Although cryopreservation of embryos has been used in most terrestrial animals, the application of this technique has not been succeeded for aquatic animals. In this study, the authors investigate the effect of differ...Although cryopreservation of embryos has been used in most terrestrial animals, the application of this technique has not been succeeded for aquatic animals. In this study, the authors investigate the effect of different combinations of sucrose （SUC, C12H22OH） and cryoprotectants （CPAs） on the survival of the catfish embryos （Pangasidae hypophthalmus） at low temperatures （4, 0 and -20 ℃） for short-term storage. For this aim, embryos with somites and optic cups were exposed to different combinations of sucrose with methanol （SUC ＋ MeOH）, 1.2-propylene glycol （SUC ＋ PROH） and ethylene glycol （SUC ＋ EG） at four concentrations ratios： （1） 0.5 M SUC ＋ 0.5 M CPA; （2） 1 M SUC ＋ 0.5 M CPA; （3） 0.5 M SUC ＋ 1 M CPA; （4） 1 M SUC ＋ 1 M CPA for 40 min at 4, 0 and -20 ℃. Embryos kept in water at room temperature （RT）, 4, 0 and -20℃ were used as controls. The survival rate was expressed as a percentage of hatched embryos per total embryos treated. The results showed that the hatching rate declined significantly when embryos were stored in water at 0 ℃ and -20℃. For embryos at 0 ℃ storage, the highest survival rate （87.78%） was obtained with 1 M SUC ＋ 1 M MeOH combination while at -20 ℃, only embryos in the combined treatments of 0.5 M SUC ＋ 1 MEG and 0.5 M SUC ＋ 1 M PROH reached the hatching stage （40% and 83.33%, respectively）. In conclusion, the results showed that the catfish embryos are sensitive to sub-zero temperatures and the combined treatment of 0.5 M sucrose and 1 M propylene glycol can be used to protect catfish embryos from damages caused by low temperature （0 ℃ and -20 ℃）.展开更多
The purpose of this study is to estimate the monetary value of the main environmental and external costs of Yali Hydropower Plant (YHPP) and to incorporate them into the financial viability indices of the plant, namel...The purpose of this study is to estimate the monetary value of the main environmental and external costs of Yali Hydropower Plant (YHPP) and to incorporate them into the financial viability indices of the plant, namely its net present value and electricity price. The results were found that if the electricity price is kept at its original level of 5.2 US cents/kWh to cover direct costs only, the net present value of the plant would be reduced to about 27% by incorporating environmental and external costs. Alternatively, the electricity price would have to be increased to 5.68 US cents/kWh in order to cover the full costs of YHPP and to maintain the original net present value. The main policy recommendations are: Government regulations should require that the financial analysis and appraisal of all future electricity sources include the full cost of these schemes, including not only direct costs but also environmental and external costs related to preventing or mitigating the environmental impact caused by them. An appropriate financial mechanism should be established to allocate the revenue from full cost electricity pricing to a fund to cover the environmental protection and compensation costs.展开更多
文摘Although cryopreservation of embryos has been used in most terrestrial animals, the application of this technique has not been succeeded for aquatic animals. In this study, the authors investigate the effect of different combinations of sucrose （SUC, C12H22OH） and cryoprotectants （CPAs） on the survival of the catfish embryos （Pangasidae hypophthalmus） at low temperatures （4, 0 and -20 ℃） for short-term storage. For this aim, embryos with somites and optic cups were exposed to different combinations of sucrose with methanol （SUC ＋ MeOH）, 1.2-propylene glycol （SUC ＋ PROH） and ethylene glycol （SUC ＋ EG） at four concentrations ratios： （1） 0.5 M SUC ＋ 0.5 M CPA; （2） 1 M SUC ＋ 0.5 M CPA; （3） 0.5 M SUC ＋ 1 M CPA; （4） 1 M SUC ＋ 1 M CPA for 40 min at 4, 0 and -20 ℃. Embryos kept in water at room temperature （RT）, 4, 0 and -20℃ were used as controls. The survival rate was expressed as a percentage of hatched embryos per total embryos treated. The results showed that the hatching rate declined significantly when embryos were stored in water at 0 ℃ and -20℃. For embryos at 0 ℃ storage, the highest survival rate （87.78%） was obtained with 1 M SUC ＋ 1 M MeOH combination while at -20 ℃, only embryos in the combined treatments of 0.5 M SUC ＋ 1 MEG and 0.5 M SUC ＋ 1 M PROH reached the hatching stage （40% and 83.33%, respectively）. In conclusion, the results showed that the catfish embryos are sensitive to sub-zero temperatures and the combined treatment of 0.5 M sucrose and 1 M propylene glycol can be used to protect catfish embryos from damages caused by low temperature （0 ℃ and -20 ℃）.
文摘The purpose of this study is to estimate the monetary value of the main environmental and external costs of Yali Hydropower Plant (YHPP) and to incorporate them into the financial viability indices of the plant, namely its net present value and electricity price. The results were found that if the electricity price is kept at its original level of 5.2 US cents/kWh to cover direct costs only, the net present value of the plant would be reduced to about 27% by incorporating environmental and external costs. Alternatively, the electricity price would have to be increased to 5.68 US cents/kWh in order to cover the full costs of YHPP and to maintain the original net present value. The main policy recommendations are: Government regulations should require that the financial analysis and appraisal of all future electricity sources include the full cost of these schemes, including not only direct costs but also environmental and external costs related to preventing or mitigating the environmental impact caused by them. An appropriate financial mechanism should be established to allocate the revenue from full cost electricity pricing to a fund to cover the environmental protection and compensation costs.
