电沉积参数对Cr2O3超疏水膜层表面形貌和润湿性的影响

采用电沉积法在碳钢片表面制备Cr2O3微纳膜层,并用硬脂酸对其进行表面修饰降低其表面能。通过单因素法依次优化电流密度、铬酸浓度、极间距和电沉积时间,并分析所得Cr2O3超疏水膜层的表面形貌和润湿性。当电流强度为4A、铬酸浓度为1.5 mol/L、极间距为5 mm及电沉积时间为1 h时,经硬脂酸修饰后Cr2O3膜层的超疏水性能优异,其静态接触角达到153.52°且滚动角为2.17°。     

Fe3O4/Mg(OH)2复合材料的制备及形貌控制

通过种子沉积法制备出Fe_3O_4/Mg(OH)_2复合材料并进行XRD、SEM测试分析。探究了氨水的浓度与加入速度、搅拌速度及等因素对磁性复合材料形貌的影响。氨水浓度与注入速度的降低,对氢氧化镁基体形貌的影响是相同的,但要使合成磁性复合材料形貌和四氧化三铁粒子在氢氧化镁中分散性均匀,应控制氨水浓度(ω=2.5%)或加入速度在一个合理的较低值。     

Fe3O4/Mg(OH)2复合材料的制备及对铅离子的移除应用

通过种子沉积法制备出Fe_3O_4/Mg(OH)_2复合材料并进行了XRD、SEM、TEM、SAED测试分析。将该复合材料对水溶液中Pb~(2+)进行移除应用实验,接触时间为240 min时达到平衡。平衡时,水溶液中的Pb~(2+)超过90%被移除,移除量为950.8 mg/g。通过动力学研究发现,移除过程符合准二级动力学模型,这意味着移除过程中可能为化学吸附及沉淀过程。     

干旱程度对C3植物红砂和C4植物珍珠光合生理参数的影响

 C3和C4植物混生在草地生态系统中较多,而在荒漠生态系统少见。在中国荒漠地区,C3小灌木红砂和C4半灌木珍珠在特定生境下混生在一起,以独特方式适应高温强光和干旱的极端环境。通过在不同干旱程度下测定它们生长期叶片的光合气体交换参数,探讨它们在混生条件下对极端环境的生理响应特征。结果表明,红砂的净光合速率(Pn)、蒸腾速率(E)、气孔导度(Gs)均要高于珍珠;而珍珠的水分利用效率(WUE)则要高于红砂。这表明珍珠和红砂在水分匮乏的荒漠生境下采取了不同的生存策略。红砂通过维持较高净光合速率和较高蒸腾速率来生存;而珍珠则通过高水分利用效率生存。     

温度升高和CO2浓度增加对冬小麦生物量的影响和不确定性分析（英文）

Impacts of climatic change on agriculture and adaptation are of key concern of scientific research. However, vast uncertainties exist among global climates model output, emission scenarios, scale transformation and crop model parameterization. In order to reduce these uncertainties, we integrate output results of four IPCC emission scenarios of A1FI, A2, B1 and B2, and five global climatic patterns of HadCM3, PCM, CGCM2, CSIRO2 and ECHAM4 in this study. Based on 20 databases of future climatic change scenarios from the Climatic Research Unit (CRU) , the scenario data of the climatic daily median values are generated on research sites with the global mean temperature increase of 1 ℃(GMT+1D), 2 ℃ (GMT+2D) and 3 ℃(GMT+3D). The impact of CO2 fertilization effect on wheat biomass for GMT+1D, GMT+2D and GMT+3D in China’s wheat-producing areas is studied in the process model, CERES-Wheat and probabilistic forecasting method. The research results show the CO2 fertilization effect can compensate reduction of wheat biomass with warming temperature in a strong compensating effect. Under the CO2 fertilization effect, the rain-fed and irrigated wheat biomasses increase respectively, and the increment of biomass goes up with temperature rising. The rain-fed wheat biomass increase is greater than the irrigated wheat biomass. Without consideration of CO2 fertilization effect, both irrigated and rain-fed wheat biomasses reduce, and there is a higher probability for the irrigated wheat biomass than that of the rain-fed wheat biomass.     

大气CO2浓度升高和施氮对棉田土壤理化性质及微生物区系的影响

针对耕地非农转化过程中产生的一系列社会问题,采用参与性农户调查方法,对西部欠发达地区西宁市郊区5个样本村190户农户进行了随机入户调查。根据城市开发进程、到市区距离和种植类型等条件,将调查样本村分为近郊城区化农村、近郊农村和远郊农村,就农户对耕地非农转换的基本认知及耕地非农转换的经济、社会和环境价值感知进行分析。结果表明:耕地征用后农户能理性感知和判别耕地非农转换价值,并普遍认为失去耕地后生活费用增加、生活保障降低、收入来源和就业机会少;感知主要受耕地数量、区位条件、耕地开发阶段等因素的影响;处于不同区位条件的农户对耕地非农转换的价值感知存在差异性,城区化农户已逐渐适应城市生活,近郊农户的非农转换经济和社会感知压力最大,远郊农民也感知经济和生活保障压力,但更希望能通过打工增加收入。     

NH4Cl-CaCl2-H3BO3-H2O体系中H3BO3介稳区性质的研究

为探究南翼山油田水中NH_4Cl对H_3BO_3低温介稳区性质的影响,采用浊度法测量了253.15 K～303.15 K温度范围不同浓度的NH_4Cl对CaCl_2溶液中硼酸的溶解度影响和介稳区宽度;依次根据Nyvlt自洽方程理论求得成核级数m、经典三维成核理论求得固—液界面能γ,实验结果表明,CaCl_2溶液中的NH_4Cl对H_3BO_3溶解度影响很小;CaCl_2溶液中H_3BO_3的介稳区宽度随着NH_4Cl浓度的增加先变小后变大,氯化铵质量分数在0.12%～1.13%之间存在着一个临界值,此时硼酸的介稳区宽度最小。     

