Gregory Möller

BIODEGRADABILITY OF BIODIESEL IN THE AQUATIC ENVIRONMENT

The biodegradability of various biodiesel fuels was examined by the CO2 evolution method (EPA 560/6-82-003), BOD5 (EPA 405.1), COD (EPA 410), and gas chromatography (GC) analyses in an aquatic system. The fuels examined included the methyl- and ethyl-esters of rapeseed oil and soybean oil, neat rapeseed oil, neat soybean oil and Phillips 2-D low sulfur, reference petroleum diesel. Blends of biodiesel/petroleum diesel at different volumetric ratios, including 80/20, 50/50, and 20/80, were also examined. The results demonstrate that all the biodiesel fuels are “readily biodegradable”. Moreover, in the presence of REE, the degradation rate of petroleum diesel increased to twice that of petroleum diesel alone. The pattern of biodegradation in the blends and reasons why biodiesel is more readily degradable than petroleum diesel are discussed. The biodegradation monitoring results from both CO2 evolution and GC methods are compared.

Effect of ultrasound frequency on antioxidant activity, total phenolic and anthocyanin content of red raspberry puree

Ultrasound in the 20-1000 kHz range show unique propagation characteristics in fluid media and possess energy that can break down fruit matrices to facilitate the extraction of valuable bioactive compounds. Red raspberries carry significant amounts of specific antioxidants, including ellagitannins and anthocyanins that are important for human health. The objective of this study was to investigate the effects of ultrasound frequencies associated with cavitation (20 kHz) and microstreaming (490 and 986 kHz) on total antioxidant activity (AOA), total phenolics content (TPC), and total monomeric anthocyanin content (ACY) of red raspberry puree prepared from crushed berries. The pureed fruit was subjected to high-intensity (20 kHz) and higher frequency-low intensity (490 and 986 kHz) ultrasound for 30 min. The temperature of treated purees increased to a maximum of 56 °C with 986 kHz. Sonication at 20 and 490 kHz significantly (p<0.05) affected the AOA, ACY, and TPC of red raspberry puree, while 986 kHz had no significant effect on ACY and AOA (p<0.05). In all cases, ultrasound treatment had significant and positive effect on at least one of the measured parameters up to 30 min. Sonication beyond 10 min (and up to 30 min) using 20 kHz either produced no change or caused a drop in AOA and ACY. However, for 986 and 20 kHz, TPC, increased by 10% and 9.5%, respectively after 30 min (p<0.05) compared to the control. At 20 kHz, AOA and ACY increased by 17.3% and 12.6% after 10 min. It was demonstrated that 20 kHz ultrasound treatment, when limited to 10 min, was the most effective for extraction of bioactive compounds in red raspberry compared to 490 and 986 kHz although the effect could be similar at the higher frequencies if different amplitudes are used.

Micro-spectroscopic investigation of selenium-bearing minerals from the Western US Phosphate Resource Area

Mining activities in the US Western Phosphate Resource Area (WPRA) have released Se into the environment. Selenium has several different oxidation states and species, each having varying degrees of solubility, reactivity, and bioavailability. In this study we are investigating the speciation of Se in mine-waste rocks. Selenium speciation was determined using bulk and micro-x-ray absorption spectroscopy (XAS), as well as micro-x-ray fluorescence mapping. Rocks used for bulk-XAS were ground into fine powders. Shale used for micro-XAS was broken along depositional planes to expose unweathered surfaces. The near edge region of the XAS spectra (XANES) for the bulk rock samples revealed multiple oxidation states, with peaks indicative of Se(-II), Se(IV), and Se(+VI) species. Micro-XANES analysis of the shale indicated that three unique Se-bearing species were present. Using the XANES data together with ab initio fitting of the extended x-ray absorption fine structure region of the micro-XAS data (micro-EXAFS) the three Se-bearing species were identified as dzharkenite, a di-selenide carbon compound, and Se-substituted pyrite. Results from this research will allow for a better understanding of the biogeochemical cycling of Se in the WPRA.

