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791.
The three-dimension (3D) ecological footprint makes the analysis of the relationships between the demand and supply of natural capital more credible by importing footprint depth and footprint size. This article used China’s regions as the object to analyze the high-level sustainability of the natural capital from the view of “ecology – efficiency – fairness” multidimensional framework. Research showed that China’s ecological footprint has risen while bio-capacity per capita has descended in recent 20 years. This paper also discusses the spatial distribution of China’s natural capital ecological sustainability, efficiency sustainability and fairness sustainability. Finally, it builds multi-criteria evaluation (MCE) models to get multidimensional sustainability framework taking ecological sustainability, efficiency sustainability, and fairness sustainability into consideration.  相似文献   
792.
滤料粒径对给水曝气生物滤池运行稳定性的影响   总被引:3,自引:1,他引:2  
利用给水曝气生物滤池(UBAF)处理刘屋洲水源水,考察了不同陶粒粒径对氨氮、高锰酸盐指数的去除效果以及水头损失变化的影响。结果表明,陶粒3~5 mm的UBAF对氨氮、高锰酸盐指数的去除效果较高,但是其水头损失较大,且反冲洗前后水头损失变化偏大,不利于UBAF稳定运行。陶粒6~10 mm的UBAF运行状况良好,氨氮的去除率为73.8%,高锰酸盐指数的去除率为18.6%,滤池24 h过滤水头损失<0.4 m,反冲洗前后过滤水头损失变化量<5 cm。其出水氨氮和高锰酸盐指数均达到《生活饮用水卫生标准》(GB5749-2006),滤池的水头损失小,反冲洗前后也变化甚微。进一步的实验表明陶粒破碎会导致滤料粒径级配变化,使得水头损失增加。  相似文献   
793.
实验考察了直接回用未脱水的给水厂污泥(undewatered water treatment sludge,UWTS)做絮凝剂进行畜禽养殖废水预处理的可行性.单因素实验结果表明,随着投加量和pH的增加,出水悬浮物浓度(suspended solid,SS)、化学需氧量(chemical oxygen demand,COD)和总磷(total phosphorus,TP)的去除率不断增加;随着快速搅拌速度的提高,UWTS的絮凝效果呈现先增强后减弱的趋势;随着沉淀时间的延长,出水中SS、COD和TP的去除率起初逐渐增大,但15 min后去除率变化不明显.进一步的正交实验分析结果表明,UWTS回用做絮凝剂的最佳反应条件为投加量2 800 mg/L,快速搅拌速度300 r/min,沉淀时间15 min,此时对应的SS、COD和TP的去除率分别为74.8%、54.6%和60.5%.最佳反应条件下的粒径分析结果表明,UWTS的投加使得粒径范围在40 ~ 180 μm的颗粒物得到了去除.尽管与商品化絮凝剂相比,UWTS的絮凝效果略差,但是,利用其预处理畜禽养殖废水具有成本优势,因而具有应用潜力.  相似文献   
794.
为揭示三峡水库干流消落带的泥沙沉积规律、分析沉积泥沙来源,本研究采用原位观测方法采集沉积泥沙样品,利用激光粒度仪测试泥沙粒径,分析沉积泥沙粒径在水平、垂直和高程3个维度上的变化特征,并与三峡水库入库泥沙的粒径特征相结合,阐述消落带沉积泥沙来源。结果表明:(1)三峡水库干流消落带沉积泥沙粒径在水平方向上存在比较强烈的空间变化,中值粒径沿河流流向方向呈逐渐下降趋势,并在忠县及其下游河段基本保持稳定;(2)泥沙粒径随高程的变化存在较大的空间差异,河流挟沙是消落带下部粗颗粒泥沙的主要来源,而消落带上方的土壤侵蚀强度越高,消落带顶部的沉积颗粒就越容易变粗;(3)在水库尾端,泥沙剖面存在较明显的旋迴分层现象,其中值粒径数值较大、变化幅度较宽,越往下游推进,中值粒径的数值越低、变化幅度越小,泥沙旋迴分层现象逐渐消失;(4)水库尾端的沉积泥沙以库区外来沙为主,越往下游推进,库区内产沙对粗颗粒泥沙的贡献逐渐升高,但库区内外来沙都能够为沉积泥沙提供丰富的细颗粒物源,因此,细沙的来源具有一定的复杂性和多样化特征。  相似文献   
795.