MgCl2+NaCl+H2O体系相图计算及其在氯化镁重结晶提纯中的应用

利用Pitzer电解质溶液热力学模型,对MgCl2+NaCl+H2O体系部分多温相图进行了模拟。借助获得的多温相图,对含有NaCl杂质的六水氯化镁试剂重结晶提纯中出现的异常现象进行了分析。研究结果表明,重结晶法提纯化学纯试剂的有效性不是绝对的。虽然化学试剂中的杂质含量已经很低,但是是否能够使用重结晶法进一步提纯是由试剂和试剂中所含杂质的类型决定的。对于主要含有NaCl杂质的六水氯化镁试剂,只有当NaCl杂质含量低于一定值时才能够利用一步重结晶取固相的方法进行提纯;高于此值时,利用一步重结晶取固相的方法反而会使产品质量越来越差。当六水氯化镁中杂质含量高于临界值时,想要对其进行提纯,必须采用分步结晶的方法,首先去除先析出的NaCl杂质。     

A review on the ambit and prospects of C3 and C4 plants in Nigeria

Despite the enormous applications of photosynthesis in global carbon budget and food security, photosynthesis research has not been adequately explored as a research focus in Nigeria. Previous works on C₃ and C₄ plants in Nigeria were mainly on the use of anatomical characteristics to delimit plant species into their respective pathways, with no attention being paid to its applications. In this review, past and present knowledge gaps in this area of study are elucidated. Information used in this review were sourced from referred research articles and books in reputable journals. The results revealed that C₃ and C₄ plants are distributed among 21 genera and 11 families in Nigeria. In addition there is dearth of informatio such that only three genera have been classified based on diverse photosynthetic pathways with no information found on the physiological and biochemical characterization of these genera. Moreover, further research is also suggested for tackling new challenges in the area of food productivity and climate change.     

散射辐射对西藏高原高寒草甸净生态系统CO2交换的影响

2003~2006年在当雄草原站用涡度相关法对西藏高原广泛分布的高寒草甸生态系统的碳通量和常规气象数据进行了连续观测。基于这些数据,根据净生态系统CO₂交换量(NEE)对晴朗指数(k)和土壤温度的响应特征,分析了净生态系统CO₂交换量与散射辐射之间的关系。依据地面接受的散射辐射量把天气划分为云隙天、晴天和多云天。结果表明,散射辐射不能提高西藏高原高寒草甸生态系统的碳吸收水平。该生态系统的碳收支过程主要受光合有效辐射控制,碳排放过程主要受土壤温度控制;且NEE随k的变化趋势受散射辐射的影响较小,生态系统碳收支更多地受太阳辐射对土壤强烈加温的影响。三种散射辐射天气条件下,NEE随k的变化趋势基本一致,先增加后减小;NEE达最大值时的土壤温度皆为15℃左右,k值皆为0.7~0.8。     

Influence of environmental, root, and stand parameters on soil surface CO2 efflux in a Populus euphratica of desert forest in extreme arid region

Spatial variation in soil surface CO2 efflux was measured in a stand of Populus euphratica in the Ejina Oasis of desert riparian forest in the extreme arid region in northwestern China from April 2007 through October 2007.Measurements were taken with a gas-exchange analyzer linked to a soil-respiration chamber.The mean soil CO2 efflux in the stand was 2.71 μmol/(m2·s) during the growing season and 1.38 μmol/(m2·s) in the nongrowing season.The seasonal maximum (end of May through early June) andminimum (October) CO2 efflux were 3.38 and 0.69 μmol/(m2·s),respectively.The diurnal fluctuation of CO2 efflux was relatively small (< 20 percent),with theminimum appearing around 05:00 and the maximum around 15:00.Linear regression analysis showed soil-surface CO2 efflux to be most highly correlated with soil temperature (R2=0.435) and soil moisture (R2=0.213).When all variables were considered simultaneously,only soil temperature (R2=0.378),soil moisture (R2=0.147),and root volume density (R2=0.021) explained a significant amount of variance in soil surface CO2 efflux.Stand volumes were not correlated with soil CO2 efflux on our sites.     

白令海CO_2源汇与控制因素研究进展

白令海是北冰洋太平洋扇区的边缘海,是亚北极生态系统向北极生态系统过渡的典型区域,白令海CO_2源汇的研究可为高纬度边缘海相关的研究提供重要的参考。在全球持续变暖的背景下,白令海正在发生着一些气候和环境的变化,这些变化对CO_2源汇以及控制CO_2源汇的生物地球化学过程产生重要影响。对目前白令海CO_2源汇特征及其控制因素相关研究进行了归纳总结,预测了白令海CO_2源汇的未来变化趋势并提出了展望。以往的研究都认为白令海是一个大气CO_2的汇区,但是碳汇研究结果差异较大,最近的研究结果表明白令陆架区的碳汇约–6.81 Tg C·a~(–1)(1 Tg=10~(12)g),整个白令海的碳汇约–34 Tg C·a~(–1)。在未来白令海气候和环境变化继续加剧的条件下,使得白令海碳汇增强或减弱的因素将同时存在,因此,未来白令海的碳汇是增强还是减弱尚无定论。