Assessment of Pb uptake, translocation and immobilization in kenaf (Hibiscus cannabinus L.) for phytoremediation of sand tailings

The potential of kenaf (Hibiscus cannabinus L.) for phytoremediation of lead (Pb) on sand tailings was investigated.A pot experiment employing factorial design with two main effects of fertilizer and lead was conducted in a nursery using sand tailings from an ex-tin mine as the growing medium.Results showed that Pb was found in the root,stem,and seed capsule of kenaf but not in the leaf.Application of organic fertilizer promoted greater biomass yield as well as higher accumulation capacity of Pb.In Pb-spike...     

Immiscible fluid flow in porous media: dielectric properties

The movement and retention of immiscible fluids in porous media was determined using a microwave dielectric measuring technique. The technique was used to monitor the composite dielectric constant of columns containing model soil materials to observe the effect of displacement of various saturating fluids by water and determine the retained immiscible components. Various combinations of displacing fluids, both miscible and immiscible, were studied, yielding time-dependent flow characteristics as well as the total retention factor. The flow circumstances were similar to what would be encountered in an accidental spill of chlorocarbons or crude oil.The retention of chlorocarbons and crude oil was determined for model soils consisting of sand or glass spheres. The storage capacity of the sand for immiscible fluids was dependent on the fluid initially saturating the porous medium. For chlorocarbons, it was increased in water-wet compared to dry sands while the inverse was true for crude oil. The retention of crude oil in the sand was dependent on the water flow velocity and was much larger than that for chlorocarbons. The crude oil could be displaced by solvents such as cyclohexane in the sand but the net volume occupied by the two immiscible fluids after water flushing did not change appreciably, i.e. the crude oil component was replaced by the solvent. Application of a miscible fluid-water mixture or surfactants improved the ability of water to displace the immiscible fluid from the sand column.     

Contribution of vehicle emissions from an attached garage to residential indoor air pollution levels

The infiltration of vehicle emissions into a house from the attached garage was studied for 16 homes of differing designs using the same extensively characterized vehicle at each home. Before the in-home measurement program, the cold-start and hot-start tailpipe emissions and hot-soak evaporative emissions from a 1993 Buick Regal were measured using standard vehicle emissions measurement methods. The emissions were chemically characterized for methane, nonmethane hydrocarbons (NMHC), and carbonyl compounds. The in-home measurements occurred over two winter seasons (1997-1998 and 1998-1999) in Ottawa, Ontario, Canada. Samples of indoor air and garage atmosphere were characterized for carbon monoxide, carbon dioxide, methane, NMHC, and carbonyl compounds. During the second year, real-time measurements of carbon, carbon dioxide, and total hydrocarbons were made to determine when and for how long the emissions plume infiltrates the house. Chemical mass balance modeling results using 31 NMHC species suggest that between 9 and 71% of the concentrations measured in the house during the hot-soak test and between 13 and 85% of the concentrations measured in the house during the cold-start test could be attributed to vehicle emissions infiltrating from the garage. In contrast, increases in carbonyl compound concentrations caused by the vehicle were difficult to detect above the already significant levels found in the houses.     

What shall we teach in environmental statistics?

The need for statistical methodology in environmental and ecological applications has grown dramatically over the past few decades, to where targeted and/or specialized courses in environmental statistics are necessary at both the undergraduate and graduate levels. We discuss here the construction of such courses, and pose questions on the course development process for the statistical and environmental community. Our exposition is based upon our own experience with the design of a graduate environmental statistics course.     

Documentation of selected constructs and parameter values in the aquatic model cleaner

Process representations critical to the phytoplankton and zooplankton submodels are described. These include constructs for: light- and nutrient-limitations and their interaction, temperature, consumption, and population-age structure. Values for key parameters are documented with reference to the literature on aquatic ecology and ecological modelling. Time-course relationships of the processes affecting the phytoplankton, zooplankton, phosphorus and nitrogen compartments are presented and discussed. These serve as additional documentation and are an important result of modelling synthesis.     

