Effect of atmospheric pollutants and acid precipitation on the algal density of epiphytic terrestrial microalgae

Epiphytic terrestrial algae are plant-like protists with lack of plant characteristics, usually found on other plants. Carbon monoxide, nitrogen oxide and sulphur dioxide are the main contributors of atmospheric pollutants that could enhance or limit algal density. This study set out with the aim of assessing algal density and species composition of the epiphytic terrestrial microalgae from polluted (Banting) and less polluted area (Kuala Selangor). Another objective is to determine the effect of atmospheric pollutants in precipitation on algal density, species composition, size of cells and chlorophyll content of epiphytic terrestrial algae inhabiting Taman Botani Negara Shah Alam (TBNSA) using simulated acid rain. The finding shows that density in polluted areas is significantly higher with 118 ±8.06 x107 cells/cm2 compared to the control site with only 71 ±6.55 x107 cells/cm2 . The bark pH in polluted area is more acidic 5.17* ± 0.12 compared to 5.90** ±0.24 in less polluted area. After simulation of atmospheric deposition in TBNSA, it is found that density of algae has increased significantly in all treatment, with highest recorded by carbon dioxide 142.9%, followed by nitrogen oxides 129.1%, control 104.4%, and the least was in sulphur dioxide 62.8%. Bark pH of the tree hosting the algae was found to increase from 4.19* ±0.14 to 4.36**±0.13, 4.69**±0.14, 4.82**±0.18 and 4.87**±0.16 after exposure to the pollutants in precipitation. On the contrary, chlorophyll content is highest in sulphur dioxide with a total of 563.81 ±220.36 and carbon dioxide as the least with 348.77 ±147.14. In conclusion, several parameters have been measured to quantify the effects of atmospheric pollutants in epiphytic terrestrial algae and some recommendations have been identified for future research.