Modelling geochemical and microbial consumption of dissolved oxygen after backfilling a high level radiactive waste repository

Dissolved oxygen (DO) left in the voids of buffer and backfill materials of a deep geological high level radioactive waste (HLW) repository could cause canister corrosion. Available data from laboratory and in situ experiments indicate that microbes play a substantial role in controlling redox conditions near a HLW repository. This paper presents the application of a coupled hydro-bio-geochemical model to evaluate geochemical and microbial consumption of DO in bentonite porewater after backfilling of a HLW repository designed according to the Swedish reference concept. In addition to geochemical reactions, the model accounts for dissolved organic carbon (DOC) respiration and methane oxidation. Parameters for microbial processes were derived from calibration of the REX in situ experiment carried out at the Asp? underground laboratory. The role of geochemical and microbial processes in consuming DO is evaluated for several scenarios. Numerical results show that both geochemical and microbial processes are relevant for DO consumption. However, the time needed to consume the DO trapped in the bentonite buffer decreases dramatically from several hundreds of years when only geochemical processes are considered to a few weeks when both geochemical reactions and microbially-mediated DOC respiration and methane oxidation are taken into account simultaneously.     

Modification in the soil and traffic-related sources of particle matter between 1998 and 2007 in Santiago de Chile

Santiago de Chile is one of the most polluted South American cities, concentrating its pollution episodes during winter. Daily PM2.5 (particulate matter [PM] < or = 2.5 microm in aerodynamic diameter) concentrations over 80 microg/m3 have been reached frequently since 1998. Despite several regulations introduced over the past 20 yr to improve the air quality, PM concentration levels remain high. In this work, sampling in downtown Santiago was conducted from April 1998 to August 2007 for PM2.5 and from October 2003 to March 2006 for PM10-2.5 (PM between 2.5 and 10 microm in aerodynamic diameter) with dichotomous samplers. Elemental analysis was performed on the samples with X-ray fluorescence. The resuming series of 859 samples and 216 elements identified were divided into semiannual periods and analyzed with factor analysis. Five factors are clearly discerned: soil, motor vehicles, residual oil, marine aerosols, and secondary sulfates. The soil factor in the fine fraction shows a clear increase from 2002 to 2006, whereas the coarse fraction of this factor shows a stable trend. The most probable cause for this trend is the growth in the number of vehicles in Santiago (6.5%/yr), which increases the resuspension of particles from the ground. Another cause for the increase is the growth in the construction activity (4.2%/yr). The motor vehicle factor in the fine fraction shows a decrease between 1998 and 2006. The decrease in the apportionment of this factor can be explained by the improvement in the vehicle fleet. In Santiago, the number of noncatalytic vehicles has been reduced from 389,000 in 2001 to 275,000 in 2006. The residual oil factor also shows a decrease between 1998 and 2006. The decrease could be attributed to the adoption of cleaner technologies and norms regarding gasoline and diesels.     

Temporal dynamics and plasticity in the cellular immune response of the sea fan coral, Gorgonia ventalina

The temporal dynamics of the invertebrate immune response often determines an organism’s success in responding to physiological stress, physical damage, and pathogens. To date, most immune challenge studies have been conducted under highly controlled laboratory conditions, with few attempts to study immune function in the wild. In this study, we characterized the temporal dynamics of the Caribbean sea fan, Gorgonia ventalina, cellular immune response [granular amoebocyte aggregation and prophenoloxidase (PPO) activation] to allogenic grafts in the laboratory and field using a clonally replicated design. Amoebocyte reaction time differed markedly between the lab (% amoebocyte surface area in tissue sections peaked at 2 days) and field (peak at 6 days). PPO activity decreased between 0 and 6 days after grafting in both ungrafted and grafted tissue, suggesting PPO is decoupled from other cellular components. The reaction norms of the fold induction in % amoebocyte area between disease-grafted and healthy-grafted tissue of each colony across time indicate high intercolony plasticity in cellular immune response. The plasticity between colonies was also evident in the magnitude of cellular immune response, ranging from a 0.88- to 1.60-fold increase in amoebocyte area between initial and 6 days for the disease-grafted tissue. With the demonstration of highly dynamic cnidarian cellular immune responses, our study expands understanding of the evolutionary ecology of metazoan immune defense mechanisms.     

The roles of cleaner production in the sustainable development of modern societies: an introduction to this special issue

This issue of the Journal of Cleaner Production is based upon papers presented at the 1st International Workshop Advances in Cleaner Production (CP) held in São Paulo, Brazil, in 2007. The conference had the short-term purpose of deepening the Brazilian discussion on “The Roles of Cleaner Production in the Sustainable Development of Modern Societies”, and it had the long-term objective of providing an on-going interdisciplinary forum for knowledge development and exchange on Cleaner Production (CP) and Sustainable Development. This issue is devoted to papers covering a broad range of perspectives of CP practices and strategies. A special focus is placed upon methodological tools designed to support effective decision-making pertaining to quantitative benefits from CP.The ten papers provide insights from research designed to holistically integrate CP to help society make effective progress to sustainability. Papers cover the importance of informal knowledge, as complementary to formal knowledge, in performing effective ‘Environmental Impact Assessments.’ One paper explores the roles of radical and incremental innovation in the context of alternative automotive technologies. Benefits of Ecodesign are explored in two papers; one concerning its integration with remanufacturing to extend the life of used products and one focusing the adoption of ‘Emergy Environmental Accounting,’ as a complementary decision-making tool. The development of the Brazilian LCI database for ‘hydroelectric power generation’ and its contribution to support regionally relevant LCA studies is highlighted in one paper. The complete production chains of biodiesel and bioethanol are evaluated by using global methodologies, which help in the development of more objective and effective solutions. A “compensatory area”, calculated in terms of emergy, is proposed in order to work in a sustainable way for bamboo production. Finally, a paper about a novel approach for recycling used PET is also included.     

