Monitoring of river contamination derived from acid mine drainage using airborne imaging spectroscopy (HyMap data, South-West Spain)

Imaging spectroscopy is used in this work as an essential mapping tool to monitor changes in contaminated river sediments. Multidate hyperspectral image data (HyMap) are utilized to identify spatial mineral patterns, to detect temporal changes in mineralogy and to link these changes with geochemical processes and short-term climate characteristics. River sediments contaminated by acid mine drainage are covered by crusts with variably hydrated iron sulphate. The mineralogy of the crusts and the grain size of the underlying fluvial sediments overlap. The spectra used to build up maps from HyMap data are diagnosed mineralogically with archive spectral libraries from pyrite oxidation minerals from well-known sequences of minerals. The maps compiled from hyperspectral imagery display generalized oxidation shown by the coatings over river sediments following warm and dry periods with low water level. After the wet periods, the area covered by oxidized mineralogical phases recedes in favour of hydrated sulphate. The iteration of image processing algorithms and the mineralogical and potential contamination in a geological context are described. Change detection of the mineral crusts on the river sediments by mapping using hyperspectral remote sensing data may thus enable a quantitative and qualitative environmental evaluation by the regulators

El seguimiento espacial hiperespectral de residuos mineros de piritas, un registro geológico de variabilidad climática

Código JEL.: Q34, Q53, Q54. JEL Code.: Q34, Q53, Q54Las sustancias que se producen por oxidación de piritas en las minas abandonadas de sulfuros generan aguas ácidas y concentran metales pesados en las mismas. La mineralogía de las costras superficiales formadas por sulfatos fácilmente solubles, es función de la temperatura y humedad disponibles durante el año. Estas sustancias pueden cartografiarse desde aviones o satélites usando sensores hiperespectrales. De este modo, puede realizarse un seguimiento desde el espacio de las sustancias producto de meteorización de piritas durante las estaciones del año, que contribuye a predecir la calidad del agua superficial estimando cuantitativamente tanto el drenaje ácido de mina, como la contaminación por metales pesados. En este trabajo, se ha cartografiado la evolución temporal de eflorescencias salinas en residuos mineros en la mina de Sotiel (Huelva), usando datos aeroportados Hymap en cuatro fechas distintas, a comienzos de la estación seca, y en plena estación seca. A partir de estas cartografías, se realizan estimaciones de variabilidad climática basadas en series minerales conocidas por oxidación de piritas y espectrotecas de referencia. De este modo, las cartografías de sustancias de meteorización de piritas realizadas con sensores hiperespectrales pueden usarse como un registro de variabilidad climática estacional y anual, constituyendo una herramienta para establecer geoindicadores en zonas semiáridas. Los residuos mineros de sulfuros masivos podrían formar parte de los ambientes geológicos sensibles a cambios climatológicos rápidos, como los arrecifes de coral, las turberas, los sistemas periglaciares o las zonas costeras.Monitoring of mine waste on sulphide deposits through hyperspectral remote sensing data contributes to predicting surface water quality quantitatively estimating acid drainage and metal contamination on a yearly basis. The mineralogy of surface crusts loaded with highly soluble salts is a record of available humidity and temperature along the year. A temporal monitoring of salt efflorescence on mine wastes at a mine site in the Iberian Pyrite Belt (Huelva, Spain) has been mapped in this work using hyperspectral airborne Hymap data. Climate variability estimations are made based on oxidation stages derived from well-known sequences of minerals tracing sulphides oxidation intensity, using archive spectral libraries. Therefore, mine waste weathering products of sulphide mapped from airborne hyperspectral remote sensing data can be used as a short-term record of climate change, providing a useful tool for assessing environmental geoindicators in semi-arid areas. Recognized rapidly changing earth systems are coral reefs, periglacial systems or coastal areas.Instituto Geológico y Minero de España (IGME), Tres Cantos (Madrid), España. CSIRO Exploración y Minería, Kensington, Australia. DLR_Agencia Espacial Alemana, Centro de Datos de Teledeteccion, Oberpfaffenhofen, Alemania. Junta de Andalucía, Servicio de Información y Evaluación Ambiental, Sevilla, España

Mapping of semi-arid iron bearing red sands on emerged areas around lake marshes (Tablas de Daimiel, Spain) using hyperspectral DAIS 7915 spectrometer data

