Clarification of Dry deposition of Suifer dioxide to Basic Soils and Estimation of Its deposition amount

2003-2005财政年度，我们与中日环境保护友好中心和中国环境科学研究院的海外合作研究人员在北京、兰州和大同的中国测量了二氧化硫和臭氧的干沉降速度。在采样点的选择上，考虑了交通便利、物资供应方便、地面平整度、范围面积、地表条件(包括植被)、二氧化硫基线浓度、代表风速、平均温度、湿度等地形信息，在各自的采样点分别采用气象梯度法和被动法(代表面法)，利用实际土壤进行了一、两季的沉积速度测量实验。尽管如此，北京和兰州是黄沙接受区和空气污染城市，…在中国观测到的光化学烟雾较多。利用气象梯度法得到了二氧化硫和臭氧的干沉降速率。用代表面法计算了二氧化硫的沉积速度。在对上述两种方法估算的二氧化硫干沉降速度进行比较时，一般情况下，梯度法的干沉降速度高于被动法。为了弄清二氧化硫干沉降速度的控制因素，对兰州采集的黄土进行了室内接触二氧化硫的实验，考虑到与现场测量数据的一致性，在臭氧、氮氧化物、硝酸、甲醛和湿度变化的单一和共存条件下进行了实验。虽然臭氧的存在并没有改变二氧化硫的沉积速率，但从沉积硫化物的分析来看，随着臭氧浓度的增加，[S(IV)-S(VI)]氧化沉积的二氧化硫所占的比例有增大的趋势。在干燥条件下，硝酸或甲醛的共存使二氧化硫的沉积速度降低到较小的程度。硫氧化物的沉积速度随着湿度的增大而增大，在干燥等实际观测条件下，硫氧化物的沉积速度比加湿时低得多。较少

During fiscal 2003-2005, we measured dry deposition velocity of sulfur dioxide and ozone in Beijing, Lanzhou, and Daton in China with the overseas cooperative researchers belong to Sino-Japanese Friendship Center for Environmental Protection and Chinese Research Academy of Environmental Sciences. In the selection of sampling sites, the following items were considered ; Convenience of the traffic, convenience of the material supply, flatness of the ground, terrain information such as the area of the extent, earth surface condition including the vegetation, base line concentration of sulfur dioxide, representative wind velocity, mean temperature, humidity, etc. In their sites, measurement experiment of the deposition velocity was respectively carried out at one or two seasons using the meteorological gradient method and passive method (representative surface method) using actual soil proposed by us. Still, Beijing and Lanzhou are yellow sand receptor region and air-polluted cities where … More the photochemical smog was observed in China. Thus, we can examine the dry deposition of the ozone to the loess with it of sulfur dioxide.The dry deposition velocity of sulfur dioxide and ozone was obtained by the meteorological gradient method. Still, the deposition velocity of sulfur dioxide was obtained with representative surface method. In comparison of dry deposition velocity for sulfur dioxide estimated the above two methods, generally, the gradient method gave higher velocity than the passive method.In order to clarify control factor of the deposition velocity, laboratory exposure experiment of loess collected in Lanzhou to sulfur dioxide was carried out under single and coexistence condition of the ozone, nitrogen oxide, nitric acid, formaldehyde, and humidity changed considering the consistency with the field measurement data. Though the sulfur dioxide deposition velocity did not change by the coexistence of the ozone, as a result of the analysis of depositing sulfur compound, the proportion that oxidation of [S(IV)- S(VI)] for deposited sulfur dioxide was done tended to increase, as the ozone concentration is higher, more. In the dry condition, coexistence of nitric acid or formaldehyde caused to decrease the deposition velocity of sulfur dioxide to less. The deposition velocity of sulfur oxide increased, as the humidity is higher, and under the drying condition such as the actual observation, it became low deposition velocity further than the humidifying. Less