Release of Heavy Metals and Metalloids from Two Contaminated Soils to Surface Runoff in Southern China: A Simulated-Rainfall Experiment

Wei Wei,Zhang Zhang,Routh Routh,Tang Tang,Liu Liu,Luo Luo,Li Li

doi:10.3390/w11071339

Abstract

The release of heavy metals and metalloids (HMs), including Pb, Zn, Cd, As, and Cu, from two typical contaminated soils with different properties, namely red soil and limestone-dominated soil, was characterized through simulated-rainfall experiments in order to investigate the effects of soil properties on HM release. Significant differences in the HM concentrations between the two soils resulted in various concentrations of dissolved and particulate HMs in the runoff. Differences in the dissolved HM concentrations in the runoff were inconsistent with the HM concentrations in the soils, which is attributed to the variable solubilities of HMs in the two soils. However, the HM enrichment ratios were not significantly different. The strong correlation between dissolved organic carbon and dissolved HMs in the runoff, and between the total organic carbon and particulate HMs in sediments, were observed, especially in the limestone-dominated soil. The speciﬁc surface area and HM concentrations in sediments were weakly correlated. Acid-rainfall experiments showed that only the limestone-dominated soil buffered the effects of acid rain on the runoff; the concentrations of dissolved Pb, Zn, Cd, and Cu increased in the red soil under acid rainfall and were 60, 29, 25, and 19 times higher, respectively, than under the neutral conditions. The results contribute to the understanding of HM behavior in the two typical soils in southern China, exposed to frequent storms that are often dominated by acid rainfall.

Highlights

Anthropogenic activities often result in the contamination of heavy metals and metalloids (HM) in soils [1]
Using indoor simulated-rainfall experiments, the present study investigated the release of multiple HMs from two soil samples with different properties contaminated by the mining activities
The release of HMs from two soil types with different chemical properties under simulated-rainfall was investigated in this study

Summary

Introduction

Anthropogenic activities (e.g., application of fertilizers, mining, and ore processing) often result in the contamination of heavy metals and metalloids (HM) in soils [1]. HMs are released and transported from the upland contaminated soil to riverine systems, resulting in deterioration of water quality, which is a major environmental problem worldwide [2,3]. Understanding the rainfall-derived release of HMs from the topsoil and its subsequent mobilization and transport are essential for the sustainable management of contaminated areas, and important for the conservation of the surrounding water resources and ecosystems. Heavy metals and metalloid transport in water is conventionally classified into dissolved-HM and particulate-HM transport. Dissolved HM species are generally limited compared with particulate

Objectives

Discussion

Conclusion