Rehabilitation of a Riparian Site Reached by Contaminated Tailings from the Fundão Dam Using Different Remediation Strategies in Brazil.

The tailings spilled by the Fundao dam rupture in the Doce River basin (Brazil) presented high pH, elevated sodium and ether-amine contents as well as low soil organic matter. Aiming at alleviating these toxic compounds, we established two remediations strategies: T1-phytoremediation with tolerant native species of the Atlantic Forest cultivated on scraped sediment plus the incorporation of organic matter (OM) and T2-phytoremediation with native species plus superficial deposition of OM. The experimental site (ES) was compared with a degraded site (DS) reached by dam tailings and a preserved site (PS), a fragment of preserved Atlantic Forest. After twelve months, plants showed an outstanding growth, especially in T1(~ 4 m) and the remediation procedures resulted in a significant decrease of pH (from 8.0 to ~ 6.0), sodium (from 154 mg/kg to 22-35 mg/kg) and electrical conductivity as well as ether-amine (from 6.0 mg/kg to 0.5 mg/kg) in both treatments. By contrast, ammonium, a product of ether-amine degradation, showed a significant increase in ES, followed by a significant increase of nitrate and improvement of soil microbial populations assessed by phospholipid fatty acid analysis. The treatments also improved the soil fertility in ES, as estimated by soil nutrients, cation exchange capacity (CEC) and soil aggregation. Based on the analysed parameters, a principal component analysis (PCA) showed that samples from DS and PS clustered in an opposed position and those from ES grouped in an intermediate position but closer to PS. Overall, our results demonstrated that the remediation procedures adopted were effective and allowed the rehabilitation of a riparian forest reached by dam tailings contaminated with sodium and ether-amine. This article is protected by copyright. All rights reserved.