Objective To compare selenium content in hair samples of people in Kaschin-Beck disease(KBD)areas and non KBD areas two months after stopping selenium salt in Shaanxi Province,to provide a scientific basis for KBD con...Objective To compare selenium content in hair samples of people in Kaschin-Beck disease(KBD)areas and non KBD areas two months after stopping selenium salt in Shaanxi Province,to provide a scientific basis for KBD control and prevention.Methods In September2012,four historical KBD areas were selected,including Yongshou,Yuyang,Linyou and Nanzheng,four展开更多
Most studies do not consider the potential variation in carbon concentration among the different tree components of the same species in regional scale. This study examined the carbon concentrations of the compo- nents...Most studies do not consider the potential variation in carbon concentration among the different tree components of the same species in regional scale. This study examined the carbon concentrations of the compo- nents （i.e., foliage, branch, stem, and root） in a 10-year-old poplar species （Populus davidiana Dode） from the Desertification Combating Program of Northern China. The highest and lowest carbon concentrations were found in the stem and foliage, respectively. There was a significant difference in carbon concentrations among the different tree components. All of the observed carbon concentrations of tree components were lower than those predicted using the conversion factor of 0.5 applied to component biomass. Stem carbon made up 59.7% of the total tree biomass carbon. The power equation estimating proportion of tree biomass carbon against the independent variable of diameter at breast height explained more than 90% of the variability in allocation of carbon among tree components. Tree height, as a second independent variable is also discussed. Our results suggest that the difference in organic carbon concentration among tree components should be incorporated into accurately develop forest carbon budget. Moreover, further investigations on how the diameter at breast height equation developed in the present study performs across broader scales are required.展开更多
文摘Objective To compare selenium content in hair samples of people in Kaschin-Beck disease(KBD)areas and non KBD areas two months after stopping selenium salt in Shaanxi Province,to provide a scientific basis for KBD control and prevention.Methods In September2012,four historical KBD areas were selected,including Yongshou,Yuyang,Linyou and Nanzheng,four
基金Acknowledgements We thank Xinqiang Zhang, Xinhua Zeng, and Xin Zhao for their assistance in the field survey and laboratory analysis. This work was funded jointly by the Strategic Priority Research Program of the Chinese Academy of Sciences （No. XDA05060600）, the Natural Science Foundation of Hebei Province （No. C2015503008）, and the Doctoral Initial Fund Project of Hebei Academy of Sciences （No. 20150503LR62-1）. We would also like to thank Christine Verhille at the University of British Columbia for her assistance with the English language and grammatical editing of the manuscript.
文摘Most studies do not consider the potential variation in carbon concentration among the different tree components of the same species in regional scale. This study examined the carbon concentrations of the compo- nents （i.e., foliage, branch, stem, and root） in a 10-year-old poplar species （Populus davidiana Dode） from the Desertification Combating Program of Northern China. The highest and lowest carbon concentrations were found in the stem and foliage, respectively. There was a significant difference in carbon concentrations among the different tree components. All of the observed carbon concentrations of tree components were lower than those predicted using the conversion factor of 0.5 applied to component biomass. Stem carbon made up 59.7% of the total tree biomass carbon. The power equation estimating proportion of tree biomass carbon against the independent variable of diameter at breast height explained more than 90% of the variability in allocation of carbon among tree components. Tree height, as a second independent variable is also discussed. Our results suggest that the difference in organic carbon concentration among tree components should be incorporated into accurately develop forest carbon budget. Moreover, further investigations on how the diameter at breast height equation developed in the present study performs across broader scales are required.
