Acid deposition critical loads modeling for the simulation of sulfur exceedanceand reduction in Guangdong, China

The current acid deposition critical loads in Guangdong, China were calculated using the PROFILE model with a 3 km × 3 km resolution. Calculations were carried out for critical loads of potential acidity, actual acidity, sulfur and nitrogen, with values in extents of 0–3.5, 0–14.0, 0–26.0 and 0–3.5 kmol/(hm²·year), respectively. These values were comparable to previously reported results and reflected the influences of vegetation and soil characteristics on the soil acid buffering capacity. Simulations of SO₂ emission and sulfur deposition in this study showed that sulfur deposition core areas mirrored SO₂ emission centers. The prediction of sulfur deposition after 20% and 40% reduction of SO₂ emission suggested that the reduction of area sources contributed greatly to the decrease of sulfur deposition. Thus, abatement of area source emissions could be the primary way to mitigate sulfur deposition in Guangdong to meet both the provincial and national regulations of air pollution control.