Environmental impacts of the coal ash spill in Kingston, Tennessee: an 18-month survey.

An 18 month investigation of the environmental impacts of the Tennessee Valley Authority (TVA) coal ash spill in Kingston, Tennessee combined with leaching experiments on the spilled TVA coal ash have revealed that leachable coal ash contaminants (LCACs), particularly arsenic, selenium, boron, strontium, and barium, have different effects on the quality of impacted environments. While LCACs levels in the downstream river water are relatively low and below the EPA drinking water and ecological thresholds, elevated levels were found in surface water with restricted water exchange and in pore water extracted from the river sediments downstream from the spill. The high concentration of arsenic (up to 2000 μg/L) is associated with some degree of anoxic conditions and predominance of the reduced arsenic species (arsenite) in the pore waters. Laboratory leaching simulations show that the pH and ash/water ratio control the LCACs' abundance and geochemical composition of the impacted water. These results have important implications for the prediction of the fate and migration of LCACs in the environment, particularly for the storage of coal combustion residues (CCRs) in holding ponds and landfills, and any potential CCRs effluents leakage into lakes, rivers, and other aquatic systems.

Impacts of shale gas wastewater disposal on water quality in western Pennsylvania.

The safe disposal of liquid wastes associated with oil and gas production in the United States is a major challenge given their large volumes and typically high levels of contaminants. In Pennsylvania, oil and gas wastewater is sometimes treated at brine treatment facilities and discharged to local streams. This study examined the water quality and isotopic compositions of discharged effluents, surface waters, and stream sediments associated with a treatment facility site in western Pennsylvania. The elevated levels of chloride and bromide, combined with the strontium, radium, oxygen, and hydrogen isotopic compositions of the effluents reflect the composition of Marcellus Shale produced waters. The discharge of the effluent from the treatment facility increased downstream concentrations of chloride and bromide above background levels. Barium and radium were substantially (>90%) reduced in the treated effluents compared to concentrations in Marcellus Shale produced waters. Nonetheless, (226)Ra levels in stream sediments (544-8759 Bq/kg) at the point of discharge were ~200 times greater than upstream and background sediments (22-44 Bq/kg) and above radioactive waste disposal threshold regulations, posing potential environmental risks of radium bioaccumulation in localized areas of shale gas wastewater disposal.

Isotopic imprints of mountaintop mining contaminants.

Mountaintop mining (MTM) is the primary procedure for surface coal exploration within the central Appalachian region of the eastern United States, and it is known to contaminate streams in local watersheds. In this study, we measured the chemical and isotopic compositions of water samples from MTM-impacted tributaries and streams in the Mud River watershed in West Virginia. We systematically document the isotopic compositions of three major constituents: sulfur isotopes in sulfate (δ(34)SSO4), carbon isotopes in dissolved inorganic carbon (δ(13)CDIC), and strontium isotopes ((87)Sr/(86)Sr). The data show that δ(34)SSO4, δ(13)CDIC, Sr/Ca, and (87)Sr/(86)Sr measured in saline- and selenium-rich MTM impacted tributaries are distinguishable from those of the surface water upstream of mining impacts. These tracers can therefore be used to delineate and quantify the impact of MTM in watersheds. High Sr/Ca and low (87)Sr/(86)Sr characterize tributaries that originated from active MTM areas, while tributaries from reclaimed MTM areas had low Sr/Ca and high (87)Sr/(86)Sr. Leaching experiments of rocks from the watershed show that pyrite oxidation and carbonate dissolution control the solute chemistry with distinct (87)Sr/(86)Sr ratios characterizing different rock sources. We propose that MTM operations that access the deeper Kanawha Formation generate residual mined rocks in valley fills from which effluents with distinctive (87)Sr/(86)Sr and Sr/Ca imprints affect the quality of the Appalachian watersheds.

Boron and strontium isotopic characterization of coal combustion residuals: validation of new environmental tracers.

