Knowledge about the oil and water contents in olive fruits is required to determine orchard management, harvest time, and the oil extraction process. The simplification of procedures and of equipment based on NIR Spectroscopy is of major interest. Estimation models for oil and water contents on a fresh matter basis were developed by partial least square regression with NIR spectral data (700 wavelengths). For raw absorbance data the r2 for the test set reached 0.9 and 0.92 for oil and water contents; and RPIQt was 4.9 and 4.3, respectively. The identification of a useful relation of the relative absorbance at 1724 nm and 1760 nm to the oil content allowed for restricting the wavelengths to three. For oil content the r2 showed 0.88 with ad RPIQt of 4.4. For water content the r2 value was 0.84 and the RPIQt was 3.1. Estimation performance with only three wavelengths was comparable to that obtained with PLSR with 700 variables. | El contenido de aceite y agua en aceitunas es requerido para gestionar el manejo del cultivo, el momento de cosecha y el proceso de extracción de aceite. La simplificación de los procedimientos y de los equipos basados en espectroscopia NIR es de gran interés. Se desarrollaron modelos de estimación para el contenido de aceite y agua sobre peso fresco por regresión de mínimos cuadrados parciales con datos espectrales NIR (700 longitudes de onda). Para los datos de absorbancia crudos, el r2 para el conjunto de validación externa alcanzó 0.9 y 0.92 para el contenido de aceite y agua; y RPIQt fue 4,9 y 4,3 respectivamente. La identificación de una relación útil de la absorbancia relativa a 1724 nm y 1760 nm con el contenido de aceite, permitió restringir las longitudes de onda a tres. Para el contenido de aceite, el r2 alcanzó 0,88 y RPIQt fue 4,4. Para el contenido de agua, el valor de r2 fue de 0,84 y el RPIQt fue de 3,1. La calidad de la estimación con solo tres longitudes de onda fue comparable al obtenido con PLSR en 700 variables.

This work focuses on the geochemical processes taking place in the acid drainage in the Ribeira da Água Forte, located in the Aljustrel mining area in the Iberian Pyrite Belt. The approach involved water and stream sediment geochemical analyses, as well as other techniques such as sequential extraction, Mössbauer spectroscopy, and X-ray diffraction. Ribeira da Água Forte is a stream that drains the area of the old mine dumps of the Aljustrel mine, which have for decades been a source of acid waters. This stream flows to the north for a little over than 10km, but mixes with a reduced, organic-rich, high pH waste water from the municipal waste water pools of the village. This water input produces two different results in the chemistry of the stream depending upon the season: (i) in the winter season, effective water mixing takes place, and the flux of acid water from the mine dumps is continuous, resulting in the immediate precipitation of the Fe from the acid waters; (ii) during the summer season, acid drainage is interrupted and only the waste water feeds the stream, resulting in the reductive dissolution of Fe hydroxides and hydroxysulfates in the stream sediments, releasing significant quantities of metals into solution. Throughout the year, water pH stays invariably within 4.0–4.5 for several meters downstream of this mixing zone even when the source waters come from the waste water pools, which have a pH around 8.4. The coupled interplay of dissolution and precipitation of the secondary minerals (hydroxides and sulfates), keeps the system pH between 3.9 and 4.5 all along the stream. In particular, evidence suggests that schwertmannite may be precipitating and later decomposing into Fe hydroxides to sustain the stream water pH at those levels. While Fe content decreases by 50% from solution, the most important trace metals are only slightly attenuated before the solution mixes with the Ribeira do Rôxo stream waters. Concentrations of As are the only ones effectively reduced along the flow path. Partitioning of Cu, Zn and Pb in the contaminated sediments also showed different behavior. Specific/non-specific adsorption is relevant for Cu and Zn in the upstream branch of Ribeira da Água Forte with acid drainage conditions, whereas the mixture with the waste water causes that the association of these metals with oxyhydroxide to be more important. Metals bound to oxyhydroxides are on the order of 60–70% for Pb, 50% for Cu and 30–60% for Zn. Organic matter is only marginally important around the waste water input area showing 2–8% Cu bound to this phase. These results also show that, although the mixing process of both acid and organic-rich waters can suppress and briefly mitigate some adverse effects of acid drainage, the continuing discharge of these waste waters into a dry stream promotes the remobilization of metals fixed in the secondary solid phases in the stream bed back into solution, a situation that can hardly be amended back to its original state.