Sensitivity analyses of woody species exposed to air pollution based on ecophysiological measurements

GOAL, SCOPE AND BACKGROUND: Air pollution has been of a major problem in the Pearl River Delta of south China, particularly during the last two decades. Emissions of air pollutants from industries have already led to damages in natural communities and environments in a wide range of the Delta area. Leaf parameters such as chlorophyll fluorescence, leaf area (LA), dry weight (DW) and leaf mass per area (LMA) had once been used as specific indexes of environmental stress. This study aims to determine in situ if the daily variation of chlorophyll fluorescence and other ecophysiological parameters in five seedlings of three woody species, Ilex rotunda, Ficus microcarpa and Machilus chinensis, could be used alone or in combination with other measurements for sensitivity indexes to make diagnoses under air pollution stress and, hence, to choose the correct tree species for urban afforestation in the Delta area. METHODS: Five seedlings of each species were transplanted in pot containers after their acclimation under shadowing conditions. Chlorophyll fluorescence measurements were made in situ by a portable fluorometer (OS-30, Opti-sciences, U.S.A). Ten random samples of leaves were picked from each species for LA measurements by area-meter (CI-203, CID, Inc., U.S.A). DW was determined after the leaf samples were dried to a constant weight at 65 degrees C. LMA was calculated as the ratio of DW/LA. Leaf N content was analyzed according to the Kjeldhal method, and the extraction of pigments was carried out according Lin et al. RESULTS AND DISCUSSION: The daily mean Fv/Fm (Fv is the variable fluorescence and Fm is the maximum fluorescence) analysis showed that Ilex rotunda and Ficus microcarpa were more highly resistant to pollution stress, followed by Machilus chinensis, implying that the efficiency of photosystem II in I. rotunda was less affected by air pollutants than the other two species. Little difference in daily change of Fv/Fm in I. rotunda between the polluted and the clean site was also observed. However, a relatively large variation of Fv/Fm appeared in the other two species, particularly in M. chinensis, suggesting that they were more sensitive to air pollutants than I. rotunda. The mean LA was reduced for all species growing at the polluted site. The mean LMA for all species exceeded the sclerophylly threshold given by Cowling and Campbell and increased for those under pollution stress, which could be explained as one of the acclimation strategies for plants to air pollution stress. Little difference in leaf chlorophyll content was observed in F. microcarpa and M. chinensis, while remarkable differences were found in I. rotunda growing at the polluted and the clean site. Content of leaf carotenoids was largely reduced in I. rotunda growing at the polluted site, but increased in F. microcarpa and M. chinensis, compared with plants growing at the clean site. Plants growing at the clean site had a lower leaf N content than those growing at the polluted site. In addition, species with a higher resistance to pollution stress showed less difference in leaf N content than those sensitive species. CONCLUSION: Based on Fv/Fm measurements of the three woody species, I. rotunda showed the highest resistance to air pollutants from ceramic industries, followed by F. microcarpa. M. chinensis was the most sensitive species to air pollution, had lowest capacities to cope with the air pollution stress, which was consistent with visual injury symptoms observed in the crown profiles of plants at the polluted site. Fv/Fm, LAM, LA, leaf pigments and N content could be used alone or in combination to diagnose the extent of the physiological injury. The ratio of Fv/Fm, however, was the best and most effective parameter. RECOMMENDATION AND OUTLOOK: Tree species which have higher air-pollutant resistance, as diagnosed by such ecophysiological parameters, should be considered first and planted widely for urban afforestation or forest regeneration in areas where the forest was seriously degraded or forest health was markedly effected by the same kind of air pollutants.     

沸石曝气生物滤池去除氨氮性能及生物学特征分析

天然沸石具有较大的孔隙率和比表面积,对氨氮有较强的选择性离子交换能力.运用天然沸石曝气生物滤池处理城市污水厂二级生化出水,结果表明,曝气生物滤池有良好的去除效果.在气水比为3∶1,水力负荷为1 m/h,温度＞20℃情况下,沸石曝气生物滤池对城市污水厂二级生化出水COD去除率为12.7%,NH3-N去除率为96.6%;试验系统沿程微生物活性和微生物量呈现逐渐下降趋势,而单位生物量的生物活性沿程分布则与此相反;曝气生物滤池对水中污染物的去除主要集中在底部进水端部分,当水流达到距进水端上方105 cm时,曝气生物滤池对水中NH3-N的去除率已达86.8%(占氨氮总去除率的90%),COD的去除率为13.3%(占COD总去除率的67%).     

