Improvements of nano-SiO2 on sludge/fly ash mortar

Sewage sludge ash has been widely applied to cementitious materials. In this study, in order to determine effects of nano-SiO(2) additives on properties of sludge/fly ash mortar, different amounts of nano-SiO(2) were added to sludge/fly ash mortar specimens to investigate their physical properties and micro-structures. A water-binding ratio of 0.7 was assigned to the mix. Substitution amounts of 0%, 10%, 20%, and 30% of sludge/fly ash (1:1 ratio) were proposed. Moreover, 0%, 1%, 2%, and 3% of nano-SiO(2) was added to the mix. Tests, including SEM and compressive strength, were carried out on mortar specimens cured at 3, 7, and 28 days. Results showed that sludge/fly ash can make the crystals of cement hydration product finer. Moreover, crystals increased after nano-SiO(2) was added. Hence, nano-SiO(2) can improve the effects of sludge/fly ash on the hydration of mortar. Further, due to the low pozzolanic reaction active index of sludge ash, early compressive strengths of sludge/fly ash mortar were decreased. Yet, nano-SiO(2) could help produce hydration crystals, which implies that the addition of nano-SiO(2) to mortar can improve the influence of sludge/fly ash on the development of the early strength of the mortar.     

Perspectives and limits for cement kilns as a destination for RDF

RDF, the high calorific value fraction of MSW obtained by conventional separation systems, can be employed in technological plants (mainly cement kilns) in order to obtain a useful energy recovery. It is interesting and important to evaluate this possibility within the general framework of waste-to-energy solutions. The solution must be assessed on the basis of different aspects, namely: technological features and clinker characteristics; local atmospheric pollution; the effects of RDF used in cement kilns on the generation of greenhouse gases; the economics of conventional solid fuels substitution and planning perspectives, from the point of view of the destination of RDF and optimal cement kiln policy. The different experiences of this issue throughout Europe are reviewed, and some applications within Italy are also been considered. The main findings of the study are that the use of RDF in cement kilns instead of coal or coke offers environmental benefits in terms of greenhouse gases, while the formation of conventional gaseous pollutants is not a critical aspect. Indeed, the generation of nitrogen oxides can probably be lower because of lower flame temperatures or lower air excess. The presence of chlorinated micro-pollutants is not influenced by the presence of RDF in fuel, whereas depending on the quality of the RDF, some problems could arise compared to the substituted fuel as far as heavy metals are concerned, chiefly the more volatile ones.     

Sorption of imidazolium-based ionic liquids to aquatic sediments

Ionic liquids (ILs) have received much attention as "green" alternatives to traditional solvents because they do not evaporate, eliminating concerns over fugitive emissions. However, if ionic liquids are used in industrial applications, they may enter aquatic systems via effluent, and their fate and transport may be influenced by sorption to sediments. In this study, we conducted batch mixing experiments with four alkylmethylimidizolium-based ILs and four types of aquatic sediments to asses the capacity for natural aquatic sediments to remove these chemicals from the water column. The concentration isotherms were non linear with point estimates of the distribution coefficient (K(d)) decreasing with increasing concentration. Apparent distribution coefficients ranged from 7.9 to 95.7l kg(-1) at an initial concentration of 0.5mM and were positively related to sediment organic matter (SOM) content. These K(d) values indicate that the ILs did not sorb strongly to the tested sediments. Increased alkyl chain length did not lead to increased sorption suggesting that hydrophobic interactions were not the most important sorption mechanism. We conclude that aquatic sediments have a limited capacity to sorb alkylmethylimidazolium ILs and that the transport of these contaminants in aquatic systems will not be strongly attenuated by sediments.     

Short- and medium-term effects of experimental nitrogen fertilization on arthropods associated with Calluna vulgaris heathlands in north-west Spain

We studied the short- and medium-term effects of experimental nitrogen fertilization (3 and 15 months after the treatment) on the arthropods of Calluna vulgaris heathlands in NW Spain. Three heathland sites were selected with two permanent plots per site: control and fertilized. Ammonium nitrate fertilizer (56 kg N ha(-1) yr(-1)) was applied monthly and insects were caught using pitfall traps. We found mainly species-level responses to nitrogen addition. Seven species (e.g. Lochmaea suturalis) showed a consistent trend (benefited or harmed) in both periods and were proposed as possible reliable indicators of the effects of nitrogen deposition in these ecosystems. We also found variable arthropod trophic-group responses: (a) herbivores (leaf beetles, true bugs) increased in abundance on a short-term scale; (b) predators (carabid beetles, true bugs) showed opposite and less clear responses in both periods. Further long-term studies are needed to determine the mechanisms underlying the observed arthropod responses.     