Wetlands are particularly sensitive environments receiving attention from the natural sciences community due to their wealth of both flora and fauna, and often considered as natural parks. In the Tablas de Daimiel (La Mancha, Central Spain), Digital Airborne Imaging Spectrometer data (DAIS 7915) have been analyzed to map geological processes on areas around the receding wetland which have never been flooded by water in the past. Sediments permanently exposed to the atmosphere dehydrate and oxide, developing different mineralogical associations arranged on planation surfaces. Such planation surfaces are key in the geological knowledge of recent climate change and landscape evolution. Progressive iron oxide/hydroxide rate and decarbonation can be spectrally followed on the Holocene sands framing the current marshy area. Such mineralogical changes are geologically registered on flat surfaces at different heights over the receding shore of the paleolake. Interacting erosion and sedimentation processes are responsible for the development of the flat morphological surfaces with increasing dryness. Maps are built for four different morphological units consisting of planation surfaces following chronologically the receding marsh during the last 2000 years before the present. Interactive spectral responses of mineralogical associations are described on the imagery, field and laboratory spectra

Mapping marine and fluvial salt crusts in estuaries collecting acid water using hyperspectral Hyperion imagery (Marshes of the river Odiel, Huelva)

Revista oficial de la Asociación Española de Teledetección[EN] Temporal monitoring of salt efflorescence on the marshes at the mouth of the river Odiel (Huelva) is made using hyperspectral archive Hyperion data. Climate variability estimations are made based on well-known spectral features related to vegetation and shallow water, using archive spectral libraries. The observations point to spectral and geomorphological indicators which can be monitored through image processing supported by field and laboratory spectral data, on a repeatable basis. Mapping a larger sequence of images under different climate regime and wider tidal range, would improve the estimation of spectral features to ensure a routine monitoring of salt crusts with hyperspectral data.[ES] Se realiza un seguimiento temporal de eflorescencias salinas en las Marismas del río Odiel, que ocupan el estuario en su desembocadura, con imágenes hiperespectrales Hyperion de archivo. A partir de varias cartografías elaboradas con tratamiento de imágenes, se han realizado estimaciones de variabilidad climática basadas en series minerales conocidas, utilizando respuestas espectrales típicas en vegetación y aguas someras. En este trabajo, se esbozan indicadores espectrales y geomorfológicos susceptibles de un seguimiento repetible con tratamiento de imágenes en las marismas, que permita cuantificar cambios climáticos combinados con la influencia de las mareas, enfocados a estudiar la evolución de las costras salinas que aparecen sobre la superficie de los sedimentos, al retirarse la vegetación y la lámina de agua. En este marco, se presentan cartografías elaboradas a partir de imágenes Hyperion en varias fechas. Se describe el tratamiento preinterpretativo de las imágenes Hyperion, y la secuencia de algoritmos que permiten elaborar las cartografías de sustancias salinas en zonas intermareales. El análisis de una secuencia más amplia de imágenes con condiciones climatológicas distintas, y más amplitud de oscilación mareal, enriquecerá la estimación de parámetros espectrales para el seguimiento rutinario de costras salinas con datos hiperespectrales.Los datos Hyperion y la metodología de trabajo para la cartografía con datos hiperespectrales se desarrollaron durante la subvención CGL2007- 60004/CLI. Las bases para comenzar este trabajo surgieron durante la tesis doctoral de Jorge Buzzi Marcos (BES-2008-003648).Riaza, A.; García-Meléndez, E.; Carrère, V.; Mueller, A. (2014). Cartografía de sales marinas y fluviales en estuarios receptores de aguas ácidas con imágenes hiperespectrales Hyperion (Marismas del río Odiel, Huelva). Revista de Teledetección. (41):1-7. https://doi.org/10.4995/raet.2014.2255SWORD1741BELLUCO, E., CAMUFFO, M., FERRARI, S., MODENESE, L., SILVESTRI, S., MARANI, A., & MARANI, M. (2006). Mapping salt-marsh vegetation by multispectral and hyperspectral remote sensing. Remote Sensing of Environment, 105(1), 54-67. doi:10.1016/j.rse.2006.06.006Buzzi, J., 2012. Imaging spectroscopy to evaluate the contamination from sulphide mine waste in the Iberian Pyrite Belt using hyperspectral sensors (Huelva, Spain), Tesis Doctoral Universidad de León, 212 p.Jupp, D.L.B., 2001. Discussion around Hyperion Data. CSIRO Office of Space Science Applications, Earth Observation Centre: 1-9.RSI, 2000. ENVI User’s Guide. Research Systems Inc. Publications

