment of trace metals in tea (Camellia sinensis): A national reconnaissance

Accumulation of potentially toxic elements in soil and tea leaves is a particular concern for tea consumers worldwide. However, the contents of potentially toxic elements and their potential health and ecological risks in Chinese tea gardens have rarely been investigated on the national scale. In this study, we collected 225 paired soil and tea plant samples from 45 tea gardens in 15 provinces of China to survey the current risk of potentially toxic element accumulation in Chinese tea gardens. The results suggest that the average contents of most trace metals in rhizosphere soils meet the risk control standard for agricultural land in China. However, the mean contents of As, Cr, Cd, Zn, Cu, and Ni in rhizosphere soils were 1.94, 2.14, 1.23, 1.15, 1.18, and 1.19 times their corresponding background soil values in China. Cd had the highest geo-accumulation index, followed by As, Zn, Cr, Ni, Cu, Pb, and Mn in rhizosphere soils. Nearly 2.22% and 4.44% of soils were moderately to heavily contaminated with As and Cd, respectively. The risk index ranged from 18.0 to 292, with an average value of 90.0, indicating low to moderate ecological risk in Chinese tea gardens. This is the first national-scale reconnaissance of trace metals in tea across China. Our findings provide a useful reference for ensuring the quality and safety of tea production and mitigating the risk of toxic element accumulation in tea. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study investigated the accumulation of potentially toxic elements in Chinese tea gardens and found that while most trace metals in rhizosphere soils meet the risk control standard for agricultural land in China, some elements still exceed the standard, particularly Cd and As.