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351.
Using Demographic Invariants to Detect Overharvested Bird Populations from Incomplete Data 总被引:1,自引:0,他引:1
Abstract: Conservation biology must be able to provide guidelines even when available data are incomplete, because data on rare and endangered species are usually limited. For instance, data on the effect of additional—human-induced—sources of mortality on vertebrate populations, such as bycatch of seabirds by longline fisheries, are typically incomplete. The importance of an additional source of mortality can be evaluated by comparing it with the maximum annual growth rate of the species of concern, and various authors have attempted to determine the maximum growth rate from incomplete data. We developed a procedure we call the "demographic invariant method" (DIM). First we determined that the maximum growth rate per generation does not vary, by recalling that it is a dimensionless number primarily independent of body weight and also by empirically establishing its near constancy over a restricted set of bird species for which reliable demographic information was available. This first step provided an implicit function linking generation time and maximum annual growth rate, from which we obtained the maximum annual growth rate as a simple function of generation time. From several different ways of obtaining estimates of generation time, we derived in turn several ways to estimate the maximum annual growth rate of a bird species from incomplete demographic data set. We applied our approach to the Black-footed Albatross (Phoebastria nigripes) and determined from incomplete data that longline fishery bycatch has a biologically significant impact on the growth potential of Black-footed Albatross populations. Our method can be applied broadly to the conservation and management of harvested bird populations. 相似文献
352.
陈子明 《城市环境与城市生态》1997,(2)
在工业企业噪声环境影响评价中,由于测点与测量时段选择的不妥,导致测量及预测值“以偏代全”的结果;本文提出了测点合理布设与测量,预测时段科学选择的原则,以使测量与预测结果能较好地符合项目建成前、后噪声环境实际状况。 相似文献
353.
采用正交实验优化湿热法处理厨余垃圾的工艺条件 总被引:4,自引:0,他引:4
实验采用3因素3水平的正交实验设计方法,研究了湿热法处理厨余垃圾并使其饲料化的加工工艺中,时间、温度、加水量对厨余垃圾饲用价值的影响,选取粗蛋白、粗脂肪、粗纤维、粗灰分、钙和盐分为评价指标,确定反应的最佳工艺条件.实验结果表明,反应的最佳工艺条件为温度100℃、加水量50%、反应时间30 min. 相似文献
354.
355.
对ABR反应器的水力流态进行了示踪剂试验,分析了特征截面面积对ABR水力特性的影响,采用停留时间分布(RTD)法研究了不同进水COD浓度和HRT条件下ABR反应器的水力特性,结果表明:不同进水COD浓度时ABR反应器的RTD曲线相似,表明进水COD浓度不是影响ABR水力特性的主要因素;不同HRT条件下RTD曲线差异很大,表明HRT对ABR的水力特性影响较大,随着水力停留时间的延长,Ⅳ值增大,1/Pe减小,ABR的流态趋于推流流态,随着HRT的缩短,Ⅳ值减小,1/Pe数增大,ABR反应器趋于完全混合流态。 相似文献
356.
Stasinakis AS Thomaidis NS Giannes AS Lekkas TD 《Environmental science and pollution research international》2003,10(3):177-182
The inhibition effect of arsenite, As(III), arsenate, As(V), inorganic mercury, Hg(II) and methylmercury, MeHg, on the respiration rate of activated heterotrophic sludge microorganisms was evaluated. As(III) and MeHg were much more toxic to activated sludge than As(V) and Hg(II) respectively. The effect of various experimental parameters on the toxicity, such as sludge age, concentration of suspended solids and exposure time, was investigated. An increase of sludge age or the concentration of suspended solids reduces the observed inhibition. Longer exposure seems to dramatically increase the inhibition of As(III), MeHg and Hg(II) during the first hours of exposure, while the later inhibition increases at a slower rate. On the contrary, in the presence of As(V), 24 hours after exposure, the respiration rate was similar to that of the control biomass. 相似文献
357.
结合姜堰市城市生活污水处理厂的设计,在CAS工艺中,进行了曝气时间对COD和NH3-N去除率影响的探讨。实验研究表明,延长曝气时间对于COD和NH3-N的去除是有利的,曝气时间控制在3h较为适宜。 相似文献
358.
The prothrombin time of the normal human pooled plasma was shortened by Aldrich humic acid well water humic substances and lignin at final concentrations ranging from 5 × 10–3 mg mL–1 to 5 × 10–2 mg mL–1, with a maxmum effect at 1 × 10–2 mg mL–1. At this concentration the shortening was 5.5 s, 4.4 s, and 3.5 s by Aldrich humic acid, well water humic substances and lignin respectively. However, monomeric components of humic acid such as syringic acid, protocatechuic acid, pyrogallol, vanillic acid, gallic acid, resorcinol, ferulic acid, catechol, caffeic acid and p-coumaric acid did not have such ability to shorten prothrombin time at the same final concentration ranges. Certain reducing agents such as t-butanol (2.5 × 10– –2.0 × 10–2 mg mL–1), glutathione (8.0 × 10–2–1 .0 mg mL–1), ascorbic acid (4.2 × 10–2–5.0 × 10–1 mg mL–1) and dithiothreitol (1.0 × 10–2–1.7 × 10–1mg mL–1) could prevent the shortening effects of humic substances or lignin on prothrombin time. These results suggested that humic substances and lignin with a polymerised structure had an ability to affect activities of some blood coagulating enzymes. 相似文献
359.
360.
霍林河中游径流量序列的多时间尺度特征及其效应分析 总被引:7,自引:1,他引:7
霍林河是松嫩平原西部地区科尔沁、向海和查干湖湿地的重要补给水源。通过对其中游白云胡硕水文测站46a的年径流量序列的多时间尺度分析,探讨霍林河径流演变的近似周期性,识别霍林河径流变化对其下游洪泛湿地水源补给的规律,以及这种规律控制下的洪泛湿地环境演变。小波分析表明,霍林河白云胡硕水文站年径流序列主要存在3个尺度的周期变化,不同时间尺度下周期信号的强弱在时频域中的分布具有较强的局部特征,以大于30a尺度的年代际周期变化起主导作用,该尺度下,霍林河径流演变呈现出丰、枯、丰的交替振荡,下游洪泛湿地景观演变相应表现出阶段性特征,1990年代以前尤为突出。能量相对较弱的中、小时间尺度径流量周期性变化,与强烈的人类干扰活动相比,对下游洪泛湿地环境演变的作用效果不明显,突出表现在1990年代以后。 相似文献