Key Takeaways & Executive Findings
- •• • Regional soil pollution is mild (Nemerow Index Pn=1.65) with low ecological risk (RI=121.17), but construction land shows moderate pollution (Pn=2.37) and medium risk (RI=190.78), indicating a need for targeted remediation in urban-industrial zones. • • PMF source apportionment identified four sources: natural pedogenic (43.54%), metallogenic (19.88%), agricultural-transportation (24.79%), and industrial (11.93%), with natural sources dominating (63.42%), yet anthropogenic sources drive As, Pb, and Hg accumulation, necessitating source-specific controls. • • Cd and Hg are the primary ecological risk factors, with Hg enrichment in construction land from industrial sources posing high risk, underscoring the urgency of regulating industrial emissions and land use planning. • • As concentrations are generally below background levels, indicating no pollution, while Pb exceeds standards but has low ecological risk, highlighting the importance of distinguishing risk levels for effective management.
Abstract
Land use types profoundly influence the accumulation, speciation, and ecological risk of heavy metals through differences in human activity intensity, pollution input pathways, and soil self-regulation capacity. This study investigated soils of different land use types in Longhua County, downstream of the Yixun River Basin, central Chengde City, Hebei Province. Using the Nemerow Index and Potential Ecological Risk Index, the overall regional pollution was mild (Pn=1.65) with low ecological risk (RI=121.17). Main pollutants were Cd, Pb, Zn, and Hg, with Cd and Hg as primary ecological risk factors. Construction land exhibited moderate pollution and medium risk, with a Nemerow Index of 2.37 and average RI of 190.78, significantly exceeding other land use types. PMF model identified four pollution sources: pedogenic parent material natural source (43.54% contribution) dominating Cr, Cu, Ni, Zn enrichment; metallogenic parent material natural source (19.88%) controlling Cd spatial differentiation; agricultural-transportation mixed source (24.79%) driving As and Pb accumulation; and industrial source (11.93%) causing local Hg enrichment. Natural sources contributed 63.42% of total heavy metals, being the primary contributor. As was generally below background values, not constituting pollution; Pb exceeded standards but posed low ecological risk; industrial Hg enrichment in construction land presented high pollution and ecological risk, requiring priority control.
1. Introduction
Industrial and agricultural activities have led to widespread soil heavy metal contamination, posing significant risks to ecosystems and human health. However, the extent and sources of contamination vary markedly across land use types due to differences in anthropogenic inputs and soil properties. Conventional assessment methods often overlook these variations, leading to inefficient remediation strategies. The Yixun River Basin, a typical mineral resource area in Hebei Province, faces complex contamination from natural weathering and mining, yet systematic studies on land-use-specific pollution are lacking.
This research addresses the gap by conducting a comprehensive assessment of heavy metal pollution in soils under different land use types in the Yixun River Basin. Employing the Nemerow Index, Potential Ecological Risk Index, and Positive Matrix Factorization (PMF) model, the study quantifies pollution levels and apportions sources. The findings reveal that construction land is a hotspot of moderate pollution and medium ecological risk, primarily driven by industrial Hg inputs. This work provides a scientific basis for differentiated land management and targeted pollution control, which is critical for sustainable development in mineral-rich regions.
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CAO Wenjia, WEI Xiaofeng, XUE Boqiang, CHEN Ziran, XUE Leilei, JIANG Ying, LIU Yang (2026). Assessment and Source Analysis of Soil Heavy Metal Pollution under Different Land Use Types in the Yixun River Basin. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2025031905
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Frequently Asked Questions
What are the dominant heavy metal pollutants and their ecological risk levels in the Yixun River Basin?
The dominant pollutants are Cd, Pb, Zn, and Hg. The overall ecological risk is low (RI=121.17), but Cd and Hg are the primary risk factors. Construction land shows moderate pollution (Pn=2.37) and medium risk (RI=190.78), significantly higher than other land uses.
How does the PMF model apportion heavy metal sources, and what are their contributions?
PMF identified four sources: natural pedogenic (43.54%), metallogenic (19.88%), agricultural-transportation (24.79%), and industrial (11.93%). Natural sources dominate (63.42%), but anthropogenic sources significantly influence As, Pb, and Hg.
Which land use type poses the highest pollution risk, and what are the implications for management?
Construction land exhibits the highest pollution and risk (Pn=2.37, RI=190.78), primarily due to industrial Hg enrichment. This necessitates strict emission controls and soil remediation in industrial and urban areas.
Are there any heavy metals that do not pose a significant risk despite exceeding background levels?
Yes, As concentrations are generally below background, indicating no pollution. Pb exceeds standards but has low ecological risk, suggesting that risk assessment should consider both concentration and bioavailability.
What is the contribution of natural sources to heavy metal pollution, and why is it important?
Natural sources contribute 63.42% of total heavy metals, primarily from pedogenic and metallogenic processes. This high baseline is crucial for establishing background levels and distinguishing anthropogenic impacts, guiding regulatory thresholds.
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