| Ammonia?NH3?is one of the most important alkaline gases in the atmosphere.It reacts with sulfur dioxide?SO2?and nitrogen oxides?NOx?to form secondary particles,such as ammonium sulfate and ammonium nitrate.It has an important impact on the formation of haze and air pollution.Agricultural sources are the main sources of ammonia emissions,mainly including nitrogen fertilizer and livestock ammonia emissions.Ammonia emissions from livestock are the main source of agricultural ammonia emissions.China is a big country,which has a large number of pigs.While the current domestic research in this area is still relatively small.Therefore,the research on the ammonia emission characteristics of typical large-scale pig farms in Shanghai has a great significance to clarify the current situation of ammonia emission from typical agricultural sources,to control the pollution of atmospheric particulate matter and improve the quality of ambient air.In this study,the ammonia levels of the three major ammonia excrement sites in typical pig farms,composting and sewage storage were monitored by using the on-line electrochemical sensor and manual sampling laboratory analysis.Then it needed to discuss the influence factors of temperature and wind speed on the ammonia emission.Finally,the ammonia emission flux level and emission coefficient of three large ammonia emissions from the shed,compost and sewage storage were calculated.The results showed that:?1?In general,ammonia emissions from the shed showed a higher level.The average concentration of four seasons were 10.48,1.82,8.98,9.78 mg/m3 and the maximum reached 13.62,2.01,16.99,15.95 mg/m3.Ammonia emissions showed significant changes of hour characteristics.Ammonia concentration was higher during the daytime than nighttime.The maximum value appeared near 13-15 o'clock,the minimum value appeared at 1-7 o'clock.The maximum value was about three times of the minimum value.The ammonia emission coefficients in the four seasons were 4.51 ±0.70,11.89±0.60,8.91±2.14,4.54±1.13 g/?pig·d?,and coefficients in summer and autumn were twice than the spring and winter.The annual average ammonia emission coefficient was 7.97±3.41 g/?pig·d?.?2?The average ammonia concentration of composting in four seasons were 1.05,0.64,0.67,0.36 mg/m3,and the maximum reached 1.37,1.01,1.04,0.51 mg/m3.The diurnal variation of ammonia emission in each season showed significant bimodal characteristics.The first peak appeared at 10-12 am and the second peak at 15-17 pm.The minimum value appeared at 3-6 am and the maximum value was about three times of the minimum.The ammonia emission coefficients in the four seasons were 0.71 ±0.19,0.87±0.14,1.05±0.35,0.2531±0.10 g/?pig·d?.The average annual ammonia emission coefficient for post-fermentation was 0.76±0.35 g/?pig·d?.The average annual ammonia emission coefficient for pre-fermentation was 1.04 g/?pig·d?.The total ammonia emission coefficient of the pre-fermentation and post-fermentation manure compost was 1.80 g/?pig·d?.?3?The average ammonia concentration of sewage storage in four seasons were 0.51,0.58,0.38,0.33 mg/m3,and the maximum reached 0.66,0.90,0.57,0.49 mg/m3.Ammonia emissions showed no obvious regularity of hour characteristics,which mainly affected by wind speed and peaked at random.The ammonia emission coefficients in the four seasons were 1.49±0.39,2.5210.38,1.08±0.34,1.50±0.55 g/?pig·d?,and the coefficient in summer was higher.The annual average ammonia emission coefficient was 1.68±0.71 g/?pig·d?.?4?The correlation study showed that temperature was the most important meteorological factor,and wind speed also had an important influence on ammonia emission,both of which had good correlation with ammonia emission from the shed,compost and sewage storage.In the autumn and winter,the temperature had greater impact on ammonia emissions of the shed,composting and sewage storage.R2 were 0.6628,0.3090,0.6481 and 0.2895,0.7091,0.2628;In contrast,in the summer and autumn,the wind speed had greater impact on ammonia emissions of the shed,composting and sewage storage.R2 were 0.5285,0.5948,0.4810 and 0.5102,0.5484,0.5879.?5?A typical comparative study of ammonia emissions showed that the shed was the main source of ammonia emissions from large-scale farms.The average concentration of each season was 8.98-10.48 mg/m3?1.82 mg/m3 of mechanical ventilation in summer?,which was much higher than that of composting 0.36-1.05 mg/m3 and 0.33-0.58 mg/m3 for sewage storage.The ammonia concentration of the shed was about 10-20 times of composting and sewage storage.It indicated that the ammonia emission of the shed was worthy of attention.Ammonia emission coefficient studies also showed that the ammonia emission coefficients of the shed in the four seasons were 4.51-11.89 g/?pig·d?,which was much higher than that of composting 0.31-1.05 g/?pig·d?and 1.08-2.52 for sewage storage.It also showed that large-scale pig farms breeding was an important part of ammonia emissions,which could be used as a priority control target.?6?This study showed that large-scale pig farm was one of the important source from agricultural ammonia emissions.The three major levels of ammonia emission concentration were 1.82-10.48,0.36-1.05 and 0.33-0.58 mg/m3.It respectively reached about 100-500 times,30-50 times and 10-30 times of the ambient air background ammonia concentration??0.010-0.020 mg/m3?.The average emission coefficients of the shed,composting and sewerage were 7.97±3.41.1.80?late fermentation:0.76?,and 1.68±0.71 g/?pig·d?.The total emission coefficient reached 11.45 g/?pig·d?,and the annual emission level reached 4.18 kg/pig. |
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