Technical and environmental long-term properties of industrial residues--summary of field and laboratory investigations

In Sweden, use of industrial residues is still hindered by concern for their long-term properties. A three-year research project was therefore initiated aiming to (1) identify the crucial processes of ageing related to the usefulness of residues in roads; (2) investigate the consequences of these processes for technical and environmental properties of the residues, and (3) propose a method for accelerated ageing to predict the long-term properties. This paper gives an overview of the project methodology, a summary of the test results and references to papers where further details are given.The project, running through 2006-2008, compared naturally aged samples of two residues used as sub-bases in existing asphalt paved roads with samples of fresh residues from producers’ piles. Steel slag of electric arc furnace (EAF) type and municipal solid waste incinerator (MSWI) bottom ash were chosen. The samples were thoroughly characterised in order to identify which ageing processes had been crucial.The results showed that:

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Bottom ash from the pavement edge was more aged than bottom ash from the road centre. However, no difference in pH was found, instead the differences were caused by differences in water exposure.

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Steel slag from the pavement edge showed traces of carbonation and leaching processes, whereas slag from the road centre was identical to fresh slag.

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Water exposure to the subbase materials after ten years in an asphalt paved road was calculated to less than 0.1-0.5 litres per kg.

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Ageing reactions in steel slag and MSWI bottom ash, ready for use, were too small to be verified by laboratory measurement of deformation properties under loaded conditions.

An accelerated ageing test for steel slag was set up to achieve the carbonation (decrease in pH) and leaching that was observed in the pavement edge material.An accelerated ageing test for bottom ash was set up to achieve the pozzolan reactions that were observed in SEM analyses of in situ specimens.It is recommended to use uncrushed particles when properties of aged material are studied, in order to preserve the original particle surfaces.     

Why are we growth-addicted? The hard way towards degrowth in the involutionary western development path

By questioning the origins of the inertia facing the degrowth movement, this contribution identifies property as the constitutive institution of capitalism, and property expansion as the dominant socioeconomic process leading world societies to economic path dependence, techno-institutional lock-in and eco-social impasse. Demonstrating why and how property-based economic rationality subordinates ecological and social considerations to capitalist requirements, this paper stresses both the need for an inversion in the hierarchy of social norms and the systemic opposition to such an inversion, which emanates from the capitalist/industrial expansion. The text also brings to light some disregarded processes underlying the current economic crisis, by pointing out the institutional and technological locked-in situation into which the western development path has led our societies.     

Quantification of carbamazepine and atrazine and screening of suspect organic contaminants in surface and drinking waters

A new approach for the identification of suspect trace organic contaminants in drinking and surface waters is presented. Samples were initially analyzed using a target determination method for two contamination tracers, carbamazepine (CBZ) and atrazine (ATZ). This method used offline solid-phase extraction and online solid-phase extraction techniques coupled to liquid chromatography-triple quadrupole mass spectrometry to accelerate the sample preparation process and improve method performance. CBZ and ATZ were found respectively in 31% and 56% of the samples, and concentrations were usually <20 ng L⁻¹. These samples were re-analyzed with a similar method on a quadrupole time-of-flight mass spectrometer to identify suspect contaminants by means of exact mass measurements and isotope patterns. A database of 264 common organic contaminants was built and used in conjunction with a Molecular Feature algorithm to identify the presence of these substances in drinking and surface water collected from different sources at various locations across Canada. Several organic contaminants were identified in the samples, but only the presence of caffeine, desethylatrazine, simazine and venlafaxine could be verified by comparison to pure standards. The presence of desethylatrazine was also confirmed by MS/MS experiments. These results suggest that target analysis for tracers of organic contamination may be a helpful tool to prioritize samples which should be further screened for suspect contaminants. This study also shows that the combination of separation techniques (offline and online SPE, LC) contribute to advance the applicability of high-resolution mass spectrometry for the identification of trace organic contaminants by accelerating the preparation step, reducing complexity and increasing analyte concentrations for optimal detection.     