In the U.S., coal fired power plants produce over 136 million tons of coal combustion residuals (CCRs) annually. CCRs are enriched in toxic elements, and their leachates can have significant impacts on water quality. Here we report the boron and strontium isotopic ratios of leaching experiments on CCRs from a variety of coal sources (Appalachian, Illinois, and Powder River Basins). CCR leachates had a mostly negative δ(11)B, ranging from -17.6 to +6.3‰, and (87)Sr/(86)Sr ranging from 0.70975 to 0.71251. Additionally, we utilized these isotopic ratios for tracing CCR contaminants in different environments: (1) the 2008 Tennessee Valley Authority (TVA) coal ash spill affected waters; (2) CCR effluents from power plants in Tennessee and North Carolina; (3) lakes and rivers affected by CCR effluents in North Carolina; and (4) porewater extracted from sediments in lakes affected by CCRs. The boron isotopes measured in these environments had a distinctive negative δ(11)B signature relative to background waters. In contrast (87)Sr/(86)Sr ratios in CCRs were not always exclusively different from background, limiting their use as a CCR tracer. This investigation demonstrates the validity of the combined geochemical and isotopic approach as a unique and practical identification method for delineating and evaluating the environmental impact of CCRs.

Rizofiltración de plomo de aguas y efluentes contaminados y concentración en raíces de plantas terrestres

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Precipitation of heavy metals from wastewater using simulated flue gas: sequent additions of fly ash, lime and carbon dioxide

Lime is a preferred precipitant for the removal of heavy metals from industrial wastewater due to its relatively low cost. To reduce heavy metal concentration to an acceptable level for discharge, in this work, fly ash was added as a seed material to enhance lime precipitation and the suspension was exposed to CO2 gas. The fly ash-lime-carbonation treatment increased the particle size of the precipitate and significantly improved sedimentation of sludge and the efficiency of heavy metal removal. The residual concentrations of chromium, copper, lead and zinc in effluents can be reduced to (mg L-1) 0.08, 0.14, 0.03 and 0.45, respectively. Examination of the precipitates by XRD and thermal analysis techniques showed that calcium-heavy metal double hydroxides and carbonates were present. The precipitate agglomerated and hardened naturally, facilitating disposal without the need for additional solidification/stabilization measures prior to landfill. It is suggested that fly ash, lime and CO2, captured directly from flue gas, may have potential as a method for wastewater treatment. This method could allow the ex-situ sequestration of CO2, particularly where flue-gas derived CO2 is available near wastewater treatment facilities. (C) 2009 Elsevier Ltd. All rights reserved.

The Application Of Radioisotopes In The Study Of Estuarine Sedimentary Processes

The spatial and temporal distributions of some radionuclides in effluents originating from the British Nuclear Fuels Ltd (BNFL) reprocessing plant at Windscale, which are released into the Irish Sea, have been studied in sediments at 16 sites in the salt marsh region near Newbiggin on the Esk estuary Cumbria, England. The concentration of non-conservative radionuclides in surface sediments of the area cannot be described by a single parameter, but there is a high correlation with organic C, Cu, Al and the Si : Al ratio with particle size. The preservation of the historical record of the BNFL effluents in the Esk sediments is dependent on the hydrology of the area, as it effects such processes as accretion, erosion and remixing. From the 106Ru and 210Po concentrations and the 137Cs : 134Cs ratio in the sediment profiles with depth, we have identified these processes. Sedimentation rates at sites of accretion vary between 0·5 and 3 cm year−1. However, at some sites they appear to be much higher, approximately 6 cm year−1 in the top 10 cm, but they are not consistent throughout the depth profiles. This may be a true reflection of variable accretion related to sediment type, or one which is influenced by surficial mixing. Some cores showed evidence of continuous accretion but no significant radioactivity was detected at depths below 35–40 cm, indicating an overall sedimentation rate of approximately 1·5 cm year−1 for the 25–30-year period since BNFL effluents first entered the Irish Sea.

