Ecological Assessment of Polluted Soils: Linking Ecological Risks, Soil Quality, and Biota Diversity in Contaminated Soils

Understanding the correlation between soil pollution, environmental indices, humic substances, and soil biota diversity is critical for assessing ecological health, particularly in areas with prolonged contamination. In this study, 90 soil samples were collected from ten locations in El-Mahla El-Kobra area, Egypt, affected by industrial pollution and unsustainable agricultural practices. Significant variations in organic matter, humic substances, microbial biomass carbon, and microbial populations were observed. Heavy metal contamination was highest in site S3, with a contamination degree (CD) of 29.45 and a pollution load index (PLI) of 1.67. Self-organizing maps showed the possible need for targeted remediation to mitigate ecological risk. Biodiversity analysis identified Oribatida as the dominant species, with shifts in diversity indices indicating species adaptation to pollution levels. Positive correlations between soil contamination (CD, PLI) and both Shannon–Wiener and Simpson indices, alongside negative correlations between MCD, PLI, and the Berger–Parker dominance index, suggest a complex shift toward species dominance in polluted environments. The findings highlight the complex interplay between soil contamination and biodiversity, offering critical insights for ecological risk assessment and sustainable soil management in contaminated regions.