Crop‐based systems for sustainable risk‐based land management for economically marginal damaged land

The increasing need for biomass for energy and feedstocks, along with the need to divert organic methane generating wastes from landfills, may provide the economic leverage necessary to return this type of marginal land to functional and economic use and is strongly supported by policy at the European Union (EU) level. The use of land to produce biomass for energy production or feedstocks for manufacturing processes (such as plastics and biofuels) has, however, become increasingly contentious, with a number of environmental, economic, and social concerns raised. The REJUVENATE project has developed a decision support framework to help land managers and other decision makers identify potential concerns related to sustainability and what types of biomass reuse for marginal land might be possible, given their particular circumstances. The decision‐making framework takes a holistic approach to decision making rather than viewing biomass production simply as an adjunct of a planned phytoremediation project. The framework is serviceable in Germany, Sweden, and the United Kingdom. These countries have substantive differences in their land and biomass reuse circumstances. However, all can make use of the set of common principles of crop, site, value, and project risk management set out by REJUVENATE. This implies that the framework should have wider applicability across the EU. This article introduces the decision support framework. © 2011 Wiley Periodicals, Inc.     

Iron isotopic fractionation in industrial emissions and urban aerosols

A study on tropospheric aerosols involving Fe particles with an industrial origin is tackled here. Aerosols were collected at the largest exhausts of a major European steel metallurgy plant and around its near urban environment. A combination of bulk and individual particle analysis performed by SEM–EDX provides the chemical composition of Fe-bearing aerosols emitted within the factory process (hematite, magnetite and agglomerates of these oxides with sylvite (KCl), calcite (CaCO₃) and graphite carbon). Fe isotopic compositions of those emissions fall within the range (0.08‰ < δ⁵⁶Fe < +0.80‰) of enriched ores processed by the manufacturer (−0.16‰ < δ⁵⁶Fe < +1.19‰). No significant evolution of Fe fractionation during steelworks processes is observed. At the industrial source, Fe is mainly present as oxide particles, to some extent in 3–4 μm aggregates. In the close urban area, 5 km away from the steel plant, individual particle analysis of collected aerosols presents, in addition to the industrial particle type, aluminosilicates and related natural particles (gypsum, quartz, calcite and reacted sea salt). The Fe isotopic composition (δ⁵⁶Fe = 0.14 ± 0.11‰) measured in the close urban environment of the steel metallurgy plant appears coherent with an external mixing of industrial and continental Fe-containing tropospheric aerosols, as evidenced by individual particle chemical analysis. Our isotopic data provide a first estimation of an anthropogenic source term as part of the study of photochemically promoted dissolution processes and related Fe fractionations in tropospheric aerosols.     

Direct measurement of denitrification activity in a Gulf coast freshwater marsh receiving diverted Mississippi River water

Wetland loss along the Louisiana Gulf coast and excessive nitrate loading into the Gulf of Mexico are interrelated environmental problems. Nitrate removal by soil denitrification activity was studied in a ponded freshwater marsh receiving diverted Mississippi River water for the purpose of reversing or slowing wetland loss. Labeled ¹⁵N-nitrate was applied at 3.8 g N m⁻² into four replicate study plots after removing above ground vegetation. Nitrogen gas (N₂) and nitrous oxide (N₂O) emissions from the plots were determined by isotope ratio mass spectrometry (IRMS). Nitrous oxide emissions were also compared with the results determined by gas chromatograph (GC). Results showed that it took 2 weeks to remove the added nitrate with N₂O emission occurring over a period of 4 d. The apparent denitrification dynamics were assumed to follow the Michaelis–Menten equation. The maximum denitrification rate and K_m value were determined as 12.6 mg N m ⁻² h⁻¹, and 6.5 mg N l⁻¹, respectively. Therefore the maximum capacity for nitrate removal by the marsh soil would be equivalent to 110 g N m⁻² yr⁻¹, with more than 30% of nitrogen gas evolved as N₂O. For typical nitrate concentrations in Mississippi River water of about 1 mg N l⁻¹, nitrate would be removed at a rate of 14.7 g N m⁻² yr⁻¹ with N₂O emission about 1.5%. A denitrification dynamic model showed that the efficiency of nitrate removal would largely depend on the water discharge rate into the ponded wetland. Higher discharge rate will result in less retention time for the water in the marsh where nitrate is denitrified.