Zhang Jiaen

Toxicological effect of Agave sisalana Perrine extract on golden apple snail (Pomacea canaliculata Lamarck).

Pomacea canaliculata Lamarck is an invasive alien species that is very harmful to the ecosystem and rice production in South China.To verify the toxicity and related mechanism of Agave sisalana Perrine to golden apple snail,the toxic effects of aqueous,n-butanol and ethanol extracts of A.sisalana were tested via the snail-immersed method.The effects of n-butanol(59 mg·L-1,96 mg·L-1) and ethanol(180 mg·L-1,325 mg·L-1) extracts on cholinesterase(ChE),superoxide dismutase(SOD) and adenosine triphosphatase(ATPase) activities in hepatic tissue of golden apple snails were also investigated.Based on the results,aqueous,n-butanol and ethanol extracts of A.sisalana had toxic effects on golden apple snail.Their semi-lethal concentrations(LC50) on golden apple snail for 72 h toxicity exposure were 35.3 g·L-1,93.3 mg·L-1 and 298.6 mg·L-1,respectively.The corresponding 95% confidence interval ranges were 32.9~37.7 g·L-1,87.6~99.7 mg·L-1 and 272.9~318.7 mg·L-1,respectively.When treated with n-butanol and ethanol extracts for 12 h,SOD activity in snail hepatic tissues showed no obvious change at low concentrations.SOD activity,however,increased significantly at high concentrations.After treatment for 48 h,SOD activity at high concentrations of n-butanol extract was significantly higher than that of the control.However,SOD activity did not show any obvious change in both low and high concentrations of ethanol extract.All A.sisalana extracts somehow increased ChE activity,with n-butanol extract exhibiting higher effect on ChE activity.When treated with 96 mg·L-1 n-butanol extract for 48 h,ChE activity significantly exceeded that of the control(P 0.05).Overall,n-butanol extract treatment enhanced ATPase activity at low concentrations and suppressed it at high concentrations.Irrespectively,no obvious pattern change was noted under ethanol extract treatment.In conclusion,A.sisalana was somehow toxic to golden apple snail.A better mode of application was needed for future exploitations.

Eco-efficiency of circular economy development of Guangdong Province.

On the base of the essentials of circular economy and connotations of eco-efficiency, an eco-efficiency index system for assessing the circular economy of Guangdong Province was established with reference to local and international research. By using the established index system, variations in the economy and eco-efficiency for the period from l990 to 2007 were analyzed. The results indicate that Guangdong provincial GDP achieves a high and rapid growth during the last 18 years. Concurrent eco-efficiency indicators and labor productivity display increasing trends for especially the eco-efficiency of total water consumption and construct land. Average annual growth rate of the two indicators respectively reach 21.29% and 17.28%, both are lower than that for GDP. Prediction results from transformed human-environment equation (IPAT) reveal that under present economic growth, strategic objectives for the augmentation of Guangdong provincial economy could be realized by 2015. However, increase in energy consumption and environment load may induce high pressure on the eco-environment.