Interactions between diesel emissions and gaseous copollutants in photochemical air pollution: Some health implications

A complete assessment of the health effects of diesel emissions must take into account the possible chemical transformations (and associated biological impacts) of particulate organic matter (POM) due to reactions with the many gaseous copollutants which have now been unambiguously demonstrated to be present in atmospheres burdened by photochemical air pollution. These copollutants include the “trace” species, nitric (HNO₃) and nitrous (HONO) acids, the nitrate radical (NO₃), formaldehyde (H₂CO) and formic acid (HCOOH), as well as the criteria pollutants, ozone (O₃) and nitrogen dioxide (NO₂). Techniques for establishing the atmospheric concentrations of the trace pollutants (and their spatial and temporal variations) are briefly described, and we present results of investigations into the reactions of polycyclic aromatic hydrocarbons (PAH) coated on filters and exposed to ambient concentrations of O₃ and NO₂. Environmental health implications of these results are discussed and include the potential for sampling “artifacts” and their possible effects on the correlation (or lack thereof) between ambient PAH levels and urban lung cancer rates, as well as the problems associated with understanding the appropriate POM “dose” to be employed in animal testing and assessments of impacts on human health.     

(210)Pb content in natural gas pipeline residues ("black-powder") and its correlation with the chemical composition

The present work was carried out to assess the (210)Pb content in "black-powder" found in pigging operations on gas pipelines in Brazil, in particular, on the Campos Basin gas pipeline. Additionally, the chemical composition of such deposits was determined and an eventual correlation with (210)Pb concentration evaluated. Typical "black-powder" generated in the natural gas pipeline from Campos Basin oilfield contains mainly iron oxide ( approximately 81%) and residual organic matter ( approximately 9%). The (210)Pb content ranges from 4.9 to 0.04k Bqkg(-1) and seems to be inversely correlated with the distance to the platforms. On the other hand, (226)Ra concentration is higher on the pipeline branch between the platform and the onshore installations. (228)Ra was only observed in few samples, in particular, in the samples with the highest (226)Ra content.     

Wastewater treatment with a double-layer submerged biological aerated filter,using waste materials as biofilm support

The aim of this research was to determine the performance of a submerged biological aerated filter, composed of a double-layer bed. This bed is made up of a top layer of ceramic material and a bottom layer of plastic material (both from previously used waste material). Effluent concentrations are presented related to the volumetric and hydraulic loads applied. The results were very satisfactory. If effluent concentrations of under 20 mg TBOD5/L and 25 mg SS/L are to be achieved, 4.87 kg TBOD5/m3/d and 3.0 kg SS/m3/d could be applied, respectively. For that maximum TBOD5 volumetric load that can be applied, a very reasonable consumption value of 1.0 kg O2/kg TBOD5, eliminated was obtained. The counter-current flow system outperformed the co-current flow system with respect to TBOD5 and SS removal. The tests were performed at a pilot plant with full scale height. The influent used was primary effluent of a conventional treatment plant. A multivariant analysis (ANOVA) was applied to the results.     

Microfibrous mesh coated with titanium dioxide: a self-sterilizing,self-cleaning filter

The utility of metal microfibrous mesh coated with titanium dioxide as a self-sterilizing, self-cleaning filter for air is explored. The low-cost mesh is produced via a roll-to-roll process similar to paper manufacturing. The titanium dioxide is applied by spraying an aqueous suspension of the photocatalyst on the surface of the mesh using an airbrush. Photocatalytic activity comparable to a powder layer is achieved at one quarter of the mass loading. The coating enhanced the separation of Escherichia coli (E. coli) from aqueous suspension, but also led to an increase in pressure drop in an air stream flowing through the mesh. The self-cleaning property of the coated mesh is established by recovery of pressure drop performance lost due to biofilm buildup. This is accomplished via a photocatalytic regeneration process involving exposing the mesh to ultraviolet light in air. Oxidation is confirmed by monitoring CO2 evolution during the regeneration. Scanning electron photomicrographs also provide visual evidence of successful regeneration via photocatalysis.     

Chemical studies on Indopacific Ceratosoma nudibranchs illuminate the protective role of their dorsal horn

Summary. Two Ceratosoma species, C. trilobatum and C. gracillimum (Mollusca: Gastropoda: Opistobranchia), collected along the South China Sea coast, have been studied in order to investigate their defensive strategies. Both species contain four typical sponge furanosesquiterpenoids, probably with a dietary origin. The tissue distribution of these compounds has been studied by ¹H-NMR analysis and preliminary bioassays have been carried out in order to evaluate the ecological role of the isolated metabolites. The main sesquiterpene component in both species was (–)-furodysinin (2), which showed significant feeding-deterrent and ichthyotoxic properties in bioassays with freshwater organisms. The work has been performed studying a very limited number of molluscs that prevented the realization of ecologically relevant experiments. However, the almost exclusive presence of compound 2 in the crude extract of the mantle glands concentrated in the dorsal horn of C. gracillimum strongly supports the defensive role of that dorsal protuberance, which probably acts as a defensive lure attracting potential predators to the part of the animal that contains the distasteful chemicals.