火焰原子吸收测定土壤中的铜

采用硝酸-盐酸-高氯酸代替传统的消解方法分解土壤样品,火焰直接喷入原子吸收法测定土壤中的铜。相对标准偏差为0.6％～3.5％,加标回收率97.5％～101％。     

火焰原子吸收分光光度法测定土壤中金属镍消解方法的改进

探讨一种快捷有效的土壤样品消解方法，即采用王水-过氧化氢体系消化土壤样品。该法操作简便，减少了耗酸量与操作时间。测定结果精密度高，准确性好。     

Comparison of biomass production and biological nitrogen fixation of multi-species pastures (mixed herb leys) with perennial ryegrass-white clover pasture with and without irrigation in Canterbury, New Zealand

Legume-based pastures in Australasia are predominantly perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). These pastures have disadvantages such as limitations in the production and persistence of white clover and ryegrass in drought prone regions. With the increasing interest in organic agriculture, more complex pasture mixtures are seen as an alternative to the standard ryegrass-white clover (RWC) pasture. Although anecdotal evidence exists to support the benefits of alternative pastures, there is insufficient scientific evidence to support or refute these claims. The present study was conducted to compare three different alternative multi-species (mixed herb leys) (MSP) pastures with the standard RWC pasture with and without irrigation, in terms of biomass and biological nitrogen fixation (BNF) over a period of 1 year under field conditions in Canterbury, New Zealand. Isotopic dilution technique involving field ¹⁵N-microplots were used to measure BNF. Irrigation doubled dry matter yields (DMY) of all pastures compared with those under dryland. There was no significant difference between DMY of all pastures under dryland. However, under irrigation, MSP pastures out-yield RWC pasture in total and legume DMY. Red clover MSP produced significantly lower DMY than the comprehensive or lucerne MSP treatment, probably due to the ability of lucerne in extracting water from deeper soil depth. Seasonal changes in plant composition varied according to the species sown, soil moisture status and temperature. Total and seasonal amounts of N₂ fixed followed the same trend as the DMY and were related to the DMY of legumes. On average, about 26–34 kg N was fixed per tonne of legume DMY, showing a uniformity across all pastures. Overall, based on the present results of 1-year study, the MSP pastures tend to result in higher DMY, BNF and legume growth compared with that of the RWC pasture, provided irrigation is available. With increased BNF, these irrigated MSP pastures may provide high quality feed to grazing animals.     

水和废水、土壤中总铬的测定方法研究

对二苯碳酸二肼分光光度法(A法)和火焰原子吸收法(B法)测定水和废水、土壤中总铬的方法进行了研究,A法灵敏度高准确度好,但操作复杂,耗时.B法干扰少,测定快速,但富燃型火焰不稳定,影响测定结果,通过实验找出最佳乙炔流量,使测定结果准确、可靠,同时扩展仪器的应用范围,提高仪器使用率.     

Is big the best? Queen size,usurpation and nest closure in a primitively eusocial sweat bee (<Emphasis Type="Italic">Lasioglossum malachurum</Emphasis>)

For primitively eusocial insects in which a single foundress establishes a nest at the start of the colony cycle, the solitary provisioning phase before first worker emergence represents a risky period when other, nestless foundresses may attempt to usurp the nest. In the primitively eusocial sweat bee Lasioglossum malachurum (Hymenoptera, Halictidae), spring foundresses compete for nests which are dug into hard soil. Nest-searching foundresses (‘floaters’) frequently inspected nests during this solitary phase and thereby exerted a usurpation pressure on resident queens. Usurpation has been hypothesised to increase across the solitary provisioning phase and favour closure of nests at an aggregation, marking the termination of the solitary provisioning phase by foundresses, before worker emergence. However, our experimental and observational data suggest that usurpation pressure may remain constant or even decrease across the solitary provisioning phase and therefore cannot explain nest closure before first worker emergence. Levels of aggression during encounters between residents and floaters were surprisingly low (9% of encounters across 2 years), and the outcome of confrontations was in favour of residents (resident maintains residency in 94% of encounters across 2 years). Residents were significantly larger than floaters. However, the relationship between queen size and offspring production, though positive, was not statistically significant. Size therefore seems to confer a considerable advantage to a queen during the solitary provisioning phase in terms of nest residency, but its importance in terms of worker production appears marginal. Factors other than intraspecific usurpation need to be invoked to explain the break in provisioning activity of a foundress before first worker emergence.     

