Interacting effects of habitat destruction and changing disturbance rates on biodiversity: Who is going to survive?

Changes in disturbance rates due to climate change may increase or decrease diversity, whereas permanent loss of habitat is generally believed to decrease diversity. It is, however, very likely that the effects of disturbances and habitat destruction interact. Understanding such combined effects is essential to predict the response of communities to global changes and in particular which functional types of species are most endangered. Using an individual-based spatially explicit community model, we investigate (1) whether diversity-disturbance curves alter when spatially uncorrelated or autocorrelated habitat destruction is added, and (2) which functional types of species are able to survive under these altered conditions. Model communities consisted of four functional types of species trading off between colonisation ability and competition strength. We found that habitat destruction may alter both height and shape of diversity-disturbance curves: maximum diversity at intermediate disturbance rates may shift to other disturbance rates or even split into two peaks giving rise to bimodal diversity-disturbance relationships with different sub-communities persisting at low and high disturbance rates. Diversity responded differentially depending on how the colonisation-competition trade-off was represented. Our results suggest that, for trade-offs in seed production rate, generally the best coloniser will better withstand the interacting effects of habitat destruction and changing disturbance rates; however, for trade-offs in mean dispersal distances, functional types characterized by intermediate abilities will perform best. We conclude that predictions of the impacts of changing disturbance rates on biodiversity depend on community structure and cannot be made without knowledge of concurrent permanent habitat destruction.     

福建省经济发展与工业污染水平计量模型研究

经济增长和环境污染之间的关系常用环境库兹涅茨曲线（EKC）来描述,典型的EKc一般呈倒u形。对福建省1988—2008年的经济与环境系列数据研究表明,福建省工业“三废”排放与人均GDP之间存在明显的相关性,但并不完全符合EKC的典型倒“U”模型。工业废水和工业s02排放曲线为“U＋倒U”形,EKC的转折点已分别在2006年和2008年到达;工业废气排放曲线为正“U”形的右半部分,EKc的转折点尚未出现。因此,福建省要进一步调整产业结构,提升第三产业在整个国民经济中的比重,优化第二产业结构,减少工业废气排放量,争取尽早跨越EKC拐点。     

猪场废水生产微生物絮凝剂发酵特性及动力学特征

以猪场废水作为原材料生产微生物絮凝剂,考察了发酵过程中溶解氧(DO)、COD、氨氮、总磷及pH值的变化规律,利用Logistic和Luedeking-Piret模型对絮凝菌生长和代谢产物生成的动力学过程进行了拟合.结果显示,菌体的生长在0~60h是对数生长期,12~36h菌体快速生长,菌体干重、细胞浓度OD600和菌落数分别由0.09g/L,0.26和1.3×107cfu迅速增加到0.76g/L,0.58和3.5×107cfu,稳定期(66h)菌落数达到5×107cfu.絮凝菌代谢产物的主要絮凝活性成分是蛋白质,与菌体生长呈相关型.猪场废水中磷源含量充足,作为缓冲液,基本维持了絮凝菌发酵过程中pH值的恒定.此外,Logistic和Luedeking-Piret模型的拟合结果能够较好地描述絮凝菌生长和代谢产物生成的动力学过程.     

延迟型膨胀剂对水泥基封孔材料性能的影响研究

为解决水泥基封孔材料在煤矿封孔应用中产生收缩变形问题,现以水泥浆材料为基料,利用微胶囊技术对铝粉膨胀剂进行改性处理,通过单因素试验确定环境温度,并在所确定环境温度下利用正交试验研究不同芯/壁质量比、水灰比,微胶囊掺量条件下延迟型膨胀剂对封孔材料膨胀、抗压性能的影响。结果表明:芯/壁质量比1.5:1,水灰比0.5,环境温度35℃,掺入4‰改性膨胀剂封孔材料膨胀性能最佳。较基准组延迟膨胀4h,膨胀率终值为15%,抗压强度在膨胀剂的影响下没有明显降低,并保持良好的强度性能。1d抗压强度2.3MPa,3d强度14.6MPa,7d强度21.2MPa,28d强度31.7MPa。     

