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The impact of flue gas from the combustion of natural gas or coal in a combustion test facility on the activity of catalysts for the synthesis of cyclic carbonates from epoxides and waste carbon dioxide has been investigated. In batch reactions with styrene oxide as substrate, some loss of catalyst activity was apparent and this was greater for catalyst exposed to flue gas generated from burning coal than for catalyst exposed to flue gas obtained by burning gas. In a gas-phase flow reactor with ethylene oxide as substrate, the detrimental effect of flue gas exposure on catalyst activity was much less apparent.

Based on the seasonal surveying data and long-term data, the annual changes in the geographical locations, occurrence frequency, affected areas and the minimum oxygen level as well as the formation mechanism of the summer hypoxia off the Changjiang estuary are summarized and discussed in this paper. The historical data indicates that there were episodes of hypoxia in the past 50 years but not every year, and the event of summer hypoxia could be traced back to as early as late 1950s off the Changjiang estuary. The minimum oxygen levels in the hypoxia zone did not show any decline in the past 50 years, but all the events with large size of affected area (>5000km(2)) were observed after the late 1990s, suggesting an enlarging trend. The author argues that the development of summer hypoxia off the Changjiang estuary was related not only to stratification and input of suspended particulate matter, but also to the inflow of Taiwan warm current water as well as the bottom topography.

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