Post-remediation evaluation of a LNAPL site using electrical resistivity imaging

Present understanding of the earth's subsurface is most often derived from samples at discrete points (wells) and interpolations or models that interpret the space between these points. Electrical resistivity imaging techniques have produced an improved capability to map contaminants (especially NAPLs--NonAqueous Phase Liquids) away from traditional wells using actual field data. Electrical resistivity image data, confirmed by drilling, have demonstrated that LNAPL (Light NAPL--less dense than water, such as gasoline) contaminants exist outside of a delineated and remediated area in Golden, Oklahoma. The data also demonstrate that LNAPL exists between monitoring and remediation wells which indicate low contaminant levels when sampled. Additionally, the electrical images provided the drilling location with the highest concentration of hydrocarbon ever found on the site, even after two phases of remediation work had been performed, although the sampling protocols varied. The results indicate that current methods of post-remediation site characterization are inadequate for complete site characterization.     

The gas/particle partitioning of polycyclic aromatic hydrocarbons collected at a sub-Arctic site in Canada

Polycyclic aromatic hydrocarbons (PAH) were measured in air samples at a remote air monitoring site established in the Yukon Territory, Canada as part of a global project (International Polar Year; IPY) to study the potential for atmospheric long-range transport of anthropogenic pollutants to the Arctic. Gas- and particle-phase PAH were collected in polyurethane foam plugs and on glass fibre filters respectively from August 2007 to October 2009. PAH concentrations were found to be highest in the winter months and lowest in summer. The gas/particle partitioning coefficients of 3–5 ringed PAH were computed and seasonal averages were compared. In the summer time, lower molecular mass PAH exhibited relatively higher partitioning into the particle-phase. This particle-phase partitioning led to the shallowest slopes being recorded during summer for the log–log correlation plots between the PAH partition coefficients and their sub-cooled vapour pressures. Air mass back trajectories suggest that local impacts may be more important during the summer time which is marked by increased camping activities at camping sites in the proximity of the sampling station. In conclusion, both summer and wintertime variations in PAH concentrations and gas/particle partitioning are considered to be source- and phototransformation-dependent rather than dependent on temperature-driven shifts in equilibrium partitioning.     

Carbon dioxide adsorption on amine-impregnated mesoporous materials prepared from spent quartz sand

Mesoporous MCM-41 was synthesized using cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and spent quartz sand as the silica source. Modification of the mesoporous structure to create an absorbent was then completed using 3-aminopropyltrimethoxysilane. Amine-Quartz-MCM (The A-Q-MCM) adsorbents were then characterized by N₂ adsorption/desorption, elemental analysis (EA), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), as well as the carbon dioxide (CO₂) adsorption/desorption performance. In this study, spent quartz sand was utilized to synthesize Quartz-MCM (Q-MCM) and the amine functionalized material, A-Q-MCM, which exhibited a higher uptake of CO₂ at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The surface area, pore volume, and pore diameter were found to be as high as 1028 m²/g, 0.907 cm³/g, and 3.04 nm, respectively. Under the condition of CO₂ concentration of 5000 ppm, retention time of 50 cc/min, and the dosage of 1 g/cm³, the mean adsorption capacity of CO₂ onto A-Q-MCM was about 89 mg/g, and the nitrogen content of A-Q-MCM was 2.74%. The adsorption equilibrium was modeled well using a Freundlich isotherm.

Implications:In this study, spent quartz sand was utilized to synthesize Q-MCM. The amine functionalized material exhibited a higher uptake of CO₂ at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The adsorption equilibrium was modeled well using a Freundlich isotherm.     

Hospital admissions due to diseases of arteries and veins peaked at physiological equivalent temperature −10 to 10 °C in Germany in 2009–2011

We aimed to understand relationships of the weather as biometeorological and hospital admissions due to diseases of arteries and veins by subtypes, which have been scarcely studied, in a national setting in recent years. This is an ecological study. Ten percent of daily hospital admissions from the included hospitals (n?=?1,618) across Germany that were available between 1 January 2009 and 31 December 2011 (n?=?5,235,600) were extracted from Statistisches Bundesamt, Germany. We identified I70-I79 Diseases of arteries, arterioles and capillaries and I80-I89 Diseases of veins, lymphatic vessels and lymph nodes by International Classification of Diseases version 10 as the study outcomes. Daily weather data from 64 weather stations that covered 13 German states including air temperature, humidity, wind speed, cloud cover, radiation flux and vapour pressure were obtained and generated into physiologically equivalent temperature (PET). Two-way fractional-polynomial prediction was plotted with 95 % confidence intervals. For most of the subtypes from diseases of arteries and veins, hospital admissions slightly peaked in spring and dropped when PET was at 10 °C. There were no other large differences across 12 months. Admissions of peripheral vascular diseases, arterial embolism and thrombosis, phlebitis and thrombophlebitis, oesophageal varices and nonspecific lymphadenitis peaked when PET was between 0 and ?10 °C, while others peaked when PET was between 0 and 10 °C. More medical resources could have been needed on days when PETs were at ?10 to 10 °C than on other days. Adaptation to such weather change for health professionals and the general public would seem to be imperative.