Regional atmospheric budgets of S and N fluxes: how well can they be quantified?

Abstract

SynopsisRegional atmospheric sulphur/nitrogen budgets have been used in several regions of the world to help build up an overview of fluxes, reservoir contents and turnover times, and as a basis for quantitative modelling. However, there are some deficiencies in the regional budget approach. The analysis is of necessity superficial, and can give a false impression of certainty. This paper reviews the regional budgets for sulphur/nitrogen which have been created in various regions of the world, analyses their common findings, addresses the issue of uncertainty, and recommends areas of future research.Most regional sulphur/nitrogen budgets have been constructed for North America, northern Europe and a few in other parts of Europe. A common finding is that anthropogenic emissions are large relative to natural emissions and that there is substantial international transport. The results of the budget analysis, while having elements of uncertainty, have proved to be valuable both in the synthesis of knowledge, and in their contribution to the increased awareness among policy makers and the public at large about the long-range transport of sulphur/nitrogen emissions.Unfortunately, there have been few regional budgets for the developing portions of the world. Given the projected increase in population – and per capita S and N emissions for these regions – we encourage a future focus on regional sulphur/nitrogen budgets for the less developed regions of the world.