Biomass fuel flexibility in future conventional power generation

Power generation from the combustion of solid fuels has been a conventional technology for electricity production in the UK and most of the world for many decades. While the phasing out of coal as a fuel is an important aspect of the ‘decarbonising’ the electricity sector, the respective power plant technology could still play an important role into the future by use of abundant sources of solid biomass fuels. If such resources are to be effectively utilised, it is then necessary to accommodate the wide variation in the characteristics and behaviour of biomass fuels. Some of the key challenges in this context include: control of burn-out efficiency for different fuels; predictability of ash behaviour including operational problems and emissions arising from high ash and high potassium content fuels; the fate of fuel nitrogen content and the consequent effects on NOx emissions. This article presents an overview of these issues, their significance in the context of power plant design and operation and details of some recent research seeking to address them. Results of laboratory scale experiments showing the variation in properties and behaviour of different types of biomass fuel are also presented. These include studies on the relationship between fuel particle size and burn-out duration, gas-phase potassium release from biomass materials during combustion, variability in biomass ash composition and nitrogen release patterns from fuels in high temperature combustion

AISA Eagle II hyperspectral data for carbonate geological mapping in a vegetated high relief area: a geologically orientated atmospheric correction

[EN] Carbonated rocks are crucial targets for oil exploration, outcropping often in large areas with minimum spectral differences among geological units. The typical carbonate spectral absorptions in 2200 nm and 2300 nm, are excluded from the wavelength range of AISA Eagle II. AISA Eagle II hyperspectral data are processed in flight lines of 1024 swath pixels in the visible to near-infrared wavelength range (400 to 970 nm). The flight has a spatial resolution of 1 m and records a total of 128 channels with a spectral resolution of 4,8 nm. The area of study is a carbonate rocky mountain densely vegetated, covered by variably dense trees and bushes. Masking vegetation cover and shade effects is prior to any geological analysis using hyperspectral image processing. Carbonate units occur in mountain slopes, with small areas of ridges of rock outcrops and wide fans of loose material. The background soil of different geological units differ spectrally only by overall reflectance. Instead, limestone rocky outcrops display spectral responses with smooth typical iron oxide absorptions that distinguish them apart from loose boulders of limestone. Trying to enhance spectral differences in the visible wavelength range among carbonate geological units, an atmospheric correction using field spectra from geologically selected targets in a limestone quarry was performed. This way, it was possible to map apart lithologically similar detrital units dominated by carbonate in a river plain. The limy river bottom displays spectra with a straight line in the visible wavelength range due to abundant organic matter and small grain size. The spectra of the upper terraces record spectral absorption features related to iron oxide contents similar to the rock outcrops in ridges of mountains. The use of field spectra from geologically selected targets improves the mapping capability of hyperspectral imagery in areas with geological units with a homogeneous spectral response.[ES] Las calizas son rocas críticas en la exploración de petróleo. Desarrollan series estratigráficas a menudo espesas, que afloran con frecuencia en zonas extensas de la superficie terrestre. Estas formaciones litológicas predominantemente carbonatadas presentan diferencias espectrales mínimas entre sí, que permiten su diagnóstico por su respuesta espectral y su cartografía con imágenes. Las bandas de absorción espectral típicas de los carbonatos en 2200 nm y 2300 nm no forman parte del intervalo de longitudes de onda del espectrómetro AISA Eagle II (400 nm-970 nm), con una resolución espectral de 4,8 nm en 128 canales, y 1 m de resolución espacial en el vuelo de estudio. La zona de estudio se encuentra localizada en el Prepirineo español formando un relieve rocoso carbonatado con vegetación densa. El suelo de las distintas formaciones geológicas carbonatadas cartografiadas se distingue espectralmente sólo por su reflectancia global. Los afloramientos rocosos de calizas in situ presentan respuestas espectrales con absorciones típicas de óxidos de hierro. La expresión espectral de las formaciones calizas en las imágenes iniciales mostraban defectos sistemáticos. Para