[Estimation of Agricultural Greenhouse Gas Emissions and Emission Reduction Potential of Beijing During the 14th Five-Year Plan Period Under the Background of "Carbon Peak and Neutrality"].

To achieve the goal of "carbon peak and neutrality," the strict requirements for greenhouse gas (GHG) emissions control in the agricultural sector were recommended in relevant plans for Beijing during the 14th Five-Year Plan period. Through collecting agricultural activity data and calculating and screening the emission factors, the amount and emission characteristics of agricultural GHG emissions in Beijing in 2020 were estimated and set as the baseline condition. On this basis, the GHG emissions in 2025 with optimized measurements implemented, which were selected in combination with the natural conditions and planting-breeding mode of Beijing, were set as the reduction condition. The emission reduction potential and its distribution during the 14th Five-Year Plan Period were predicted simultaneously. Meanwhile, the reduction effects on the GHG emissions of optimized measurements were evaluated. In addition, relevant policy recommendations on GHG reduction were proposed accordingly. The results revealed that the total agricultural GHG emissions in Beijing were estimated to be 456000 t (CO2-eq) in 2020, primarily from sources of animal intestinal fermentation and manure management, with contribution rates of 50.7% and 26.7%, respectively. Spatially, it was mainly distributed in districts with large livestock and poultry breeding scales, such as Shunyi District, Miyun District, and Yanqing District, etc. It was predicted that in 2025, the total agricultural GHG emissions would be 349000 t (CO2-eq), and the emission reduction potential in the 14th Five-Year Plan period would be 107000 t (CO2-eq). Animal intestinal fermentation would be the emission source with the largest reduction potential (60000 tons, CO2-eq), followed by the emission source of animal manure management (37000 tons, CO2-eq). Adjusting fodder composition and optimizing manure management were analyzed to be the most effective optimized measurements for agricultural GHG emission reduction. Moreover, the emission reduction potential of CH4 would be greater than that of N2O. The emission reduction potential would be mainly distributed in Miyun District, Shunyi District, Yanqing District, Fangshan District, Tongzhou District, and other suburbs with large livestock and poultry breeding scales, accounting for more than 10% of the total emission reduction potential for each. These regions with large emission reduction potential should be prioritized and then the assessments should be extended to the whole city. The measurements were recommended as follows:① the research and promotion of technologies such as fodder optimization and the efficient treatment of manure should be strengthened, ② the scope of the combination of planting and breeding model should be expanded to promote the development of circular agriculture, and ③ relevant standards, guidelines, and specifications for green and low-carbon agriculture should be formulated, and the regulatory and policy system for synergy reduction of agricultural pollution and GHG should be developed.

Formic acid catalyzed gas-phase reaction of H2O with SO3 and the reverse reaction: a theoretical study.

The formic acid catalyzed gas-phase reaction between H(2)O and SO(3) and its reverse reaction are respectively investigated by means of quantum chemical calculations at the CCSD(T)//B3LYP/cc-pv(T+d)z and CCSD(T)//MP2/aug-cc-pv(T+d)z levels of theory. Remarkably, the activation energy relative to the reactants for the reaction of H(2)O with SO(3) is lowered through formic acid catalysis from 15.97 kcal mol(-1) to -15.12 and -14.83 kcal mol(-1) for the formed H(2)O⋅⋅⋅SO(3) complex plus HCOOH and the formed H(2)O⋅⋅⋅HCOOH complex plus SO(3), respectively, at the CCSD(T)//MP2/aug-cc-pv(T+d)z level. For the reverse reaction, the energy barrier for decomposition of sulfuric acid is reduced to -3.07 kcal mol(-1) from 35.82 kcal mol(-1) with the aid of formic acid. The results show that formic acid plays a strong catalytic role in facilitating the formation and decomposition of sulfuric acid. The rate constant of the SO(3)+H(2)O reaction with formic acid is 10(5) times greater than that of the corresponding reaction with water dimer. The calculated rate constant for the HCOOH+H(2)SO(4) reaction is about 10(-13) cm(3) molecule(-1) s(-1) in the temperature range 200-280 K. The results of the present investigation show that formic acid plays a crucial role in the cycle between SO(3) and H(2)SO(4) in atmospheric chemistry.