Tridimensional spatial distribution of manganese in a river impacted by metallurgical activity and mining.

Abstract

A three-dimensional interpolation method based on a digital elevation model (DEM) was developed to assess the impact of mining and metallurgical activity on the Claro River (Hidalgo, Mexico). This method was used to analyze the spatial concentration of manganese in sediments, water, and fish (viscera and muscle). Input data correspond to chemical manganese (Mn) analysis of the aforementioned environmental matrices, mining discharge volumes, and rainfall data. The three-dimensional model made it possible to (a) define Mn dispersion (19 km for sediments and 13 km for viscera); (b) identify northern meanders of the Claro River as areas of Mn accumulation in sediments and fish; and (c) determine river features that influence Mn concentration in fish. Results indicate that Mn concentration increases in areas receiving industrial discharges, as well as in meanders located near Acuimantla village. Total Mn levels in the water are between < 0.01 and 6.57 mg/L, while soluble and colloidal Mn concentrations range from < 0.01 to 0.49 mg/L. The highest Mn values in the water (total Mn: 6.57 mg/L and soluble-colloidal Mn: 0.49 mg/L) were detected in tributary rivers near industrial discharge sites. The concentration in water compared with that in sediments (160-213,867 mg/kg) and fish (viscera: 5-5236 mg/kg and muscle: 10.7-398.8 mg/kg) indicates low solubility of this mineral. The geoaccumulation index (Igeo) and contamination factor (CF) show that sediment composition has been affected.