Acid rain : A New Zealand viewpoint

Abstract

New Zealand has a low level of industrialisation, and is free from large scale air pollution. However, concern has been expressed that acid rain, derived from transport across the Tasman Sea of sulphur oxides from Australian industry, could become a problem here in the future. This study has compared the emissions and transport of sulphur oxides from the United Kingdom, which totals about 4.25 million tonnes per year, dispersed as sulphur dioxide mostly out to sea, with the Australian emissions of 1.75 million tonnes transported across the Tasman Sea to New Zealand. United Kingdom emissions result in an annual deposition of about 180 kT as SO₂ on Scandinavia. Australia deposits at most about 56 kT on New Zealand per year. Indigenous sources including New Zealand industry raise this total by 28 kT per year to 84 kT as SO₂ This gives an average total acid deposition loading per square metre on terrestrial New Zealand of about 12.5% of that found for Sweden and less than 4 % of the average for the United Kingdom. We conclude that, apart from local depositions derived directly from a point source or industrial conurbation, no significant effects from acid rain can be expected in New Zealand. Since there is no significant land mass to the east downwind of New Zealand, our use of high stacks for SO₂ dispersion from industrial sources, without flue gas desulphurisation, is correct and appropriate for this country.

Keywords:

• Acid rain
• sulphur dioxide
• pollution modelling
• longrange pollution effects
• air pollution