近地层大气臭氧对作物光合作用影响的数值模拟研究

近地层O3浓度增加对作物光合产生不利影响,因此,利用TE-49C型臭氧自动观测仪对常熟农田上方O3浓度进行了逐时测定,同时利用OTC-1型农田开顶式气室,测定了不同O3浓度对冬小麦叶片光合作用的影响.在此基础上,首次建立了O3对冬小麦光合作用影响的数值机理模式,模式分辨率达到瞬时时间尺度,空间积分采用Ross方案,具有较高分辨率和准确度.对O3浓度观测表明:O3浓度逐时值变化在0～160×10-9之间,相比之下日平均值变化较小,仅在5×10-9～60×10-9之内;长江中下游地区农田上方O3存在三种典型日变化形式:高浓度单峰型、高浓度多峰型和低浓度平缓型.数值分析表明:全晴天状况下高浓度单峰型对光合作用日总量影响最大.数值敏感分析表明:O3浓度和辐射同步变化时,随着日总辐射量的加大,臭氧浓度增加对光合作用的影响程度逐渐加强.全生育期积分表明:水肥适宜时,由于O3影响冬小麦光合总损失量约为9.22%.

A Numerical Simulation of the Impacts of Ozone in the Ground Layer Atmosphere on Crop Photosynthesis

The increase of O 3 concentration in the ground layer has negative impacts on crop photosynthesis. The O 3 concentration above the wheat field was observed hour by hour with TE-49C ozone automonitor in Changshu, and the impact of O 3 on the wheat leaf photosynthesis was measured in the OTC-1 open top chamber simultaneously. Based on the observed parameters, a numerical model for simulating the impact of O 3 on wheat canopy photosynthesis was developed, which has higher resolution and accuracy. The results of O 3 observation showed that there are three typical patterns of O 3 diurnal variation in the Yangtze River Delta, including the unimodal curve with high concentration, multimodal curve with high concentration and smooth variation curve with low concentration. The result of numerical analysis identified that the unimodal variation with high concentration has greater impact on daily photosynthesis than the others. When the O 3 concentration and daily radiation changed synchronously, the impact of O 3 on photosynthesis becomes more intense as daily radiation increasing. The lost of the wheat photosynthesis due to O 3 in the whole growth period was integrated, and the calculated results showed that the accumulated lost of daily photosynthesis is about 9.22% in the wheat growth period under suitable moisture and fertilizer conditions.