Toxic hazards of the industrial atmospheric pollutant sulphur dioxide on tree crops
A study was conducted to assess the effect of the industrial atmospheric pollutant, sulphur dioxide on tree crops such as coconut. The area around the Travancore Titanium Products at Trivandrum district of Kerala State, India, concerned with the manufacture of titanium dioxide was selected as the experimental site. Coconut palm (Cocos nucifera L.)was selected as the test crop since it dominates the tree crops in the area. Chemical analysis of leaves and nuts were made to assess the extent of damage caused by sulphur dioxide pollution. Samples were taken from five radial distances of 250, 500, 1000, 1500 and 2000m from the factory. Control samples from palms of the same age were collected at a distance of 5000m from the same radii. Palms close to the source of pollution showed a high degree of chlorosis and necrosis of leaves accompanied by malformation of young leaves. The total sulphur content showed remarkable increase as distance from the factory decreased with the values being 1.731 per cent at 250m and 0.202 per cent at 5000m. Sulphate sulphur also showed marked increase upto 500m from the pollution source. The nitrogen content of palms at a distance of 1km from the factory was significantly lower compared to the control palms whereas phosphorus and potassium contents were markedly reduced up to 2 km. There was a significant decrease in the calcium content of leaves up to 1500m from the pollution source but no marked difference was observed in the magnesium content. A significant reduction was observed in the concentration of plant pigments of coconut leaves especially total chlorophyll, chlorophyll ‘a’, chlorophyll ‘b’, and total carotenoids and also the copra and oil contents of mature nuts.