The purpose of this paper is to investigate reasonable cost benefit criteria within the framework of environmental formal safety assessment （FSA）. In this study a statistical analysis of oil spill data was carried o...The purpose of this paper is to investigate reasonable cost benefit criteria within the framework of environmental formal safety assessment （FSA）. In this study a statistical analysis of oil spill data was carried out based on the report of International Oil Pollution Compensation Funds. According to the statistical study of actual oil spill from tankers, it is found that collisions and groundings are the most probable causes of the oil spills from tankers. Probability distributions of costs of oil spill and oil spill amount are investigated, and a non-linear regression formula between costs of oil spills and oil spill weight are derived. Using the regression formula, an oil spill weight dependent CATStm （Cost of Averting a Ton of oil Spilt） is proposed. Moreover in order to apply the weight dependent CATSthr to cost benefit analysis （CBA）, a new cost-effective criterion is newly proposed with considering its concrete application to environmental FSA.展开更多
The ring-width chronology of a Juniperus przewalskii tree from the middle of the Qilian Mountain was constructed to estimate the annual precipitation (from previous August to current July) since AD 1480.The reconstruc...The ring-width chronology of a Juniperus przewalskii tree from the middle of the Qilian Mountain was constructed to estimate the annual precipitation (from previous August to current July) since AD 1480.The reconstruction showed four major alternations of drying and wetting over the past 521 years.The rainy 16th century was followed by persistent drought in the 17th century.Moreover,relatively wet conditions persisted from the 18th to the beginning of 20th century until the recurrence of a drought during the 1920s and 1930s.Based on the Empirical Mode Decomposition method,eight Intrinsic Mode Functions (IMFs) were extracted,each representing unique fluctuations of the reconstructed precipitation in the time-frequency domain.The high amplitudes of IMFs on different timescales were often consistent with the high amount of precipitation,and vice versa.The IMF of the lowest frequency indicated that the precipitation has undergone a slow increasing trend over the past 521 years.The 2-3 year and 5-8 year time-scales reflected the characteristics of inter-annual variability in precipitation relevant to regional atmospheric circulation and the El Ni?o-Southern Oscillation (ENSO),respectively.The 10-13 year scale of IMF may be associated with changing solar activity.Specifically,an amalgamation of previous and present data showed that droughts were likely to be a historically persistent feature of the Earth's climate,whereas the probability of intensified rainfall events seemed to increase during the course of the 19th and 20th centuries.These changing characteristics in precipitation indicate an unprecedented alteration of the hydrological cycle,with unknown future amplitude.Our reconstruction complements existing information on past precipitation changes in the Qilian Mountain,and provides additional low-frequency information not previously available.展开更多
文摘The purpose of this paper is to investigate reasonable cost benefit criteria within the framework of environmental formal safety assessment （FSA）. In this study a statistical analysis of oil spill data was carried out based on the report of International Oil Pollution Compensation Funds. According to the statistical study of actual oil spill from tankers, it is found that collisions and groundings are the most probable causes of the oil spills from tankers. Probability distributions of costs of oil spill and oil spill amount are investigated, and a non-linear regression formula between costs of oil spills and oil spill weight are derived. Using the regression formula, an oil spill weight dependent CATStm （Cost of Averting a Ton of oil Spilt） is proposed. Moreover in order to apply the weight dependent CATSthr to cost benefit analysis （CBA）, a new cost-effective criterion is newly proposed with considering its concrete application to environmental FSA.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41001058, 41001009, 40971119 and 40890052)the China Postdoctoral Science Foundation (Grant Nos. 201003194)
文摘The ring-width chronology of a Juniperus przewalskii tree from the middle of the Qilian Mountain was constructed to estimate the annual precipitation (from previous August to current July) since AD 1480.The reconstruction showed four major alternations of drying and wetting over the past 521 years.The rainy 16th century was followed by persistent drought in the 17th century.Moreover,relatively wet conditions persisted from the 18th to the beginning of 20th century until the recurrence of a drought during the 1920s and 1930s.Based on the Empirical Mode Decomposition method,eight Intrinsic Mode Functions (IMFs) were extracted,each representing unique fluctuations of the reconstructed precipitation in the time-frequency domain.The high amplitudes of IMFs on different timescales were often consistent with the high amount of precipitation,and vice versa.The IMF of the lowest frequency indicated that the precipitation has undergone a slow increasing trend over the past 521 years.The 2-3 year and 5-8 year time-scales reflected the characteristics of inter-annual variability in precipitation relevant to regional atmospheric circulation and the El Ni?o-Southern Oscillation (ENSO),respectively.The 10-13 year scale of IMF may be associated with changing solar activity.Specifically,an amalgamation of previous and present data showed that droughts were likely to be a historically persistent feature of the Earth's climate,whereas the probability of intensified rainfall events seemed to increase during the course of the 19th and 20th centuries.These changing characteristics in precipitation indicate an unprecedented alteration of the hydrological cycle,with unknown future amplitude.Our reconstruction complements existing information on past precipitation changes in the Qilian Mountain,and provides additional low-frequency information not previously available.
