大气气溶胶增加对作物的影响研究进展

大气气溶胶是指悬浮在大气中的固态和液态颗粒物总称。近年来空气污染带来了一些区域大气气溶胶浓度上升明显,一定程度上对作物生长环境带来影响。国内外关于大气气溶胶增加可能对作物产生的影响表现在:(1)大气气溶胶增加会导致直接辐射减少,而散射辐射可能会有一定程度增加;散射辐射增加有利于一些作物整个冠层光合能力的提高。(2)大气气溶胶带来辐射的改变也会影响近地面小气候环境,尤其是大气昼夜温度变化,从而影响作物干物质积累;而辐射与温度的改变同时也会影响农田蒸散和最终水分利用效率。(3)大气气溶胶形成的干沉降会停留在叶片表面,减少光合有效辐射到达叶片的量,同时对作物叶片结构和功能产生直接影响。在总结国内外研究进展基础上,提出未来关于大气气溶胶增加对作物影响需要进一步明确大气气溶胶带来的作物生长环境改变对作物碳同化、积累和消耗的影响以及直接和散射辐射比例改变如何影响作物光合和蒸腾的相互关系,通过全面系统的研究大气气溶胶对作物产量形成的影响机制,提出有针对性的田间应对技术。

A review of the research on crop responses to the increase in aerial aerosol

Aerial aerosol is defined as a colloid of fine solid particles or liquid droplets in the atmosphere. With the improvements in economic and social development, aerosol emissions are rapidly increasing in some Chinese regions. Consequently, haze and fog frequently occur and there are widespread concerns about the possible harmful effects of the haze on human beings. Its possible effects on agricultural production have also been studied and some results, based on related studies carried out globally, have shown that (1) Anthropogenic fossil fuel and biomass combustion have released aerosols into the atmosphere that have affected the quantity and optical properties of aerosols (known as aerosol optical depth). Changes in aerosol optical depth modify the solar radiation reaching the ground, which directly affects the carbon balance of terrestrial ecosystems. The change in crop yield due to the influence of aerosols was found to be extremely dependent on the magnitude of the reduction in direct radiation and the increase in the diffuse fraction. These particles can directly scatter and/or absorb surface solar radiation in different ways because of differences in the composition and density of air pollutants. The accepted view is that the increase in the aerosol optical depth will reduce direct radiation, and that diffuse radiation will increase to some extent. Furthermore, the increased diffuse radiation should benefit crop canopy photosynthesis and have a larger effect on gross primary production than the latent radiation. (2) The change in radiation also affects air temperature near the surface. The daytime temperature will decrease, but the nighttime temperature might increase, which may lead to a reduced diurnal temperature difference. As a result, crop production and crop water use might fall. (3) The direct effects of aerosol on crops have also been measured, along with the indirect effects of air pollution on crop growth and yield production. The deposition of dry particles on the leaf surface may block the radiation reaching the leaf surface and negatively affect leaf structure and function, which could reduce the photosynthetic capacity of crops. The above-mentioned results showed that there were possible positive and negative effects of air pollution on crop growth. However, the overall effects of the aerosol on crop production are still not clear in regions with serious air pollution problems. Therefore, it is necessary to further quantify the influence of aerosols on radiation partitioning, and their interactions with carbon processes, crop-water relations, crop leaf properties, and photosynthetic functions, to determine the magnitude of the air pollution effects on crop performance and provide possible counter-measures to mitigate the negative effects of air pollution on crop growth.