大气臭氧污染对冬小麦气孔吸收通量的影响机制及其时空格局

近地层臭氧作为一种二次污染物,其不断增加的浓度及其对作物的影响已经成为各国政府和公众关注的焦点.本文以冬小麦为研究对象,基于大田OTC试验,对OTC内气象因子和气孔导度进行连续观测.引进气孔导度模型,并进行本地参数化研究,结合通量模型,研究冬小麦气孔臭氧吸收通量的变化特征,并对江苏省各市冬小麦气孔导度和O_3吸收通量的时空分布进行模拟.结果表明,O_3浓度增加会限制其叶片气孔导度,浓度越高,限制作用越明显;利用修订后的气孔导度模型对冬小麦叶片气孔导度进行模拟,表明模型解释了实测气孔导度90%、77%和83%的变异性.结合通量模型对冬小麦气孔O_3通量进行模拟,则CK(约为53.67 n L·L~(-1))、100 n L·L~(-1)和150 n L·L~(-1)O_3浓度处理下冬小麦在整个O_3熏期的累积吸收通量分别为6.42、12.27和13.90 mmol·m-2;江苏地区冬小麦在其生长季期间O_3浓度呈逐渐增加的趋势,冬小麦平均气孔导度的大小表现为:中期后期前期的时间变化特点,在整个中期时段气孔O_3累积吸收通量最多.

Influencing Mechanism and Spatio-temporal Pattern of Stomatal Ozone Flux of Winter Wheat Under Ozone Pollution

As one of the main atmospheric pollutants over surface layer,researches on the increasing surface ozone concentration and its impact on main crops have become the focus of every government and the public.In this paper,based on the observations in Nanjing using the main local cultivars in China''s major winter wheat producing areas,it was expected to obtain the data including ozone concentration,meteorological data and stomatal conductance by continuous observation.Stomatal conductance model was used and parameterized,combined with flux model,we analyzed the characteristics of stomatal flux in winter wheat under ozone pollution.At the same time,the stomatal conductance and stomatal ozone absorption flux of winter wheat were simulated in Jiangsu Province.The main results were as follows:Elevated ozone concentration could reduce stomatal conductance of winter wheat leaf and stomatal conductance decreased with the increase of ozone concentration.According to the observational data through the experiment,based on the boundary line technology,stomatal conductance model was parameterized to simulate stomatal conductance of wheat leaves from environmental factors.Approximately 90%,77% and 83% variation of measured stomatal conductance could be explained by the stomatal conductance model.In the experiment,the total ozone absorption flux in ozone concentration of CK (53.67 nL·L^-1),100nL·L^-1,150nL·L^-1 was 6.42 mmol·m^-2,12.27 mmol·m^-2,13.90 mmol·m^-2 respectively.The ozone concentration gradually increased from early period to late period during the period of winter wheat growth in Jiangsu area.The average stomatal conductance followed the order of the middle stage >the later stage >the early stage.Winter wheat ozone cumulative absorption flux was the highest during the middle stage.