Modeling atmospheric transport and deposition of calcium in China

Abstract

Basic cation (Ca2+, Mg2+, K+, and Na+) deposition plays an important role in preventing soil and water acidification, especially in China, where basic cation deposition is commonly much higher than in Europe. The long-range transport and deposition of calcium was estimated using a multi-layer, dynamic Eulerian model. Results show that the total deposition of calcium in China was about 5.29 Mt (with 1.45 Mt as wet deposition and 3.84 Mt as dry deposition), of which anthropogenic sources contributed 67.1% (92.4% as wet deposition and 57.6% as dry deposition). The calcium emitted from natural sources was mainly deposited in northwest China, while the anthropogenic sources greatly affected deposition in the southeast. The calcium deposition was commonly higher than 0.10 kmol·hm-2·a-1, or even higher than 0.25 kmol·hm-2·a-1 in southeast China, where acid deposition is very high.