颗粒物表面酸碱特性与孔表面分形的研究

通过电位滴定试验,证明了5种颗粒物的表面存在着一定量的OH-受体,其表面位浓度(Hs)在0.1219～0.3134 mmo.·L-1之间,表面位密度(DoH)在0.8586～2.1305个·nm-2之间,且不同采样点的颗粒物,其表面位浓度和表面位密度差别很大.所采集的5种颗粒物的孔结构接近平行板狭缝,孔尺寸分布不是均一的,平均孔径分布范围较宽(1.8～76nm);BET比表面积为9.5669～34.5605 m2·g-1,累积脱附孔体积为0.01729～0.06711 cm3·g-1,BJH脱附平均孔径为5.6768～7.7388nm,处于中孔范围,且平均孔径均大于其PSD峰值对应的孔径.通过分形FHH方程模拟N2吸附和脱附等温线数据计算出这些颗粒物的孔表面分形维数Ds比较接近(2.68～2.82之间),但它们的分形标度区间不同.另外,采用热力学模型和分形FHH理论计算出的表面分形维数的差异主要归因于这些样品孔尺寸分布的不均一性.     

δ-MnO2的制备及其对水中Cd2+的吸附

利用溶液中MnSO4与KMnO4之间的氧化还原反应制备了δ-MnO2。用透射电镜和BET法对δ-MnO2进行了表征。实验结果表明：δ-MnO2比表面积为324.58m^2/g,孔体积为0.39cm^3/g,孔径为4.82nm。对Cd2＋的吸附实验结果表明：δ-MnO2对Cd2＋具有很强的吸附能力,吸附作用强烈依赖体系的pH,吸附边界pH为2.50;pH为6.05时Cd2＋的吸附率为98.5%。宏观的吸附-解吸热力学实验证明：当pH为3.30时,为可逆吸附;当pH为6.05时,吸附过程存在固体浓度效应,为不可逆吸附。吸附过程主要为一价阳离子的交换吸附。     

半干旱区沙尘天气对0010～10 μm沙尘气溶胶分布的影响

利用WPS粒子谱仪对内蒙古朱日和背景天气及沙尘天气的气溶胶数浓度进行了观测,研究了不同天气背景下沙尘气溶胶数浓度及谱分布特征. 结果表明:在背景天气和沙尘天气下,0.010～0.020,0.021～0.100,0.101～1.000,1.001～2.500 μm等粒径段的气溶胶数浓度差别较大;沙尘天气对各粒径段,尤其是大于1.0 μm的气溶胶数浓度影响较大,沙尘暴过程中1.001～2.500 μm粒径段的气溶胶数浓度约为背景天气的35倍;各粒径段气溶胶数浓度在不同天气背景下的日变化规律有所不同,受气象要素的影响较大. 对沙尘气溶胶谱分布的分析可知,沙尘暴发生前后1 h的沙尘气溶胶谱型均符合Lorentz分布,背景天气下同时段的沙尘气溶胶谱型也符合Lorentz分布;沙尘天气下沙尘气溶胶谱型在沙尘暴发生前1 h的主峰值比背景天气高1个数量级,沙尘暴发生后1 h的峰值半径明显移向大粒子.      

不同泥龄下活性污泥絮体性状的研究

采用序批式反应器对不同泥龄下污泥絮体的化学性状(胞外聚合物成分及含量)、物理性状(表面电荷)、形态性状(粒度分布、分形维数)等进行了对比研究.结果表明:泥龄对胞外聚合物总量及各组分含量的影响规律并不明显;多糖/蛋白质愈大,污泥絮体表面电负性愈强;污泥絮体的平均粒径随泥龄的延长呈逐渐减小的趋势,且粒度分布愈来愈均匀;不同泥龄下,污泥絮体形态结构亦不相同,泥龄短时,絮体表面粗糙,结构开放疏松;泥龄长时,絮体表面平滑,结构紧凑;随着泥龄的增大,絮体分形维数逐渐增加.由于不同泥龄下所表现出的污泥絮体性状的差异,直接影响了污泥的絮凝和沉降性能.     

How deep is the footprint? A 3D representation

Depletion of natural capital stocks and use of natural capital flows are the central issues in the sustainability debate. Differentiation of these two components, considering natural capital and its limits, is important for planning and management of land use. This paper offers insights into this issue and proposes a new perspective of the Ecological Footprint (EF) in three dimensions, considering not only its size but also its depth: according to this viewpoint the footprint is not an area but a volume, although maintaining the same value as the one in two dimensions. Use of annual flows provided by the Earth is represented by the footprint size, expressed in global hectares (gha) and plotted in the (x,y) plane. Footprint depth represents the demand for extra land to meet human needs through depletion of stocks of natural capital. It is plotted on the z-axis. It can be seen as the number of years necessary to regenerate resources liquidated in 1 year (and to absorb the respective wastes) or as the number of planets necessary to support the inhabitants of the planet Earth. The evolution of these two components in the last five decades is studied and discussed.     