Microbial studies of a selenium-contaminated mine site and potential for on-site remediation

Surface water Selenium (Se) concentrations are above regulatory standards at several active and inactive phosphate mine sites in the US Western Phosphate Resource Area. The focus of the present study was to examine the impacts of the microbial communities on the oxidation state of Se in overburden waste from the Smoky Canyon phosphate mine in Idaho, USA. Microbial populations were found that reduce soluble selenate (SeO42−) to insoluble elemental Se. Microcosm experiments were conducted for molecular genetic analysis of this microbial community by rRNA gene profiling. An acetone pretreatment step was developed to remove interfering pre-petroleum hydrocarbons from the samples prior to extraction. PCR was used to amplify 16S and 18S rRNA genes present in the microbial community DNA. The amplified products were subjected to denaturing gradient gel electrophoresis (DGGE). Isolates and excised DGGE bands were amplified and sequenced for identification to determine the relative importance of culturable isolates to the total microbial population. Analysis of samples from different sites at the mine showed how Se contamination and previous remediation treatments changed the microbial populations across the site. Members of the family Enterobacteriaceae were dominant among the selenate reducing isolates from the site containing high Se levels. In particular, Serratia fonticola was isolated repeatedly from contaminated Smoky Canyon Mine site samples. Packed column studies were performed with seleniferous waste rock fractions from Smoky Canyon Mine. Column amendments consisted of combinations of iron, compost, and whey. Eh, pH, and extractable Se measurements were taken. Tests with infiltrated water showed columns containing an organic amendment combined with iron metal were the most resistant to Se leaching. Iron-based compounds from the corroding metal are thought to strongly bind the Se reduced by microbial activity, thereby stabilizing the Se in an insoluble form. We conclude that long-term stabilization of selenium at contaminated mine sites may require reductive microbial processes combined with abiotic immobilization by iron, either natural or engineered, to stabilize the Se and retard re-oxidation and release. Iron-selenide or iron-selenite compounds are more stable and resistant to leaching, especially when removed from active weathering.

Unknown risk: co-exposure to lead and other heavy metals among children living in small-scale mining communities in Zamfara State, Nigeria

The lead poisoning crisis in Zamfara State, Northern Nigeria has been called the worst such case in modern history and it presents unique challenges for risk assessment and management of co-exposure to multiple heavy metals. More than 400 children have died in Zamfara as a result of ongoing lead intoxication since early in 2010. A review of the common toxic endpoints of the major heavy metals advances analysis of co-exposures and their common pathologies. Environmental contamination in Bagega village, examined by X-ray fluorescence of soils, includes lead, mercury, cadmium, arsenic and manganese. Co-exposure risk is explored by scoring common toxic endpoints and hazard indices to calculate a common pathology hazard risk ranking of Pb > As > Hg >> Cd > Mn. Zamfara presents an extreme picture of both lead and multiple heavy metal mortality and morbidity, but similar situations have become increasingly prevalent worldwide.

Chemical speciation and bioavailability of selenium in the rhizosphere of Symphyotrichum eatonii from reclaimed mine soils.

Knowledge of rhizosphere influences on Se speciation and bioavailability is required to predict Se bioavailability to plants. In the present study, plant-availability of Se to aster (Symphyotrichum eatonii (A. Gray) G.L. Nesom) was compared in rhizosphere soils and nonrhizosphere (bulk) soils collected from a reclaimed mine site in southeastern Idaho, U.S. X-ray spectroscopy was used to characterize the oxidation state and elemental distribution of Se in aster roots, rhizosphere soils, and bulk soils. Percent extractable Se in aster rhizosphere soil was greater than extractable Se in corresponding bulk soils in all samples (n = 4, p = 0.042, 0.051, and 0.052 for three extractions). Selenium oxidation state mapping of 28 regions within the samples and X-ray absorption near edge structure (XANES) spectra from 26 points within the samples indicated that the rhizosphere and bulk soil Se species was predominantly reduced Se(-II,0), while in the aster roots, high concentrations of Se(VI) were present. Results show that within the rhizosphere, enhanced Se bioavailability is occurring via oxidation of reduced soil Se to more soluble Se(VI) species.

