**2.6 Collecting contaminated water by metals in the Doce river basin**

The water samples were collected in two different areas of the Doce river basin, in the state of Minas Gerais, in the years 2016, 2017 and 2018. The areas were chosen in relation to the contamination gradient. Two samples were collected at each point (**Figure 1**) whose latitude and longitude are described below: P1- 18° 52′ 55.31 (S) 41° 57′ 86″(W) and P2 - 18° 51′ 22.54″ (S) 41° 56′ 10.55″(W). The first point is located in the water and sewage treatment system and the second point in the city center of Governador Valadares, Brazil.

The water samples were collected according to the procedure adopted by the Environmental Sanitation Technology Company [14]. Briefly, 1000 mL vials of Falcon BD® model polypropylene were contaminated free of contaminants were used for collection. Water samples were stabilized with ultrapure nitric acid (0.5% HNO3). The concentrations of the metals in the samples were determined using ICP-MS according to EPA method 200.8 [15].
