N2O emissions from agricultural soils in the North China Plain:the effect of chemical nitrogen fertilizer and organic manure

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Sequential female choice and the previous male effect in sticklebacks

Summary Female choice, identified as a major force in sexual selection theory, has recently been demonstrated in a number of species. These tests concentrated on simultaneous choice situations although females have to compare males sequentially in most territorial species, which is the more demanding task. Here it is shown that female three-spined sticklebacks, Gasterosteus aculeatus L., rate sequentially presented males according to their brightness. With increasing costs of sampling the females become less choosy. Furthermore, a male's attractiveness has a significant effect on the female's rating of the next male; a given male is rated higher when preceded by a duller male than by a brighter one and vice versa. Female sticklebacks use a stochastic decision rule in sequential mate choice that is attuned to the attractiveness of the present and previously encountered male. This demonstration of a previous male effect not only indicates an efficient mechanism for finding the best of a number of males but also extends the applicability of sexual selection theory.Offprint requests to: T.C.M. Bakker     

Bacterioplankton Community Structure and Dynamics in Enclosures During Bioremediation Experiments in an Acid Mining Lake

In an acid mining lake (pH 2.6) enclosure experiments wereperformed with the addition of different concentrations oforganic carbon, nitrogen and phosphorus. SSCP-communityfingerprints, based on 16S rRNA gene amplicons, were performed tomonitor changes in the structure of the total bacterialcommunity and the sulfate reducing bacteria (SRB) in themesocosms. Total bacterial cell counts, as assessed byepifluorescence microscopy, were increased in the mesocosmsamended with organic carbon. The addition of carbon alsoincreased the number of abundant bacterial taxa substantiallyalong depth. Sulfate reducing bacteria (SRB) could be detected inall enclosures and all parts of the water column. These SRBbelonged to genus Desulfobacter as indicated bycoroborating molecular data.     

Assessing the Ecological Footprint of a Large Metropolitan Water Supplier: Lessons for Water Management and Planning towards Sustainability

Faced with the task of communicating their combined social, environmental and economic impact, water service providers are seeking to report overall performance in an aggregated way. Such a methodology must be scientifically robust, easily communicated and allow benchmarking of performance while reflecting a transition towards sustainability. In this paper the ecological footprint (EF) is calculated for Sydney Water Corporation (SWC), using input-output analysis and land disturbance in an innovative approach that overcomes problems identified in the original EF concept. This pilot study has allowed SWC to gain some valuable insights into its impacts: SWC's annual EF is about 73 100 ha in terms of land disturbance. Of this, 54 000 ha are projected to become disturbed as a consequence of climate change, with the remainder of 19 100 ha being disturbed on SWC's premises (2400 ha) and on those of upstream suppliers (16 700 ha). Total on-site impacts equal 9300 ha, while indirect land disturb ance contributes 63 600 ha. The EF appears promising as an educational and communi cation tool and may have potential as a decision support tool. However, further research is needed to incorporate downstream impacts into the EF, which would have significant benefits to SWC in terms of assessing and communicating the organization's overall progress towards sustainability.     

A Successful Pilot Project of Decentralized Household Waste Management in Brazil

Summary Present municipal waste management paradigms in Brazil do not allow for flexible approaches to solving an extremely dynamic problem. This paper discusses the basic flaws in present thinking models of residents and municipal administrators. Fundamental arguments presented on municipal solid waste relate to nomenclature, destinations, definitions, logistics, social dynamics, social assistance programs, education and employment philosophies. In each case, the consequences of the stalemate are explained in terms of the unsustainable situation of constantly growing landfills. In sequence, a proactive thinking model is presented and explained that has the potential of drastically reducing landfill size. It is called Municipal Transit Material Processing. The model has been tested successfully in small communities and is now available for scale-up. The landfill diversion achieved stands at 62% of household waste in comparison with 15% theoretically possible in Brazil with selective collection models. Although of necessity the arguments apply directly to Brazil, the basic ideas behind the reasoning may be extrapolated to other Southern countries. The following simple example will illustrate to the reader the type of paradigm inversion the paper proposes to convey. The classical political slogan in Brazil is “get children out of garbage dumps”. The inversion proposed and explained is “do away with garbage dumps”.