Abstract

Two formulation concentrates of the insecticide, RH‐5992 [N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyI) hydrazine], an aqueous flowable (2F) and an emulsion‐suspension (ES), were diluted with water to provide spray mixes containing dosage rates ranging from 35 to 150 g of the active ingredient (AI)/ha. The mixes were sprayed in a laboratory chamber, onto balsam fir branch tips collected from field trees and greenhouse‐grown seedlings. Droplet spectra and spray mass recovery were determined on artificial samplers. Simulated rainfall of two different intensities was applied at different rain‐free periods, and rain droplet sizes were determined. Foliar washoff of RH‐5992 was assessed after application of different amounts of rain, and the increase in soil residues was evaluated.

A direct relationship was indicated between the amount of rainfall and RH‐5992 washoff. The larger the rain droplet size, the greater the amount washed off. Longer rain‐free periods made the deposits more resistant to rain. Regardless of the amount of rainfall, rain droplet size and rain‐free period, foliar deposits of the 2F formulation were washed off to a greater extent than the ES formulation. The increase in soil residues due to foliar washoff was greater for the 2F than for the ES formulation. The deposits of the emulsion‐suspension were consistently more resistant to rain‐washing than those of the aqueous flowable formulation.  相似文献   
796.
Coral reefs provide shoreline protection, biological diversity, fishery harvests, and tourism, all values that stem from the physically-complex coral infrastructure. Stony corals (scleractinians) construct and maintain the reef through deposition of calcium carbonate. Therefore, assessment of coral reefs requires at least some measurement endpoints that reflect the biological and physical condition of stony corals. Most monitoring programs portray coral quantity as live coral cover, which is the two-dimensional proportion of coral surface to sea floor viewed from above (planar view). The absence of the third dimension, however, limits our ability to characterize coral reef value, physiology, health and sustainability. A three-dimensional (3D) approach more realistically characterizes coral structure available as community habitat and, when combined with estimates of live coral tissue, quantifies the amount of living coral available for photosynthesis, growth and reproduction. A rapid coral survey procedure that coupled 3D coral quantification with more traditional survey measurements was developed and tested in the field. The survey procedure relied on only three underwater observations – species identification, colony size, and proportion of live tissue – made on each colony in the transect. These observations generated a variety of metrics, including several based on 3D colony surface area, that are relevant to reef management.  相似文献   
797.
Contrary to the assumptions of many previous theoretical models, group size has recently been shown in experiments to have an effect on the relative (as well as absolute) competitive abilities of group members. Here we introduce a novel and effective mathematical tool for describing how relative competitive ability will change for any two specified individuals within a group as group size changes. We show that there is no simple general rule for describing how relative competitive ability will change with group size. A subsequent empirical test of the model helps to illustrate that very specific knowledge of the system under study is needed in order to produce robust predictions. Received: 23 December 1998 / Received in revised form: 26 July 1999 / Accepted: 2 October 1999  相似文献   
798.
