The water purification function of natural wetland systems is widely recognized,but rarely studied or scientifically evaluated.Extensive studies have been carried out by various international wetland research communit...The water purification function of natural wetland systems is widely recognized,but rarely studied or scientifically evaluated.Extensive studies have been carried out by various international wetland research communities to quantify the water quality improvement ability of the natural wetlands,in order to maintain such ability and wetland ecological health.This study aims to evaluate the purification function of Zhalong Wetland in China for removing total nitrogen(TN) and phosphorus(TP),based on ex-situ experiments and the development of a combined water quantity-quality model.Experiments and model predictions were carried out with different input TP and TN concentrations.Statistical analyses demonstrated that the relative errors between model simulations and experimental observations for TN and TP were 8.6% and 12.4%,respectively.With water retention time being maintained at 90 d,the removal rate of these pollutants could not reach the required Grade V standards,if the inflow TN concentration was over 42 mg L-1,or the input TP concentration was over 14 mg L-1.The simulation results also demonstrated that,even with Grade V quality standard compliance,when the water inflow from surrounding industries and agriculture lands into Zhalong Wetland reaches 0.3×10 8 m 3 a-1,the maximum TN and TP loads that the reserve can cope with are 1.26×10 3 t a-1 and 0.42×10 3 t a-1,respectively.Overall,this study has produced a significant amount of information that can be used for the protection of water quality and ecological health of Zhalong Wetland.展开更多
Based on the Chinese General Social Survey 2006 and 2008 data,this paper assesses the influence of the family planning policy on the qualitative development of children using education attainment and individual income...Based on the Chinese General Social Survey 2006 and 2008 data,this paper assesses the influence of the family planning policy on the qualitative development of children using education attainment and individual income of only children versus children with siblings as parameters.Our results show the following:(1)only children are better-educated than their counterparts with siblings;(2)only children earn higher income in comparison to their counterparts with siblings;(3)the income and education gaps between girls with and without siblings are greater than those between boys;(4)the education gaps between only children and children with siblings are greater for those born in the 1970s,but the income difference between only children and children with siblings is only significant for those born in the 1980s;and(5)the income and education gaps between only children and children with siblings are higher in urban regions.Results indicate that families with only one child invest more resources in children's quality under the family planning policy,which is consistent with the"quantity-quality trade-off"theory proposed by Gary Becker.展开更多
基金supported by the Knowledge Innovation Programs of Chinese Academy of Sciences (Grant No. KZCX2-YW-Q06-2)the National Basic Research Program of China ("973" Program) (Grant No.2010CB428404)
文摘The water purification function of natural wetland systems is widely recognized,but rarely studied or scientifically evaluated.Extensive studies have been carried out by various international wetland research communities to quantify the water quality improvement ability of the natural wetlands,in order to maintain such ability and wetland ecological health.This study aims to evaluate the purification function of Zhalong Wetland in China for removing total nitrogen(TN) and phosphorus(TP),based on ex-situ experiments and the development of a combined water quantity-quality model.Experiments and model predictions were carried out with different input TP and TN concentrations.Statistical analyses demonstrated that the relative errors between model simulations and experimental observations for TN and TP were 8.6% and 12.4%,respectively.With water retention time being maintained at 90 d,the removal rate of these pollutants could not reach the required Grade V standards,if the inflow TN concentration was over 42 mg L-1,or the input TP concentration was over 14 mg L-1.The simulation results also demonstrated that,even with Grade V quality standard compliance,when the water inflow from surrounding industries and agriculture lands into Zhalong Wetland reaches 0.3×10 8 m 3 a-1,the maximum TN and TP loads that the reserve can cope with are 1.26×10 3 t a-1 and 0.42×10 3 t a-1,respectively.Overall,this study has produced a significant amount of information that can be used for the protection of water quality and ecological health of Zhalong Wetland.
文摘Based on the Chinese General Social Survey 2006 and 2008 data,this paper assesses the influence of the family planning policy on the qualitative development of children using education attainment and individual income of only children versus children with siblings as parameters.Our results show the following:(1)only children are better-educated than their counterparts with siblings;(2)only children earn higher income in comparison to their counterparts with siblings;(3)the income and education gaps between girls with and without siblings are greater than those between boys;(4)the education gaps between only children and children with siblings are greater for those born in the 1970s,but the income difference between only children and children with siblings is only significant for those born in the 1980s;and(5)the income and education gaps between only children and children with siblings are higher in urban regions.Results indicate that families with only one child invest more resources in children's quality under the family planning policy,which is consistent with the"quantity-quality trade-off"theory proposed by Gary Becker.
