Impacts of uncertainties in base‐cation deposition on the assessment of critical loads for acid deposition

Abstract

Less attention has been paid to changes in the concentration and the deposition amounts of base cations. This has brought about great uncertainty in the determination of critical loads for acid deposition. The paper utilized a newly developed long‐term soil acidification model (LTSAM), to simulate the effects of atmospheric base cations on the critical load of red earth in Wenzhou, Zhejiang Province. Results showed that great changes in atmospheric base‐cation deposition decreased the critical load by 68%. This suggested that by only reducing S deposition without considering changes in the atmospheric base‐cation deposition, would substantially overestimate the critical load of soils. Therefore, more attention should be focused on changes in base cations during reductions of SO₂ emissions, and the long‐term monitoring of base cation deposition needs to be strengthened, especially in China.

Key words:

• Base cation
• base saturation
• critical load
• alkalinity
• acid deposition

Notes

Corresponding author; email: [email protected]