I describe siblicide in the laughing kookaburra (Dacelo novaeguineae), a reverse size-dimorphic, cooperatively breeding kingfisher. Clutches were usually of three eggs, and nestlings hatched asynchronously, with intervals of 2–72 h between successive eggs. Siblicide occurred in two temporally and mechanistically distinct episodes. The youngest nestling died in one-third of all nests within days of hatching as a result of aggression from its elders. Kookaburra nestlings attacked each other using a hook on their upper beak – a rare example of a morphological specialisation for sibling rivalry. In one-fifth of all nests, the youngest nestling starved to death much later, without overt aggression, when nestling growth rates were highest. I examined the effects of food availability and competitive disparities between nestlings on the incidence of both types of siblicide. The probability of late, starvation-mediated mortality was negatively correlated with the number of male helpers. Early, aggressively mediated siblicide occurred in nests characterised by a suite of correlated variables that I call the ”kookaburra siblicide syndrome”: (1) no male helpers attended the nest, (2) the third-hatched nestling was much smaller than the second-hatched nestling, (3) the first and second nestling to hatch were male and female, respectively, and (4) there was a short hatch interval between the first two nestlings. The kookaburra siblicide syndrome variables could be inter-correlated if they were all related to the female’s condition at the onset of incubation. Females in poorer condition may be less likely to have male helpers, more likely to lay small third eggs, and more likely to hatch the first two eggs relatively synchronously because of nutritional constraints during the onset of incubation. These females may further promote siblicide by modifying the sexes of the first two nestlings. If a female hatches soon after an older but eventually smaller brother, dominance between the first two nestlings could be destabilised. I suggest this leads to escalated aggression in the nest and the death of the third nestling, which is least able to defend itself. Received: 17 December 1999 / Received in revised form: 8 May 2000 / Accepted: 20 May 2000  相似文献   
799.
The mating system of the Australian lycaenid butterfly, Jalmenus evagoras, is highly unusual compared to most other Lepidoptera. Characteristics of this system, which has been termed an ’explosive mating strategy,’ include the formation of an intensely competitive mating aggregation of males, a highly male biased operational sex ratio, a lack of discrimination and mate choice by both sexes, a high variance in male mating success, and female monogamy. In this study, we tested the hypothesis that multiple mating by males imposes physiological costs resulting in smaller spermatophores, and that this results in a fitness cost to females. We found that male J. evagoras transferred only 2.2% of their eclosion weight during their first mating, consistent with the hypothesis that males of monandrous species produce a relatively small investment. The wet weight of the ejaculate declined by an average of 27% at the second mating and the dry weight by 29%, and an intermating interval of 5–9 days was needed for the ejaculate to return to the size at the first mating, regardless of male size or age. Wet ejaculate mass increased proportionally with male size, though dry mass was proportionally larger in smaller males. Ejaculate mass tended to increase with male age at both first and second matings. Female characteristics, in general, did not affect ejaculate mass, although the wet weight of the ejaculate was positively associated with female weight at the second mating. Copulation duration increased from 2.4 h to approximately 3 h at the second mating, and to over 4 h at the third and fourth matings. Fecundity was positively correlated with female size but not with mating history, copulation duration, or any other characteristics measured for either males or females. Female longevity declined significantly as the number of times the male partner had previously mated increased. We conclude that despite the small male investment in ejaculate, the costs of multiple mating may nonetheless be significant, as indicated by the reduction in ejaculate mass, an increase in copulation duration, and reduction in female lifespan with increasing mating number. Received: 22 January 1999 / Received in revised form: 28 July 1999 / Accepted: 18 September 1999  相似文献   
800.
本文详细介绍了喷淋液滴的一些动力学参数:(1)液滴动量喷淋的最大动量和体积流量与流量系数有关.水流碰到溅水盘和盘臂后,动量减少,其动量减少量约63%.(2)液滴粒径分布当液滴直径小于平均体积直径DV50时,分布符合log-normal分布,当液滴直径大于DV50时,分布符合Rosin-Rammler分布.(3)水流量分布对不同的喷头,其水量分布是不同的.有的喷头水流量沿径向逐渐降低,有的喷头中心地带流量最高.(4)液滴路径分析液滴越大,自由沉降速度越大,水平通过的距离越大.最后对喷头的进一步发展进行展望.  相似文献   
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