Phytomonitoring of air pollution around brick kilns in urban area: exploring the potential of plants for the remediation of pollutants

This study examines the impacts of various pollutants on foliar biochemical parameters, including relative water content (RWC), total chlorophyll, leaf extract pH, and ascorbic acid content, and their relationship with the Air Pollution Tolerance Index (APTI). RWC, a crucial indicator of plant resilience, showed a significant positive correlation with APTI values (r = 0.4503, p < 0.05). Species with higher RWC, such as Carica papaya and Cassia fistula, demonstrated enhanced tolerance to pollutants, with RWC values reaching up to 85%. Chlorophyll content, which is vital for photosynthesis, exhibited a significant reduction in polluted areas, with levels ranging from 0.28 to 3.23 mg/g (p < 0.05). Notably, Cassia fistula had high APTI values but lower chlorophyll content, reflecting the complex relationship between tolerance and chlorophyll levels. Leaf extract pH was significantly lower in polluted areas, with pH values consistently below 7, correlating with higher APTI values (p < 0.05). Ascorbic acid content, an important antioxidant, was significantly higher in plants exposed to pollution, with positive correlations to APTI (r = 0.9214) and pH levels (r = 0.62). Principal Component Analysis (PCA) identified that pH, ascorbic acid, and APTI were positively correlated, while total chlorophyll and RWC showed opposing trends. Sensitivity analysis indicated that RWC (95.84% impact on Carica papaya and 85.92% on Cassia fistula) and pH were the primary factors influencing APTI and Metal Accumulation Index (MAI) values. The findings underscore the role of RWC, chlorophyll, pH, and ascorbic acid as biomarkers for plant responses to pollution and highlight the effectiveness of species with high MAI values in heavy metal accumulation and environmental monitoring.