Native Plants as Living Sensors: Tracking Air Pollution in Industrial Zones
摘要
Industrial activities are major contributors to atmospheric contamination, adversely affecting local vegetation and ecosystem health. Green plants, particularly native species, can serve as effective bio-indicators and phyto-remediators of environmental pollution. The present study assessed the air pollution tolerance and adaptive responses of six native plant species—Calotropis procera, Aerva javanica, Capparis spinosa, Solanum surratense, Salsola imbricata, and Tribulus terrestris—growing around the Industrial Estate of Rahim Yar Khan, Pakistan. Plants were analyzed for foliar dust deposition, heavy metal accumulation, growth, physio-biochemical parameters, and anatomical traits. Results revealed a substantial increase in foliar dust and heavy metal concentrations at polluted sites, confirming the suitability of these species as bioindicators. C. procera exhibited the highest dust and metal accumulation (Fe, Cu, Pb, Cd, Ni), while S. imbricata accumulated the greatest Zn content, indicating species-specific uptake capacities. Air Pollution Tolerance Index (APTI) and Anticipated Pollution Index (API) values identified A. javanica and C. procera as pollution-tolerant species, whereas C. spinosa, S. surratense, S. imbricata, and T. terrestris were classified as sensitive. Growth parameters, including plant height, leaf number, and biomass, declined significantly under polluted conditions, with A. javanica and C. procera maintaining superior performance. Physio-biochemical analyses showed reductions in total soluble proteins, sugars, and pigments in most species, while C. spinosa and S. surratense exhibited elevated osmolyte accumulation, higher antioxidant activity, and greater relative water content—indicating enhanced physiological resilience. Anatomical assessments revealed notable variations: C. procera maintained thicker vascular and storage tissues and increased stomatal density, signifying structural adaptability to dust stress, while T. terrestris and S. imbricata displayed reduced tissue thickness and greater sensitivity. Overall, the integrated assessment of morphological, biochemical, and anatomical traits demonstrates that C. procera and A. javanica are highly tolerant and well-suited for greenbelt establishment and phytoremediation programs in industrial zones. In contrast, C. spinosa, S. surratense, S. imbricata, and T. terrestris may serve as sensitive bioindicators for long-term air quality monitoring and ecosystem health assessment.
Graphical Abstract