Transfer of reactive nitrogen in Asia: development and evaluation of a source–receptor model

Abstract

A simple model of chemistry and transport, ATMOS-N, has been developed to calculate source–receptor relationships for reactive nitrogen species within Asia. The model is intended to support discussion of energy and environmental issues in Asia, to compare sulfate and nitrate contributions to regional acidification, and to estimate how each nation's acid deposition and air quality relates to domestic versus foreign emissions. ATMOS-N is a Lagrangian “puff” model in which non-interacting puffs of emissions are advected horizontally and mixed between three vertical layers. Results are compared with wet nitrate deposition observations in Asia. On an annual average, the model estimates that long-range transport contributes a significant percentage of total nitrate deposition throughout east Asia. China, the largest emitter of the region, contributes 18% to nitrate deposition in Taiwan, 18% in Japan, 46% in North Korea, and 26% in South Korea. South Korea contributes 12% to nitrate deposition in Japan, due to its close upwind proximity. Compared with total acid deposition (nitrate+sulfate), nitrate contributes 30–50% over northern Japan, 30–60% in India, and 50–90% in southeast Asia where biomass burning emits high levels of NO x . The percentage contribution of nitrate is very low in China, where emissions and deposition of sulfur are extraordinarily high.