Effects on anatomy of some abundantly growing herbs in the effluents contaminated soil of oil refinery.

The soil contaminations from refinery effluents are still a burning problem in the oil-producing nations of the globe. In the present study, the effect of oil refinery effluents on anatomical characteristics of some selected herbs has been studied. The abundantly growing herb species of the contaminated sites that includes Ageratum conyzoides, Alternanthera paronychioides, and Cyperus brevifolius were selected for the anatomical investigation. The samplings site of these herbs was adjacent to Numaligarh oil refinery, Assam, India, where a huge amount of oil effluents are released every day. For comparison, the same plant species were collected from the control sites where effluent contamination was not evident. The results showed that anatomical sections of both shoots and roots of the studied herbs are adversely affected by oil refinery effluents contamination and showed various structural abnormalities. Dark/blackish depositions were traced in the different tissues that include the epidermis, cortex, vascular bundles and pith region in the plant samples collected from the effluents contaminated areas. The results also revealed widening, thickening, and reduction of different tissues of the studied plants besides affecting overall shoot diameter; cell sizes; and length of epidermis, cortex, vascular bundles, and pith as a defense mechanism against the adverse condition created due to effluent contamination. Such abnormalities were not observed in control plants.