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近地层高浓度臭氧(O_3)会给植物的生长发育带来严重的负效应,而O_3本身难溶于水,主要通过干沉降方式沉降到陆地生态系统。该研究采用涡度相关法对冬小麦(Triticum aestivum)田主要生育期的O_3干沉降过程进行了观测,利用边界线技术和线性相关法分别分析了O_3干沉降速率最大值(Vdmax)和太阳辐射(SR)、温度(T)、相对湿度(RH)及O_3干沉降速率(Vd)和摩擦速度(u*)的关系,并运用彭曼公式结合总初级生产力(GPP)估算不同O_3沉降通道的分配比例。研究结果表明:(1)观测期间30 min平均O_3浓度(CO_3)、O_3干沉降通量(FO_3)、Vd分别为32.9 n L·L–1、–5.09 nmol·m–2·s–1、0.39 cm·s–1,CO_3、FO_3、Vd的变化范围分别为16–58 n L·L–1、–2.9––11.7 nmol·m–2·s–1、0.17–0.63 cm·s–1,其中FO_3和CO_3、Vd的关系并不是同步的。(2)初步推断出较强光照(SR≥400 W·m–2)、适宜的温度(T=18℃)以及较为湿润(RH>40%)的环境条件比较有利于O_3干沉降过程。其中Vdmax与SR呈增长关系(y=1.06–exp(–0.0094–x)),SR<400 W·m–2时Vdmax随SR的增大而增大,并在SR=400 W·m–2左右达到最大值,当SR≥400 W·m–2时Vdmax持续维持在最大值;Vdmax与T呈“钟形”曲线关系(y=1.06–(x–18)2/169),当T=18℃时Vdmax达到最大;当RH<40%时Vdmax呈下降趋势(y=0.030x–0.106);当相对湿度较高时,白天的Vd随RH下降有下降趋势,而夜间的Vd随RH增加而上升,因此Vd可能随RH增大而增大,也可能随RH增大而减小。u*与Vd存在一定的线性正相关关系,但相关并不显著。(3)整个观测期平均气孔O_3沉降通道和非气孔O_3沉降通道占总O_3干沉降通量的分配比例分别是32%和68%;白天通过气孔O_3沉降通道和非气孔O_3沉降通道所沉降的O_3通量平均占总O_3干沉降通量的比例分别是42%和58%,其中叶面积指数和降雨均会影响气孔O_3沉降。
High concentrations of ozone (O 3) in the near-surface layer have a serious negative effect on the growth and development of plants. However, O 3 itself is hardly soluble in water and settles mainly into the terrestrial ecosystems by dry deposition. In this study, we used the eddy covariance method to observe the dry deposition process of O_3 in the main growth period of winter wheat (Triticum aestivum) field. By using the boundary line technique and the linear correlation method, the maximal dry deposition rate of O_3 and the solar radiation SR), temperature (T), relative humidity (RH) and dry deposition rate (Vd) and friction velocity (u *) of O_3 were calculated and the distribution of different O_3 sedimentation channels was estimated by Penman’s formula and total primary productivity (GPP) proportion. The results showed that: (1) The average O_3 concentration and the O_3 dry deposition flux (FO_3) at 30 min were 32.9 nL·L-1 and -5.09 nmol · m-2 · s-1, respectively, The ranges of 0.39 cm · s-1, CO 3, FO 3 and Vd were 16-58 nL·L-1, -2.9-11.7 nmol · m-2 · s-1, 0.17-0.63 cm · s-1 , Where FO_3 and CO_3, Vd relationship is not synchronized. (2) It is preliminarily concluded that the environmental conditions of relatively strong light (SR≥400 W · m-2), appropriate temperature (T = 18 ℃) and relatively wet (RH> 40%) are more favorable for the dry deposition of O_3. Vdmax increases with SR (y = 1.06-exp (-0.0094-x)). When SR <400 W · m-2, Vdmax increases with the increase of SR and increases with SR = 400 W · m-2 (Max), the maximum value of Vdmax kept at SR≥400 W · m-2, and the relation between Vdmax and T was “bell” (y = 1.06- (x-18) 2/169) Vdmax reaches the maximum at T = 18 ℃; Vdmax decreases at RH <40% (y = 0.030x-0.106); when the relative humidity is high, RH increases and rises, so Vd may increase with increasing RH, may also decrease with increasing RH. There is a certain linear positive correlation between u * and Vd, but the correlation is not significant. (3) The distribution ratio of average stomatal O_3 settling channel and non-stomatal O_3 settling channel in the whole observation period is 32% and 68% of the total O_3 dry settling flux, respectively. During the day, the distribution of stomatal O_3 settling channel and non-stomatal O_3 settling channel The average flux of O_3 accounted for 42% and 58% of the total O_3 dry deposition flux, respectively, of which leaf area index and rainfall all affected stomatal O_3 sedimentation.