The Olivargas Reservoir is located in a remote and scarcely monitored area in the Odiel River Basin (Southwest Spain) and is used for domestic, agricultural and mining water supplies. In contrast with highly monitored reservoirs, this paper explores the application of the CE-QUAL-W2 model, that was designed by Cole and Wells in 2005, to a poorly monitored reservoir and the utility of the results obtained. The model satisfactorily reproduced the water head measured continuously over three years, temperature (T), total dissolved solids (TDS), dissolved oxygen (DO) and pH measured bimonthly in a depth profile near the dam. A significant increase in TDS and decrease in DO and pH profiles were observed for four months, especially in the hypolimnion. The model reproduced changes in the parameters by assuming the occurrence of an acid water spill into the reservoir. A comparison of calculated results and measured TDS and DO prompted the conclusion that the spill consisted of approximately 3000 t of TDS (mainly sulfates) and 26 t of Fe(II) flowing into the reservoir for approximately 15 days at rates of approximately two and 0.02 kg/s, respectively.Water 2017, 9, 613 2 of 15 applications are based on a broad understanding of reservoir geometry and time-series data on flow, temperature profiles and chemical and biological quality.Many small reservoirs (<50 hm 3 ), however, exist in remote and mountainous areas. They supply water to small communities, and there is rarely accurate monitoring or complete datasets on their physical, chemical and biological parameters. For such communities, water resource management is just as necessary, but the application of the conventional W2 can be challenging and has yet not been explored.The present work describes the calibration of the W2 model for a small reservoir with scarce monitoring in the upper basin of the Odiel River (in Southwest Spain). This region is known for its mining activity, and water from the reservoir is used for domestic consumption, agriculture and mining. As the only form of surveillance, a depth profile of temperature (T), electric conductivity (EC), dissolved oxygen (DO), pH and oxidation-reduction potential (ORP) was taken every two months close to the dam of the reservoir from June 2009 to December 2012. All these data were obtainable by the user without permanent stations or monitoring programs. Besides, an anomalous EC, DO and pH values were detected in one surveillance campaign and were attributed to a possible mining spill.For the reconstruction and evaluation of a possible pollution event, a W2 model was built and calibrated with the data from the bimonthly profiles. In contrast with the highly detailed models on highly monitored reservoirs, this paper explores the application of W2 to a poorly monitored reservoir and the utility of the results obtained.
RESUMENLos depósitos de jales del distrito minero de Tlalpujahua y El Oro (DIMITO) fueron apilados sobre laderas y cañadas con un sistema de drenaje activo y cubriendo un basamento constituido por calizas carbonosas y lutitas ± andesitas que constituyen la roca encajonante de las vetas auríferas de tipo epitermal. Su morfología actual muestra profundos canales y cárcavas de erosión y se ha estimado una pérdida de material >27-34 % de su volumen original. Se presentan los resultados de un estudio cartográfico de cinco depósitos de jales que fueron abandonados hace ~68 años, así como la caracterización mineralógica y geoquímica de 12 perfiles y 48 muestras representativas. Los jales están constituidos, en general, por una matriz limo-arenosa calcárea que contiene abundantes clastos líticos. Su pH es ligeramente alcalino de 7.5 a 8.5 y muestran una baja conductividad eléctrica <80 µS/cm. Están conformados por fragmentos de cuarzo (≥ 53-68 %), seguido de líticos (7-20 %), calcita (≥12 %), silicatos (9-11 %), FeTi-óxidos (≥2-3 %) y sulfuros y sulfosales (≤2 %). Su composición química varía de SiO 2 (56-92 %), Al 2 O 3 (>5-13 %), CaO+MgO (≥5-11 %), Fe tot (≤3-5 %), S total (0.3-0.91 %) y C total (3.4-6.1 %). Los jales presentan concentraciones promedio de elementos potencialmente económicos: Au (1.2-1.61 g/ton), Ag (28.1-46.8 g/ton), Pb (53.3-145.2 g/ton) y Zn (155.9-354.5 g/ton), que podrían tener un cierto rendimiento económico. En relación con las concentraciones de los elementos potencialmente tóxicos, los valores del Sb (43.9-72.2 g/ ton) superan ampliamente el LMP de alto riesgo (WHO, 2015) y una docena de muestras de Pb y Zn y de As (25.2-40.5 g/ton) muestran valores más altos a los del LMP de bajo riesgo. Sin embargo, éstos valores se observan dispersos y aleatorios en cada perfil, por lo que se discute su potencial tóxico con base en su correlación geoquímico-mineralógica y su potencial movilidad. Con el objetivo de estimar el balance ácido-base en los jales del DIMITO, se realizó un modelo matemático de normalización (reducción de Gauss) de los elementos mayores y su relación con los minerales normativos y su potencial tóxico. Se encontró que la mineralogía representa un potente indicador en el análisis de residuos mineros y su potencial tóxico, así como en general que los jales mostraron un bajo riesgo en la generación de drenaje ácido de mina. Sin embargo, se discuten el uso y manejo de la cobertura natural y su relación con los residuos y obras mineras del DIMITO.Palabras clave: geoquímica; mineralogía; jales; drenaje ácido; distrito minero Tlalpujahua y El Oro; México. (53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66)(67)(68) calcite (≥12 %), . , , and , suggesting that they could still have some economic recovering. In relation to the concentrations of the potentially toxic elements, the values of significantly exceed high risk of the LMP (WHO, 2015), and a dozen samples of ABSTRACT The tailing dumps of the mining district of Tlalpujahua and El
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