源头寻根

背包并不重,脚步踏着山路,阳光明媚,暖和地照着身体。穿过马岭桥,谷底幽深,令人有种畏惧的感觉。面对天下第一罗盘,双手合十虔诚地许下生日愿望,希望快乐到老,如此足矣。急不可待往珠江源头走。潺潺水流,从岩洞流出来的便是中国南方最富饶地区的水源,焉能想象?流水不紧不慢地淌着,与南方急速的节奏形成鲜明的对比。多美的风光,铺个防潮垫,发呆一会儿,躺着就睡起来。     

How aerosol direct effects influence the source contributions to PM2.5 concentrations over Southern Hebei,China in severe winter haze episodes

The aerosol direct effects result in a 3%–9% increase in PM_2.5 concentrations over Southern Hebei. These impacts are substantially different under different PM_2.5 loadings. Industrial and domestic contributions will be underestimated if ignoring the feedbacks. Beijing-Tianjin-Hebei area is the most air polluted region in China and the three neighborhood southern Hebei cities, Shijiazhuang, Xingtai, and Handan, are listed in the top ten polluted cities with severe PM_2.5 pollution. The objective of this paper is to evaluate the impacts of aerosol direct effects on air quality over the southern Hebei cities, as well as the impacts when considering those effects on source apportionment using three dimensional air quality models. The WRF/Chem model was applied over the East Asia and northern China at 36 and 12 km horizontal grid resolutions, respectively, for the period of January 2013, with two sets of simulations with or without aerosol-meteorology feedbacks. The source contributions of power plants, industrial, domestic, transportation, and agriculture are evaluated using the Brute-Force Method (BFM) under the two simulation configurations. Our results indicate that, although the increases in PM_2.5 concentrations due to those effects over the three southern Hebei cities are only 3%–9% on montly average, they are much more significant under high PM_2.5 loadings (~50 μg·m⁻³ when PM_2.5 concentrations are higher than 400 μg m⁻³). When considering the aerosol feedbacks, the contributions of industrial and domestic sources assessed using the BFM will obviously increase (e.g., from 30%–34% to 32%–37% for industrial), especially under high PM_2.5 loadings (e.g., from 36%–44% to 43%–47% for domestic when PM_2.5>400 μg·m⁻³). Our results imply that the aerosol direct effects should not be ignored during severe pollution episodes, especially in short-term source apportionment using the BFM.     

2，2‘,4,4’和3，3‘,4,4’—四氯联苯（TCB）对小白鼠体外受精的影响

采用体外受精技术评价环境污染物2，2',4,4'-和3，3',4,4'-四氯联苯对小白鼠卵母细胞受精能力和2-细胞胚胎发育的毒性作用，实验结果表明：ρ（PCB）=0.1,1.0,10.0mg/mL的2，2',4,4'-和3，3',4,4'-四氯联苯均显著降低小白鼠卵母细胞的受精能力；ρ（PCB）=1.0,10.0mg/mL的2，2',4,4'-和3，3',4,4'-四氯联苯使卵母细胞的退人弦和2-细胞的畸形率显著增加；两种四氯联苯对小白鼠卵母细胞体外受精能力、退化率和2-细胞胚胎的畸形率无统计差异。     

城市及其遗产:保存的根源和条件

城市遗产的保存和利用将都市管理的负责人置于艰难选择的境地.下面的文字对城市的构 成进行了简短的历史回顾，得出了在场所利用及其保存之间保持平衡发展条件.     

Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake, Lake Taihu, China

The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT_1.92 > DGT_0.78 > DGT_0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.     

英国利用采矿废渣和其它废渣复垦土地的新进展

引言1987年是“欧洲环境年”,值得注意的是英国环保部(Dept.ofEnvironment)在该年颁布了一系列和处理采矿废碴有关的法规。1984年进行的英国废弃土地调查表明:可复垦的废弃土地,有45000ha而其中比例最高的部分(29％)和煤矿开采有关。还有40000ha废弃土地直接影响城市环境,也需     

Risk-evaluation of Hi-tech Enterprise in the Process of Approaching Global Market

In the high technology industry, small and medium sized technology enterprises (SMSTEs) play a pivotal role in advancing the whole industry. To achieve sustainable development, they need to extend their scope of business activities beyond a national view and exploit international market actively to meet international competitions that increase quickly in the form of allocating resources within the scope of the world. However, the SMSTEs are also facing risks associated with themselves during the process of exploiting international market owing to their own restrictions, so what they should do is to consider risk evaluations in exploiting the international market.     

陆壳组成与年龄的关系:花岗质岩石中Nd同位素变异所提供的证据

地壳花岗质岩石源区的Nd同位素体系可用来估算与陆壳年龄呈函数关系的陆壳Sm/Nd比值。现已发现,从早太古代到晚元古代,陆壳内花岗岩岩浆源的Sm/Nd比值随年龄的减小而增大,即从球粒陨石值的47%增至64%。这一变化趋势与根据沉积岩的稀土(REE)模式推测的变化趋势相反。观测到的这一变化趋势可能仅适用于地壳的长英质部分,但只要较老地壳比较年轻地壳含有更多的镁铁质(50%对0%),该变化趋势也可应用于整个地壳。因为地球上最古老地壳的某部分可能已被继后的地质过程所破坏,所以该变化趋势可能是地壳组成的保留倾向所致(preservational bias),而不是地壳组成真正随时间发生了变化。同位素数据和地壳年龄的分布表明,整个陆壳的Sm/Nd比值不低于球粒陨石值的60%。地壳的Nd浓度的这个极限值和估算值与质量平衡(要求大陆的Nd含量与约700km深处的地幔中丢失的Nd的量相等)一致。