First Report of Field Remediation of Contaminated Tailings from the Collapsed Fundão Dam in Brazil

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Proceedings of the 5th World Congress on New Technologies (NewTech'19)
Lisbon, Portugal – August, 2019
Paper No. ICEPR 163
DOI: 10.11159/icepr19.163
ICEPR 163-1
First Report of Field Remediation of Contaminated Tailings from the
Collapsed Fundão Dam in Brazil
Maria Rita Scotti1, Stephania S Avila1, Leonardo Mendes1, Tomas. J. Lacerda1, Samuel Lourenço L.
Silva1, Arthur C Antão1, Alessandra R. F Gomes1, Mirelli B Medeiros2, Stael Alvarenga2, Carlos
Henrique B Santos3, Everlon C Rigobelo3
1Depto de Botânica/ICB/UFMG
Av Antonio Carlos 6627, Belo Horizonte, Brasil
mrsm.ufmg@gmail.com
2Escola de Arquitetura /UFMG Programa Pós Graduação em Ambiente Construído e Patrimônio Sustentável
Av Antonio Carlos 6627, Belo Horizonte, Brasil.
3Dept. Produção Vegetal/ Universidade do Estado de São Paulo /Unesp
Via Professor Paulo Donato Castelane Castellane S/N - Vila Industrial, 14884-900 Jaboticabal, Brasil.
Abstract- The failure of the Fundão dam in Brazil spilled contaminated sediments to the Doce river basin with high levels of
pH,ether-amine and sodium. In the present study, it was established a riparian forest over contaminated sediment using two main
remediation strategies: phytoremediation with native species to the Atlantic Forest, previously selected for tolerance to the sediment
toxicity, and physico-chemical remediation by management of the sediment with incorporation of OM. In the experimental site (ES),
12 native species were cultivated under two treatments: T1- management of the sediments with incorporation of OM and T2- non-
managed sediment + superficial deposition of OM. The results were compared with a degraded site (DS) affected by the contaminated
sediments and a preserved site (PS) composed of a fragment of preserved Atlantic Forest. After 6 month of transplanting, plants from
T1 showed a better height growth performance (up to 3m) and survival index in relation to T2, as well as a significant decline of
ether- amine and sodium contents. Besides the improvement of soil fertility, the amendment with OM promoted a pH reduction,
favoring ether-amine destabilization, sodium sequestration and improvement of soil microbial populations. Soil nitrification was
improved as revealed by the significant increase of nitrate which seems to have favoured the rampant growth of tolerant plant species
after 6 months of planting. Therefore, it is recommended the incorporation of OM to the sediment and phytoremediation with selected
tolerant species to remediate sodium and ether-amine toxicity.
Keywords: Dam tailings, Ether-amine, Sodium, pH, Phytoremediation, Reclamation.
1. Introduction
The failure of the Fundão dam which belonged to the mining company Samarco S/A and was located in the Mariana
town (Brazil), has spread a sediment wave that reached the Doce River basin until the Atlantic Ocean, constituting the
largest environmental disaster in Brazil [1].
The main environmental impact of this dam rupture has been attributed to the elevated amounts of ether-amine and
sodium as well as the high pH found in the sediments as compared to preserved sites not reached by the tailings [2].
Ether-amines and NaOH are products that were found into the dam and derived from the Reverse Cationic Flotation
technique used in iron ore benefitiation process by Samarco mine [3,4,5]. The toxic effects of ether amines and sodium
in the reached zones [2] have been associated with plant mortality and a strong decline of microbial populations and
diversity [2,6].
Therefore, the aim of this study was to assess physico-chemical and phyto-remediation procedures to reclaim
ether-amine and sodium toxicity under field conditions.
2. Material and methods
2.1. Study site
The study sites consisted of the following riparian sites: 1- Preserved site (PS) located along the Lavras Velhas river
(20º20'313 4"S 43º17'13.61"W), 2- Degraded Site (DS) located in the Gualaxo river, reached by the dam tailings
(20º17'55.79"S 43º14'07.31"W) and a 3- Experimental Site (ES) located in the same river where the remediation
procedures were installed over a 2 m sediment layer (Fig 1).

