Biofilm enhanced geologic sequestration of supercritical CO2

In order to develop subsurface CO₂ storage as a viable engineered mechanism to reduce the emission of CO₂ into the atmosphere, any potential leakage of injected supercritical CO₂ (SC-CO₂) from the deep subsurface to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing the permeability of deep subsurface porous geological matrices under high pressure and in the presence of SC-CO₂, using a unique high pressure (8.9 MPa), moderate temperature (32 °C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor containing the sandstone core was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm growth and accumulation under high-pressure conditions in the rock pore space which caused >95% reduction in core permeability. Permeability increased only slightly in response to SC-CO₂ challenges of up to 71 h and starvation for up to 363 h in length. Viable population assays of microorganisms in the effluent indicated survival of the cells following SC-CO₂ challenges and starvation, although S. fridgidimarina was succeeded by Bacillus mojavensis and Citrobacter sp. which were native in the core. These observations suggest that engineered biofilm barriers may be used to enhance the geologic sequestration of atmospheric CO₂.     

Linking GIS-based models to value ecosystem services in an Alpine region

Planning frequently fails to include the valuation of public goods and services. This can have long-term negative economic consequences for a region. This is especially the case in mountainous regions such as the Alps, which depend on tourism and where land-use changes can negatively impact key ecosystem services and hence the economy. In this study, we develop a semi-automatic procedure to value ecosystem goods and services. Several existing process-based models linked to economic valuation methods are integrated into a geographic information system (GIS) platform. The model requires the input of a digital elevation model, a land-cover map, and a spatially explicit temperature dataset. These datasets are available for most regions in Europe. We illustrate the approach by valuing four ecosystem services: avalanche protection, timber production, scenic beauty, and habitat, which are supplied by the “Landschaft Davos”, an administrative district in the Swiss Alps. We compare the impacts of a human development scenario and a climate scenario on the value of these ecosystem services. Urban expansion and tourist infrastructure developments have a negative impact on scenic beauty and habitats. These impacts outweigh the benefits of the developments in the long-term. Forest expansion, predictable under a climate change scenario, favours natural avalanche protection and habitats. In general, such non-marketed benefits provided by the case-study region more than compensate for the costs of forest maintenance. Finally, we discuss the advantages and disadvantages of the approach. Despite its limitations, we show how this approach could well help decision-makers balance the impacts of different planning options on the economic accounting of a region, and guide them in selecting sustainable and economically feasible development strategies.     

CuFe2O4/activated carbon composite: a novel magnetic adsorbent for the removal of acid orange II and catalytic regeneration

CuFe2O4/activated carbon magnetic adsorbents, which combined the adsorption features of activated carbon with the magnetic and the excellent catalytic properties of powdered CuFe2O4, were developed using a simple chemical coprecipitation procedure. The prepared magnetic composites can be used to adsorb acid orange II (AO7) in water and subsequently, easily be separated from the medium by a magnetic technique. CuFe2O4/activated carbon magnetic adsorbents with mass ratio of 1:1, 1:1.5 and 1:2 were prepared. Magnetization measurements, BET surface area measurements, powder XRD and SEM were used to characterize the prepared adsorbents. The results indicate that the magnetic phase present is spinel copper ferrite and the presence of CuFe2O4 did not significantly affect the surface area and pore structure of the activated carbon. The adsorption kinetics and adsorption isotherm of acid orange II (AO7) onto the composites at pH 5.2 also showed that the presence of CuFe2O4 did not affect the adsorption capacity of the activated carbon. The thermal decomposition of AO7 adsorbed on the activated carbon and the composite was investigated by in situ FTIR, respectively. The results suggest that the composite has much higher catalytic activity than that of activated carbon, attributed to the presence of CuFe2O4. The variation of the adsorption capacity of the composites after several adsorption-regeneration cycles has also been studied.     

Enhanced removal of heavy metals in primary treatment using coagulation and flocculation.

The goal of this study was to determine the removal efficiencies of chromium, copper, lead, nickel, and zinc from raw wastewater by chemically enhanced primary treatment (CEPT) and to attain a total suspended solids removal goal of 80%. Operating parameters and chemical doses were optimized by bench-scale tests. Locally obtained raw wastewater samples were spiked with heavy metal solutions to obtain representative concentrations of metals in wastewater. Jar tests were conducted to compare the metals removal efficiencies of the chemical treatment options using ferric chloride, alum, and anionic polymer. The results obtained were compared with those from other studies. It was concluded that CEPT using ferric chloride and anionic polymer is more effective than CEPT using alum for metals removal. The CEPT dosing of 40 mg/L ferric chloride and 0.5 mg/L polymer enhanced heavy metals removal efficiencies by over 200% for chromium, copper, zinc, and nickel and 475% for lead, compared with traditional primary treatment. Efficient metals capture during CEPT can result in increased allowable headworks loadings or lower metal levels in the outfall.     

