Cercopagis pengoi and Mysis spp. alter their feeding rate and prey selection under predation risk of herring (Clupea harengus membras)

The anti-predator behaviour of Baltic crustacean planktivores was studied in feeding experiments under predation pressure of herring. The experiments were conducted with pelagic mysids: Mysis mixta and Mysis relicta, and with Cercopagis pengoi, a non-indigenous cladoceran, which invaded the Baltic Sea in 1992. Zooplankton was offered as prey. Two kinds of experiments were performed in the absence and presence of chemical predator cues: (1) two-prey experiments with prey, which have poor or good escape responses and all three planktivores and (2) natural prey experiments with mysids in natural zooplankton assemblages. The results showed that all three species reacted to the chemical cue of herring by decreasing their feeding rate and altering prey selection. C. pengoi selected easily captured prey (rotifers) in two-prey experiments under predation risk while selection for any prey was evident in mysids in natural prey experiments only in the absence of predator cues. This indicates that planktivores have different anti-predator strategies, which are modified by their own prey capture abilities. C. pengoi was a very efficient predator on small prey with size-specific prey consumption rate 5 to 18 times the rate of mysids. Results show that the studied planktivores are capable of adjusting their feeding behaviour to decrease their conspicuousness in order to increase survival under predation risk. Further, results support the view that C. pengoi has adapted well to the Baltic ecosystem, sharing food niche with pelagic mysids and most probably having a strong influence on the whole pelagic food web.     

Pneumatic vs. door-to-door waste collection systems in existing urban areas: a comparison of economic performance

Pneumatic waste collection systems are becoming increasingly popular in new urban residential areas, and an attractive alternative to conventional vehicle-operated municipal solid waste (MSW) collection also in ready-built urban areas. How well pneumatic systems perform in ready-built areas is, however, an unexplored topic. In this paper, we analyze how a hypothetical stationary pneumatic waste collection system compares economically to a traditional vehicle-operated door-to-door collection system in an existing, densely populated urban area. Both pneumatic and door-to-door collection systems face disadvantages in such areas. While buildings and fixed city infrastructure increase the installation costs of a pneumatic system in existing residential areas, the limited space for waste transportation vehicles and containers cause problems for vehicle-operated waste collection systems. The method used for analyzing the cost effects of the compared waste collection systems in our case study takes into account also monetized environmental effects of both waste collection systems. As a result, we find that the door-to-door collection system is economically almost six times more superior. The dominant cost factor in the analysis is the large investment cost of the pneumatic system. The economic value of land is an important variable, as it is able to reverse the results, if the value of land saved with a pneumatic system is sufficiently high.     

Governance experiments in climate action: empirical findings from the 28 European Union countries

Climate targets call for novel policy measures to facilitate widespread adoption of low-carbon solutions and innovations. The literature on socio-technical systems argues that experimentation has a prominent role in enabling sustainability transition. Experiments represent ways of testing new ideas and methods across a wide range of policy fields. Governance experiments in particular can support accelerated diffusion of new solutions, because they integrate policy with innovations. Here, types of success factors in the implementation of governance experiments to mitigate climate change are examined. Statistical analysis of sustainability innovations in the 28 European Union countries indicates that the types of success factors in governance experiments differ from those of product and social experiments. Governance experimentation is more positioned within socio-technical regimes than in strategic niches. These results suggest that governance experiments may indeed provide new transition opportunities towards low-carbon societies.     

Filter materials for metal removal from mine drainage—a review

A large number of filter materials, organic and inorganic, for removal of heavy metals in mine drainage have been reviewed. Bark, chitin, chitosan, commercial ion exchangers, dairy manure compost, lignite, peat, rice husks, vegetal compost, and yeast are examples of organic materials, while bio-carbons, calcareous shale, dolomite, fly ash, limestone, olivine, steel slag materials and zeolites are examples of inorganic materials. The majority of these filter materials have been investigated in laboratory studies, based on various experimental set-ups (batch and/or column tests) and different conditions. A few materials, for instance steel slag materials, have also been subjects to field investigations under real-life conditions. The results from these investigations show that steel slag materials have the potential to remove heavy metals under different conditions. Ion exchange has been suggested as the major metal removal mechanisms not only for steel slag but also for lignite. Other suggested removal mechanisms have also been identified. Adsorption has been suggested important for activated carbon, precipitation for chitosan and sulphate reduction for olivine. General findings indicate that the results with regard to metal removal vary due to experimental set ups, composition of mine drainage and properties of filter materials and the discrepancies between studies renders normalisation of data difficult. However, the literature reveals that Fe, Zn, Pb, Hg and Al are removed to a large extent. Further investigations, especially under real-life conditions, are however necessary in order to find suitable filter materials for treatment of mine drainage.     

Environmental sustainability comparison of a hypothetical pneumatic waste collection system and a door-to-door system

Waste collection is one of the life cycle phases that influence the environmental sustainability of waste management. Pneumatic waste collection systems represent a new way of arranging waste collection in densely populated urban areas. However, limited information is available on the environmental impacts of this system. In this study, we compare the environmental sustainability of conventional door-to-door waste collection with its hypothetical pneumatic alternative. Furthermore, we analyse whether the size of the hypothetical pneumatic system, or the number of waste fractions included, have an impact on the results. Environmental loads are calculated for a hypothetical pneumatic waste collection system modelled on an existing dense urban area in Helsinki, Finland, and the results are compared to those of the prevailing, container-based, door-to-door waste collection system. The evaluation method used is the life-cycle inventory (LCI). In this study, we report the atmospheric emissions of greenhouse gases (GHG), SO(2) and NO(x). The results indicate that replacing the prevailing system with stationary pneumatic waste collection in an existing urban infrastructure would increase total air emissions. Locally, in the waste collection area, emissions would nonetheless diminish, as collection traffic decreases. While the electricity consumption of the hypothetical pneumatic system and the origin of electricity have a significant bearing on the results, emissions due to manufacturing the system's components prove decisive.