conseguir espectros geológicamente diagnosticables con espectrotecas de referencia, se ha ensayado una corrección atmosférica con espectros de campo tomados en una cantera de calizas, y en afloramientos rocosos de formaciones calcáreas seleccionados, con un espectrómetro de campo y laboratorio ASD Fieldspec 3. En las imágenes hiperespectrales así corregidas, se cartografían formaciones geológicas litológicamente similares correspondientes a la cuenca fluvial del río Noguera Ribagorzana, a su paso por Alfarrás (Lérida), en la que los sedimentos de la llanura aluvial con limos de materiales comparativamente más finos y materia orgánica, presentan espectros típicos con un trazo rectilíneo en el visible, que no aparecía en las imágenes anteriores a la corrección. El uso de espectros de campo seleccionados con criterios geológicos para la corrección atmosférica de imágenes hiperespectrales, mejora la capacidad de las imágenes para elaborar cartografías de formaciones litológicamente similares usando espectrotecas de referencia.El sensor AISA Eagle II fue cedido en préstamo por SPECIM al Institut Cartogràfic i Geològic de Catalunya (ICGC) para su prueba en vuelo y pre-tratamiento digital. Los estudios de interpretación geológica se han realizado en un convenio entre la Universidad de Barcelona y REPSOL Exploración para formación postdoctoral. Las bases para comenzar este trabajo surgieron durante la tesis doctoral de Buzzi (BES-2008-003648).Buzzi, J.; Costa, E.; Riaza, A.; Fernández, O.; García-Sellés, D.; Corbera, J. (2018). Cartografía de calizas con datos hiperespectrales AISA Eagle II en una zona montañosa con vegetación densa: cómo orientar geológicamente la corrección atmosférica. Revista de Teledetección. (51):125-133. https://doi.org/10.4995/raet.2018.8998SWORD12513351ASD. 2006. FieldSpecR 3 User Manual, ASD Document 600540 Rev. F. Analytical Spectral Devices, Inc. Disponible en: http://www.asdi.com [Último acceso: junio de 2018].Buzzi, J. 2012. Imaging spectroscopy to evaluate the contamination from sulphide mine waste in the Iberian Pyrite Belt using hyperspectral sensors (Huelva, Spain), Tesis Doctoral Universidad de León, 212 p.Buzzi, J., Riaza, A., García-Meléndez, Carrère, V., Bachmann, M. 2011. Aplicación de modelos Gaussianos modificados a datos hiperespectrales de una zona contaminada por drenaje ácido. Caso del río Odiel (Huelva, España). XIV Congreso de la Asociación Española de Teledetección, Mieres, 21- 23 Septiembre 2011, 285-288.Clark, R.N., Swayze, G.E., Wise, R., Livo, E., Hoefen, T., Kokaly, R., Sutley, S.J. 2007. USGS Digital Spectral Library splib06a. Digital Data Series 231, USGS: Denver, Co, USA, 2007.EXELIS, 2011. ENVI User's Guide. Exelis Visual Information Solutions: Boulder, Co, USA.Hunt, G.R., Salisbury, J.W. 1971a. Visible and Near-infrared Spectra of Minerals and Rocks: II. Carbonates. Modern Geology, 2, 23-30.Hunt, G.R., Salisbury, J.W., Lenhof, J. 1971b. Visible and Near-infrared Spectra of Minerals and Rocks: III Oxides and Hydroxides. Modern Geology, 2, 191-205.Hunt, G.R., Salisbury, J.W., 1976. Visible and Near-infrared Spectra of Minerals and Rocks: XI. Sedimentary Rocks. Modern Geology, 5, 211-217.López-Mir, B., Antón Muñoz, J., García-Senz, J. 2016, 3D geometric reconstruction of Upper Cretaceous passive diapirs and salt withdrawal basins in the Cotiella Basin (southern Pyrinees), Journal of the Geological Society, 173, 616-627. https://doi.org/10.1144/jgs2016-002Martínez, L., Tardà, A., Palà, V., Arbiol, R. 2006. Atmospheric correction algorithm applied to CASI multi-height hyperspectral imagery. Proceedings Second International Symposium Recent Advances in Quantitative Remote Sensing, 25-29 Septiembre 2006.Riaza, A. Buzzi, J., García-Meléndez, E., del Moral, B., Carrère, V., Richter, R. 2017. Monitoring salt crusts on an AMD contaminated coastal wetland using hyperspectral Hyperion data (Estuary of the River Odiel, SW Spain). International Journal of Remote Sensing, 38(12), 3735-3762. https://doi.org/10.1080/01431161.2017.1302621Riaza, A., García-Meléndez, E., Carrère, V., Mueller, A. 2014. Cartografía de sales marinas y fluviales en estuarios receptores de aguas ácidas con imágenes hiperespectrales Hyperion (Marismas del río Odiel, Huelva). Revista de Teledetección, 41, 1-7. https://doi.org/10.4995/raet.2014.2255Riaza, A., Buzzi, J., García-Meléndez, E., Carrère, V., Müller, A. 2011. Monitoring the extent of contamination from acid mine drainage in the Iberian Pyrite Belt (SW Spain) using hyperspectral imagery. Remote Sensing, 3, 2166-2186. https://doi.org/10.3390/rs3102166Riaza, A., Buzzi, J., García-Meléndez, E., Vázquez, I., Bellido, E., Carrère, V., Müller, A. 2012. Pyrite mine waste and water mapping using Hymap and Hyperion hyperspectral data. Environmental Earth Sciences, 66-7, 1957-1971. https://doi.org/10.1007/s12665-011-1422-

