Wet deposition of acidifying substances in different regions of China and the rest of East Asia: Modeling with updated NAQPMS

- We updated NAQPMS model so that it can trace the secondary formation species at real time.
- We modeled the acidic deposition and the SRRs based on the updated NAQPMS.
- Eastern and Central China are the highest export regions in wet deposition of acidic substances.
- The total acidic deposition in Southwestern and Northeastern China exceeded the critical loads.

The traditional way to study Sources-Receptor Relationships (SRRs) of wet deposition is based on sensitivity simulation, which has weakness in dealing with the non-linear secondary formation pollutants (e.g. ozone and nitrate). An on-line source tracking method has been developed in the Nested Air Quality Prediction Modeling System (NAQPMS) coupled with cloud-process module for the first time. The new model can not only quantify the total volume of the sulfate, nitrate and ammonium wet deposition with more accuracy, but also trace these acidic species to their emitted precursors. Compared with previous studies, our result clearly shows: (1) East China and Central China, which are the two primary export regions, have 15-30% and 10% effect on wet deposition in other areas, respectively; (2) Besides the above two regions, the total acid deposition in Southwestern and Northeastern China have reached or exceeded the critical loads under their own environmental conditions.