Reserch On Ozone Stomatal And Non-Stomatal Flux Of Rice And Winter Wheat

Ozone is one of the most important atmospheric pollutants in the near-surface layer.It has been paid more and more attention due to its rising concentration and serious harm to human health and natural ecosystems.Based on field experiments under natural conditions,the rice and winter wheat were taken as the research object in this paper.The ozone dry deposition process and its impact factors of two crops were analyzed.Besides,further research about the distribution proportion of ozone stomatal and non-stomatal flux,variation characteristics and influencing factors in two crops were studied according to the eddy covariance system and model simulation.The results are as follows:(1)The mean values of the ozone concentration((?)o3),the ozone dry deposition flux(Fo3),and the ozone deposition velocity(Vd)were 36.0 nL L-1,-250.6 ng·M-2·s-1(negative sign means that the deposition direction is down to the soil)and 0.38 cm·s-1,respectively for the rice.While,for the winter wheat,the mean values of the ozone concentration,the ozone dry deposition flux,and the ozone deposition velocity were 42.1 nL L-1,-237.7 ng·m-2· s-1 and 0.32 cm·s-1,respectively.During two trial periods,(?)O3?Fo3 and Vd showed that there was obvious diurnal variation,and all of them showed the tendency that the daytime mean values were higher than the nighttime.(2)For the rice,ozone stomatal flux accounted for 26.7%,and non-stomatal flux accounted for 73.3%in ozone dry deposition process all day long.The ratio of daytime ozone stomatal and non-stomatal flux was 34.7%and 65.3%,respectively.For the winter wheat,ozone stomatal flux accounted for 26.1%,and non-stomatal flux accounted for 73.9%in ozone dry deposition process all day long.The ratio of daytime ozone stomatal and non-stomatal flux was 35.6%and 64.3%,respectively.And in the two comparison periods,the ratio of stomatal flux which were absorbed by the two crops through stomata to Fo3 was similar.(3)High solar radiation,high temperature,and moderate humidity were favorable for ozone stomatal absorption of two comparative periods of the two crops.Stronger air turbulence,the suitable temperature and radiation as well as the wetter conditions were conducive to the ozone non-stomatal deposition of two comparative periods of the two crops.