Surface and Rainwater Chemistry in Sri Lanka – A Risk of Acidification

Article type: Research Article

Authors: Silva, E.I.L. | Manuweera, L.

Affiliations: Institute of Fundamental Studies Hantana Rd, Kandy, Sri Lanka. E-mail: sil@ifs.ac.lk | City Analyst Laboratory, Central Market, Kandy, Sri Lanka

Note: [] Corresponding Author

Abstract: Abstract: Chemical constituents of surface and rain water in Sri Lanka were analysed to examine the susceptibility of aquatic environment for episodic acidification. The buffer intensity of different types of surface water ranged from 8.09 ± 4.61 × 10^{-4} to 55.05 ± 21.18 × 10^{-4} moles l^{-1} pH^{-1}. The pH values of the rainwater samples collected island-wide once and at Kandy on a regular basis varied from 4.82 to 7.30 and from 4.46 to 6.89 respectively. About 37% of rainwater samples collected island-wide and at Kandy had pH range of 5.40–5.80. Rainwater collected from urban centres with high population densities had moderate concentrations of nitrate, sulphate and chloride ions. Although a majority of rainwater samples were within the pH defined for non-contaminated rainwater, there is a tendency towards slight acidification. If acid rain prevails, headwater streams and rivers draining the wet zone and reservoirs located at the highest elevation are more susceptible for episodic acidification.

Keywords: Buffer intensity, acid rain, surface water, Sri Lanka

Journal: Asian Journal of Water, Environment and Pollution, vol. 1, no. 1-2, pp. 79-86, 2004