Urban observatories opportunities for environmental monitoring: solid wastes

Towns concentrate around 50% of world-wide population and the trend is oriented to underscore an urban profile of population. In addition, towns have become important for their economic contribution to the Gross Internal Product. The negative side of towns is the environmental and social impacts as a result of productive and domestic activities, besides the lack of available data. In order to overcome these shortcomings, the United Nations has established a project of urban monitoring throughout the Global Network of Urban Observatories; Mexico joined the project in 2005. The Local Urban Observatory of Mexicali has the task to produce information about cities that is useful to design public policies. Some of this information deals with a set of environmental indicators in the United Nations Habitat Agenda, which includes solid wastes. Therefore, this paper deals with two main topics; firstly, from the Habitat Agenda, a comparative urban analysis of waste production and coverage of domestic waste collection services; secondly, from the Local Agenda, the identification and ranking of environmental problems according to public perception coming from people involved in the municipal planning and decision making process. Results will be used to develop local indicators and public environmental policies.     

Experimental evidence of a testosterone-induced shift from paternal to mating behaviour in a facultatively polygynous songbird

Previous studies have suggested that testosterone (T) profiles of male birds reflect a trade-off between mate attraction behaviours (requiring high T levels) and parental care activities (requiring low T levels). In this study, we experimentally elevated T levels of monogamous males in the facultatively polygynous European starling (Sturnus vulgaris), and compared mate attraction and paternal behaviour of T-treated males with those of controls (C-males). T-males significantly reduced their participation in incubation and fed nestlings significantly less often than C-males. Females paired to T-treated males did not compensate for their mate’s lower paternal effort. The observed reduction in a male’s investment in incubating the eggs was accompanied by an increased investment in typical female-attracting behaviours: T-males spent a significantly higher proportion of their time singing to attract additional females. They also occupied more additional nestboxes than C-males, although the differences just failed to be significant, and carried significantly more green nesting materials into an additional nestbox (a behaviour previously shown to serve a courtship function). T-males also behaved significantly more aggressively than C-males. During the nestling period, the frequency of mate-attracting behaviours by T-treated and control males no longer differed significantly. Despite the reduced paternal effort by T-males and the lack of compensation behaviour by females, hatching and breeding success did not differ significantly between T- and C-pairs. Received: 7 February 2000 / Revised: 10 August 2000 / Accepted: 3 September 2000     

Aggression and resource sharing among foundresses in the social wasp Polistes dominulus: testing transactional theories of conflict

Tug-of-war models of within-group conflict predict that the frequency of conflict will be positively related to the degree of reproductive sharing within the group; in contrast, a negative relationship supports transactional models, in which reproductive payments among group members limit the degree of within-group selfishness. We tested predictions of the tug-of-war and transactional models by examining cofoundress interactions during the founding (preworker) phase of colony development in 30 naturally nesting colonies of the paper wasp Polistes dominulus. We found that the mean rate of foundress aggression and the mean probability of food sharing were significantly negatively associated, which supports the prediction of the transactional, not the tug-of-war model. Further, cofoundress aggression significantly increased over the founding phase (independently of temperature), while the fraction of aggression initiated by the dominant (alpha) foundress significantly decreased over this period. We show that both of these results are predicted by the transactional model of within-group conflict. Interestingly, the alpha’s rate of aggression was significantly positively temperature dependent, while the beta’s was not. This indicates that the alpha’s aggression level may often be near her physiological maximum, while the beta’s aggression is limi- ted by other factors, contradicting the prediction of the tug-of-war model. Moreover, the alpha’s aggression was significantly positively temperature dependent only in the second half of the founding period, as predicted by the transactional model since this is when there is least reproductive sharing. Finally, our results indicate that the alpha’s level of aggression depends on the resources controlled by the beta. Received: 18 January 2000 / Revised: 19 June 2000 / Accepted: 24 June 2000     

