Reduction of wheat photosynthesis by fine particulate (PM_2.5) pollution over the North China Plain

Abstract

The negative impact of rapid urbanization in developing countries has led to a deterioration of urban and regional air quality. Much attention has been given to the impact of fine particulate pollution on urban public health. However, very little attention has been given to its impact on the regional ecosystem such as the agricultural ecosystem. Thus, we evaluate the direct impact of air pollution on the reduction of wheat photosynthesis by fine particulate matter (PM) pollution in the world's most heavily polluted area, the North China Plain, using remote sensing observations and ground measurements. We found the following to be true: (1) Heavy PM pollution could significantly reduce wheat photosynthesis and cause an expositional relationship between the PM concentration and wheat photosynthesis (R = 0.9824, P < 0.05); (2) Heavy PM pollution makes up 2% for the reduction in wheat photosynthesis at all wheat-plant farmlands in the North China Plain, approximately covering an area of 354,400 km; (3) Increasing heavy PM pollution significantly reduced wheat photosynthesis by 87% in wheat-planted farmland during 1999-2011. We hope the results presented here could draw attention to the effect of PM pollution on the agricultural ecosystem and encourage further studies to evaluate the feedback of atmospheric pollution on the agricultural ecosystem using remote sensing. Abbreviation: Northern China Plain (NCP); normalized difference vegetation index (NDVI); The Moderate Resolution Imaging Spectroradiometer (MODIS); fine particulate matter (PM).

Responses of Photosynthesis And Long-Term Water Use Efficiency To Ambient Air Pollution In Urban Roadside Trees

“…This result con rms our previous study (Kiyomizu et al 2019) and the study for Norway spruce in central Europe that reported decreased Δ 13 C with air pollution (Čada et al 2016), which indicates that long-term water use e ciency becomes higher as nitrogen oxides increase (Kume et al 2006). The evaluation of the effect of air pollution on long-term water use e ciency by using the leaf carbon isotope ratio (δ p ) can be di cult because of the opposite effect of fossil fuel δ 13 (δ p ) of Pinus densi ora foliage in Japanese and Korean cities, respectively. In spite of these di culties, we successfully obtained a clear trend of Δ 13 C in relation to atmospheric nitrogen oxides (Fig.…”

“…In spite of these di culties, we successfully obtained a clear trend of Δ 13 C in relation to atmospheric nitrogen oxides (Fig. 3) by both correction of the effect of fossil fuel δ 13 C and evaluation of relative changes in Δ 13 C (Eq. 2).…”

“…Finally, restrictions of A max and the deviation in Δ 13 C of each section were estimated using the correlations between NO 2 and restriction of A max or deviation in Δ 13 C in Fig. 3…”

“…In the years 2007 and 2014, δ p was measured using powdered leaf samples using the combined system of an elemental analyzer (EA1108, Carlo-Erba, Italy), interface (Con o II, Thermo Fisher Scienti c, MA, USA), and isotope mass spectrometer (Delta S, Thermo Fisher Scienti c, MA, USA) at the Center of Ecological Research of Kyoto University corrected with standards (Tayasu et al 2011). From 2015 to 2019, δ 13 C was measured using an elemental analyzer (Flash 1112, Thermo Fisher Scienti c, MA, USA), interface (Con o IV, Thermo Fisher Scienti c, MA, USA), and isotope mass spectrometer (delta V advantage, Thermo Fisher Scienti c, MA, USA) at the Research Institute for Humanity and Nature.…”

“…To compare Δ 13 C values across the different years, we calculated deviations in the Δ 13 C value of each year using the maximum value as a reference (Δ 13 where Δ 13 C obs is the observed Δ 13 C. The larger deviations in Δ 13 C mean smaller Δ 13 C obs , and in turn, higher long-term water use e ciency.…”