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.
