CHANGES IN AIRBORNE LEAD PARTICULATE IN PORT-PIRIE, SOUTH-AUSTRALIA, 1986-1996

Port Pirie is 230 km north of Adelaide, the capital of South Australia . The major industry in the city is a lead smelter owned by Pasminco. Fume, dust, and fugitive emissions from the smelter have been deposite d in and around Port Pirie over the past 100 years. The results presen ted in this paper are from an air monitoring station situated at the s outheast entrance of the smelter, approximately 600 m from the blast f urnace. Measurements include total suspended particulate (TSP) and tot al suspended particulate lead (TSPL) reported as concentrations (mu g/ m(3)). Data are available from 1986 to 1996 and consist of 548 measure ments. Analysis of geometric mean concentration levels by wind directi on showed that while for TSP there was little relationship with wind d irection, TSPL increased substantially as the wind came from the direc tion of the smelter. An analysis of geometric mean concentration level s by wind speed showed that TSP was significantly correlated with mind speed for all wind sectors apart from winds coming from the smelter p roduction area. The lack of correlation between TSP and wind speed whe n the wind blows from the direction of the smelter is probably due to the dilution effect of particulate from a point source as wind speed i ncreases. TSPL was significantly correlated with wind speed for all wi nd sectors apart from winds coming from the city. As expected, both TS P and TSPL concentrations were significantly lower on days when rain f ell. Both mean geometric TSP and TSPL concentrations were lower in the period 1993-1996 than in 1986-1992. Multiple linear regression analys is was used to demonstrate that this decline was statistically signifi cant after adjusting for weather conditions. Wind directions were divi ded into four sectors: winds from the smelter production area; winds f rom the smelter nonproduction area; winds from the zinc wharf and east of the city; and winds from the city. Structural equation models for each sector were used to demonstrate that the decline in geometric mea n TSPL concentrations over the two periods were of a similar order of magnitude for all four sectors. The relevance of this to the lead abat ement programs that have been undertaken both within the city of Port Pirie and inside the smelter itself is discussed. (C) 1998 Academic Pr ess.