Fecal Coliform Export From Four Coastal North Carolina Areas1

Abstract: Fecal coliform (FC) bacteria in coastal waters impair the use of these waters for shellfish harvesting and recreation. This study was designed to quantify and compare FC levels and export in two coastal watersheds with different land uses. Continuous monitoring of rainfall and discharge at three sites in the Jumping Run Creek watershed and one site in the Pettiford Creek watershed were conducted during a 4.5‐year period. Primary land use in the drainage area of one of the three Jumping Run Creek sites is low density industrial, while the other two are residential. Land use in the Pettiford Creek watershed is managed national forest. Nonstorm or base‐flow grab and flow‐proportional storm‐event samples were collected and analyzed for turbidity, conductivity, suspended sediment, nitrogen, phosphorus, and FC. Geometric mean FC levels for the Jumping Run Creek monitoring sites ranged from 593 to 2,096 mpn/100 ml, while the mean level at the Pettiford Creek site was 191 mpn/100 ml. Levels of most other parameters were greater in storm discharge from the Jumping Run Creek sites as compared to Pettiford Creek indicating that pollutant export from a watershed increases with development. Statistical analysis of the monitoring data suggested that FC levels in stormwater samples consistently increased with storm rainfall, but were not consistently correlated with any other parameter, including total suspended solids. Multivariate analysis indicated that the weekly FC export for each of the four sites was lowest during the December‐February quarter. Export was highest during the spring and summer at the Jumping Run Creek sites, while for the Pettiford Creek site, FC export was highest during September‐November. The cause of the seasonal variability was unknown but was thought to be associated with human activity in the watersheds.     

Aseptic hydroponics to assess rhamnolipid-Cd and rhamnolipid-Zn bioavailability for sunflower (<Emphasis Type="Italic">Helianthus annuus</Emphasis>): a phytoextraction mechanism study

The availability of cadmium (Cd) and zinc (Zn) to sunflower (Helianthus annuus) was investigated in rhamnolipid- and ethylenediaminetetraacetic acid (EDTA)-buffered solutions in order to evaluate the influence of aqueous speciation of the metals on their uptake by the plant, in relation to predictions of uptake by the free ion activity model (FIAM). Free metal ion activity was estimated using the chemical equilibrium program MINTEQ or measured by Donnan dialysis. The uptake of Cd followed the FIAM for the EDTA-buffered solution at EDTA concentrations below 0.4 μM; for the rhamnolipid-buffered solution, the uptake of both metals in roots was not markedly affected by increasing rhamnolipid concentrations in solution. This suggests rhamnolipid enhanced metal accumulation in plant roots (per unit free metal in solution) possibly through formation and uptake of lipophilic complexes. The addition of normal Ca concentrations (low millimetre range) to the rhamnolipid uptake solutions reduced Cd accumulation in shoots by inhibiting Cd translocation, whereas it significantly increased Zn accumulation in shoots. This study confirms that although rhamnolipid could enhance accumulation of Cd in plants roots at low Ca supply, it is not suitable for Cd phytoextraction in contaminated soil environments where Ca concentrations in soil solution are orders of magnitude greater than those of Cd.     

Effects of rarity form on species’ responses to land use

Anthropogenic land-use change causes substantial changes in local and global biodiversity. Rare and common species can differ in sensitivity to land-use change; rare species are expected to be affected more negatively. Rarity may be defined in terms of geographic range size, population density, or breadth of habitat requirements. How these 3 forms of rarity interact in determining global responses to land use is yet to be assessed. Using global data representing 912 vertebrate species, we tested for differences in responses to land use of species characterized by different types of rarity. Land-use responses were fitted using generalized linear mixed-effects models, allowing responses to vary among groups of species with different forms of rarity. Species considered rare with respect to all 3 forms of rarity showed particularly strong declines in disturbed land uses (>40% of species and 30% of individuals in the most disturbed land uses). In contrast, species common both geographically and numerically and with broad habitat requirements showed strong increases (up to 90% increase in species and 40% in abundance in some land uses). Our results suggest that efforts to understand the vulnerability of species to environmental changes should account for different types of rarity where possible. Our results also have potentially important implications for ecosystem functioning, given that rare species may play unique roles within ecosystems.     

Constraints to implementation of sustainability indicator systems in five Asian cities

Contemporary studies on sustainability indicator systems (SISs) typically focus on the technical advancement of indicator construction, on qualitative impacts of indicator programmes and on impacts on governance, decision-making and sustainability as a social construct. Yet, their implementation so far has rarely been addressed, even though monitoring and the use of indicator results fall far behind the number of SISs developed. This study aims at the identification of requirements for the development of and constraints to the implementation of SISs in five Asian cities of developing countries. Interviews with local key actors are held, and a qualitative content analysis is carried out. Findings include evidence on the degree of indicator implementation in the case study cities, a hexagonal model for the classification of requirements and constraints, as well as general conclusions for barriers to the use of SISs.     

Low Back Pain Among Residential Carpenters: Ergonomic Evaluation Using OWAS and 2D Compression Estimation

Occupational low back pain (LBP) remains a leading safety and health challenge. This cross-sectional investigation measured the prevalence of LBP in residential carpenters and investigated ergonomic risk factors. Ninety-four carpenters were investigated for LBP presence and associated risk factors. Ten representative job-tasks were evaluated using the Ovako Working Posture Analysis System (OWAS) and ErgoMaster? 2D software to measure elements of posture, stress, and risk. Job-tasks were found to differ significantly for total lumbar compression and shear at peak loading (p < .001), ranging from 2 956 to 8 606 N and 802 to 1 974 N respectively. OWAS indicated that slight risk for injury was found in 10 job-tasks while distinct risk was found in 7 of the 10 job-tasks. Seven of the 10 job-tasks exceeded the National Institute for Occupational Safety and Health (NIOSH) action limit of 3 400 N for low back loading. The point prevalence for LBP was 14% while the annual prevalence was 38%.