Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental Research

During the past decades, agricultural soil heavy metal pollution has been becoming increasingly severe due to urbanization and industrialization. However, the impact of externally input heavy metals on deep soils remains unclear because most previous relevant research only focused on surface soils....

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Main Authors: Zhenwei Bi, Yu Guo, Zhao Wang, Zhaoyu Zhu, Mingkun Li, Tingping Ouyang
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Toxics
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Online Access:https://www.mdpi.com/2305-6304/13/7/548
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author Zhenwei Bi
Yu Guo
Zhao Wang
Zhaoyu Zhu
Mingkun Li
Tingping Ouyang
author_facet Zhenwei Bi
Yu Guo
Zhao Wang
Zhaoyu Zhu
Mingkun Li
Tingping Ouyang
author_sort Zhenwei Bi
collection DOAJ
description During the past decades, agricultural soil heavy metal pollution has been becoming increasingly severe due to urbanization and industrialization. However, the impact of externally input heavy metals on deep soils remains unclear because most previous relevant research only focused on surface soils. In the present study, Concentrations of eight heavy metals (Cu, Zn, Ni, Pb, Cr, Cd, As, and Hg) were determined for 72 pairs of surface and deep soil samples collected from an agricultural region close to the Pearl River estuary. Subsequently, heavy metal pollution and potential health risks were assessed using the Geo-accumulation Index and Potential Ecological Risk Index, a dose response model and Monte Carlo simulation, respectively. Principal component analysis (PCA) and the positive matrix factorization (PMF) receptor model were combined to analyze heavy metal sources. The results indicated that average concentrations of all heavy metals exceeded their corresponding background values. Cd was identified as the main pollutant due to its extremely high values of <i>I<sub>geo</sub></i> and <i>Er</i>. Unacceptable potential heavy metal non-carcinogenic and carcinogenic risks indicated by respectively calculated HI and TCR, higher than thresholds 1.0 and 1.0 × 10<sup>−4</sup>, mainly arose from heavy metals As, Cd, Cr, and Ni through food ingestion and dermal absorption. Anthropogenic sources respectively contributed 19.7% and 38.9% for soil As and accounted for the main contributions to Cd, Cu, and Hg (Surface: 90.2%, 65.4%, 67.3%; Deep: 53.8%, 54.6%, 56.2%) within surface and deep layers. These results indicate that soil heavy metal contents with deep layers were also significantly influenced by anthropogenic input. Therefore, we suggest that both surface and deep soils should be investigated simultaneously to gain relatively accurate results for soil heavy metal pollution and source apportionments.
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publishDate 2025-06-01
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series Toxics
spelling doaj-art-dd4efb1d2baf4903804662f36ca3565e2025-08-20T03:56:49ZengMDPI AGToxics2305-63042025-06-0113754810.3390/toxics13070548Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental ResearchZhenwei Bi0Yu Guo1Zhao Wang2Zhaoyu Zhu3Mingkun Li4Tingping Ouyang5School of Geography, South China Normal University, 55 Zhongshan Road West, Guangzhou 510631, ChinaGeological Survey of Guangzhou, Guangzhou 510440, ChinaGeological Survey of Guangzhou, Guangzhou 510440, ChinaGuangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, ChinaSchool of Geography, South China Normal University, 55 Zhongshan Road West, Guangzhou 510631, ChinaSchool of Geography, South China Normal University, 55 Zhongshan Road West, Guangzhou 510631, ChinaDuring the past decades, agricultural soil heavy metal pollution has been becoming increasingly severe due to urbanization and industrialization. However, the impact of externally input heavy metals on deep soils remains unclear because most previous relevant research only focused on surface soils. In the present study, Concentrations of eight heavy metals (Cu, Zn, Ni, Pb, Cr, Cd, As, and Hg) were determined for 72 pairs of surface and deep soil samples collected from an agricultural region close to the Pearl River estuary. Subsequently, heavy metal pollution and potential health risks were assessed using the Geo-accumulation Index and Potential Ecological Risk Index, a dose response model and Monte Carlo simulation, respectively. Principal component analysis (PCA) and the positive matrix factorization (PMF) receptor model were combined to analyze heavy metal sources. The results indicated that average concentrations of all heavy metals exceeded their corresponding background values. Cd was identified as the main pollutant due to its extremely high values of <i>I<sub>geo</sub></i> and <i>Er</i>. Unacceptable potential heavy metal non-carcinogenic and carcinogenic risks indicated by respectively calculated HI and TCR, higher than thresholds 1.0 and 1.0 × 10<sup>−4</sup>, mainly arose from heavy metals As, Cd, Cr, and Ni through food ingestion and dermal absorption. Anthropogenic sources respectively contributed 19.7% and 38.9% for soil As and accounted for the main contributions to Cd, Cu, and Hg (Surface: 90.2%, 65.4%, 67.3%; Deep: 53.8%, 54.6%, 56.2%) within surface and deep layers. These results indicate that soil heavy metal contents with deep layers were also significantly influenced by anthropogenic input. Therefore, we suggest that both surface and deep soils should be investigated simultaneously to gain relatively accurate results for soil heavy metal pollution and source apportionments.https://www.mdpi.com/2305-6304/13/7/548heavy metal pollutionhealth risk assessmentsource analysissurface soildeep soilagricultural area
spellingShingle Zhenwei Bi
Yu Guo
Zhao Wang
Zhaoyu Zhu
Mingkun Li
Tingping Ouyang
Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental Research
Toxics
heavy metal pollution
health risk assessment
source analysis
surface soil
deep soil
agricultural area
title Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental Research
title_full Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental Research
title_fullStr Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental Research
title_full_unstemmed Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental Research
title_short Comparison of Heavy Metal Pollution, Health Risk, and Sources Between Surface and Deep Layers for an Agricultural Region Within the Pearl River Delta: Implications for Soil Environmental Research
title_sort comparison of heavy metal pollution health risk and sources between surface and deep layers for an agricultural region within the pearl river delta implications for soil environmental research
topic heavy metal pollution
health risk assessment
source analysis
surface soil
deep soil
agricultural area
url https://www.mdpi.com/2305-6304/13/7/548
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