[Observation of ozone dry deposition in the field of winter wheat.] / 冬麦田臭氧干沉降过程的观测.

Ozone is one of the main atmospheric pollutants over surface layer, and its increasing surface ozone concentration and its impact on main crops have become the focus of the public. In order to explore ozone deposition law and environmental factors influencing ozone deposition process, this study used the micrometeorological methods and carried out the experiment under natural conditions. The results showed that during the observational period (the vigorously growing season of wheat), the mean value of ozone flux was -0.35 µg·m-2·s-1(the negative sign indicated that the deposition direction was toward the ground). The mean rate of ozone deposition was 0.55 cm·s-1. The mean value of aerodynamic resistance was 30 s·m-1, the mean value of sub-layer resistance was 257 s·m-1, and that of the canopy layer stomatic resistance was 163 s·m-1. All the test parameters presented distinct diurnal fluctuation. The ozone deposition resistance was influenced by friction velocity, solar radiation velocity, temperature, relative humidity and other factors.

[Nitrous oxide flux at the water-air interface of the rivers in Nanjing during summer].

Employing floating static chamber-chromatography method, the N2O diurnal fluxes at the water-air interface of four rivers (Tuanjie River, Jinchuan River, Inner and Outer Qinhuai River) and Jinniu Lake were monitored in Nanjing during summer. The results show that four rivers act as the sources of N2O emission, but Jinniu Lake is characterized by the absorption of N2O. The highest N2O flux from Inner Qinhuai presented at 20:00 because of the changing of hydrodynamic conditions. Both Jinchuan and Tuanjie rivers' minimum N2O fluxes were detected when the content of dissolved oxygen was extremely low. The tendency of N2O from Outer Qinhuai showed a double-peak because of its daytime nitrification and nocturnal denitrification. The flux of N2O from Jinniu Lake had been noted as being generally higher at night than that during light hours due to the effect of wind. For natural rivers, the proper sampling period is from 08:00 to 12:00, but for the river subjected to interference, the sampling period is different.