Alpha-Particle Radioactivity Of Hot Particles From The Esk Estuary

Transuranium radionuclides (Pu, Am and Cm) present in effluents discharged into the north-east Irish Sea by British Nuclear Fuels Limited, Windscale, Cumbria, UK, are found in sediment and biota of the Esk estuary ~10 km to the south. The site of the present investigation was at Newbiggin and the materials examined were suspended particulate debris samples at the sea surface, bottom sediments and some forms of biota collected in September 1977. It is shown here that hot particles (defined as small volumes of material emitting a particles recorded in a dielectric detector as dense clusters of tracks from a common origin) found in the estuary are likely to be original effluent debris derived from the processing of Magnox uranium fuel elements and not formed in situ as a result of natural processes common to the estuary.

Simulating The Impact Of Technological-Change On Dissolved Cadmium Distribution In The Severn Estuary

An estuarine model is described which computes the dispersive and advective properties of the Severn Estuary. It was calibrated and validated using 50 measured salinity distributions and then used to predict the magnitude and sitings of the major inputs of dissolved cadmium levels throughout the estuary. The results provided an impetus for implementing tighter controls on effluents and for improving estimates of cadmium discharges from industrial sources. The model has also been used to investigate the sensitivity of the estuarine system to changes in dispersion; by considering large reductions in the dispersion coefficients it is hoped that the results might be indicative of the environmental consequences following the construction of a tidal power generating scheme.

Adsorption isotherm models for basic dye adsorption by peat in single and binary component systems

Coloured effluents from textile industries are a problem in many rivers and waterways. Prediction of adsorption capacities of dyes by adsorbents is important in design considerations. The sorption of three basic dyes, namely Basic Blue 3, Basic Yellow 21 and Basic Red 22, onto peat is reported. Equilibrium sorption isotherms have been measured for the three single component systems. Equilibrium was achieved after twenty-one days. The experimental isotherm data were analysed using Langmuir, Freundlich, Redlich-Peterson, Temkin and Toth isotherm equations. A detailed error analysis has been undertaken to investigate the effect of using different error criteria for the determination of the single component isotherm parameters and hence obtain the best isotherm and isotherm parameters which describe the adsorption process. The linear transform model provided the highest R2 regression coefficient with the Redlich-Peterson model. The Redlich-Peterson model also yielded the best fit to experimental data for all three dyes using the non-linear error functions. An extended Langmuir model has been used to predict the isotherm data for the binary systems using the single component data. The correlation between theoretical and experimental data had only limited success due to competitive and interactive effects between the dyes and the dye-surface interactions.

Prueba de inmigración y márgenes legales del desencuentro. Políticas públicas, prácticas sociales y construcción de la persona

La redacción de las directrices y los procedimientos administrativos que hacen virtualmente posible la inmigración, contribuye a construir no sólo los itinerarios sino también el imaginario social sobre la alteridad. El principal objetivo del artículo es poner de relieve –mediante el análisis discursivo de las Hojas informativas publicadas en la WEB del Ministerio de Empleo y Seguridad Social- cómo la construcción social del emigrante/inmigrante y el proyecto migratorio topan con unas representaciones y envites, instituidos y refrendados  en y por la propia formulación de la reglamentación, pero no del todo explícitos. Entendiendo el texto como una acción que genera otras acciones, se examinan las consecuencias que tiene sobre la practica social de los inmigrantes. En suma, se trata  de vislumbrar los elementos (terminología, fórmulas, esquemas y prácticas inducidas) que van constituyendo al inmigrante como agente social subordinado a micro-procesos y relaciones que se le escapan en gran parte (en contra de las apariencias que parecieran sugerir lo contrario) y van marcando su propia capacidad de acción. En conclusión y retomando la distinción entre principio de diferencia y principio de indiferencia sugerida por Foucault, se muestra que mientras el primero rige las clausulas generales, el segundo articula las específicas.