螺旋隧道火灾特性小尺寸实验研究

为探明螺旋隧道火灾特性,防止人员高温伤害,基于Froude准则,搭建比例1∶67的小尺寸螺旋隧道实验模型,采用模型实验方法研究不同坡度和不同风速下螺旋隧道火灾温度分布规律及烟气蔓延特性。研究结果表明:低坡度条件下,螺旋隧道内高温区以火源为中点呈对称分布状态;随着坡度的增加,隧道内高温区逐渐向下游延伸,火源处拱顶下方温度呈现先增大后降低再升高的变化规律;无论是自然风还是机械纵向通风,新鲜冷空气的吹入对隧道温度的降低起到主导作用,且风速越大,温降幅度越大;随着隧道坡度和自然风速的增加,火羽流由竖直狭长型转变为燃烧不稳定的大截面火焰,同时坡度增加抑制了火灾烟气逆流,促进了烟气向火源下游的蔓延速度,大大提高了排烟的有效性,减少人员伤害。     

被动桩-土相互作用的简化分析

首先简要地分析了地面堆载作用下处于被动状态下的桩及桩侧土的反应,基于桩和土的变形协调条件,确定了桩侧土压力表达式。在此基础上,建立了桩身挠曲的控制微分方程,并联合采用非线性p y关系曲线与有限差分法进行求解。通过算例分析,验证了所建议分析方法的合理性和实用性。最后对影响被动桩—土相互作用体系工作性能的各种因素进行了系统的对比计算与分析。     

Evolution of unsaturated hydraulic properties of municipal solid waste with landfill depth and age

Successful modeling of liquid and air flow and hence designing of liquid and air addition systems in the landfills are constrained by the lack of key parameters of unsaturated hydraulic properties of municipal solid waste (MSW), which are strongly dependent on the depth of burial and the degree of decomposition. In this study, water retention curves (WRC) of MSW are measured using pressure plate method on samples repacked according to the in situ unit weight measured during borehole sampling, representing the MSW in shallow, middle, and deep layers. The measured WRC of MSW is well-reproduced by the van Genuchten-Mualem model, and is used to predict the unsaturated hydraulic properties of MSW, including water retention characteristics and unsaturated hydraulic conductivity. The estimated model parameters are consistent with other studies, suggesting that the pressure plate method yields reproducible results. As the landfill depth and age increase, the overburden pressure, the highly decomposed organic matter and finer pore space increase, hence the capillary pressure increases, causing increases in air-entry values, field capacity and residual water content, and decreases in steepness of WRC and saturated water content. The unsaturated hydraulic properties of MSW undergo changes with landfill depth and age, showing more silt loam-like properties as the landfill age increases.     

环境监测校准曲线制作和应用研究

对校准曲线的制作和应用中的有关问题进行了研究，为正确使用校准曲线提供科学参考。     

Political Economy of Transnational Water Pollution: What Do the LMB Data (1985–2000) Say?

On the basis of the cross-section and time-series data of the Lower Mekong Basin (LMB)—including large sections of Thailand, Lao PDR, Vietnam, and Cambodia, we find little evidence in support of the environmental Kuznets curve (EKC) hypothesis. Instead, our regressions support the general views that water pollution had been positively related to income level and that, as a result of the end of the Cold War era, it had been significantly reduced in the 1990s vis-à-vis the 1980s. In most circumstances, water resources were more seriously polluted in the transnational border areas than in the other areas. Specifically, the estimated coefficients on the political boundary dummies show that political influence on transnational water pollution was more significant in areas near the international border along which the river runs (denoted by BORDER2) than in places near the international border across which the river runs (denoted by BORDER1). The estimated coefficients on the ASEAN dummy present some information about the positive role of the Association for Southeast Asian Nations (ASEAN) membership in the reduction of transnational water pollution. Finally, the country-specific dummies are found to present conflicting information about the transnational differences of water pollution, although Thailand is found to have the least water pollution in the LMB.     

STOCHASTIC FLOW DURATION CURVES FOR EVALUATION OF FLOW REGIMES IN RIVERS1

ABSTRACT: A stochastic estimation of low flow in the upper reaches of streams is needed for the planning, development, and management of water resources and/or water use systems. In this paper, the definition and development procedure for the stochastic flow duration curve is presented and applied to five catchments located in eastern Japan and to two catchments in western Thailand. The probability distribution of N‐year daily discharge data is extracted at various percentages of time for which specified discharges are equaled or exceeded in a water year. Such a distribution is usually represented with a straight line on log‐normal probability paper. However, some of the probability plots for the annual minimum daily discharge are best represented with a straight line on Weibull probability paper. The effectiveness of the stochastic flow duration curve defined for the evaluation of flow regime is illustrated through its application. The ten year probability for the discharge exceeded 97 percent of the time may be recognized as an index of low flow. The recession shape of the lower part of the flow duration curve is dependent on the strength of low flow persistence.