Sulfur dioxide emissions and sectorial contributions to sulfur deposition in Asia

Anthropogenic and volcanic emissions of SO2 in Asia for 1987–1988 are estimated on a 1° × 1° grid. Anthropogenic sources are estimated to be 31.6 Tg of SO2 with the regionsʹ volcanoes emitting an additional 3.8 Tg. For Southeast Asia and the Indian sub-continent, the emissions are further partitioned into biomass, industrial, utilities, and non-specific sources. In these regions emissions from biomass, utilities and industrial sources account for 16.7, 21.7, and 12.2%, respectively. In Bangladesh, 90% of the SO2 emissions result from biomass burning and nearly 20% of Indiaʹs 5 Tg of SO2 emissions are due to biomass burning. Malaysia and Singaporeʹs emissions are dominated by the utilities with 42 and 62% of their respective emissions coming from that sector. The spatial distribution of sulfur deposition resulting from these emissions is calculated using an atmospheric transport and deposition model. Sulfur deposition in excess of 2 g m−2 yr−1 is predicted in vast regions of east Asia, India, Thailand, Malaysia, Taiwan, and Indonesia with deposition in excess of 5 g m−2 yr−1 predicted in southern China. For the Indian sub-continent and Southeast Asia the contribution of biomass burning, industrial activities, and utilities to total sulfur emissions and deposition patterns are evaluated. Biomass burning is found to be a major source of sulfur deposition throughout southeast Asia. Deposition in Bangladesh and northern India is dominated by this emissions sector. Deposition in Thailand, the Malay Peninsula and the island of Sumatra is heavily influenced by emissions from utilities. The ecological impact of the deposition, in 1988 and in the year 2020, is also estimated using critical loads data developed in the RAINS-ASIA projects. Much of eastern China, the Korean Peninsula, Japan, Thailand, and large regions of India, Nepal, Bangladesh, Taiwan, the Philippines, Malaysia, Indonesia, and sections of Vietnam are at risk due to deposition in excess of their critical loads if emission trends continue at the current rate.