Plume Contamination Research Articles

Geophysical technique and groundwater monitoring to detect leachate contamination in the surrounding area of a landfill – Londrina (PR – Brazil)

The aim of the present study was to define leachate plume by using two techniques: geophysical and groundwater sampling in order to evaluate groundwater contamination. After performing a topographic survey and using geophysics, the leachate plume was identified. With this data, the wells for groundwater monitoring were located. Groundwater samples were analyzed for: COD, BOD, pH, alkalinity, conductivity, TKN and heavy metals. Through the electroresistivity method it was possible to define the shape of plume contamination. This method was important to locate the groundwater monitoring wells. The results of the physicochemical parameters showed the suitability of the geophysical study. The highest values of electric conductivity and alkalinity correspond to the wells located in the area interpreted as contaminated by leachate in the map of the resistivity. Even with seasonal variations, BOD values are low if compared to Brazilian environmental regulations, but COD values are higher up to 40 times the values of BOD. The concentrations of Ni, Zn, Cd and Cu in the groundwater are below the limits established by the potable water quality standards in Brazil, except for Pb whose concentration in groundwater were higher if compared to Brazilian legislation.

Self-docking capability and control strategy of electromagnetic docking technology

Electromagnetic docking technology has lots of advantages, such as no propellant consumption and plume contamination, as well as continuous, reversible and synchronous controllability, ensuring a broad prospect of application in regular on-orbit servicing missions. However, the advantages come at the cost of inherent highly nonlinear and coupled dynamics, and the far-field electromagnetic force/torque models are uncertain because of the gradually decreasing relative distance, making the control problem very challenging. From the daily phenomenon of automatic magnetic attraction and some similar results of electromagnetic experiments, this paper firstly attempts to study the self-docking capability of electromagnetic docking technology, from ground research to on-orbit research with both theoretical analysis and simulation verification. Making advantage of the self-docking capability, the paper secondly studies the control strategy to better resolve the inherent control problems. A novel control strategy that combines the merits of Artificial Potential Function Method (APFM), Lyapunov theory and Extended State Observer (ESO) is put forward, and a simple coplanar docking example is presented. Theoretical analysis and simulation results verify the existence of self-docking capability, as well as the feasibility of this novel control strategy.

The MERSADE (European Union) project: Testing procedures and environmental impact for the safe storage of liquid mercury in the Almadén district, Spain

The MERSADE Project (LIFE — European Union) tested the Las Cuevas decommissioned mining complex (Almadén mercury district, Spain) as a potential site for the installation of a future European prototype safe deposit of surplus mercury from industrial activities. We here present the results of a baseline study on the distribution of mercury in soils and air in the Las Cuevas complex and surrounding areas, and show the results of a plume contamination model using the ISC-AERMOD software. Despite restoration works carried out in 2004, the Las Cuevas complex can still be regarded as hotspot of mercury contamination, with large anomalies above 800 μg g − 1 Hg (soils) and 300 ng Hg m − 3 (air). In the case of soils, high, and persistent concentrations above 26 μg g − 1 Hg extend well beyond the complex perimeter for more than 2 km. These concentrations are about three orders of magnitude above world baselines. The same applies to mercury in air, with high concentrations above 300 ng Hg m − 3 inside the perimeter, which nonetheless fade away in a few hundred meters. Air contamination modelling (Hg gas) predicts formation of a NW–SE oriented narrow plume extending for a few hundred meters from the complex perimeter. The geographic isolation of Las Cuevas and its mining past make the complex an ideal site for mercury stocking. The only potential environmental hazards are the raising of livestock only a few hundred meters away from the complex and flash floods.

