Dust Accumulation, Heavy Metal Content and Stomata Morphology of Some Medicinal Plants at Rock Quarrying Locations at Lokpaukwu, Nigeria

Aims: This study evaluated the effect of rock quarrying on dust accumulation, heavy metal content and stomata features of some medicinal plants at Lokpaukwu, Nigeria.

Place and Duration of Study: Sample collection was carried out at the quarry sites in Lokpaukwu, followed by laboratory analyses which were conducted in the Department of Pharmacognosy and Environmental Medicines and Centre for Energy Research and Development (CERD), University of Nigeria, Nsukka between January and March, 2019.

Methodology: Five (5) commonly used medicinal plants were selected and collected from the two pollution sites (A and B). Same species collected 20 km away from the sites served as control. Clearing method was employed in foliar micro-analysis while heavy metal accumulation in the samples was estimated by atomic absorption spectrometry (AAS).

Results: The study showed considerable variation in dust load among the plants from each study site. This led to some observed physiological anomalies– occlusion of stomata pores, plasmolysis, and shrunk epidermal cells. Quantitative stomata parameters were also affected as plants from polluted sites had narrower pores and more number of stomata than the control. Concentrations of heavy metals (Pb, Zn, Cd, As and Cu) in plants collected from dust polluted sites were also higher than those from the control location. For example, lead and cadmium concentration in most of the plants were in this order: site A > site B > site C.

Conclusion: These findings have further validated reports of earlier researchers on the deleterious effects of dust pollution as a result of quarrying activities on plant health. Strict compliance to precautionary and mitigation measures by both the inhabitants and quarry companies are recommended for safer environment and good health.