Study And Applicaton Of Monitoring Methods Of Atmospheric Peroxides

Peroxide is a important pollutant in troposphere atmospheric chemistry. Research has pointed out that peroxide especially hydrogen peroxide (H2O2) is not only the main antioxidant which can convert SO2into sulfuric acid or SO42-in liquid phase,but also the source and sink for free radicals, such as OH and HO2. In addition, Peroxide can endanger human health and affect plant growth. Therefore it is very important to accurately determine the concentration of peroxide in the atmosphere and master the chemistry process. However, peroxides is extremely unstable and its concentration is very low in atmosphere. Besides that it can be affected by the interference of SO2during the monitoring. In order to accurately determine the concentration of peroxide in the atmosphere, there is an urgent need to develop a better method for the elimination of interference from SO2and analysis which has low limits of detection and is economic as soon as possible expecially in our country whose photochemical smog pollution is relatively serious and the concentration of SO2is high. It not only provide necessary technical support and scientific data for studying the formation mechanism of photochemical smog and the causes of acid rain and aerosol, but also provide scientific evidence for making H2O2pollution prevention correctly and control countermeasures.This thesis, researched the methods for the analysis of peroxide and sampling methods which was used when photochemical smog pollution was relatively serious or concentration of SO2was high. At last,, we did preliminary research about the changes of atmospheric peroxides and its influence factors in Beijing. The results of analytical methods show that compared with Hemin method, HRP method has a low detection limit, high correlation coefficient, precision, sensitivity, accuracy and suitability in analysing peroxide. Therefore HRP method is more suitable for the analysis of peroxides in atmosphere. The results of sampling methods show that the method for fog liquid absorption which used pH7H2O as the absorption liquid is the best sampling method for peroxide. The monitoring results showed that atmospheric peroxides in Beijing city in summer was mainly for H2O2and MHP as well as that the concentration of H2O2ranged from0.02to2.36ppb and its concentration is higher in sunny day than it in cloudy day. Moreover,.the concentration of H2O2showed the diurnal variation: it was lower in the morning and evening than it in afternoon in sunny day while the concentration of H2O2increased with the increase of O3, T and SR, but decreased with the increase of NOx, RH and SO2. So we can concluded that H2O2was mainly generated by photochemical reaction and the reaction between VOCs which was come from motor vehicle emissions and O3or OH was also one of the source of H2O2. The concentration of MHP ranged from0.05to0.254ppb, which showed that its concentration was lower in sunny day than in the cloudy day and the concentration of MHP showed diurnal variation:it was lower during the day than in the evening. The concentration of MHP reduced with the increase of the SR, SO2and RH. As a result MHP mainly comes from the reaction between VOCs and O3or OH generated by the motor vehicle.