Behavioural toxicity of organic chemical contaminants in fish: application to ecological risk assessments (ERAs)

Chemical pollutants rarely attain acutely lethal concentrations in nature; thus the majority of their effects are expected to be sublethal. Estimation of the likelihood of effects from exposures to sublethal concentrations of contaminants in effluent plumes downstream of point sources poses a challenge when conducting ecological risk assessments (ERAs). This is an issue for regulatory agencies worldwide. This paper reviews the importance and availability of information on behavioural toxicity and identifies opportunities for its inclusion in ERAs. One of the major advantages of using data on behavioural effects is that they are more sensitive indicators of potential for impacts on survival in the field than are measures of lethality. Indications from available data for fish suggest that behavioural effects of organic contaminants often occur at concentrations 1 to 2 orders of magnitude lower than those found to elicit mortality. As a result, it is believed that the use of data on behavioural toxicity in ERAs could benefit the assessment process a great deal, allowing for the consideration of more ecologically significant and protective hazard and exposure scenarios.

Application of satellite infrared data for mapping of thermal plume contamination in coastal ecosystem of Korea

The 5900 MW Younggwang nuclear power station on the west coast of Korea discharges warm water affecting coastal ecology [KORDI report (2003). Wide area observation of the impact of the operation of Younggwang nuclear power plant 5 and 6, No. BSPI 319-00-1426-3, KORDI, Seoul, Korea]. Here the spatial and temporal characteristics of the thermal plume signature of warm water are reported from a time series (1985-2003) of space-borne, thermal infrared data from Landsat and National Oceanic and Atmospheric Administration (NOAA) satellites. Sea surface temperature (SST) were characterized using advanced very high resolution radiometer data from the NOAA satellites. These data demonstrated the general pattern and extension of the thermal plume signature in the Younggwang coastal areas. In contrast, the analysis of SST from thematic mapper data using the Landsat-5 and 7 satellites provided enhanced information about the plume shape, dimension and direction of dispersion in these waters. The thermal plume signature was detected from 70 to 100 km to the south of the discharge during the summer monsoon and 50 to 70 km to the northwest during the winter monsoon. The mean detected plume temperature was 28 degrees C in summer and 12 degrees C in winter. The DeltaT varied from 2 to 4 degrees C in winter and 2 degrees C in summer. These values are lower than the re-circulating water temperature (6-9 degrees C). In addition the temperature difference between tidal flats and offshore (SSTtidal flats - SSToffsore) was found to vary from 5.4 to 8.5 degrees C during the flood tides and 3.5 degrees C during the ebb tide. The data also suggest that water heated by direct solar radiation on the tidal flats during the flood tides might have been transported offshore during the ebb tide. Based on these results we suggest that there is an urgent need to protect the health of Younggwang coastal marine ecosystem from the severe thermal impact by the large quantity of warm water discharged from the Younggwang nuclear power plant.

Terrestrial discharge into the Great Barrier Reef Lagoon: nutrient behavior in coastal waters

Pollution of coastal regions of the Great Barrier Reef World Heritage Area (GBRWHA) is dominated by river discharge associated with agricultural development of the adjacent catchments. Runoff of sediment, nutrients and pesticides has sharply increased since European settlement. Since 1991 plumes from river discharge entering the GBRWHA have been mapped by aerial mapping of plume edges and concentrations of contaminants in plumes measured. Plume dispersion is governed primarily by wind speed and direction. Most plumes spread in a band up to 50 km from the coast. Particulate material discharged in the plumes is trapped within 10 km of the coast. Dissolved nutrients disperse much further and elevated nutrient concentrations are measurable at distances of hundreds of kilometres from river mouths. This differential transport of particulate versus dissolved nutrients is important for the potential effects of these materials and management of their generation on the Great Barrier Reef catchment.

