Analysis Of Ammonia Emission Trends Of Nitrogen Fertilizer In Main Crops Of Beijing,Tianjin And Hebei And Research On Emission Reduction Countermeasures

In recent years,air pollution in the Beijing-Tianjin-Hebei region has been severe in autumn and winter,and smog has occurred frequently.The integration of Beijing-Tianjin-Hebei region is not only economic integration,but also requires ecological integration.The application of nitrogen fertilizer to crops will cause the volatilization of ammonia,which is an important precursor of fine particles and plays a key role in the formation of PM_2.5.In order to understand the historical dynamics of ammonia emissions from the main crops in the Beijing-Tianjin-Hebei region,and provide theoretical and data support for the ammonia control from the source in the Beijing-Tianjin-Hebei region,this paper obtains the planting area and various nitrogen fertilizers of the main crops in the Beijing-Tianjin-Hebei region.According to the emission factor method recommended by the Ministry of Environmental Protection,the amount of ammonia in the nitrogen fertilizer application of the main crops in the Beijing-Tianjin-Hebei region from 2007 to 2016 was estimated,and its emission characteristics and influencing factors were analyzed.Considering the three aspects of planting area,fertilization amount and emission reduction measures,through setting scenarios,the ammonia emission trends and emission reduction potentials of major crops in the Beijing-Tianjin-Hebei region in 2020 are predicted,and ammonia reduction measures are given.The main results are as follows:（1）Among the five major crops in the Beijing-Tianjin-Hebei region,the ammonia emissions of winter wheat increased during 2007²016,while maize,soybean and cotton showed a downward trend,and the annual fluctuation of peanut ammonia emissions was large.Ammonia emissions from five crops are mainly affected by the intensity of ammonia emissions and the area planted.For example,the ammonia emissions of winter wheat can be roughly divided into three periods:the ammonia emissions of winter wheat in2007²010 are rising,from 63.99 kt in 2007 to 73.58 kt in 2010,with an average annual growth rate of 4.78%.During this period,the planting area of winter wheat was stable at around 2566.10khm²,and the increasing emission intensity was the influencing factor of the increase of ammonia emissions in winter wheat during this period.The ammonia emissions of winter wheat in 2010²013 are decreasing,with an average annual decline rate of 3.11%.During this period,the reduction of ammonia emissions was caused by the simultaneous reduction of planting area and emission intensity:（1）The area planted with winter wheat decreased at an average annual rate of 1.01%.（2）The amount of compound fertilizer with a small ammonia emission coefficient increased year by year and urea with higher emission coefficient.The use of ammonium bicarbonate decreases,resulting in a decrease in ammonia emission intensity.In 2013²016,the ammonia emission continued to increase,with an annual growth rate of 2.32%,mainly due to the increase in emission intensity caused by the increase in urea consumption.（2）From the results of the scenario analysis,in the first stage,if the nitrogen application rate and the fertilization method are kept unchanged,the area is estimated to be developed according to the trend（ie A₁BC scenario）.The ammonia emissions of winter wheat,soybean,peanut and cotton are lower than the ammonia emissions in 2016（ie ABC scenario）,and the ammonia emissions of maize are higher than the ammonia emissions of the ABC scenario.if the area is developed according to the planned target（ie A₂BC scenario）,ammonia emissions from winter wheat and cotton are lower than ABC scenarios,and ammonia emissions from other crops are lower than ABC scenarios.In the second stage,if reasonable fertilization is adopted under the trend of estimating the area（ie,A1B1Cscenario）,the ammonia emissions of winter wheat and soybean are lower than those of ABC,and the ammonia emissions of maize,peanut and cotton are higher than those of ABC.If the planting area of the five crops reaches the planned target area by 2020 and the rational fertilization is adopted（ie,A2B1Cscenario）,the ammonia emissions of maize,soybean,peanut and cotton will increase compared with the ABC scenario,and the ammonia emissions of winter wheat will be lower than the ABC scenario.In the third stage,In the third stage,if the planting area of winter wheat,maize,peanuts and cotton reaches the planned target area by 2020 and reasonable fertilization is adopted,the measures for reducing the amount of deep-covering measures（ie A₂B₁C₁ scenario）will be adopted in the topdressing period.The ammonia emissions of each crop were reduced by69.93%,66.33%,33.89%,and-54.92%compared with the ABC scenario.The ammonia emissions of winter wheat,maize,peanuts and cotton topdressing using urease inhibitors（ie A₂B₁C₂ scenario）were 89.80%,79.86%,60.28%,and 7.53%lower than the ABC scenario.The ammonia emissions from the winter wheat,maize,peanut and cotton topdressing to the ammonium nitrate nitrogen fertilizer（ie A₂B₁C₃ scenario）were 72.76%,21.09%,-54.33%and-263.70%lower than the ABC scenario.All four crops had the best ammonia reduction effect under the A₂B₁C₂ scenario with urease inhibitor.If by 2020,maize and soybeans reach the planned target area,the use of coated compound fertilizers for one-time rational fertilization（ie A2B2C4 scenario）will have a significant effect on ammonia reduction,and the ABC scenario emission reduction effect will reach 99.60%and34.09%.In summary,with the adjustment of planting structure and the increasing general fertilization,the ammonia emissions of maize,soybean,peanut and cotton in the Beijing-Tianjin-Hebei region are increasing,while the ammonia emissions of winter wheat are decreasing.Winter wheat,maize,peanuts and cotton can reduce the ammonia volatilization by adding urease inhibitors and other abatement measures during the topdressing stage.Maize and soybean can reduce ammonia volatilization through the application of coated compound fertilizer.