DETERMINATION OF ATMOSPHERIC SULFUR-DIOXIDE BY ION CHROMATOGRAPHY IN THE CITY OF CABIMAS, VENEZUELA

Sulfur dioxide (SO2) is an atmospheric pollutant that at certain conce ntrations may produce harm to human health and contribute to acid rain formation. Measurements of SO2 concentrations were made at two sampli ng sites in the city of Cabimas, Venezuela, during several months of t he dry season (March and April) and of the rainy season (May to July) of 1994. SO2 samples were collected in a dilute solution of hydrogen p eroxide (H2O2) with a Graseby/Andersen sampler, Model 209068 and analy zed as sulfate by ion chromatography (IC) using Dionex equipment, Mode l 2000i/sp. The detection limit for sulfate was 0.044 mu g/ml, based o n three times the standard deviation of the blank (n=23). For a sulfat e sample with a mean of 0.198 mu g/ml (n=7), a relative standard devia tion of 5.56% was obtained. The recovery of a sulfate standard (0.2 mu g/ml) was 99%, The pararosaniline method was also used during the dry season in order to compare the results. Most of the SO2 concentration s were detected during the dry season by the H2O2 IC method. The avera ge concentrations at the sampling sites were 15.4 mu g/m(3) (n=14) and 16.6 mu g/m(3) (n=15). The total average (16.0 mu g/m(3)) represents 20% of the lowest Venezuelan air quality standard (80 mu g/m(3)).