CIPC residues on stored russet burbank potatoes : 1. Maximum label application

Residue concentrations of chlorpropham (CIPC) on stored Russet Burbank potatoes were evaluated after thermal aerosol treatment at maximum labeled rates. The aerosol was applied after the potatoes had been placed in the storage structure and the wound healing process was complete. Average residue concentrations four days after the initial application ranged from 6 to 8 mg/kg fresh tuber weight depending on the storage temperature and the application rates. A second aerosol treatment applied 90 days after the first treatment kept the residue concentrations above 5 mg/kg for the duration of the storage period. A direct spray application to the tubers at various times during the study raised the average CIPC concentration an additional 2 to 3 mg/kg. All CIPC residue concentrations measured on tubers in this study were below the EPA established (1996) tolerance of 30 mg/kg. Residue concentrations of CIPC were greater on potatoes near the bottom of the pile than near the top of the pile. These variations in CIPC residue concentrations (3–8 mg/kg between top and bottom of the bulk pile) are appropriate justification for the development of improved application methodology.CompendioConcentraciones residuales de cloroprofam (CIPC) en papas Russet Burbank almacenadas fueron evaluadas luego de recibir un tratamiento termal de aerosol en proporciones consideradas como máximas. El aerosol se aplicó después de que las papas fueron colocadas en la estructura de almacenamiento y el proceso de cicatrización de heridas estuvo completo. Cuatro días después de la aplicación inicial, las concentraciones residuales promedio fluctuaron de 6 a 8 mg/kg del peso del tubérculo fresco, dependiendo de la temperatura de almacenamiento y de las proporciones aplicadas. Un segundo tratamiento de aerosol efectuado 90 días después del primer tratamiento mantuvo las concentraciones residuales encima de los 5 mg/kg para la duratión del período de almacenamiento. Una aspersión directa sobre los tubérculos en diferentes momentos durante el experimento elevó la concentración promedio de CIPC entre 2 y 3 mg/kg más. Todas las concentraciones residuales que se midieron en los tubérculos durante este estudio se encontraron debajo de la tolerancia establecida por la EPA (1996) de 30 mg/kg. Las concentraciones residuales de CIPC fueron mayores en las papas que se encontraban próximas al fondo del montón que cerca de la rima. Estas variaciones en las concentraciones residuales (3–8 mg/kg entre la cima y la base del montón total) justifican el desarrollo de una metodología de aplicación mejorada.

Selenium biogeochemical cycling and fluxes in the hyporheic zone of a mining-impacted stream.

The influence of hyporheic exchange on selenium (Se) biogeochemistry and mobility in sediments is unknown. A multiscale investigation of Se biogeochemistry in the hyporheic zone of East Mill Creek (EMC), southeastern Idaho, USA, was performed using in situ surface water and pore water geochemical measurements, a field-based stream tracer test, and energy-dependent micro synchrotron X-ray fluorescence (mu-SXRF) measurements of Se speciation in sediments. The active hyporheic zone was determined to be 12 +/- 3 cm. Pore water redox profiles indicated that a transition to suboxic conditions begins at approximately 6 cm. Modeling pore water Se and solid phase analysis suggested Se uptake is occurring. Micro-SXRF analysis of sediments showed reduced elemental Se or selenides throughout the profile and selenite in surface sediments. Field geochemical measurements and microscale analysis both support the hypothesis that reduction in the hyporheic zone promotes sequestration of surface water Se.

Laboratory studies of polyoxymethylene: Application to comets

Abstract Mass spectrometry experiments are described which show that polymeric forms of formaldehyde can exist in the gas phase and can sublimate at temperatures as low as 300°K. The results of the experiments are used to discuss the possible origin of the polymeric ions that have been observed with the PICCA instrument on the Giotto mission to Halleys comet. All of the experiments are consistent with the hypothesis that formaldehyde polymers are present in comets.

Electronic, vibrational, and ODMR studies of solid oxalyl halides

The lowest excited singlet and triplet states of the oxalyl halides, (COX)2 with X = F, Cl, and Br, have been investigated at ˇ- 4 K by optical and ODMR spectroscopy. The observed excited states are assigned as the 1, 3A u (nπ*) states of the planar trans isomers. A partial reassignment of the ground state fundamentals is presented, based on the ODMR activities in the vibronically resolved emission spectra. Variations seen in the kinetic parameters and fine structure splittings of the 3A u state in the series are interpreted in terms of oxygen- and halogen-centred spin-orbit interactions.