We analyzed vertical distributions of ozone(O3)in the lower troposphere(<5 km above ground)at Lin’an(119.75°E,30.30°N),Zhejiang Province using electrochemical concen-tration cell(ECC)ozonesonde data obta...We analyzed vertical distributions of ozone(O3)in the lower troposphere(<5 km above ground)at Lin’an(119.75°E,30.30°N),Zhejiang Province using electrochemical concen-tration cell(ECC)ozonesonde data obtained from February 21 to April 13,2001.The results showed that the vertical O3 distributions are controlled by metrological conditions and the char-acteristics of O3 profiles are related to those of wet bulb potential temperature and wind field.O3 below 2 km showed that the strongest variability and enhanced O3 mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the Yangtze River Delta(YRD)region.Vertical O3 profiles below 5 km can be grouped into 5 categories:(1)peak mixing ratio type,(2)well-mixed type,(3)layered-structure type,(4)episodic pollution type and(5)alti-tudinal increasing type.Vertical distributions of O3 affected by regional transport of polluted air masses were investigated.Transport of polluted air from high latitudes of northern China,ac-companying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3 at Lin’an.The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the YRD and cen-tral-eastern China also lead to regional accumulation of O3 and high O3 mixing ratio at Lin’an.Long-range transport of O3 and pollutants from the Pearl River Delta in South China and in-situ O3 formation also resulted in elevated O3 mixing ratios at around 1 km altitudes and layered O3 distribution in the lower troposphere.展开更多
Ozonation has been widely applied in advanced wastewater treatment. In this study, the effect of ozonation on assimilable organic carbon （AOC） levels in secondary effluents was investigated, and AOC variation of dif...Ozonation has been widely applied in advanced wastewater treatment. In this study, the effect of ozonation on assimilable organic carbon （AOC） levels in secondary effluents was investigated, and AOC variation of different molecular weight （MW） organic components was analyzed. Although the removal efflciencies were 47%-76% and 94%-100% for UV2s4 and color at ozone dosage of 10 mg/L, dissolved organic carbon （DOC） in secondary effluents was hardly removed by ozonation. The AOC levels increased by 70%-780% at an ozone dosage range of 1-10 mg/L. AOC increased significantly in the instantaneous ozone demand phase, and the increase in AOC was correlated to the decrease in UV254 during ozonation. The results of MW distribution showed that, ozonation led to the transformation of larger molecules into smaller ones, but the increase in low MW （〈1 kDa） fraction did not contribute much to AOC production. The change of high MW （〉100 kDa and 10-100 kDa） fractions itself during ozonation was the main reason for the increase of AOC levels. Furthermore, the oxidation of organic matters with high MWs （〉 100 kDa and 10-100 kDa） resulted in more AOC production than those with low MWs （1-10 kDa and 〈1 kDa）. The results indicated that removing large molecules in secondary effluents could limit the increase of AOC during ozonation.展开更多
基金supported by the Research Grant Council of Hong Kong(PolyU.5061/99E and PolyU.5048/02E)an institutional research grant of Hong Kong Polytechnic University(ASD 502)partly by the National Natural Science Foundation of China(Grant No.49975026).
文摘We analyzed vertical distributions of ozone(O3)in the lower troposphere(<5 km above ground)at Lin’an(119.75°E,30.30°N),Zhejiang Province using electrochemical concen-tration cell(ECC)ozonesonde data obtained from February 21 to April 13,2001.The results showed that the vertical O3 distributions are controlled by metrological conditions and the char-acteristics of O3 profiles are related to those of wet bulb potential temperature and wind field.O3 below 2 km showed that the strongest variability and enhanced O3 mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the Yangtze River Delta(YRD)region.Vertical O3 profiles below 5 km can be grouped into 5 categories:(1)peak mixing ratio type,(2)well-mixed type,(3)layered-structure type,(4)episodic pollution type and(5)alti-tudinal increasing type.Vertical distributions of O3 affected by regional transport of polluted air masses were investigated.Transport of polluted air from high latitudes of northern China,ac-companying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3 at Lin’an.The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the YRD and cen-tral-eastern China also lead to regional accumulation of O3 and high O3 mixing ratio at Lin’an.Long-range transport of O3 and pollutants from the Pearl River Delta in South China and in-situ O3 formation also resulted in elevated O3 mixing ratios at around 1 km altitudes and layered O3 distribution in the lower troposphere.
基金supported by Key Program of the National Natural Science Foundation of China (No. 51138006)the special fund from the State Key Joint Laboratory of Environment Simulation and Pollution Control (No. 13L01ESPC)supported by the Collaborative Innovation Center for Regional Environmental Quality
文摘Ozonation has been widely applied in advanced wastewater treatment. In this study, the effect of ozonation on assimilable organic carbon （AOC） levels in secondary effluents was investigated, and AOC variation of different molecular weight （MW） organic components was analyzed. Although the removal efflciencies were 47%-76% and 94%-100% for UV2s4 and color at ozone dosage of 10 mg/L, dissolved organic carbon （DOC） in secondary effluents was hardly removed by ozonation. The AOC levels increased by 70%-780% at an ozone dosage range of 1-10 mg/L. AOC increased significantly in the instantaneous ozone demand phase, and the increase in AOC was correlated to the decrease in UV254 during ozonation. The results of MW distribution showed that, ozonation led to the transformation of larger molecules into smaller ones, but the increase in low MW （〈1 kDa） fraction did not contribute much to AOC production. The change of high MW （〉100 kDa and 10-100 kDa） fractions itself during ozonation was the main reason for the increase of AOC levels. Furthermore, the oxidation of organic matters with high MWs （〉 100 kDa and 10-100 kDa） resulted in more AOC production than those with low MWs （1-10 kDa and 〈1 kDa）. The results indicated that removing large molecules in secondary effluents could limit the increase of AOC during ozonation.
