| Ammonia plays a key role in the nitrogen cycle in atmosphere,soil and water.Therefore,studying the on-line detection methods of the anthropogenic ammonia emission sources with high weight and regularity emission including agricultural non-point source,industrial point source,vehicle mobile source and mastering the emission laws,is very significant for the study of global nitrogen cycle and environmental protection.In order to meet the requirements for ammonia emission on-line monitoring,this paper presents the ammonia detection method of infrared spectral characteristics at high temperature and the accurate concentration inversion algorithm,and the research of on-line detection technology and application of regional ammonia emission flux.The infrared vibration-rotation absorption band and the partition function of ammonia were studied,and the absorption spectra at 6528.8cm-1 were analyzed.The experimental platform for laser absorption spectroscopy measurement of ammonia infrared band at high temperature was established,and the characteristic spectra and line strength detection experiment at high temperature was carried out.Meanwhile,the characteristic absorption spectrum of ammonia at room temperature and 500-700K at different temperature and pressure were obtained,the line shape and line strength parameters of the room temperature and high temperature environment were also analyzed and obtained.The concentration inversion algorithm for high temperature ammonia based on high-resolution near-infrared absorption spectroscopy was studied.The concentration inversion model for high temperature ammonia monitoring and spectral correlation analysis algorithm in real measurement environment were established based on the characteristic spectrum analysis,multi-line Voigt line profile fitting and temperature parameter correction.The fitting residual of the multi-line overlap is better than ±2%in the experiment,and the relative error is less than 5%when the correlation coefficient between the measured spectral and standard spectra is better than 85%.The accuracy of high temperature ammonia concentration inversion is about 4%.The system control and concentration inversion software of ammonia on-line detection at high temperature was designed,and the detection experiment at ammonia escape site of high temperature was carried out.The results showed that the ammonia emission was negatively correlated with the NOx emission concentration.The ammonia on-line detection experiment for vehicle exhaust was carried out by high temperature heating and sampling system.The mean concentration of ammonia emission was about 1.64ppm at the idle speed of 800r/min,and the mean concentration increased to 2.24ppm at the idle speed of 1500 r/min.These experiment results show that the ammonia concentration increased with increasing rotating speed.The effectiveness of the bLS model and data fusion method for flux monitoring with OP-TDLAS technology combined with bLS model was studied,including the experimental conditions of optical path and height of setting up and average period of data.Moreover,the regional open monitoring mode was optimized and the consistency was analyzed.The monitoring application research of ammonia emissions from farmland and plants were carried out,so the soil ammonia emission law under straw returning and farmland fertilization in north of Anhui province was obtained.The results show that the effect of fertilization on ammonia emission was faster and the duration period was shorter,but the effect of straw returning was more obvious and the duration period was longer.During ten days after fertilization,the ammonia volatilization flux was large and the peak value reached to 5.34 kg N/(hm~2d)at the experiment site in Huang-Huai-Hai plain.During ammonia monitoring in different seasons at typical urban dairy,the emission rate related to the temperature and weather conditions reflects the seasonal difference,which was 1.48?130.6(kg/head/hr)in autumn and 0.0045?43.32(kg/head/hr)in winter. |
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