各类VOCs在蜂窝陶瓷型La0.8Sr0.2MnO3催化剂上的催化燃烧性能

以涂有CeO2-ZrO2固溶体的堇青石蜂窝状陶瓷为载体,用浸渍法制备堇青石蜂窝陶瓷型整体La0.8Sr0.2MnO3催化剂,测试了该催化剂催化燃烧各类VOCs的特性。研究表明,VOCs催化燃烧的难易程度为：含氯烃〉烷烃〉酸〉芳烃〉酮〉酯〉醇〉醛。La0.8Sr0.2MnO3催化剂对含氧有机化合物具有较好的催化活性,完全燃烧温度均在280℃之内。通过关联VOCs的理化性质,发现VOCs在La0.8Sr0.2MnO3催化剂上的反应活性与VOCs分子中最弱C—H键键能和VOCs分子极性密切联系。     

镧(Ⅲ)离子诱导的菲律宾蛤仔金属硫蛋白性质研究

稀土离子能否诱导海洋生物的金属硫蛋白(MT)合成,将影响到MT对海水重金属的指示作用.以菲律宾蛤仔(Ruditapes philippinarum)为试验动物,采用含镧(Ⅲ)离子(La3+)的人工海水对其进行暴露培养,测定蛤仔鳃部和内脏中MT含量.结果表明,La3+暴露能够增加蛤仔体内MT含量,其中,10～1×100μg·L-1的La3+对鳃部诱导作用较大;10～1×10000μg·L-1的La3+对内脏MT均有较好诱导;同时,过柱层析洗脱液的光谱扫描及十二烷基的硫酸盐钠-聚丙烯酰胺凝胶电泳法(SDS-PAGE)分析表明,La3+诱导的蛤仔内脏中的MT在258nm处有特征吸收峰,主要以二聚体和三聚体的形式存在,分子量为13.1kD和18.3kD.     

Changes in the quality of river water before, during and after a major flood event associated with a La Niña cycle and treatment for drinking purposes

The treatment of organics present in the lower reaches of a major river system（the Murray–Darling Basin, Australia） before（March–July 2010）, during（December 2010–May 2011） and after（April–December 2012） a major flood period was investigated. The flood period（over 6 months）occurred during an intense La Nia cycle, leading to rapid and high increases in river flows and organic loads in the river water. Dissolved organic carbon（DOC） increased（2–3 times） to high concentrations（up to 16 mg/L） and was found to correlate with river flow rates. The treatability of organics was studied using conventional jar tests with alum and an enhanced coagulation model（mEnCo）. Predicted mean alum dose rates（per mg DOC） were higher before（9.1 mg alum/mg DOC） and after（8.5 mg alum/mg DOC） than during the flood event（8.0 mg alum/mg DOC）,indicating differences in the character of the organics in raw waters. To assess the character of natural organic matter present in raw and treated waters, high performance size exclusion chromatography with UV and fluorescence detectors were used. During the flood period, high molecular weight UV absorbing compounds（〉2 kDa） were mostly detected in waters collected,but were not evident in waters collected before and afterwards. The relative abundances of humic-like and protein-like compounds during and following the flood period were also investigated and found to be of a higher molecular weight during the flood period. The treatability of the organics was found to vary over the three climate conditions investigated.     

可控合成La（OH）3纳米球光催化去除NO及其催化性能机制研究

以KOH和La(NO3)3·6H2O为前驱体,柠檬酸为保护剂,采用一步水热法合成三维La(OH)3纳米球光催化剂.通过XRD、SEM、PL和UV-vis DRS等对样品进行结构表征.结果表明,柠檬酸的加入量对La(OH)3的形貌均匀性和催化活性均有较大影响.柠檬酸和La(NO3)3·6H2O的物质的量的比为2∶1时,得到的样品为形貌均匀的纳米球,光催化活性最佳且稳定性好.这是因为三维的纳米球结构更容易促进光生载流子的分离;此外,形貌均匀无团聚,增加了催化剂表面的活性位点,使反应过程中反应物和中间产物迅速扩散,从而光催化活性最高.在光催化过程中,羟基自由基(·OH)和超氧自由基(·O-2)是最主要的氧化物种.NO可以和产生的·OH和·O-2反应生成HNO2和HNO3,从而去除NO.本文研究结果充实了La(OH)3光催化材料的合成基础理论,探讨了La(OH)3光催化活性机理,为La(OH)3应用打开了新的视野.     

