Trace element content in soils of the King George and Elephant islands,maritime Antarctica

Trace element concentrations were studied in soils of the King George and Elephant islands in the maritime part of West Antarctica. The lowest concentrations of Cu, Pb, Cd, Zn, Ni and Mn were typical for the pristine soil of Elephant Island. The highest concentrations of these elements were found in the Fildes Peninsula and revealed the influence of human activities in the area of the Bellingshausen station and adjacent waste disposal sites. Ornithogenic soils of the Fildes Peninsula have shown low concentrations of Cd and As. Using geoaccumulation indexes, all the pristine soils of King George and Elephant islands and ornithogenic soils of the Fildes Peninsula were classified as unpolluted; the human-affected soils were mainly identified as moderately polluted. Obtained data can be used as background concentration levels for further researches.     

以羟胺为底物的自养脱氮微量热研究

羟胺（NH₂OH）是单级自养脱氮系统物质转化的重要中间产物。从稳定运行（氨氮去除率维持90%以上,总氮去除率维持在80%以上）的单级自养脱氮工艺（SBBR）取活性污泥放入量热池,加入不同浓度N-NH₂OH（40～200 mg/L）进行量热实验研究。结果表明,用Boltzmann模型可以很好地表达量热值与NH₂OH浓度的关系,超过一定浓度的羟胺会抑制微生物活性,自营养脱氮过程的产热增量降低。     

抗压实验法厌氧颗粒污泥机械强度的测定及影响因素分析

通过首先对厌氧颗粒污泥样品进行筛分,然后测定其机械强度,解决了实际操作过程中现有抗压实验法出现的精确度与重现性较差的问题。通过对不同来源厌氧颗粒污泥样品机械强度的测定、对比分析发现,厌氧颗粒污泥的机械强度大小与反应器的规模、反应器所采用水力负荷存在一定的正相关性,且与其主要金属元素（Ca、Fe和Mg）含量的大小存在着密切的关系。     

Genotypic Differences in Effects of Cadmium Exposure on Plant Growth and Contents of Cadmium and Elements in 14 Cultivars of Bai Cai

Abstract

Fourteen cultivars of bai cai (Brassica campestris L. ssp. chinensis var. communis) were grown in the nutrient solutions containing 0–0.5 μg mL^?1 of cadmium (Cd) to investigate genotypic differences in the effects of Cd exposure on the plant growth and uptake and distribution of Cd in bai cai plants. The Cd exposure significantly reduced the dry and fresh weights of roots and shoots, the dry weight ratio of shoot/root (S/R), total biomass, and chlorophyll content (SPAD value). Cd concentrations in bai cai ranged from 13.3 to 74.9 μg g^?1 DW in shoots and from 163.1 to 574.7 μg g^?1 DW in roots under Cd exposure, respectively. The considerable genotypic differences of Cd concentrations and accumulations in both shoots and roots were observed among 14 bai cai cultivars. Moreover, Cd mainly accumulated in the roots. Cd also caused the changes of uptake and distribution of nutrients in bai cai and under the influence of cadmium, the concentration of potassium (K) decreased in shoot and increased in root. However, the concentrations of magnesium (Mg), phosphorus (P), manganese (Mn), boron (B), and iron (Fe) increased in shoots and decreased in roots. In addition, Cd exposure resulted in an increase in calcium (Ca), sulphur (S), and zinc (Zn) concentrations in both shoots and roots but had no significant effects on the whole uptake of the examined mineral nutrients except for S.     

某军机整体壁板裂纹损伤强度评估研究

用全机有限元模型模拟损伤部位的局部位移和力边界条件,对机翼整体壁板高应力区的裂纹型损伤分析,研究了不同损伤尺寸对整体壁板强度的影响,给出损伤尺寸与残余过载、残余强度系数的关系,结论对外场评定战伤飞机损伤程度提供依据.     

爆炸荷载作用下钢筋混凝土防爆墙动力响应研究

为了研究钢筋混凝土防爆墙的抗爆能力,采用有限元分析方法对不同纵向配筋率、不同高跨比、不同厚度的墙体在爆炸动态荷载作用下的动力响应进行研究,对各种不同设置的钢筋混凝土防爆墙的抗爆性能进行评估。结果表明:减小高跨比对提高钢筋混凝土防爆墙的抗爆能力最为重要,提高纵向配筋率,增加厚度都能增加防爆墙的抗爆能力。     

重型自卸汽车车架横梁异常断裂原因分析

针对无副车架的重型自卸汽车在使用过程中出现的车架横梁异常断裂问题,建立了以板壳单元为基本单元的自卸汽车车架有限元分析模型,采用NASTRAN有限元分析软件对车架强度进行分析.有限元分析结果表明,车架横梁异常断裂现象是横梁连接部位应力值大于材料的屈服强度引起的,这与实车车架断裂结果吻合.根据实际工艺要求,改造车架结构,将连接第2根横梁和纵梁的L板厚度变大,并将平衡悬架推力杆支座由整体式支撑改为分体式支撑,从而使两处的最大应力值分别比原结构下降20.4%和51.7%.改进后车架断裂区的强度明显提高,这表明改造方法有效.     

Soil Contribution to the Elemental Composition of Epiphytic Lichens (Tuscany, Central Italy)

Total concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Sr, Ti, V and Zn in the epiphytic lichen Parmelia sulcata and superficial soils from 60 remote sampling sites in Tuscany (central Italy) were determined to evaluate the contribution of soil to the elemental composition of the lichen. The results showed that in the Mediterranean environment, the trace element content of unwashed lichen samples is greatly affected by soil contamination. However, despite the strong correlations between the concentrations of lithogene elements such as Al, Fe and Ti in P. sulcata, lichen levels of these elements were not at all linearly correlated with their concentrations in the soil, suggesting that dust contamination is highly variable and probably dependent on local site characteristics. All methods evaluated to minimize soil contamination indicated Cu, Pb and Zn as elements of atmospheric origin. However, while levels of Pb were similar to those reported for background areas, moderate pollution by Cu and Zn, probably from fertilizers used in agriculture, was revealed. For elements such as Cd and Mo, identified as atmophile, some uncertainty exists due to the fact that they are essential for lichen metabolism and accumulate intracellularly in lichens; they may therefore occur in soluble form in the lichen thallus.     

La在模拟水生态系统中的动力学行为

采用140La放射示踪技术,研究了稀土元素镧（La）在模拟水生态系统各组分中的迁移分布规律．并建立了相应的数学模型．结果表明,La在模拟水生态系统各组分中的积累率大小依次为：金鱼藻＞底泥＞螺蛳＞鱼,La在系统内的动态变化规律可用封闭分室模型来描述．     

广东省杨村华侨柑桔场土壤微量元素含量与分布的研究

采集并分析全场不同母质形成的有代表性的土壤样本142个.研究结果表明,各类土壤全B、Mo、Zn和Mn含量的平均值均低于全国平均值,全量Cu平均值高于全国平均值.有效B、Mo、Zn和Mn含量的平均值均低于临界值,有效Cu的平均值稍高于临界值;但66.7％的土样有效Cu含量低于临界值.硼、钼、锌和锰严重缺乏,铜多数缺乏.全场各类土壤的微量元素含量差异较大,各类土壤微量元素的垂直和水平分布特征不尽相同,尤其是垂直分布差异明显.从土壤微量元素的全量与母质的关系来看,以玄武岩、紫色砂页岩母质形成的土壤全量较高,砂砾岩母质形成的土壤全量中等,砂页岩和冲积物母质形成的土壤全量较低.