Emissions of organophosphate and brominated flame retardants from selected consumer products and building materials

The emissions of selected flame retardants were measured in 1- and 0.02-m³ emission test chambers and 0.001-m³ emission test cells. Four product groups were of interest: insulating materials, assembly foam, upholstery/mattresses, and electronics equipment. The experiments were performed under constant environmental conditions (23°C, 50% RH) using a fixed sample surface area and controlled air flow rates. Tris (2-chloro-isopropyl)phosphate (TCPP) was observed to be one of the most commonly emitted organophosphate flame retardants in polyurethane foam applications. Depending on the sample type, area-specific emission rates (SER_a) of TCPP varied between 20 ng m⁻² h⁻¹ and 140 μg m⁻² h⁻¹.The emissions from electronic devices were measured at 60°C to simulate operating conditions. Under these conditions, unit specific emission rates (SER_u) of organophosphates were determined to be 10–85 ng unit⁻¹ h⁻¹. Increasing the temperature increased the emission of several flame retardants by up to a factor of 500. The results presented in this paper indicate that emissions of several brominated and organophosphate flame retardants are measurable. Polybrominated diphenylethers exhibited an SER_a of between 0.2 and 6.6 ng m⁻² h⁻¹ and an SER_u of between 0.6 and 14.2 ng unit⁻¹ h⁻¹. Because of sink effects, i.e., sorption to chamber components, the emission test chambers and cells used in this study have limited utility for substances low vapour pressures, especially the highly brominated compounds; hexabromocyclododecane had an SER_a of between 0.1 and 29 ng m⁻² h⁻¹ and decabromodiphenylether was not detectable at all.     

A dynamic model of mating behavior in digger wasps: the energetics of male-male competition mimic size-dependent thermal constraints

I develop a state-based dynamic model of behavior to demonstrate that size-dependent differences in temperature tolerances are not necessary to account for the activity of small male digger wasps late in the day. In the model, males defend or patrol the nesting area, wait near nests, or feed away from the nesting area depending on time of day, energy reserves and size rank. I assume a large male competitive advantage, so mating opportunities decrease with size rank for territorial or patrolling males and are rare for all waiting males; the costs of patrolling or defense are higher than the costs of waiting. If energy reserves of all males are initially small, all males alternate feeding and territorial or patrolling behavior. If energy reserves are initially large, large males patrol or maintain territories until they risk starvation and leave the area to feed. At this time, smaller males that have conserved their resources by waiting and feeding may defend territories or patrol. I simulate the behavior of three populations representing two species of Microbembex by assuming large initial energy reserves for populations in which males were territorial and small initial reserves for populations in which males patrolled, and then convert the predicted time of activity to temperature using local regressions from field studies. Temporal patterns in the activity of large and small males were similar to those actually observed, and relationships between size and temperature predicted by the model corresponded to most observations and were sometimes positive. Thus, the delayed activity of smaller males does not correspond to activity at higher temperatures and is probably not attributable to size-dependent thermal tolerances, but may represent a temporal displacement of mating activity due to intra-sexual competition and mediated by energetics. The model makes testable predictions on the timing of feeding and depletion of energy reserves in relation to size and initial energy state, and suggests how differences among species may influence the temporal and spatial organization of male mating behavior. Received: 27 February 1997 / Accepted after revision: 26 July 1997     

Alternative male mating tactics in a cichlid, Pelvicachromis pulcher: a comparison of reproductive effort and success

