论文部分内容阅读
Air samples in China were collected and determined for the concentration of N_2O.The production rates of N_2O from agricultural soils were measured with the chamber method.The results in-dicate that the background concentration of N_2O averages(308±5)×10~(-9)in 1989,which is close to that ob-tained at the other background stations abroad.However,at both urban and rural areas,atmospheric N_2Oconcentrations are higher.N_2O emission fluxes from several farmlands are different and dependent on the fac-tors of agricultural practice and climate.But their magnitudes are at the same order.Preliminary calculationshows that the released N_2O-N from agricultural sources(cultivated soil and N-fertilizers)amounts to 122Gg/a in China in 1990.
Air samples in China were collected and determined for the concentration of N_2O. The production rates of N_2O from agricultural soils were measured with the chamber method. The results in-dicate that the background concentration of N_2O averages (308 ± 5) × 10 ~ ( -9) in 1989, which is close to that ob-tained at the other background stations abroad.However, at both urban and rural areas, atmospheric N 2 Oconcentrations are higher. N_2O emission fluxes from several farmlands are different and dependent on the fac-tors of agricultural practice and climate.But their magnitudes are at the same order. Preliminary calculation of the released N2O-N from agricultural sources (cultivated soil and N-fertilizers) amounts to 122 Gg / a in China in 1990.