麦田O_3浓度的长期变化及其对冬小麦干物质和产量损失的估算

Long Term Variations of Ozone Concentration of in a Winter Wheat Field and Its Loss Estimate Based on Dry Matter and Yield

近地层臭氧污染及其对作物产量和粮食安全的负面效应已成为国内外广泛关注的焦点之一.利用2014~2016年冬小麦主要生长季期间臭氧浓度和气象因子观测资料,分析了麦田臭氧浓度、AOT40的变化特征.根据Pleijel等2007年修正的气孔导度模型,模拟了冬小麦气孔导度的变化,并与实测值进行对比验证,同时结合通量模型,计算了冬小麦气孔臭氧通量.此外,利用前期课题组建立的模型,估算了臭氧对冬小麦干物质累积和产量的影响.结果表明:臭氧浓度在冬小麦生长季期间从前期到后期逐渐增加,并呈现明显的单峰型日变化特征.从2014~2016年的每年3月1日~5月31日,平均臭氧浓度分别为36.2、37.7和33.6 n L·L^(-1),AOT40值分别为17.08、17.90和11.84μL·(L·h)^(-1).Javis气孔导度模型可以用来模拟本地区冬小麦的气孔导度,模型解释了实测气孔导度81%的变异性.2014~2016年冬小麦气孔臭氧吸收通量分别为9.36、9.32和8.65 mmol·m^(-2).在近3年臭氧浓度平均水平下,近地层臭氧会使冬小麦产量减少18.03%,干物质累积减少19.31%.

Surface ozone pollution and its negative effects on crops and food safety have attracted the attention of many people. In this study, ozone concentration and meteorological parameters in a winter wheat field were measured from 2014 to 2016. We analyzed the variations in ozone concentration and AOT40 during the growing season for winter wheat. According to the revised stomatal model, the leaf stomatal conductance of winter wheat was simulated and verified by comparing with measured results. Based on the flux model, the leaf stomatal fluxes of winter wheat were calculated. In addition, we estimated the effects of ozone concentration on winter wheat dry matter and yield by using exposure-response relationships and flux-response relationships. The results suggested that the concentration of ozone gradually increased during the growing season for winter wheat and showed a distinct unimodal pattern of diurnal variation. The mean concentrations of ozone were 36. 2, 37. 7, and 33. 6 nL·L - 1 , respectively, and the ozone AOT40 values were 17. 08, 17. 90, and 11. 84 μL·（L·h） - 1 , respectively, during the growing seasons for winter wheat from 2014 to 2016. The Jarvis-type factorial model of stomatal conductance could be used to simulate the stomatal conductance of winter wheat in the region, and approximately 81% of the variation of measured stomatal conductance could be accounted for by the model. The leaf stomatal ozone fluxes of winter wheat were 9. 36, 9. 32, and 8. 65 mmol·m - 2 , respectively, from 2014 to 2016. Winter wheat yield decreased about 18. 03% , and its dry matter decreased about 19. 31% under ozone stress during these three years.