Development of a standard reference material containing 22 chlorinated hydrocarbon gases at 1 μmol/mol in nitrogen

A gas standard mixture containing 22 chlorinated hydrocarbons in high purity nitrogen was prepared using a two-step weighing method and a gasifying apparatus developed in-house. The concentration of each component was determined using a gas chromatograph with flame ionization detection (GC/FID). Linear regression analysis of every component was performed using the gas standard mixture with concentrations ranging from 1 to 10 μmol/mol, showing the complete gasification of volatile organic compound (VOCs) species in a selected cylinder. Repeatability was also examined to ensure the reliability of the preparation method. In addition, no significant difference was observed between domestic treated and imported treated cylinders, which were conducive to reduction of the cost of raw materials. Moreover, the results of stability testing at different pressures and long-term stability tests indicated that the gas standard at 1 μmol/mol level with relative expanded uncertainties of 5% was stable above 2 MPa for a minimum of 12 months. Finally, a quantity comparison was conducted between the gas standard and a commercial gas standard from Scott Specialty Gases (now Air Liquide America Specialty Gases). The excellent agreement of every species suggested the favorable accuracy of our gas standard. Therefore, this reference material can be applied to routine observation of VOCs and for other purposes.     

β—D—甘露糖苷化学合成的研究进展

β－Ｄ－甘露糖糖苷键由于其化学合成的特殊性和在生命过程的重要性而日益受到人们的重视。本文系统地阐述了β－Ｄ－甘露糖苷化学合成的研究进展和要解决的主要问题。     

The Buffer Capacity of Calcareous Soils in Gansu Province of China

In this study, we added increments of acid and base to three calcareous soils from the eastern, middle and western parts of Gansu Province (China) and to three treated soils to remove calcium carbonate, organic matter and both carbonate and organic matter, respectively. the titration curves were measured and the magnitudes of buffer capacities as a function of pH were computed. It was found that the buffer capacity of calcareous soil is mainly attributed to calcium carbonate, as expected from the chemical composition of calcareous soil, while cation exchange system, silicate buffer system and organic matter play a minor role. the results clearly show that these soils of Gansu Province will not become a problem in the near future from the entrance of H⁺ into these soils.     

抚顺市大中型水库水质富营养化现状及防治对策

对抚顺市五座水库的水体营养状态进行了评价，结果表明，有3座水库处于不同程度的中营养型，有2座水库处于不同程度的轻富营养型。分析认为水库富营养化受水库周围居民生活及集雨区内径流入库的氮磷量影响。并针对水库富营养化的机制及发展变化趋势，提出了水库富营养化的具体治理办法及促进库区经济、社会协调发展的有效途径。     

关于旅游开发区的环境影响评价问题

简要地介绍了环境影响评价的重要意义、评价分类,指出坚持环境影响评价是经济可持续发展的重要保证,并用实例说明了环境影响评价的方法及过程.     

徐州市大气PM2.5与O3作用关系的季节变化

通过2013~2017年徐州市环境监测资料分析季风影响下主要大气复合污染物PM_2.5和O₃的相关性,并基于气象观测资料进一步探究PM_2.5和O₃相互作用机制的季节变化特征.结果表明：夏季风季节,PM_2.5和O₃呈正相关,相关系数高达0.56;冬季风季节,PM_2.5和O₃呈负相关,相关系数为-0.34,均通过了99%的置信检验,表明徐州市PM_2.5和O₃相互作用呈现相反的季节变化.夏季风季节,太阳辐射强,气温较高,大气氧化性较强,O₃主导大气氧化性,大气氧化性通过促进二次颗粒物生成使得PM_2.5浓度升高,夏季风季节以O₃对PM_2.5的促进作用主导城市大气复合污染变化;冬季风季节,太阳辐射弱,气温较低,大气氧化性较弱,高浓度的PM_2.5削弱太阳辐射抑制大气光化学,导致O₃生成率降低,冬季风季节以PM_2.5对O₃的抑制作用主导城市大气复合污染变化.     

Purification of starch and phosphorus wastewater using core-shell magnetic seeds prepared by sulfated roasting

Core-shell magnetic seeds with certain adsorption capacity that were prepared by sulfated roasting, served as the core of a magnetic separation technology for purification of starch wastewater. XRD and SEM results indicate that magnetite's surface transformed to be porous α-Fe_2O_3 structure. Compared with magnetite particles, the specific surface area was significantly improved to be 8.361 from 2.591 m~2/g, with little decrease in specific susceptibility. Zeta potential, FT-IR and XPS experiments indicate that both phosphate and starch adsorbed on the surface of the core-shell magnetic seeds by chemical adsorption, which fits well with the Langmuir adsorption model. The porous surface structure of magnetic seeds significantly contributes to the adsorption of phosphate and starch species, which can be efficiently removed to be 1.51 mg/L(phosphate) and 9.51 mg/L(starch) using magnetic separation.     

北洛河流域植物多样性地理格局与环境关系

通过野外调查和历史文献及标本统计分析,确定并分析北洛河流域种子植物信息数据.结果表明：该区共有种子植物123科581属1671种,占黄土高原种子植物的83.67%、67.24%、51.83%,集中分布于大型科（>50种）、较大科（21~50种）和单种属（1种）、小型属（2~5种）内.11个干流流经的地理单元植物相似性聚类分为5组,较早分离的是黄龙县,最大类因子午岭山脉连接而包含4个地理单元（富县、合水县、宜君县、黄陵县）.富县、合水县和黄龙县植物丰富度SD值最高,洛川县、华池县和甘泉县SD值最低.该区地理成分在属级水平上有15个分布区类型16个变型,以温带分布及其变型为主（287属,占49.40%）,并与热带分布及其变型联系紧密（115属,占19.79%）,植物丰富度SD值与温带成分显著正相关;黄陵县、洛川县、黄龙县R/T值最高,热带性质最强,华池县、定边县R/T值最低,热带性质最弱.R/T值受海拔影响,随温度和降水从东南向西北递减.该区植物起源古老,分化程度高,物种多样性丰富,地理成分复杂,是重要的植物种质资源库.植物物种多样性地带性格局过渡性明显,体现出这些类群的生态位需求.需加强保护该区原生环境和植物,合理开发利用,可选择6大优势科（菊科、禾本科、蔷薇科、豆科、唇形科和毛茛科）中适地适树适草的物种（温带性质）,进行植被恢复和水土流失治理.