Changes in the anatomical characteristics of Avicennia marina (Forssk.) Vierh leaves exposed to petroleum hydrocarbon pollution

Abstract

The current study showed the effect of the anatomical characteristics of Avicennia marina (Forssk.) Vierh leaves exposed to different concentrations of petroleum hydrocarbon compounds. These trees are important plants that have been cultivated in our time on the shores of the Shatt al-Arab in Basra Governorate, contributing to reducing the risks of environmental changes and creating a coastal environment with high biodiversity. The cross-section of the leaf was studied, and the highest average thickness was recorded at concentrations (2.5 and 10) ppm, reaching 425 and 423µm respectively, while the lowest concentration was recorded at 255µm in the control plants. The change in the thickness of both the upper epidermis and the lower epidermis was also observed, with the upper epidermis recording a greater thickness than the lower epidermis in all samples, and a clear difference between them is evident, as the highest average thickness of the upper epidermis ranged from 181.4µm at 2.5ppm concentration compared to the control samples, which reached 122µm, while the lowest average thickness was 128µm at 7.5ppm concentration. Changes in palisade layer thickness were also observed in the samples exposed to different concentrations of petroleum hydrocarbons. The columns show a clear variation in palisade layer thickness between the different samples compared to the control samples. The midrib thickness of A. marina leaves exposed to the same concentrations was also affected. Furthermore, the upper and lower collenchyma layers of the leaf exhibited significant effects. The collenchyma thickness in the lower layer was found to be greater than the upper layer in all samples.