Acid Precipitation and its Effects on Water Quality of Small River Basins in Rhode Island

Calvin P. C. Poon
Todd Chaplin

DOI: 10.2190/W6TE-JF55-LK0R-KGMD


The effects of acid precipitation on the water acidity, alkalinity, and pH of three small rivers in Rhode Island rural areas were studied. Satellite pictures, radar scans, and pressure maps were used to trace storm paths. In general more acidity was found in storms coming from the west-southwest direction. Rainfall pH as low as 3.81 and another rainfall with strong acid components at a concentration of 1.59 × 10-4 N were recorded. The degree of impact on river water quality depended on storm acidity, storm size, amount of dry deposition prior to the storm, river flow prior to the storm, and land use pattern in the watershed. It was found that a drop of half a pH unit in a river could take place in one-half day. The largest pH drop recorded was 2.15 units and the largest increase of acidity was eleven fold. The impact on water quality could last longer than five days from the onset of the maximum impact, which generally coincided with that of the peak flow, to the time of recovery of the pre-storm water acidity, alkalinity, and pH.

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