Pelvicachromis pulcher is a small African cichlid which breeds in holes. Males may either reproduce monogamously (pair males), polygynously (harem males), or be tolerated as helpers in a harem territory (satellite males). These helpers share in defence of the territory against conspecifics, heterospecific competitors and predators. There are two male colour morphs that are fixed for life and are apparently genetically determined. These differ in their potential mating strategy. Red morph males may become harem owners, while yellow morph males may become satellite males, and males of both morphs may alternatively pair up monogamously. We compared the reproductive effort and success of these three male reproductive strategies. Effort was measured as attack rates, time expenditure and the risk of being injured or killed when attacking competitors or predators of three sympatric fish species. Reproductive success was measured by observing how many eggs were fertilized by each male when this was possible, and by using genetic markers. The number of fry surviving to independence of parental care was used as a criterion of success. The reproductive success of harem males was 3.3 times higher than that of pair males and 7 times higher than that of the average satellite male. Dominant satellite males, however, were as successful as monogamous pair males, using the measure of fertilized eggs. To our knowledge, this has not been found previously in any fish species. Both harem and pair males had lower parental defence costs per sired offspring, however, than males using the alternative satellite tactic. Defence effort was significantly related to the risk of injury. Received: 17 January 1996 / Accepted after revision: 9 June 1997     

Genetic analysis of parentage within experimental populations of a male dimorphic beetle,<Emphasis Type="Italic"> Onthophagus taurus</Emphasis>, using amplified fragment length polymorphism

We used the multilocus DNA fingerprinting technique, amplified fragment length polymorphism, to examine parentage of 902 offspring from eight experimental populations of the dung beetle, Onthophagus taurus. The males of this species exhibit a suit of morphological and behavioural traits that characterise alternative mating tactics. Hornless minor males sneak copulations with females that are guarded by horned major males. Our aims were to provide a prospective assessment of the potential role of frequency dependence in the maintenance of alternative mating tactics, to assess the levels of polyandry, and to determine the patterns of sperm usage by multiply mated females. The average proportion of offspring sired by major and minor males did not co-vary with the relative frequency of each morph present in experimental populations. However, there was some indication that the effective mating frequency (number of females producing offspring sired by a given male) of major and minor males may exhibit frequency dependence. Mating success of both male types declined with increasing numbers of major males. Paternity was positively associated with effective mating frequency. Females produced offspring sired from between one and eight males and, on average, paternity was distributed equally amongst a females mates, regardless of the number of males mated. Differences in fertilisation success among males were not associated with alternative male phenotypes. Neither did a males fertilisation success depend on his genetic dissimilarity with the female. These results are discussed in the context of the evolution of alternative mating strategies, and mechanisms of postcopulatory sexual selection.Communicated by N. Wedell     

N2和CO2抑制煤燃烧火焰特性对比试验研究

为了研究N_2和CO_2气体灭火剂在抑制煤明火燃烧特性方面的不同,通过搭建受限空间煤明火燃烧试验,分别开展了11.97%、16.81%、20.76%的N_2和10.79%、14.89%、20.32%的CO_2作用下煤明火燃烧抑制试验。鉴于火焰表面积变化与热释放速率变化呈正相关,基于火焰图像分析法开展试验研究。试验过程中,首先,通过数码摄像仪记录不同体积分数惰性气体作用下煤燃烧火焰面积的变化,然后利用Matlab软件进行火焰图像特征提取和"对比度增强"预处理,消除图像记录过程中存在的噪声,以便于有效进行火焰目标识别;其次,基于"阈值法"原理,利用Image-Pro Plus软件对预处理过的火焰目标进行识别和计算,进而实时获得试验过程中火焰表面积;最后,使用小波变换理论对火焰表面积变化曲线进行消噪处理,以获得火焰表面积变化趋势及主要波动信息。结果表明,CO_2比N_2具有更好的熄灭煤明火燃烧的能力,CO_2作用下煤火火焰表面积呈现指数下降,而N_2作用下呈现直线下降,且CO_2的灭火时间比N_2缩短了25%以上。该试验结果明确了N_2和CO_2在熄灭煤明火特性上的不同,弥补了CO_2仅比N_2具有更好的抑爆特性的认识。