Prediction of Cd toxicity to Daphnia magna in the mixture of multi-walled carbon nanotubes and kaolinite

In this study, we investigated cadmium toxicity created by adsorption kinetics in several mixtures containing two types of multi-walled carbon nanotubes (COOH-MWCNT and NH₂-MWCNT) and natural kaolinite. Characteristics of two types of MWCNTs were measured by zeta potential and ATR FT-IR graphs and TEM images. The solution of CNTs and kaolinite was tested to study Cd adsorption kinetics and mechanisms of differentiation-associated toxicity using Daphnia magna in a binary system (Cd–MWCNTs and Cd–kaolinite) and a ternary system (Cd–MWCNTs–kaolinite). In the binary system, Cd removal efficiency was nearly 100% and 40% for MWCNTs and kaolinite because of surface charge, respectively, with increasing sorbent concentration. In the ternary system, the trend of adsorption rate was similar to that of binary system. In comparison with percent mortality in the binary system, the solution in the ternary system showed higher toxicity due to the interaction of MWCNTs–kaolinite coagulated particles, thereby decreasing Cd adsorption onto CNTs and kaolinites. Overall, kaolinite can affect the adsorption process of Cd on MWCNTs in negative ways, depending on adsorption state. In conclusion, our studies suggest that kaolinite differs with adsorption ability of Cd by MWCNTs, and toxicity is likely to be produced by multivariable regression in the adsorption state.

     

Prenatal diagnosis,prediction of outcome and in utero therapy of isolated congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) can be associated with genetic or structural anomalies with poor prognosis. In isolated cases, survival is dependent on the degree of lung hypoplasia and liver position. Cases should be referred in utero to tertiary care centers familiar with this condition both for prediction of outcome as well as timed delivery. The best validated prognostic indicator is the lung area to head circumference ratio. Ultrasound is used to measure the lung area of the index case, which is then expressed as a proportion of what is expected normally (observed/expected LHR). When O/E LHR is < 25% survival chances are < 15%. Prenatal intervention, aiming to stimulate lung growth, can be achieved by temporary fetal endoscopic tracheal occlusion (FETO). A balloon is percutaneously inserted into the trachea at 26–28 weeks, and reversal of occlusion is planned at 34 weeks. Growing experience has demonstrated the feasibility and safety of the technique with a survival rate of about 50%. The lung response to, and outcome after FETO, is dependent on pre-existing lung size as well gestational age at birth. Early data show that FETO does not increase morbidity in survivors, when compared to historical controls. Several trials are currently under design. Copyright © 2008 John Wiley & Sons, Ltd.     

Overlapping defense responses to water limitation and pathogen attack and their consequences for resistance to powdery mildew disease in garlic mustard, Alliaria petiolata

Plant responses to abiotic stress can alter their response to biotic stress. We examined changes in the activity of several defense proteins in response to powdery mildew infection of garlic mustard (Alliaria petiolata) in the greenhouse and in the field. Second, we examined the effects of water limitation on the same defense protein responses, as well as on total soluble protein and glucose concentration, plant growth, and powdery mildew disease development. Similar increases in the activity of peroxidase, chitinase, and β-1-3-glucanase were observed in leaves of plants with substantial powdery mildew disease in both greenhouse- and field-grown plants. In the greenhouse, activities of chitinase and peroxidase as well as total soluble protein and glucose concentrations generally increased with the degree of water limitation. In turn, leaf growth and powdery mildew symptom development decreased as the degree of water limitation increased. This study revealed that plant chemical responses to water limitation and powdery mildew disease can overlap to a large extent, which, in addition to changing microenvironmental conditions and other indicators of plant quality, may underlie the ability of water limitation to inhibit powdery mildew disease symptom development in this wild plant pathosystem.     

Closing the carbon cycle through rational use of carbon-based fuels

In this paper, a brief overview is presented of natural gas as a fuel resource with subsequent carbon capture and re-use as a means to facilitate reduction and eventual elimination of man-made carbon emissions. A particular focus is shale gas and, to a lesser extent, methane hydrates, with the former believed to provide the most reasonable alternative as a transitional fuel toward a low-carbon future. An emphasis is placed on the gradual elimination of fossil resource usage as a fuel over the coming 35 to 85 years and its eventual replacement with renewable resources and nuclear power. Furthermore, it is proposed that synthesis of chemical feedstocks from recycled carbon dioxide and hydrogen-rich materials should be undertaken for specific applications in the transport sector which require access to high energy density fuels. To achieve the latter, carbon dioxide capture is imperative and possible synthetic routes for chemical feedstock production are briefly reviewed.