ICEPR 163-2
2.2. Experimental design
The design of ES in a area of 1500 m2 (60 m x 25 m) was composed of 2 blocks with 2 plots/treatment (15 x 25 m)
and 2 treatment/block .The remediation treatments were: T1- Plant-derived organic matter (OM) incorporation to
scrapped sediment (top layer) and T2- intact sediment plus superficial deposition of OM. The OM used in ES was
composed of Ca: 1.28 %, P: 0.22 %, K: 2.1 %, Mg 0.3 %, N :2.1 %,C/N 24 and with pH 5. Itwas added 50 kg/plot in a
proportion of 1:4 (vv).
Each plot was cultivated with 12 Atlantic forest species, which were previously selected for tolerance to the
sediment. The plants were transplanted to the field after 4 months growing under nursery conditions with a spacing of 3
x 3 m. It was established four plots of 375 m2 (15 x 25 m) in the reference sites DS and PS.
Therefore, three remediation strategies were used: 1- Phytoremediation using selected plant species tolerant to the
sediment toxicity under green-house conditions; 2- Physico-chemical remediation by management of the sediment with
incorporation of OM to reduce ether-amine and sodium toxicity, besides lowering pH.
2.3. Soil analysis
Samples were obtained from 0 to 20 cm depth, at each study site (ES, DS and PS). In ES, 16 samples or 8 mixed
samples/treatment (2 mixed soil samples/plot/treatment x 2 treatments×4 plots) were collected 6 months after
transplantation. In DS and PS, 8 samples were collected composed of 2 mixed soil samples/plot/site x 4 plots. The soil
chemical analysis was performed according to EMBRAPA [2]. Total inorganic nitrogen was determined by semimicro-
Kjeldahl digestion [8] and ammonium and nitrate contents were determined according to Bremner and Keeney [9]. Ether-
amine quantification was performed using the colorimetric bromocresol green method [2,10]. Total microbial biomass
was determined by total phospholipid fatty acids (PLFA) analysis [2].
3. Results and Discusion
Using the sediment spilled from the dam, contaminated with ether-amines and sodium [2], we performed a screening
test, resulting in the selection of native species to the Brazilian Atlantic Forest with a varying tolerance degree, to be
tested in the field. Under field conditions, the plants showed a higher survival index in T1 (84%) than T2 (61%), and the
height growth in T1 was nearly twice that observed in T2 ( Table 1 ). Therefore, the combined treatment of sediment
scrapping associated with its mixture with plant-derived OM favored the establishment and survival of native plants in
the field, which showed an outstanding growth performance only 6 months after transplanting. The better growth
performance of native plants observed in T1 may be attributed to the greater reduction of sodium and ether-amine in
comparison to T2 and both in relation to DS (Table 2), as a consequence of the physico-chemical (sediment management
+ OM incorporation) remediation procedure.
Ether-amine concentrations reached levels as low as those from the PS as did the soil ammonium content. Such
reductions may be attributed to both the physico-chemical and phytoremediation procedures. Considering that there was
a decrease of N-ammonium concomitant with an increase of N-nitrate in ES, we may conclude that the plants may have
used the ammonium derived from ether-amine degradation [11]. Indeed, the pH reduction by the OM amendment leads
to ether-amine destabilization since the ionization of secondary and tertiary amines greatly depends on pH levels [12].
Under alkaline pH conditions (~9), ether-amine shows low dissociation capacity and solubility, while in pH~5, it becomes
dissociated and soluble in aqueous solution [11]. Therefore, the reduction of soil pH using OM amendment with pH 5
was also proposed to favor the ether-amine dissociation, increasing its availability to biodegradation [11] and further
utilization for plant growth as N source. Additionally, the OM favoured the oxidation of ammonium to nitrate by the
nitrifying microbial community since there was a marked increase of both soil microbial biomass and nitrate in ES,
especially in T1 in relation to DS. Besides, the N derived from the OM itself may be considered another source of N.
Thus, such increased nitrate levels in ES may have largely contributed to the outstanding plant growth, highlighting in
T1. Sodium levels also declined in ES, mainly in T1 but still showed significantly higher levels than PS (Table 2).
Sodium reduction may be attributed to the physico-chemical remediation procedure since the OM shows chelating
properties [13,14], whose acidic characteristics [15] improve the negative charges able to hold the Na ions. Thus, the
decrease of pH promoted by the OM amendment associated with the Na decline reinforce the idea of the Na chelating
properties of OM [13,14, 16]. In fact, there was a greater reduction of Na in T1 where the OM was incorporated to the
sediment in comparison to T2 where it was deposited in the superficial layer, thus, becoming more exposed to superficial
erosion and runoff.
The incorporation of SOM to the sediment also resulted in an overall increase in soil fertility in T1 than T2, as
determined by the increase of K, Ca, Mg and P (Table 2). Such increase in soil fertility in ES, particularly in T1, may

ICEPR 163-3
likely be attributed to the incorporation of organic matter to the topsoil, becoming it more homogeneously distributed in
a thicker sediment layer than the superficial deposition in T2. In consequence, it resulted in a reduction of nutrients losses
or a better physical contact of plant root and nutrients.
4. Conclusion
This is the first report of field remediation of contaminated sediments from the Fundão dam rupture. In other to
reclaim Na and ether-amine toxicity, we first selected tolerant plant species able to growth on the contaminated sediment.
Second, we proposed physical, chemical and phyto-remediation procedures under field conditions. The physico-chemical
remediation consisted in the incorporation of OM to the sediment which promoted pH reduction, favoring the Na decline,
ether-amine destabilization and soil fertility improvement as well as the increase of microbial communities. Under this
treatment, selected tolerant plant species showed a rampant growth only 6 months after planting.
Fig. 1: A: disturbed Site before transplantation, B: Experimental site (ES) 6 months and C: ES 12 months after transplantation.
Table 1: Survival index and height growth of plants cultivated in the experimental site (ES) under treatments 1 (ES T1) and 2 (ES-
T2). The variance of analysis (ANOVA1 was applied to compare mean differences among sites (significance at p ≤ 5%). Tukey
test.

ICEPR 163-4
Table 2: Soil chemical analysis, ether-amine content and total microbial biomass in Experimental site (ES) uunder two
management treatment ( ES-T1 and ES-T2) as compared to preserved (PS) and disturbed (DS).sites . The variance of analysis
(ANOVA1 was applied to compare mean differences among sites (significance at p ≤ 5%). Tukey test.
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Soil
pH
K
(mg/k)
Ca
(mg/kg
)
Mg
(mg/kg)
P
(mg/kg)
N-NO3-
(mg/kg)
N-NH4
(mg/kg)
OM
(%)
Na
(mg/k
g)
Ether-
amine
(mg/kg)
Microbial
biomass -
C ( nmol/
g)
PS
4,5a
73,8a
274a
72,3a
6,57a
42,80a
6,50a
8,7a
4,8a
0a
137a
DS
8d
8c
182b
10,1c
4,8c
1,80d
3,40c
0,96c
54,1c
6,1d
1,53d
ES
T1
5,9b
38,8b
327,8a
48,8b
11,8ab
33,40bc
2,00b
1,82ab
22,6b
0,37b
26,7b
ES
T2
6,5c
18,7b
252,5a
24b
10,5b
17,90c
2,30 b
0,99bc
30,5b
0,72c
13,7c