Study of Interspacecraft Coulomb Forces and Implications for Formation Flying

In the course of exploiting spacecraft formations for use in separated interferometry (or other missions), it is possible that the separation distance between vehicles will be on the order of 10 m. The effects of spacecraft charging on the dynamics of very closely spaced formations are investigated. For certain high-Earth orbits, the ambient plasma conditions will conspire to produce significant spacecraft charging in an environment with a plasma Debye length of more than 100 m. For such conditions, it is shown that the potential exists to develop disruptive interspacecraft Coulomb forces and torques, with magnitude comparable to candidate formation-keeping thrusters over distances of tens of meters. Because of the unexpectedly large interaction forces, the concept of purposely charging spacecraft to affect formation-keeping Coulomb forces is also explored. Analytic methods are developed that show the existence of static equilibrium formations in Earth orbit using only inter-vehicle coulomb forces for one-, two-, and three-dimensional formations. Such Coulomb formations would be free of the risk of plume contamination due to thrusters firing in close proximity. Figures of merit for the proposed Coulomb control system are calculated in a manner analogous to traditional propulsion systems, and it is shown that required forces can be created with milliwatts of power, can be controlled on a millisecond timescale, and imply specific impulses that can be as high as 1013 seconds.

Geochemistry of the oldest Atlantic oceanic crust suggests mantle plume involvement in the early history of the central Atlantic Ocean

Controversy has surrounded the issue of whether mantle plume activity was responsible for Pangaean continental rifting and massive flood volcanism (resulting in the Central Atlantic Magmatic Province or CAMP, emplaced around 200 Ma) preceding the opening of the central Atlantic Ocean in the Early Mesozoic. Our new Sr–Nd–Pb isotopic and trace element data for the oldest basalts sampled from central Atlantic oceanic crust by deep-sea drilling show that oceanic crust generated from about 160 to 120 Ma displays clear isotopic and chemical signals of plume contamination (e.g., 87Sr/ 86Sr i=0.7032–0.7036, ϵ Nd( t)=+6.2 to +8.2, incompatible element patterns with positive Nb anomalies), but these signals are muted or absent in crust generated between 120 and 80 Ma, which resembles young Atlantic normal mid-ocean ridge basalt. The plume-affected pre-120 Ma Atlantic crustal basalts are isotopically similar to lavas from the Ontong Java Plateau, and may represent one isotopic end-member for CAMP basalts. The strongest plume signature is displayed near the center of CAMP magmatism but the hotspots presently located nearest this location in the mantle reference frame do not appear to be older than latest Cretaceous and are isotopically distinct from the oldest Atlantic crust. The evidence for widespread plume contamination of the nascent Atlantic upper mantle, combined with a lack of evidence for a long-lived volcanic chain associated with this plume, leads us to propose that the enriched signature of early Atlantic crust and possibly the eruption of the CAMP were caused by a relatively short-lived, but large volume plume feature that was not rooted at a mantle boundary layer. Such a phenomenon has been predicted by recent numerical models of mantle circulation.

Engineering Issues of Iridium Coated Rhenium Rockets

The key to the performance and lifetime of radiation-cooled rockets is the chamber temperature capability. Temperature limitations (1370°C) of current state-of-art chamber materials force the use of film cooling, which degrades rocket performance and imposes plume contamination from unburned fuel. A material system composed of a rhenium (Re) substrate and an iridium (Ir) coating has demonstrated operation, for long lifetimes (hours), at higher temperatures (2200°C). The added thermal margin afforded by iridium-coated rhenium (Ir/Re) allows the virtual elimination of film cooling, leading to higher performance and cleaner spacecraft environments. In the course of developing Ir/Re rockets for flight use, some engineering issues have arisen concerning Ir/Re rocket fabrication processes, critical Re mechanical properties, Re joining methods, and Ir/Re life-limiting mechanisms. Government- and industry-sponsored efforts are addressing these concerns.