水体中化学需氧量的快速测定

介绍了一种快速测定水体中COD的新方法，该法将近红外光谱分析技术中的化学计量学方法应用到紫外可见光区域，对水体进行COD测试，并将结果和标准试验方法进行比较，取得了令人满意的结果。     

镧、锌及其交互作用对浮萍活性氧清除系统的影响

以浮萍(Lemnaminor)为材料,研究La、Zn及其交互作用对体内活性氧清除系统的影响,单独施加20mg·L-1的La或Zn对浮萍都有明显的伤害作用,且Zn的毒性远大于La。La、Zn复合处理不同程度地减弱各自的毒性,表现为植株叶绿素含量、蛋白质含量及过氧化氢酶(CAT)活性下降减缓;谷胱甘肽(GSH)、抗坏血酸(AsA)含量提高;超氧化物歧化酶(SOD)活性增强;过氧化物酶(POD)活性降低。各处理对浮萍的毒性由大到小的顺序依次为:Zn、La、Zn+La。     

Effects of body mass,age, dominance and parasite load on foraging time of bighorn rams,<Emphasis Type="Italic"> Ovis canadensis</Emphasis>

In sexually dimorphic ungulates, males generally spend less time foraging than females, possibly because of difference in body mass or because of the energetic requirements of lactation. The relationship between body size and foraging time has received little attention at the intra-specific level, because few studies have documented activity budgets for individuals of known size. Bighorn rams are a good model to explore how body mass affects foraging time, because they range in mass from 55 to 140 kg. We examined how the foraging time of bighorn rams varied according to individual characteristics. We observed rams in a marked population and constructed time budgets during the 3 months preceding the rut. We determined ram social rank based on agonistic encounters and collected fecal samples to count lungworm larvae. Time spent foraging was negatively correlated with body mass. After accounting for age differences, larger rams spent less time foraging and more time lying than smaller rams. Among rams aged 6–12 years, dominants spent less time feeding than subordinates, while fecal output of lungworm larvae was negatively correlated with foraging time for rams of all ages. Body mass accounts for much of the individual variation in foraging time, suggesting that sexual dimorphism is important in explaining differences in feeding time between males and females.Communicated by P. Heeb     

用平板双分子层脂膜模拟研究锌离子跨细胞膜的传递过程

制备了氧化胆固醇-卵磷脂（脑磷脂）平板双分子层脂膜，研究了膜配方对双分子层脂膜的稳定性和离子传递性能的影响，得到了最佳制膜工艺，并建立了锌离子跨卵（脑）磷脂膜的吸附-扩散模型，其计算值与实验值基本吻合．     

Patterns of Genetic Diversity and Its Loss in Mammalian Populations

Abstract:  Policy aimed at conserving biodiversity has focused on species diversity. Loss of genetic diversity, however, can affect population persistence, evolutionary potential, and individual fitness. Although mammals are a well-studied taxonomic group, a comprehensive assessment of mammalian genetic diversity based on modern molecular markers is lacking. We examined published microsatellite data from populations of 108 mammalian species to evaluate background patterns of genetic variability across taxa and body masses. We tested for loss of genetic diversity at the population level by asking whether populations that experienced demographic threats exhibited lower levels of genetic diversity. We also evaluated the effect of ascertainment bias (a reduction in variability when microsatellite primers are transferred across species) on our assessment of genetic diversity. Heterozygosity did not vary with body mass across species ranging in size from shrews to whales. Differences across taxonomic groupings were noted at the highest level, between populations of marsupial and placental mammals. We documented consistently lower heterozygosity, however, in populations that had experienced demographic threats across a wide range of mammalian species. We also documented a significant ( p = 0.01) reduction in heterozygosity as a result of ascertainment bias. Our results suggest that populations of both rare and common mammals are currently losing genetic diversity and that conservation efforts focused above the population level may fail to protect the breadth of persisting genetic diversity. Conservation policy makers may need to focus their efforts below the species level to stem further losses of genetic resources.     

同位素示踪法研究有机污染物在模拟水生生态系统中的行为

应用同位素示踪技术，研究了模拟水生生态系统中三氯苯、邻苯二甲酸正丁酯，２，４，６－三氯酚－＾１４Ｃ的分布、迁移、转化行为。实验周期后，水中污染物浓度分别降低了８９％，８０％，９５％以上，三氯苯在底泥和浮游生物中有积累。测定了标记物在水、悬浮物、＾１４ＣＯ２吸收溶液，ＸＡＤ－２树脂上的放射性强度。假设水中标记物的降解遵循一级速率过程，２４ｄ后，水中２，４，６－三氯酚－＾１４Ｃ浓度已降为原来浓度的５％     

达拉布特型碱性花岗岩源岩特征初步探讨──来自稳定同位素和微量元素的证据

根据稳定同位素组成特点和微量元素组成及岩石形成演化的分析，对达拉布特型碱性花岗岩的源岩进行了初步探讨。指出其源岩具有混源特点：同时存在地幔物质和上地壳物质。结合岩石化学组成特点，源岩的化学组成可能与含基性、中基性火山岩的麻粒岩相岩石相似。     

活性污泥法的多变量最优控制Ⅱ.限制有机物(BOD)的排放总量

着重研究了有限制有机物排放总量时，使其运行费用最低的最优周期控制问题。通过增加新的状态变量和用补偿函数法，将本课题的有约束条件问题化为无约束条件问题，并提出了最优长参数的动态搜索法来修改传统的梯度法，从而较完善地解决了多变量最优周期控制的计算问题。