Creation of damage-free ferroelectric nanocapacitors via focused ion beam milling

We present a novel method for creating damage-free ferroelectric nanostructures with a focused ion beam milling machine. Using a standard e-beam photoresist followed by a dilute acid wash, nanostructures ranging in size from 1 mu m down to 250 nm were created in a 90 nm thick lead zirconate titanate ( PZT) wafer. Transmission electron microscopy and piezoresponse force microscopy ( PFM) confirmed that the surfaces of the nanostructures remained damage free during fabrication, and showed no gallium implantation, and that there was no degradation of ferroelectric properties. In fact DC strain loops, obtained using PFM, demonstrated that the nanostructures have a higher piezoresponse than unmilled films. As the samples did not have any top hard mask, the method presented is unique as it allows for imaging of the top surface to understand edge effects in well-defined nanostructures. In addition, as no post-mill annealing was necessary, it facilitates investigation of nanoscale domain mechanisms without process-induced artefacts.

Development and validation of a lateral flow device for the detection of nicarbazin contamination in poultry feeds

Concentrations of the coccidiostat nicarbazin as low as 2 mg/kg in feed can result in violative drug residues arising in poultry liver. A lateral flow device (LFD) was developed for the detection of contaminating concentrations of nicarbazin following solvent extraction of poultry feeds. Test results, as determined by both visual and instrumental measurement, are available within minutes. For 22 feed samples, nicarbazin-free and fortified at 2 mg/kg, the % relative inhibition ranged from 0 to 45% and from 53 to 85%, respectively. Nicarbazin contamination at the critical concentration (2 mg/kg) can be determined in all cases providing the sampling is representative. A wide range of feed samples taken at a mill that incorporated nicarbazin into poultry feed were analyzed. Data generated for these samples by both the LFDs and a mass spectrometric method were compared, and a significant correlation was achieved.

Deposition and depletion of five anticoccidials in eggs

Anticoccidials are compounds that are widely used as feed additives to prevent and treat coccidiosis. They are licensed for use in a prescribed concentration and during a certain time interval for broilers and pullets but not for laying hens. It was shown in the past that carry-over at the feeding mill is found to be the main reason for the presence of residues in eggs. An animal experiment was set up to investigate the effect of carry-over at the feeding mill on the presence of residues of anticoccidials in eggs. For the compounds diclazuril, robenidine, halofuginone and nicarbazin in combination with narasin, two concentration levels were tested: the maximum allowed concentration for broilers (100%) and a concentration corresponding to 5% carry-over during feed preparation. Also dimetridazole was included in the experiment but only at one concentration level. Eggs were sampled during treatment (14 days) and for a period of 30 days after withdrawal of the anticoccidial-containing feed. Residues were determined, and deposition and depletion curves were generated. Analyses were performed by ELISA and LC-MS/MS. For all compounds, substantial residues could be found in the 5% groups, which points out the risk of carry-over at the feeding mill. The distribution of the residues between egg yolk and white was determined by analyzing both fractions.

Absolute Atomic Oxygen Density Distributions in the Effluent of a Micro Scale Atmospheric Pressure Plasma Jet

The coplanar microscale atmospheric pressure plasma jet (µ-APPJ) is a capacitively coupled radio frequency discharge (13.56 MHz, ~15W rf power) designed for optimized optical diagnostic access. It is operated in a homogeneous glow mode with a noble gas flow (1.4 slm He) containing a small admixture of molecular oxygen (~0.5%). Ground state atomic oxygen densities in the effluent up to 2 × 1014 cm-3 are measured by two-photon absorption laser-induced fluorescence spectroscopy (TALIF) providing space resolved density maps. The quantitative calibration of the TALIF setup is performed by comparative measurements with xenon. A maximum of the atomic oxygen density is observed for 0.6% molecular oxygen admixture. Furthermore, an increase in the rf power up to about 15W (depending on gas flow and mixture) leads to an increase in the effluent’s atomic oxygen density, then reaching a constant level for higher powers.