Use of Basic Biological Information for Rapid Prediction of the Response of Species to Habitat Loss

Abstract:  Much research has focused on identifying traits that can act as useful indicators of how habitat loss affects the extinction risk of species, and the results are mixed. We developed 2 simple, rapid-assessment models of the susceptibility of species to habitat loss. We based both on an index of range size, but one also incorporated an index of body mass and the other an index combining habitat and dietary specialization. We applied the models to samples of birds (Accipitridae and Bucerotidae) and to the lemurs of Madagascar and compared the models' classifications of risk with the IUCN's global threat status of each species. The model derived from ecological attributes was much more robust than the one derived from body mass. Ecological attributes identified threatened birds and lemurs with an average of 80% accuracy and endangered and critically endangered species with 100% accuracy and identified some species not currently listed as threatened that almost certainly warrant conservation consideration. Appropriate analysis of even fairly crude biological information can help raise early-warning flags to the relative susceptibilities of species to habitat loss and thus provide a useful and rapid technique for highlighting potential species-level conservation issues. Advantages of this approach to classifying risk include flexibility in the specialization parameters used as well as its applicability at a range of spatial scales.     

Helpers and egg investment in the cooperatively breeding acorn woodpecker: testing the concealed helper effects hypothesis

In cooperatively breeding acorn woodpeckers (Melanerpes formicivorus), helper males have a large positive effect on fledging success in good acorn crop years but only a small positive effect in poor acorn crop years, while helper females exhibit the opposite pattern. Based on these findings, we tested the “concealed helper effects” hypothesis, which proposes that laying females reduce investment in eggs (with respect to their size, number, or quality) in a way that confounds helper effects and results in an absence of a relationship between helpers and breeding success. Results generally failed to support the hypothesis. Mean egg size was positively related to temperatures during the 10 days prior to egg-laying and negatively related to the food supply as indexed by the prior fall’s acorn crop, but there were no significant differences vis-à-vis helpers except for interactions with the acorn crop that only partly corresponded to those predicted. With respect to clutch size, females laid larger clutches when assisted by female helpers, opposite the pattern predicted. Although our results suggest that egg size is adjusted to particular ecological circumstances, we conclude that neither egg nor clutch size is adjusted in a way that confounds the apparent effects of helpers, as proposed by the concealed helper effects hypothesis.     

北京城市道路积尘多环芳烃的粒度分布特征及其影响因素

对北京城市不同道路类型的道路积尘进行了为期16个月的采样,分别分析了道路尘的粒径、多环芳烃及TOC.道路积尘的粒径呈三峰态分布,<75 μm部分的颗粒所占体积最大,>214 μm部分颗粒所占体积最小.>214 μm这部分颗粒中的多环芳烃质量分数最低,<75μm和75～214μm这两部分颗粒中多环芳烃的质量分数没有显著差异,但由于<75μm部分颗粒所占的体积和质量比例最大,这部分颗粒的多环芳烃累积量所占比例最高.不同道路的积尘粒径存在差异,海淀路和成府路机动车道的积尘颗粒相比自行车道和人行道的颗粒更粗.由于粒径分布的差异和多环芳烃质量分数的差异,不同类型道路的多环芳烃累积量的粒径分布呈现差异.多环芳烃质量分数和累积量的粒度分布也呈现季节差异,冬春季<75 μm颗粒中的多环芳烃质量分数最高,多环芳烃的累积量所占比例也较夏秋季高.在三个粒级中,TOC与多环芳烃质量分数均呈现显著的正相关.高比例的细颗粒及细颗粒中的多环芳烃使得道路积尘再悬浮进入大气以及随湿沉降进入地表径流的环境风险加大.     

人口规模预测的GM(1，1)模型应用初探

本文以山东省人口统计数据为依据,运用灰色系统理论探讨和分析了灰色建模基础数据的前滤波作用对模型精度的影响。结果表明,前滤波可极大提高模型预测值的精度     

Effects of costs and benefits of brood care on filial cannibalism in the sand goby

This study tested experimentally whether clutch size and the cost of care affect filial cannibalism in the sand goby, Pomatoschistus minutus. Evolutionary models of filial cannibalism suggest that egg eating has evolved as a way for the male parent to prolong his breeding season. These models assume that eggs function as an alternative energy source for the constrained parent. I manipulated clutch size by allowing males to mate with either one or two females, representing a small and a large clutch, respectively. The addition of a small male shore crab, a common egg predator, increased the cost of care. I quantified fat reserves as a measure of the condition of guarding males. Males who did not build nests had lower fat reserves than males who built nests, suggesting that males with low energy reserves do not start breeding. Males with small clutches lost their nest to the crab more often than males with large clutches. Neither filial cannibalism nor the amount of eggs eaten were affected by the treatments. Males who consumed eggs had a higher fat percentage than males who did not eat eggs. The result that males with small clutches lost their nests to the crabs supports the idea that eggs are defended only if the benefit from continued care will outweigh the cost and that males therefore are sensitive to the trade-off between present and future reproductive success. Received: 15 May 1997 / Accepted after revision: 15 November 1997