Evaluation of Phragmites australis for Environmental Sustainability in Bahrain: Photosynthesis Pigments, Cd, Pb, Cu, and Zn Content Grown in Urban Wastes

Abstract

Modern urban societies generate tremendous amounts of hazardous wastes, including toxic organics and metals. Toxic metals harm plants and pose a risk to human health; examples of them are copper (Cu), zinc (Zn), palladium (Pb), and cadmium (Cd). Wetland plants are excellent for the ecological restoration of toxic metal-affected environments. Phragmites australis (common reed) belongs to the family Poaceae and is a broadly distributed wetland grass that is native to Bahrain, Europe, and America. P. australis shows a high content of chlorophyll. This study aimed to assess percentages of water, chlorophyll, and toxic metal content using acetone extraction; the calculation of the concentrations was performed according to the equations proposed by Lichtenthaler and the percentage of water content was calculated. After the metal exposure, the reed plants were digested, and their total mineral analysis was accomplished by atomic absorption spectroscopy; statistical analysis was conducted by Statistical Package for the Social Sciences (SPSS) version 21. The results revealed that the immature stage showed the highest chlorophyll a (mean 1641.5 (µg/g)) carotenoids (mean 359.75 (µg/g)) and total chlorophyll (mean 2183.93 (µg/g)), and the mature flowering stem had the highest chlorophyll b (mean 676.45 (µg/g)). The mature flowering stem stage showed the highest Pb (mg/L) and Cd (mg/L) values; on the other hand, Cu was the highest in the fully elongated non-flowering stage (0.108 mg/L), and the highest Zn content was found in the immature stage (mean 2.083). Owing to its growth in contaminated environments, P. australis can be considered a potential source of phytonutrients; higher concentrations were mostly available in the immature and mature flowering stages, with a favorable immature stage. The use of such marginal wetland plants may be very useful in reducing the pollution burden of urban built environments. These plants offer a green and sustainable solution for the disposal of waste from urban areas. Hence, further planning and execution of such a green solution are pivotal for creating environmental sustainability.