Normal forms and internal regularization of nonlinear differential-algebraic control systems

In this article, we propose two normal forms for nonlinear differential-algebraic control systems (DACSs) under external feedback equivalence, using a notion called maximal controlled invariant submanifold. The two normal forms simplify the system structures and facilitate understanding the various roles of variables for nonlinear DACSs. Moreover, we study when a given nonlinear DACS is internally regularizable, that is, when there exists a state feedback transforming the DACS into a differential-algebraic equation (DAE) with internal regularity, the latter notion is closely related to the existence and uniqueness of solutions of DAEs. We also revise a commonly used method in DAE solution theory, called the geometric reduction method. We apply this method to DACSs and formulate it as an algorithm, which is used to construct maximal controlled invariant submanifolds and to find internal regularization feedbacks. Two examples of mechanical systems are used to illustrate the proposed normal forms and to show how to internally regularize DACSs

Single particle flame-combustion studies on solid biomass fuels

Combustion of solid biomass in large scale power generation has been recognized as a key technology for the transition to a decarbonized electricity sector in the UK by 2050. Much of the near-term forecast capacity is likely to be by the conversion of existing coal-fired pulverized fuel plant (DECC, 2012). In such applications, it will be necessary to ensure that the combustion behaviour of the solid biomass fuels is engineered to match, as far as practical, that of the original plant design. While biomass feedstock characteristics vary considerably, one controllable variable for pulverized fuel is the size of the particles.Useful modelling for adaptation and design of boiler plant can be improved with more detailed measurement of the real behaviour of individual particles of the varying fuels. Typical power plant biomass fuels including pine, eucalyptus and willow with particle sizes ranging from up to 3. mm (Van Loo and Koppejan, 2008) and with differing moisture content and aspect ratios were selected for study. Single particles were supported in a water-cooled cover and then exposed above a flame, simulating biomass combustion in a furnace. Measurements of ignition delay, volatile burning time and char burn-out time were undertaken using high speed image capture. Temperatures of the surrounding environment and near to the particle surface were measured with thermocouples and thermometric imaging. Thermo-gravimetric measurements on separate samples complement the single particle measurements as a means of verifying the demarcation between the different stages of combustion and providing kinetic data.Analysis of the data identified correlations between the biomass fundamental characteristics, particle size, and the observed combustion profiles. Empirical expressions for the duration of each combustion stage have been derived. These have been validated with basic modelling including the predicted devolatilisation stage calculated by the FG-Biomass model (Chen et al.,1998)

The pseudo McMillan degree of implicit transfer functions of RLC networks

We study the structure of a given RLC network without sources. Since the McMillan degree of the implicit transfer function is not a suitable measure of complexity of the network, we introduce the pseudo McMillan degree to overcome these shortcomings.Using modified nodal analysis models, which are linked directly to the natural network topology, we shaw that the pseudo-McMillan degree equals the sum of the number of capacitors and inductors minus the number of fundamental loops of capacitors and fundamental cutsets of inductors; this is the number of independent dynamic elements in the network. Exploiting this representation we derive a minimal realization of the given RLC network, that is one where the number of independent differential equations equals the pseudo McMillan degree