Bushmeat Markets on Bioko Island as a Measure of Hunting Pressure

Abstract: Counts of the number of animal carcasses arriving at Malabo market, Bioko Island, Equatorial Guinea, were made during two, 8-month study periods in 1991 and 1996. Comparisons of the availability and abundance of individual species between years showed that more species and more carcasses appeared in 1996 than in 1991. In biomass terms, the increase was significantly less, only 12.5%, when compared with almost 60% more carcasses entering the market in 1996. A larger number of carcasses of the smaller-bodied species (i.e., rodents and the blue duiker [ Cephalophus monticola ] ) were recorded in 1996 than in 1991. Although an additional four species of birds and one squirrel were recorded in 1996, these were less important in terms of their contribution to biomass or carcass numbers. Concurrently, there was a dramatic reduction in the larger-bodied species, Ogilby's duiker ( C. ogilbyi ) and seven diurnal primates. We examined these changes, especially the drop in the number of larger animals. We considered the possible following explanations: (1) the number of hunters dropped either because of enforced legislation or scarcity of larger prey; (2) a shift in the use of hunting techniques occurred (   from shotguns to snares); or (3) consumer demand for primate and duiker meat dropped, which increased demand for smaller game. Our results suggest that the situation in Bioko may be alarmingly close to a catastrophe in which primate populations of international conservation significance are being hunted to dangerously low numbers. Although there is still a need for surveys of actual densities of prey populations throughout the island, working with the human population on Bioko to find alternatives to bushmeat is an urgent priority.     

Cougar Dispersal Patterns, Metapopulation Dynamics, and Conservation

Abstract: We examined cougar (   Puma concolor ) dispersal, emigration, and immigration in the San Andres Mountains, New Mexico, from 1985 to 1995 to quantify the effects of dispersal on the local population and surrounding subpopulations. We captured, tagged, and radio-collared animals to detect the arrival of new immigrants and dispersal characteristics of progeny. We found that cougars in southern New Mexico exhibited a metapopulation structure in which cougar subpopulations were separated by expanses of noncougar habitat and linked by dispersers. Of 43 progeny (n = 20 males , 23 females ) studied after independence, only 13 females exhibited philopatric behavior. Males dispersed significantly farther than females, were more likely to traverse large expanses of noncougar habitat, and were probably most responsible for nuclear gene flow between habitat patches. We estimated that an average of 8.5 progeny (i.e., cougars born in the study area) successfully emigrated from and 4.3 cougars successfully immigrated to the San Andres Mountains each year. Concurrently, an average of 4.1 progeny were recruited into the San Andres cougar population. Protected cougar subpopulations can contribute to metapopulation persistence by supplying immigrants to surrounding subpopulations that are affected by fragmentation or offtake by humans. Cougar population dynamics and dispersal behavior dictate that cougar management and conservation should be considered on a regional scale.     

Poisoned plusiines: toxicity of milkweed latex and cardenolides to some generalist caterpillars

Summary. Larvae of Trichoplusia ni Hübner (Lepidoptera: Noctuidae) that ingested latex from Asclepias curassavica L. (Asclepiadaceae) often regurgitated and convulsed with spasms before becoming immobile and unresponsive. Some larvae required over a day to recover sufficiently to feed. Latices from four other plant species in three families were all deterrent, but none caused detectable poisoning. The toxicity of A. curassavica latex was evidently due to cardenolides because pure cardenolides had similar effects when ingested by T. ni. Other species of noctuid caterpillars (Rachiplusia ou Guenée, Anagrapha falcifera Kirby, and Autographa precationis Guenée) sometimes also suffered spasms and temporary immobility when fed A. curassavica latex. A more distantly related noctuid, Spodoptera ornithogalli, was deterred by the latex, but showed no overt physiological responses at the dosage tested. T. ni larvae failed to develop on intact leaves of A. curassavica, on leaves with latex canals deactivated by midrib severance, and on excised leaves. Similarly, larvae reared on excised A. syriaca L. leaves to the final instar died when transferred to A. curassavica leaves with either intact or severed midribs. The final instar larvae sometimes suffered from spasms and immobility even when confined on leaves with depressurized canal systems. Evidently, cardenolides stored outside the latex system suffice to poison larvae. We conclude that cardenolides in A. curassavica have potent physiological effects on some generalist caterpillars and that the presence of these compounds both inside and outside laticifers effectively protects the plant. Received 30 June 1999; accepted 18 October 1999