Plant bioindicators of pollution in Sadat City, Western Nile Delta, Egypt

Anthropogenic pollution can take various forms and affect the air, water, soil, and plants. Monitoring pollution via compounds formed in living organisms such as plants, so-called bioindicators, may be a useful approach for environmental monitoring. The purpose of this study was to investigate and compare plants growing in industrial and residential areas of Sadat City, Egypt, as bioindicators and biomarkers of industrial pollution. Phenolic compounds, flavonoids, and metals were measured in Bougainvillea glabra (paperflower) leaves by HPLC-MS, neutron activation analysis, and atomic absorption spectrophotometry. Air, water, and soil samples associated with B. glabra sampled in industrial and residential areas were also analyzed for the presence of phenolic compounds, flavonoids, metals, and particulate matter. There were significantly higher levels of flavonoids and phenolic compounds in the leaf extracts of plants growing in industrial areas compared to those growing in residential zones (P<0.05). Metal accumulation in leaves was also significantly higher in the industrial zone than the residential zone: iron, lead, zinc, nickel, and manganese were present at significantly higher levels in plants in the industrial zone compared to those growing in the residential zone (P<0.05); nevertheless, the concentrations of heavy metals in the air, water, and soil were under local legal environmental limits. This study demonstrates that pollution has significant effects on total phenolic, flavonoid and metal levels in B. glabra plants, not only demonstrating the effects of pollution on ecosystem health but also paving the way for using plants as bioindicators and for phytoremediation.