Portal de Periódicos da CAPES

River acid mine drainage: sediment and water mapping through hyperspectral Hymap data

2012; Taylor & Francis; Volume: 33; Issue: 19 Linguagem: Inglês

10.1080/01431161.2012.675454

1366-5901

A. Riaza, J. Buzzi, Eduardo García‐Meléndez, V. Carrère, Aguasanta Miguel Sarmiento, A. Müller,

Hydrocarbon exploration and reservoir analysis

Abstract The Odiel River (Huelva, southwest Spain) carries acidic water originating from mine waste contamination, including massive sulphide ore deposits. As the river approaches the coastal estuary, tidal factors influence both sediment and water dynamics. As water velocity decreases, sediment load transport capacity also decreases, building river bars consisting of boulders upstream and sands downstream. Salt water near the estuary affects river water chemistry by neutralizing acidity derived from mine wastes. The occurrence of pyrite mud and hydrated iron sulphate efflorescence, precipitated from acidic waters, is plugged by marine water with chloride, which precipitates from the salt water. Hymap airborne hyperspectral data were used to evaluate tidal influence using spectral features. Grain size variations on river pebble bars, localized crusts of variably hydrated iron sulphate and oxides and cation exchange with chloride salts in the lower river segment as it enters the estuary were spectrally described and mapped. The presence of vegetation proved particularly problematic for the spectral identification of contamination products as well as the precise delineation of inundated areas along the river. The transition from dry to wet zones is the crucial challenge in using spectral imagery to identify and track contaminants in the river and along its flood plain. The use of a reference mineralogical spectral library, developed in the laboratory, requires a careful geological context evaluation to provide efficient environmental information on contamination parameters. Based on hyperspectral analyses of critical spectral features, river locations that may be a key for tracing significant, future contaminant fluctuations were identified. Acknowledgements This research was funded by the National Research Plan of Spain (PNI, projects number CGL2005-02462, CGL2006-01544/CLI and CGL2007-60004/CLI). J.M. Moreira and A. Gil contributed information about mine inventories and regional environmental databases. The Andalusian Regional Government, the Junta de Andalucía, permitted entry to the abandoned mine site of Sotiel at the border of the river. Local industries also allowed access to the river through their facilities. The authors thank E. Bellido and J.A. Martin Rubí for their interpretation of X-Ray analysis. J. Farifteh helped to calibrate Hymap data for collection of field spectra. J.P. Calvo and R. Rodriguez made possible the application of research funds through their encouragement of the inner dynamics of the Geological Survey of Spain (IGME). The authors also thank F. Avalos and J.M. Pernia for their assistance in the administration of the project funds.