EVALUATION OF POTENTIALLY TOXIC ELEMENTS UPTAKE BY RICE CULTIVATED IN THE MUD FROM SAMARCO’S DAM MINE

On November 5th, 2015 Samarco’s iron mine dam (Minas Gerais, Brazil) collapsed and approximately 50 million m3 of mud flowed causing severe devastation1. Owing to amount of mud flowed, the present study evaluated the influence of potential toxic elements (As, Cd, Pb, Mn and Fe) in rice (var. BR-IRGA 409) cultivated at high soil mud-containing (50% mud + 50% top soil:organic matter:sand 1:2:1). Grains were analyzed by inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7900, Hachioji, Japan). Reference materials were used throughout the analysis for quality control (BCR 670 Aquatic Plant from IRMM and CRM Agro AR_01/2015 Rice Flour from EMBRAPA-USP). The samples were prepared by using 200 mg of dried sample + 1,5 ml of sub distilled HNO3 (DST-1000, Savillex, EUA) in an open system according to Batista et al. (2014)2. Our results indicated that controls presented 9.1±1.9 ng g-1, 10.1±0.6 ng g-1, 5.9±1.0 ng g-1, 15.3±2.2 µg g-1 and 13.1±2.1 µg g-1 for As, Cd, Pb, Mn and Fe, respectively. For As and Pb, the concentrations were significantly higher than the exposed rice plants which presented 2.8±0.8 ng g-1 and <2 ng g-1, respectively. Concerning Cd, Mn and Fe in exposed rice, grains presented 29.8±8.2 ng g-1, 18.6±1.0 µg g-1 and 12.1±1.9 µg g-1, respectively. Although the low levels of metals in rice grains exposed to the mud, the plants reduced their growing at 90.5%. More studies are need to discover the influence of mud in rice growing.