The development process of a temperate montane peatland and its controlling factors since the middle Holocene

Peatlands are some of the largest carbon reservoirs in terrestrial ecosystems and play a key role in the global carbon cycle.Understanding peatland development,carbon accumulation processes,and the peatland response to varying forcing factors over different temporal and spatial scales helps reveal the underlying processes and general patterns of these ecosystems.To assess the role of climate and local conditions in peatland development,the basal samples from 23 peat cores and three well dated long peat cores were used to explore peatland initiation,lateral expansion,and carbon accumulation rate in the Baijianghe peatland located in the Changbai Mountains,Northeast China.Our results reveal that the Baijianghe peatland was initiated from forest conditions at 7.9 cal.kyr BP and then expanded laterally by paludification.The rapid expansion between 5 and4 cal.kyr BP likely resulted from high precipitation and gentle topography.The mean carbon accumulation rates of the three long peat cores were 36.3,39.1 and 48.4 g C m^(-2)yr^(-1),respectively,which are higher than rates from the northern peatlands.Both climate and local conditions have exerted an important influence on carbon accumulation rates in the Baijianghe peatland since the middle Holocene.The carbon accumulation patterns between 5 and 1.5 cal.kyr BP were probably linked to local conditions rather than climatic settings,including topography,hydrological conditions,and plant composition.The consistently decreasing carbon accumulation rate values at all locations within the BJH peatland over the last 1.5 cal.kyr BP suggests that climate is the primary control.This study highlights the varying primary controls on the process of peatland development and reveals the important role of local conditions in carbon accumulation.

Preparation and properties of Nd,Yb:GGG polycrystalline nanopowders

Gadolinium gallium garnet(GGG)polycrystalline powders doped with Nd,Yb were prepared by co-precipitation method.The structure,phase and properties of powders were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS)and fluorescence spectroscopy.XRD analysis indicated that the crystallization of Nd,Yb:GGG powders occur at 900􀄇.SEM analysis showed that the morphology of the powders was irregular and the average radius is 68.74 nm.FTIR analysis manifested that pure Nd,Yb:GGG powders were formed at 900􀄇.The fluorescence spectrum revealed that the most strong emission of Nd,Yb:GGG powders was 1030 nm,which was attributed to 2F5/2􀄺2F7/2 of Yb3+.The possible formation mechanism of Nd,Yb:GGG powders were preliminarily discussed.