Greenhouse Gas Emissions And Ammonia-Nitrogen Isotope Characteristics From Composting Plants And Livestock Farms In Suburbans Of Shenyang

Carbon dioxide（CO2）,methane（CH4）and nitrous oxide（N2O）are the most important greenhouse gases in the atmosphere.It is estimated that anthropogenic CO2,CH4 and N2O emissions contributed 78%,16%and 6%,respectively,to global warming in 2010.Although the concentrations of CH4 and N2O in the atmosphere are much lower than that of CO2,the global warming potential（GWP）of unit molecules CH4 and N2O is 28 times and 265 times of CO2,respectively,on the centennial scale,according to the IPCC Fifth Assessment Report.In addition to the three greenhouse gases,anthropogenic ammonia（NH3）is also an important pollution gas.Its deposition also contributes indirectly to the greenhouse effect,and it is also an important precursor of atmospheric haze pollution（such as PM2.5）.A large amount of CO2,N2O,CH4 and NH3 can be generated in the process of livestock and poultry waste stacking and subsequent composting.It is estimated that CH4 and NH3from livestock and poultry waste account for 37%and 39%of the total anthropogenic emissions in the atmosphere,and are important factors affecting global climate change and ecological environment.However,,in order to facilitate the management of sampling,indoor small simulation tests are mostly used during previous studies,and few studies are carried out under the field conditions.Analysis of air pollutant source contribution is an important prerequisite for air pollution prevention and control.For the traceability of NH3 in the atmosphere,most studies adopted the inventory method.Due to the large spatio-temporal variation of NH3 emissions,the inventory method often fails to reflect the source of ammonia at a smaller spatio-temporal scale.In comparison,the ¹⁵N natural abundance method with different source spectra can accomplish this task well,which is a supplement and verification to the inventory method.However,there is still a lack of basic data on this aspect.Based on this,this study aimed at shenyang suburb of typical and NH3 emission source of greenhouse gases（composting plant,farms）,with the aid of static box and natural abundance isotope analysis technology,carried out in situ monitoring of greenhouse gas emissions and ammonia quantitative characteristics of the study,in order to listing accounting and atmospheric greenhouse gases in the area of ammonia source to provide data support.The main results are as follows:（1）The average emission rates of greenhouse gas and ammonia in a composting plant in the suburb of Shenyang during the composting cycle（19 days）are 86.8 g CO2-C d^-1m^-2,9.8 g CH₄-C d^-1m^-2,3.7 mg N₂O-N d^-1m^-2 and 736.6 mg NH₃-N d^-1m^-2,respectively.The contribution of greenhouse gas daily warming potential（GWP）is CH4>CO2>NH3（indirect）>N2O,of which CH4 contributes the most,accounting for 65%.（2）The isotopic characteristics of ammonia emissions from the composting plant were simultaneously quantified,and it was found that theδ¹⁵N-NH₃ emissions from livestock and poultry waste composting ranged from-21.8‰to-7.2‰,with an average of-11.6±1.2‰,which was significantly different from the previously reported ammonia volatilization sources of nitrogen fertilizer from farmland（average of-50‰）.（3）In addition to composting plants,we also measured theδ¹⁵N-NH₃ source spectrum characteristics of 74 livestock farms in the suburbs of Shenyang,and found that:Hen house29.4～13.7‰（n=17,an average of 20.5‰）,dag–34‰～25.6‰（n=6,average-30‰）,the barn to 59.4～7.7‰（n=45,an average of 38.7‰）,sheep pen-40～18.4‰（n=6,an average of 28.6‰）.Compared with other sources of ammonia nitrogen isotope,such as coal-fired sources（average-6.1‰）,motor vehicle sources（average 6.3‰）,compost（average-11.6‰）,the characteristics of ammonia nitrogen isotope emitted from ammonia volatilizing sources in livestock and poultry farming are more negative.In conclusion,the greenhouse gas emission rate and ammonia isotope characteristics of a composting plant and livestock and poultry farm in shenyang were quantified using static chamber and natural isotope analysis techniques.The results showed that CH4 was the main contributor to the warming potential during the composting of livestock and poultry waste.Theδ¹⁵N-NH3 of livestock and poultry waste is generally negative,and is significantly lower than that of other emission sources except ammonia volatilization of nitrogen fertilizer from farmland.The results of this study can provide basic data for regional GHG emission inventory accounting and atmospheric ammonia pollution traceability.