Using the mineralogy of river sediments as pollution indicator of clay mining activity

View of the difficulty to elect standards for water pollution control in clay mining activity, this study aimed to verify the possibility of using the mineralogy of river sediments as a pollution indicator of clay mining activity. The study was carried out in the Assistencia Stream basin, located in the largest ceramic pole of the Americas. Surface water samples of Assistencia Stream were collected in 67 field campaigns in 2014. This stream showed an average annual discharge of 0.8 m(3).s(-1) with an annual flux of suspended solids of 3,680 t. year-1 and an annual flux of dissolved solids of 4,234 t. year(-1). The mineralogical analysis of fluvial sediments indicated the presence of quartz, montmorillonite, illite and kaolinite in the fraction <53 micrometers. The kaolinite is from the surface soil erosion. However, the illite, predominant clay mineral in the rocks explored by mining, is practically absent in the surface horizon of the Assistencia Stream basin. Thus, its presence in the suspended solids transported by Assistencia Stream is associated with atmospheric deposition of dust produced during clay mining activities present in this watershed.