NOx在长江三角洲地区冬小麦农田与大气间的交换

利用4动态箱体系测定了NOx(NO NO2)在长江三角洲平原地区典型冬小麦农田与大气间的交换通量.NO和NO2的平均交换通量分别为169.7ng·m-2·s-1和-18.5ng·m-2·s-1,表明该地区麦田是大气中NO的一个重要源,是NO2的汇.在冬小麦主要生长期(拔节-抽穗期),NO的交换通量与地表土壤温度呈指数关系.NO2的交换通量与其在环境中的浓度存在明显的负线性关系,其在农田与大气间交换的补偿点(交换通量为0时环境大气中NO2浓度)为11.9μg·m-3.正常耕作的小麦农田以NO-N方式排放的N占施肥总N的2.3%,表明NO挥发为农田氮肥损失的重要形式.追加尿素木质素混合肥料虽然提高了小麦产量,但也显著刺激了农田对NO的排放.

Surface-exchange of NOx above a typical wheat land in the yangtze delta, China

A four-dynamic-chamber system was established to measure NO_X (NO+NO₂) surface-exchange between a typical wheat field and the atmosphere in the Yangtze Delta, China. The average fluxes of NO and NO₂ for the urine fertilized wheat filed during the main growth stages were 169.7 ng·m^-2·s^-1 and -18.5ng·m^-2·s^-1. Therefore, the wheat field acted as an important source of NO, but as a sink for NO₂. The NO flux was exponential correlated with soil temperature and the fluxes of NO₂ were negatively correlated with!their ambient concentrations during the investigated period. The compensation point of NO₂ between the winter wheat field and the atmosphere was 11.9 g·m^-3. The emission of NO-N from the urea applied to the wheat field was 2.3%, which indicated that NO-N volatilization was an important pathway of N loss form the fertilizer. Application of a mixture of urea and lignin increased the yield of the winter wheat, but also greatly stimulated the emissions of NO.