Unveiling bioearth: statistical assessment of chemical properties, nutrients and heavy metals contamination from legacy dumpsites, Tamil Nadu, India

This study presents the chemical properties, nutrient contents, heavy metals and interrelationship amongst various parameters in bioearth, a soil-like material harnessed from legacy waste dumpsites. The analysis indicates an alkaline pH of 7.75, a moderate EC of 1.89 mS cm(-1), and a relatively low C content of 4.89%, compared to optimal compost standards. The nutrient levels are suboptimal, with total N, K and P concentrations of 0.45%, 0.37% and 0.23%, respectively, all below the recommended values for effective compost. The C:N ratio of 12.64 suggests a rapid decomposition process, leading to relatively fast nutrient release. Heavy metal analysis indicates that Zn, Cu and Cd are within the safe limits, whereas Ni and Cr show high values, hence posing a potentially high risk. Statistical analysis performed through ANOVA, points out significant (p < 0.05) differences in all variables of the bioearth's quality parameters at different sites<bold>.</bold> Pearson correlation analysis reveals complex interrelationships, with strong links between C and N, and significant effects of pH on heavy metal availability. Principal component analyses manifest the predominance of heavy metals followed by nutrients in causing variability among characteristics of the bioearth. Cluster analysis classifies the sites into three distinct clusters on the basis of pH, TOC content and nutrient contents. The results highlight that improving the quality of bioearth requires enhanced waste management practices. Key recommendations include incorporating materials with higher TOC content to boost organic matter and optimizing the bioearth's nutrient profile. Additionally, it is essential to monitor and control heavy metal levels to ensure bioearth suitability for agricultural and environmental applications. These measures will help optimize the quality of bioearth and its effectiveness in soil enhancement.