The Microbial Ecology of a Hyper-Alkaline Spring,and Impacts of an Alkali-Tolerant Community During Sandstone Batch and Column Experiments Representative of a Geological Disposal Facility for Intermediate-Level Radioactive Waste

Naturally occurring hyper-alkaline springs and associated hyper-alkaline environments may have components that are analogous to a cement-based deep geological disposal facility (GDF) for intermediate level radioactive waste (ILW). Such high pH environments could give insights into the biogeochemical processes that could occur in the region of a GDF environment after the ingress of GDF-derived groundwater leads to the formation of a hyper-alkaline plume in the surrounding rock mass. This study focuses on the microbial community composition found at a highly alkaline spring near Buxton, Derbyshire, England, and the variation in community structure across spatially separated sample points of contrasting pH values (ranging from pH 7.5–13). Communities containing alkaliphilic and alkalitolerant bacteria were observed across the site by PCR amplification and 16S rRNA gene pyrosequencing and included members of the families Comamonadaceae and Xanthomonadaceae. At pH 13, the sequence library was dominated by Gammaproteobacteria of the families Pseudomonadaceae and Enterobacteriaceae. Bacterial communities from the site demonstrated the ability to reduce Fe(III) in microcosm experiments up to pH 11.5, suggesting the potential to reduce other metals and radionuclides of relevance to cement-encapsulated intermediate level radioactive waste (ILW) disposal. In laboratory column flow-through experiments, microbial communities present at the field site were also able to colonize crushed sandstone. Bacterial community composition varied between columns that had been supplied with alkali surface waters from the site amended with carbon (lactate and acetate, as proxies for products of cellulose degradation from ILW), and control columns that were not supplied with added carbon. Members of the family Clostridiaceae dominated the sequence library obtained from the carbon amended column inlet (45.8% of library), but became less dominant at the outlet (20.8%). Members of the family Sphingomonadaceae comprised 11.8% of the sequence library obtained from the control column inlet, but were not present in sediments collected from the column outlet, whereas the relative abundance of members of the family Comamonadaceae increased from the column inlet (35.2%) to the column outlet (57.2%). The spatial variation in community composition within the columns is indicative of discrete biogeochemical zonation in these flow-through systems.     

Microorganisms in a Disposal Site for Liquid Radioactive Wastes and Their Influence on Radionuclides

Deep subsurface horizons used for the disposal of liquid low- and intermediate-level radioactive wastes of the Siberian Chemical Complex (SCC, Russia) were studied by microbiological, radioisotope, and molecular biological methods. It was shown that a diverse microbial community inhabited the groundwater. The cell numbers of microorganisms of the major metabolic groups and the rates of sulfate reduction, denitrification, and methanogenesis in natural groundwater were low and increased in the zone of wastes dispersion. More than 40 strains belonging to the genera Kocuria, Microbacterium, Pseudomonas, Pantoea, Acinetobacter, Enterobacter, Klebsiella, Stenotrophomonas, Sphingomonas, Staphylococcus, Acidivorax, Shewanella, and Desulfosporosinus were isolated from the disposal sites. Among the isolates, the microorganisms were found that were able to concentrate actinides and other transuranium elements. Aerobic bacteria were able to sorb various radionuclides in laboratory experiments; however, biosorption was low in sample of groundwater and in carbonate solutions containing several radionuclides. Reduction of U(VI) by a sulfate-reducing enrichment culture from the site and reduction of U(VI) and Np(V) by an isolate Shewanella were observed in the presence of various organic substrates. These results show the necessity of further ecosystem characterization based on microbiological and radiochemical studies and modeling of biogeochemical processes at the deep disposal sites for liquid radioactive wastes.     

The Succession of Bacterial Community Structure in Groundwater from a 250-m Gallery in the Horonobe Underground Research Laboratory

We investigated the change in bacterial community structure after drilling boreholes, 09-V250-M02 and 09-V250-M03, in the 250-m deep research gallery of the Horonobe Underground Research Laboratory. In the 09-V250-M02 borehole, ?-Proteobacteria were predominantly detected in the clone library analyses of the groundwater samples conducted immediately after drilling. All the ?-Proteobacteria clones were closely related to Arcobacter spp., which are known to be sulfide-oxidizing chemoautotrophic bacteria. After 4 years, the microbial structure drastically changed, and most detected operational taxonomic units were uncultured species such as candidate division OP9 and Chloroflexi relatives, which are frequently detected in deep sea sediments. The results indicated that the microbial community structure was drastically affected by borehole drilling and was concomitant with oxidation perturbation. However, these disturbed microbial communities changed within a few years to a microbial community composed of uncultivated species such as OP9 and Chloroflexi.     

