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| 1 | Particulate matter assessment of a wetland in Beijing显示文摘To increase the knowledge on the particulate matter of a wetland in Beijing, an experimental study on the concentration and composition of PM10 and PM2.5was implemented in Beijing Olympic Forest Park from 2013 to 2014. This study analyzed the meteorological factors and deposition fluxes at different heights and in different periods in the wetlands. The results showed that the mean mass concentrations of PM10 and PM2.5were the highest at 06:00–09:00 and the lowest at 15:00–18:00. And the annual concentration of PM10 and PM2.5in the wetland followed the order of dry period(winter) > normal water period(spring and autumn) > wet period(summer), with the concentration in the dry period significantly higher than that in the normal water and wet periods. The chemical composition of PM2.5in the wetlands included NH4+, K+, Na+, Mg2+, SO42-, NO3-, and Cl-, which respectively accounted for 12.7%, 1.0%, 0.8%, 0.7%, 46.6%, 33.2%, and 5.1% of the average annual composition. The concentration of PM10 and PM2.5in the wetlands had a significant positive correlation with relative humidity, a negative correlation with wind speed, and an insignificant negative correlation with temperature and radiation. The daily average dry deposition amount of PM10 in the different periods followed the order of dry period >normal water period > wet period, and the daily average dry deposition amount of PM2.5in the different periods was dry period > wet period > normal water period. | Dongdong Qiu Jiakai Liu Lijuan Zhu Lichun Mo Zhenming Zhang | 2015 | Journal of Environmental Sciences2015，27，10： | 1 |
| 2 | Deformation dependence of symmetry energy coefficients of nuclei显示文摘Based on the semi-classical Thomas-Fermi approximation together with the Skyrme energy-density functional, we study the deformation dependence of symmetry energy coefficients of finite nuclei. The symmetry energy coefficients of nuclei with mass number A = 40, 100, 150, 208 are extracted from two-parameter parabola fitting to the calculated energy per particle. We find that the symmetry energy coefficients decrease with the increase of nuclear quadrupole deformations, which is mainly due to the isospin dependence of the difference between the proton and neutron surface diffuseness. Large deformations of nuclei can cause the change of the symmetry energy coefficient by about 0.5 Me V and the influence of nuclear deformations on the symmetry energy coefficients is more evident for light and intermediate nuclei. | MO QiuHong LIU Min CHENG LiChun WANG Ning | 2015 | Science China(Physics,Mechanics & Astronomy)2015，58，8： | 0 |
| 3 | The predicted effects of climate change on local species distributions around Beijing,China显示文摘To assist conservationists and policymakers in managing and protecting forests in Beijing from the effects of climate change,this study predicts changes for 2012–2112 in habitable areas of three tree species—Betula platyphylla,Quercus palustris,Platycladus orientalis,plus other mixed broadleaf species—in Beijing using a classification and regression tree niche model under the International Panel on Climate Change’s A2 and B2 emissions scenarios(SRES).The results show that climate change will increase annual average temperatures in the Beijing area by 2.0–4.7℃,and annual precipitation by 4.7–8.5 mm,depending on the emissions scenario used.These changes result in shifts in the range of each of the species.New suitable areas for distributions of B.platyphylla and Q.palustris will decrease in the future.The model points to significant shifts in the distributions of these species,withdrawing from their current ranges and pushing southward towards central Beijing.Most of the ranges decline during the initial 2012–2040 period before shifting southward and ending up larger overall at the end of the 88-year period.The mixed broadleaf forests expand their ranges significantly.The P.orientalis forests,on the other hand,expand their range marginally.The results indicate that climate change and its effects will accelerate significantly in Beijing over the next 88 years.Water stress is likely to be a major limiting factor on the distribution of forests and the most important factor affecting migration of species into and out of existing nature reserves.There is a potential for the extinction of some species.Therefore,long-term vegetation monitoring and warning systems will be needed to protect local species from habitat loss and genetic swamping of native species by hybrids. | Lichun Mo Jiakai Liu Hui Zhang Yi Xie | 2020 | Journal of Forestry Research2020，31，5： | 0 |
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