Identifying quantitative sources and spatial distributions of potentially toxic elements in soils by using three...

Area of Science:

• Environmental Science
• Geochemistry
• Soil Science

Background:

• Potentially toxic elements (PTEs) in soil pose risks to ecosystems and human health.
• Identifying the sources and spatial distribution of PTEs is crucial for effective soil management and remediation strategies.

Purpose of the Study:

• To determine the reliable source contributions and spatial distribution of ten PTEs (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn).
• To delineate hazardous areas for PTEs and assess the influence of parent material versus anthropogenic activities.

Main Methods:

• Employed three receptor models: US-EPA positive matrix factorization (EPAPMF), weighted alternating least squares positive matrix factorization (WALSPMF), and non-negative constrained absolutely principle analysis (NCAPCA).
• Combined receptor models for ensemble-average source contributions.
• Utilized sequential indicator simulation (SIS) and uncertainty analysis for spatial distribution and hazardous area delineation.

Main Results:

• Natural sources accounted for over 85.72% of As, Co, Cr, Cu, Mn, and Ni.
• Cadmium (Cd), Mercury (Hg), Lead (Pb), and Zinc (Zn) showed contributions from both parent material and anthropogenic sources.
• Human inputs (agriculture, industry, vehicle emissions) significantly contributed to Cd (28.04%), Hg (20.74%), Pb (43.49%), and Zn (23.71%).
• Parent materials primarily controlled the spatial distribution of most PTEs.
• Hazardous areas exceeding 1.5 times background values were identified for Cd (27.1%) and Hg (32.1%).

Conclusions:

• Natural sources are the primary contributors to several PTEs, but anthropogenic activities significantly influence Cd, Hg, Pb, and Zn levels.
• Atmospheric deposition from human emissions is a major contributor to Hg concentrations.
• SIS effectively mapped hazardous areas, highlighting the need for targeted remediation efforts, particularly for Cd and Hg.