Fate of organic contaminants in the redox zones of a landfill leachate pollution plume (Vejen, Denmark)

Samples from 75 sample locations in a landfill leachate pollution plume reveal a significant disappearance of specific organic compounds (SOC's) within the first 100 m of the plume. Only the herbicide Mecoprop® (MCPP) migrates further. Since sorption and dilution cannot account for the decreasing concentrations, degradation is considered to be the governing process. Non-volatile organic carbon shows a corresponding fate probably acting as a substrate for the microbial processes. The first 20 m of the plume are methanogenic/sulfidogenic, judged on the chemistry of the groundwater, followed by a significant ferrogenic zone exhibiting a substantial capacity to degrade the SOC's. The presence of intermediary products (here an oxidized camphor compound) supports the concept of degradation within the ferrogenic zone. This investigation draws the attention to the significant natural attenuation of organic contaminants and to the so far neglected ferrogenic zone in controlling the fate of organic contaminants in leachate plumes.

High temperature thruster technology for spacecraft propulsion

A technology program has been underway since 1985 to develop high temperature oxidation-resistant thrusters for spacecraft applications. The successful development of this technology will provide the basis for the design of higher performance satellite engines with reduced plume contamination. Alternatively, this technology program will provide a material with high thermal margin to operate at conventional temperatures and provide increased life for refuelable or reusable spacecraft. The new chamber material consists of a rhenium substrate coated with iridium for oxidation protection. This material increases the operating temperature of thrusters to 2200°C, a significant increase over the 1400°C of the silicide-coated niobium chambers currently used. Stationkeeping class 22 N engines fabricated from iridium-coated rhenium have demonstrated steady state specific impulses 20 to 25 seconds higher than niobium chambers. Ir-Re apogee class 440 N engines are expected to deliver an additional 10 to 15 seconds. These improved performances are obtained by reducing or eliminating the fuel film cooling requirements in the combustion chamber while operating at the same overall mixture ratio as conventional engines. The program is attempting to envelope flight qualification requirements to reduce the potential risks and costs of flight qualification programs.

Pulsed Plasma Thruster Backflow Characteristics

ULSED plasma thrusters (PPT's) using solid teflon propellant have a flight-demonst rated simplicity and reliability1 and are of increasing interest for future flight applications. Earlier versions of this thruster have relatively low values of impulse bit and total impulse, and hence, are limited to applications such as east-west stationkeeping and fine attitude control.2 To extend the capabilities of the PPT to longer duration missions and larger spacecraft, a one millipound average thrust PPT is currently in the advanced stages of development. 3 This thruster has an impulse bit of 22.2 mN-s, roughly 50 times larger than earlier versions, and a total impulse of 310,800 N-s, roughly 10 times larger than earlier versions. In addition, its specific impulse, propellant flow rate, efficiency, and power are also significantly larger. Applications envisioned for this millipound thruster include north-south stationkeeping, orbital acquisition and maneuvering, and large structure attitude control. The flight experience of the earlier PPT's has shown that the exhaust plume of these smaller thrusters has a negligible effect on spacecraft surfaces.4 The exhaust plume of the one millipound thruster is of potentially greater concern, primarily due to its higher energy and greater mass per pulse. In addition, longer mission durations and ever more sensitive spacecraft instrumentation will aggravate any plume contamination that may exist. Previous studies have been conducted to assess the effect of the one millipound PPT plume on spacecraft surfaces by directly measuring the plume flux impinging on a spacecraft upstream of the thrust exhaust plane.5 Unfortunately, accurate results have been masked by a backscattered flux of particles reflected and eroded from the test facility vacuum chamber walls. In order to minimize this effect and develop a more accurate measure of the plumespacecraft interaction, a study has been carried out using a special molecular sink (MOLSINK) vacuum facility. 6>7 This

Viscous Effects on Biowaste Resistojet Nozzle Performance

Viscous effects on the performance of biowaste resistojet microthrusters are calculated using Rae's numerica method for low-Reynolds number flow in a nozzle. Results are presented for a 25-mlb thruster suitable for space station attitude control using CO2, CH4, and H2O as propellants. Nozzle exit plane data (such as Mach number, velocity, and temperature profiles) useful for computations of plume contamination are also presented. The performance predictions are compared with experimental data which were available from laboratory firings of a 10-mlb thruster having a trumpet-shaped nozzle with CO2, CH4, H2O and H2 as propellants.