Heavy metal pollution of the mid-canal of Kandy: an environmental case study from Sri Lanka.

The mid-canal of Kandy, a 8-km effluent canal that runs through the city, collects massive quantities of domestic, municipal, and agricultural waste products. In this study, 37 samples from canal water and 13 from nearby drinking water wells were analyzed for their total Pb, Cd, V, Fe, and ferrous ion content. The following average values for the canal water were recorded: Pb, 269 micrograms/liter; Cd, 138 micrograms/liter; V, 18 micrograms/liter; total Fe, 4 mg/liter. These values indicate the relative levels of metal input from the effluent sources of the city of Kandy, the second largest city in Sri Lanka. The analysis of water from drinking wells near the canal showed high concentrations of metals, in some cases exceeding the maximum tolerance limits as recommended by WHO. The environmental impact of polluted city canals running through densely populated cities, particularly in developing countries, can assume serious proportions.