ZrO2掺杂对La2Ce2O7力学和热物理性能 影响的研究

目的提高La_2Ce_2O_7(LC)陶瓷材料的断裂韧性。方法采用固相反应方法合成Y_2O_3稳定ZrO_2(YSZ)掺杂的La_2Ce_2O_7(LC)陶瓷材料(LCZ),研究LCZ块材的弹性模量、断裂韧性等力学性能,以及热膨胀系数、热传导率等热物理性能。结果 10%YSZ摩尔分数掺杂的LCZ块材的断裂韧性约为1.4 MPa·m1/2,比LC提高了近10%。YSZ掺杂有效地抑制了LC在200～400℃温度区间热膨胀系数下降的现象。在200～1200℃温度范围内,LCZ块材的热膨胀系数为10×10-6～12×10-6K-1,在1200℃的热导率约为0.75W/(m·K),比YSZ降低了50%以上,显示了优异的隔热性能。结论 YSZ的掺杂使LC中部分Zr4+取代了La3+,降低了晶格中的O空位浓度,原子的横向剪切运动被削弱,有效地抑制了LC在200～400℃温度区间热膨胀系数下降的现象。由于t-ZrO_2→m-ZrO_2的相变对微裂纹的愈合作用,10%YSZ掺杂使LC块材的断裂韧性得到有效提高。     

不同浓度镧处理对铅胁迫下玉米生长和铅吸收的影响

采用温室盆栽试验的方法,研究不同浓度的镧处理(0、50、200和800 mg·kg~(-1))对中度铅胁迫下(200 mg·kg~(-1))玉米生长、矿质营养元素吸收、C∶N∶P生态化学计量比及Pb和La吸收的影响,探讨土壤-植物系统中稀土重金属的相互作用,旨在为稀土矿区稀土重金属复合污染土壤的治理提供基础数据和理论依据.结果表明,随着外源La浓度的增加土壤中乙酸铵-EDTA提取态La的浓度显著增加,而乙酸铵-EDTA提取态Pb的浓度显著降低;玉米地上部干重显著降低了17.90%~81.17%,根冠比显著增加了21.74%~86.96%;随着土壤中La浓度的增加根部P含量显著降低了19.16%~89.68%,La浓度为200 mg·kg~(-1)和800 mg·kg~(-1)时,地上部P和N含量分别显著降低了65.51%~91.98%和48.27%~76.58%;随着土壤中La浓度的增加,植株C∶P、N∶P和植株La浓度显著增加,地上部和根部Pb浓度分别显著增加了52.61%~99.01%和15.99%~44.34%;随着La浓度的升高显著降低了玉米植株K、Ca和Mg的含量.结果初步证明,在稀土-重金属复合污染土壤中,稀土元素的存在加剧了重金属对植物生长的毒害效应及其所引发的生态风险问题,应进一步深入研究稀土对植物吸收重金属的影响及作用机制.     

阿拉善地区生物多样性与自然保护区规划

由于特殊的自然地理条件和独特的地形地貌类型，阿拉善地区具有丰富的珍稀物种资源和多样的生态系统。本文依据保护生物多样性的要求，对该区重点保护区做了具体规划。     

海拉尔区生态环境状况及受损原因和保护、建设对策

运用地理信息系统软件Arcinfo，结合野外调查资料，对2002年海拉尔区遥感数据进行处理，并应用景观生态学原理，从景观水平上对海拉尔区的生态环境进行整体识别和分析。进一步了解了海拉尔区生态环境状况，并通过分析讨论该区生态环境受损原因、保护及对策。     

Avian Community Response to Lowland Tropical Rainforest Isolation: 40 Years of Change at La Selva Biological Station, Costa Rica

Abstract:  Since 1960, most of the forest surrounding the La Selva Biological Station, an intensively studied tropical research facility in Costa Rica, has been converted to agricultural uses. We used quantitative censuses and analysis of previously published categorical abundances to assess changes in the bird community, and we evaluated potential causes of species-specific changes by assessing their association with habitat, diet, participation in mixed-species flocks, and nest type. Approximately the same percentage of species increased as decreased in abundance from 1960 to 1999 (10–20% of all species, depending on method of assessment). Diet was the single most important trait associated with declining species. At least 50% of the species that declined have insectivorous diets. Use of forest habitat and participation in mixed-species flocks were also significant factors associated with declines, but nest type was unrelated to change in abundance. The species that increased in abundance tended to occur in open habitats and have omnivorous diets. These results reinforce the importance of several population risk factors associated with tropical understory insectivory and mixed-species flocking: patchy spatial distribution, low population density, large home range, and dietary specialization. La Selva's protected area (1611 ha), despite a forested connection on one boundary with a higher elevation national park, is apparently too small to maintain at least one major guild (understory insectivores). This first quantitative assessment of bird community change at La Selva highlights the need to intensify study of the mechanisms and consequences of biological diversity change in tropical forest fragments.     

固定化活性氧化镧的化学除磷及其真空再生技术研究

为降低污水除磷成本、再生循环利用高效除磷剂、回收水体中磷,在此提出并研究了一种新型的化学除磷技术——固定化活性氧化镧（La2O3）化学除磷及其真空再生技术。该技术利用电解实现镧的固定,运用真空原理,实现氧化镧的再生和磷的回收。通过归纳各种常规除磷和新型除磷方法的特点,以及新型除磷方法的技术可行性,得出固定化活性La2O3化学除磷法较常规的除磷方法运行成本低,无污泥及二次污染产生,除磷效率高,可循环利用氧化镧除磷剂．回收利用水中的磷．