pH-dependent release of cadmium,copper, and lead from natural and sludge-amended soils

The pH-dependent release of cadmium, copper, and lead from soil materials was studied by use of a stirred flow cell to quantify their release and release rates, and to evaluate the method as a test for the bonding strength and potential mobility of heavy metals in soils. Soil materials from sludge-amended and nonamended A horizons from a Thai coarse-textured Kandiustult and a Danish loamy Hapludalf were characterized and tested. For each soil sample, release experiments with steady state pH values in the range 2.9 to 7.1 and duration of 7 d were performed. The effluent was continuously collected and analyzed. Release rates and total releases were higher for the Hapludalf than the Kandiustult and higher for the sludge-amended soils than the nonamended soils. With two exceptions the relative release rates (release rate/total content of metal in soil) plotted vs. steady state pH followed the same curves for each metal, indicating similar bonding strengths. These curves could be described by a rate expression of the form: relative release rate = k[H+]a, with specific a (empirical constant) and k (rate constant) parameters for each metal demonstrating that metal release in these systems can be explained by proton-induced desorption and dissolution reactions. With decreasing pH, pronounced increases in release rates were observed in the sequence cadmium > lead > copper, which express the order of metal lability in the soils. The flow cell system is useful for comparison of metal releases as a function of soil properties, and can be used as a test to rank soils with respect to heavy metal leaching.     

Pro-Poor local economic development in South Africa: The role of pro-poor tourism

This paper describes features of the emerging nexus in South Africa between tourism, poverty alleviation and local economic development (LED) interventions. The South African experience of evolving a strong pro-poor focus in LED planning is distinctive in the international context of writings on LED. Pro-poor LED is increasingly the outcome of the application of measures and programmes that are linked to the approach of pro-poor tourism in both rural and urban areas of South Africa. Two studies are presented of Alexandra township, Johannesburg and the Madikwe Game Reserve in North West Province as examples of pro-poor tourism as a form of pro-poor LED. It is argued that the growth of pro-poor tourism initiatives in South Africa suggests that the country is currently a laboratory for the testing and evolution of new approaches towards the planning of LED that potentially will have relevance for other countries in the developing world.     

What to Buy? On the Complexity of Being a Critical Consumer

This article criticises the notion that critical/political/ethical consumerism can solve issues related to sustainability and food production. It does this by analysing the complexity of the concept of sustainability as related to food choices. The current trend of pursuing a sustainable food production through critical purchase decisions rather than through regulation is shown to be problematic, as shopping for a more sustainable food system might be much harder than initially believed due to the conflicting values and inherent trade-offs entailed in the different notions of sustainability. Thus, critical consumerism may give way to false expectations as the complexity of choices transpires. One obvious way out is to let decisions regarding food choices be made earlier in the food production chain as well as through new modes of governance engaging members of civil society in their capacity as citizens rather than consumers. This entails complementing society’s reliance on critical consumerism with a citizen-oriented and political process in support of making more sustainable food choices.     

Stalled regime transition in the upper Tisza River Basin: the dynamics of linked action situations

In river basins transformation from traditions of reactive flood defense to more adaptive management regimes is difficult. How regime components reinforce each other to set its development path may induce inertia and path dependency. Transformation may require profound shifts in the institutions, technologies, and personnel as well as the ecological, economic and social processes they influence in setting the basin's trajectory. Regime change has become an issue in Hungary following repeated failures of conventional management policies to handle a series of floods on the Tisza river starting in 1997. Increasing public participation pushed water policy debate toward more experimentation with alternatives, but implementation appears stalled. In this paper we review hypotheses about what factors are bridges or barriers to transformation and then use the Management Transition Framework to examine how the interactions linking action situations, operational outcomes, knowledge and institutions influenced the river management policy debate in Hungary from 1997 to 2009. Specifically we examined which factors characteristic of conventional Control vs. progressive Adaptive management regimes influenced these interactions in ways that contributed to or hindered transformation. We found that governance and social learning issues predominated, with lesser roles played by factors related to integration of sectors and different levels in the science and policy of river management.     

Separate collection and bio-waste valorization in the Italian poultry sector by material flow analysis

Journal of Material Cycles and Waste Management - Poultry meat production and consumption face several challenges under economic, social and environmental perspectives, and increasing concerns are...     

Abiotic aging of water- soluble 3- hydroxybutyric acid oligomers as monitored by capillary zone electrophoresis

Oligomers of poly(3-hydroxybutyric acid) (P(3-HB)) were prepared by partial degradation of high molecular weight P(3-HB) dissolved in 1,2-dichloroethane/water mixture in the presence of p-toluene sulfonic acid (p-TSA). The water-soluble fraction of the resulting oligomers was extracted from the mixture with neutral sodium phosphate buffer. Capillary zone electrophoresis showed that the aqueous extracts were composed of two series of oligomers. The first one was composed of one to seven P(3-HB) oligomers (O(3-HB)). In contrast, the second series was composed of four oligomers characterized by the presence of a terminal C=C bond [O’(3-HB)]. Both series of oligomers behaved differently insofar as their fate in aqueous medium was concerned. The 0(3-HB) compounds were stable over a period of 2 months. On the other hand, the population of the O’(3-HB) oligomers varied, the proportion of oligomers increasing with aging time.     

Nitrate and nitrite injection during municipal solid waste anaerobic biodegradation

Nitrified leachate recirculation has been proposed as a promising strategy for sustainable landfill management. In four test reactors, nitrate or nitrite was added (250 mg N-NO(x)(-)L(-1)) during municipal solid waste biodegradation. Nitrogen-oxides reduction reactions were monitored. Denitrification was the main nitrogen reducing reaction observed. On one hand, during the acidogenic waste degradation phase, as high amounts of volatile fatty acids (VFA) were present, nitrogen-oxides reductions were interpreted as heterotrophic denitrifications. On the other hand, denitrification reactions occurring during the late methanogenic phase were accompanied by sulphate productions and, as VFA were not detected, it was probably an autotrophic reaction. Denitrification inhibition was observed once. Ammonium concentration increased suggesting the occurrence of a dissimilatory nitrate reduction to ammonium (DNRA). Statistical treatment of analytical data revealed that only H(2)S concentration had a significant negative effect on N(2) production in our system. NO production was observed once when nitrite was injected during the acidogenic phase resulting in a total waste degradation inhibition. These results indicate that the consequences of nitrified leachate recirculation in full-scale landfills need to be carefully examined especially during the acidogenic phase or in the presence of waste containing high quantities of sulphur.