The Application of the Environmental Product Declaration to Waste Disposal in a Sanitary Landfill - Four Case Studies (10 pp)

Goal, Scope and Background

The aim of the present study is to evaluate, through LCA, the potential environmental impact associated to urban waste dumping in a sanitary landfill for four case studies and to compare different technologies for waste treatment and leachate or biogas management in the framework of the EPD® system. Specific data were collected on the four Italian landfills during a five-year campaign from 2000 to 2004. This work also analyses the comparability of EPD results for different products in the same product category. For this purpose, a critical review of PSR 2003:3, for preparing an EPD on ‘Collection, transfer and disposal service for urban waste in sanitary landfills', is performed.

Methods

PSR 2003:3 defines the requirements, based on environmental parameters, that should be considered in an LCA study for collecting and disposal service of Municipal Solid Waste (MSW) in a sanitary landfill. It defines functional unit, system boundaries towards nature, other technical systems and boundaries in time, cut-off rules, allocation rules and parameters to be declared in the EPD. This PSR is tested on four case studies representing the major landfills located from the farthest west to the farthest east side of the Ligurian Region. Those landfills are managed with different technologies as concerns waste pre-treatment and leachate or biogas treatment. For each landfill, a life cycle assessment study is performed.

Results and Discussion

The comparison of the LCA results is performed separately for the following phases: Transport, Landfill, Leachate and Biogas. The following parameters are considered: Resource use (Use of non-renewable resources with and without energy content, Use of renewable resources with and without energy content, Water consumption); Pollutant emissions expressed as potential environmental impact (Global Warming Potential from biological and fossil sources, Acidification, Ozone depletion, Photochemical oxidant formation, Eutrophication, Land use, Hazardous and other Waste production). The comparison of the LCA results obtained for alternative landfill and biogas management techniques in the case studies investigated shows that the best practicable option that benefits the environment as a whole must be identified and chosen in the LCA context. For example, a strong waste pre-treatment causes a high biological GWP in the Landfill phase, but a low GWP contribution in the Biogas phase, due to the consequent low biogas production, evaluated for 30 years since landfill closure.

Conclusion

The analysis of four case studies showed that, through the EPD tool, it is possible to make a comparison among different declarations for the same product category only with some modification and integration to existent PSR 2003:3. Results showed that different products have different performances for phases and impact categories. It is not possible to identify the \best product\ from an environmental point of view, but it is possible to identify the product (or service) with the lowest impact on the environment for each impact category and resource use.

Recommendation and Perspective

In consequences of the verification of the comprehensiveness of existent PSR 2003:3 for the comparability of EPD, some modifications and integration to existent rules are suggested.

     

Recent developments in the creation of a single molecular sensing tool for ternary iron (III), chromium (III), aluminium (III) ionic species: A review

Rational design of a molecular sensing tool is an important topic in molecular recognition, signalling, and optoelectronics that has piqued the interest of chemists, biologists, and environmental scientists. Approximately 150 years have passed since the beginning of the fluorescent chemosensor sector. Due to the paramagnetic properties of Cr³⁺ and Al³⁺, it is tough to prepare a photoluminescence plug-in detector. Most dye-based Al³⁺ sensors must be utilized in organic or mixed solvents for robust hydration of Al³⁺ in water. The sophisticated molecular design of sensors, conversely, allows for the detection of these metal ions in aqueous medium. The design of chemosensors using various fluorophores and their mechanisms of action have been thoroughly discussed. A literature survey covering the design of chemosensors and their mechanisms of action have been thoroughly discussed covering the period 2010–2022 and that was carried out including innovative and exemplary activities from numerous groups throughout the world that have significantly contributed to this sector. The most important advantages of these probes are their aqueous solubility and quick response with outstanding selectivity and sensitivity for temporal distribution with high fidelity of metals in living cells.     

Diversity of the Formyltetrahydrofolate Synthetase Gene (fhs), a Key Enzyme for Reductive Acetogenesis,in the Bovine Rumen

A clone library of the partial formyltetrahydrofolate synthetase gene (fhs), a key enzyme in reductive acetogenesis, was constructed from the DNA of bovine rumen contents. Diverse sequences were recovered, the majority of which were clustered with the fhs of authentic acetogens. Low similarity values to known fhs were observed in all sequences, suggesting the presence of unknown acetogens.