Deep Cut of Anthropogenic Nitrogen Oxides Emissions to Mitigate Ozone Vegetation Damages in China

The fast growing surface ozone (O3) pollution poses threats to the ecosystem health and carbon assimilation in China. Here, we apply a coupled atmospheric chemistry-vegetation model to explore the effective ways of mitigating O3-induced loss of gross primary productivity (GPP) in China through anthropogenic emission controls at different regions and for different species. For the current pollution level, surface O3 decreases national GPP by 10% in the summer. Sensitivity experiments show that such GPP loss can be alleviated by 3.6%, 2.9%, and 0.6% with 50% reductions in the anthropogenic emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) globally, inside, and outside China, respectively. The efficiencies of O3 reduction and GPP recovery increase with the deeper cut of the precursors. For the same ratio (50%) of emission reduction, domestic NOx control alone decreases national average O3 by 4.9 ppbv and mitigates 2.7% of O3-induced GPP damages, much higher than the 0.9 ppbv reduction in surface O3 and 0.6% recovery of GPP loss with VOCs control alone. Although with nonlinear and heterogeneous responses, our study suggests that the control of NOx emissions is a more effective way than VOCs to mitigate O3 pollution and related GPP damages in China.