Distribution of Cd and Cu Fractions in Chinese Soils and Their Relationships with Soil pH: A Meta-Analysis

Yinzhong Ning,Yajing Wang,Jingheng Guo,Binzhe Li,Xinmu Zhang

doi:10.3390/su11020337

Yinzhong Ning, Yajing Wang + Show 3 more

Open Access

https://doi.org/10.3390/su11020337

Copy DOI

Abstract

Soil contamination by potentially toxic metals (PTMs) has become a public concern in China. However, the distribution and controlling factors of soil PTM fractions remain largely unknown, limiting our ability to assess their health risks and thus to make sound controlling polices. Here, we investigate the fraction distribution of cadmium (Cd) and copper (Cu) in Chinese soils and their relationships with soil pH, based on a national meta-analysis of 163 published literatures. Exchangeable Cd in southern China accounted for 19.50 ± 14.97% of total Cd, significantly (p < 0.01) higher than the corresponding 13.42 ± 6.95% in northern China. Potentially available fractions constituted about 60% of total Cd at the national scale. By contrast, about half of soil Cu existed in unavailable residual fraction. Phytoavailable (i.e., exchangeable) fraction accounted for only 2.71 ± 1.65% and 2.54 ± 1.58% of total Cu in northern and southern China, respectively. Percentages of exchangeable Cd and Cu were negatively correlated (p < 0.01) with soil pH, while potentially available fractions increased significantly (p < 0.05) with soil pH. Our results provide the first national assessment of Cd and Cu fraction distribution and their responses to soil pH variations, highlighting the necessity to consider their fraction distribution and soil properties when assessing the health risks of soil PTM contamination in China.

Highlights

Soil contamination by potentially toxic metals (PTMs) has drawn much attention in China during the past decades [1,2,3], since they may endanger human health through the transfer from soil to food [4,5,6,7]
Preliminary estimates showed that 10–17% of Chinese croplands were polluted with PTM concentrations exceeding the Class II limits in China’s soil environmental quality standard, and 13.8% of the cereals were contaminated by PTMs [3,10]
The current status based on total concentration is still in an acceptable level, continuous pollutant loadings will increase soil PTM contamination in China [2,6]

Summary

Introduction

Soil contamination by potentially toxic metals (PTMs) has drawn much attention in China during the past decades [1,2,3], since they may endanger human health through the transfer from soil to food [4,5,6,7]. PTM fraction distribution and their relationships between soil pH remain unknown at the national scale Such inadequacies constituted a knowledge gap between their total concentration and potential health risk, and hinder our ability to evaluate the influence of soil acidification on crop PTM contamination. We investigate the fraction distributions of Cd and Cu in Chinese soils and their relationships with soil pH, based on a national meta-analysis

Data Compiliation

Influence of Soil pH on the Fraction Distribution of PTMs

Findings

Conclusions