Potencial de quatro espécies herbáceas forrageiras para fitorremediação de solo contaminado por arsênio

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SUMMARYArsenic has been considered the most poisonous inorganic soil pollutant to living creatures. For this reason, the interest in phytoremediation species has been increasing in the last years. Particularly for the State of Minas Gerais, where areas of former mining activities are prone to the occurrence of acid drainage, the demand is great for suitable species to be used in the revegetation and "cleaning" of As-polluted areas. This study was carried out to evaluate the potential of seedlings of Eucalyptus grandis (Hill) Maiden and E. cloeziana F. Muell, for phytoremediation of As-polluted soils. Soil samples were incubated for a period of 15 days with different As (Na 2 HAsO 4 ) doses (0, 50, 100, 200, and 400 mg dm -3 ). After 30 days of exposure the basal leaves of E. cloeziana plants exhibited purple spots with interveinal chlorosis, followed by necrosis and death of the apical bud at the 400 mg dm -3 dose. Increasing As doses in the soil reduced root and shoot dry matter, plant height and diameter in both species, although the reduction was more pronounced in E. cloeziana plants. In both species, As concentrations were highest in the root system; the highest root concentration was found in E. cloeziana plants (305.7 mg kg -1 ) resulting from a dose of 400 mg dm -3 . The highest As accumulation was observed in E. grandis plants, which was confirmed as a species with potential for As phytoextraction, tending to accumulate As in the root system and stem.

Section: Resultsmentioning

confidence: 91%

Behavior of Eucalyptus grandis and E. cloeziana seedlings grown in arsenic-contaminated soil

Melo

Dias

Mello

et al. 2010

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“…Si accumulation in plants does not always have positive effects on dry matter production (Melo et al, 2009;Araújo et al, 2011), but it can bring other beneficial effects, such as protection against physiological stress by improving the photosynthetic apparatus (Mattson and Leatherwood, 2010).…”

Section: Dry Matter Productionmentioning

confidence: 99%

Effects of Silicon on Alleviating Arsenic Toxicity in Maize Plants

Silva

Nascimento

Neto

et al. 2015

Arsenic is a metalloid highly toxic to plants and animals, causing reduced plant growth and various health problems for humans and animals. Silicon, however, has excelled in alleviating stress caused by toxic elements in plants. The aim of this study was to investigate the effects of Si in alleviating As stress in maize plants grown in a nutrient solution and evaluate the potential of the spectral emission parameters and the red fluorescence (Fr) and far-red fluorescence (FFr) ratio obtained in analysis of chlorophyll fluorescence in determination of this interaction. An experiment was carried out in a nutrient solution containing a toxic rate of As (68 μmol L -1 ) and six increasing rates of Si (0, 0.25, 0.5, 1.0, 1.5, and 2.0 mmol L -1 ). Dry matter production and concentrations of As, Si, and photosynthetic pigments were then evaluated. Chlorophyll fluorescence was also measured throughout plant growth. Si has positive effects in alleviating As stress in maize plants, evidenced by the increase in photosynthetic pigments. Silicon application resulted in higher As levels in plant tissue; therefore, using Si for soil phytoremediation may be a promising choice. Chlorophyll fluorescence analysis proved to be a sensitive tool, and it can be successfully used in the study of the ameliorating effects of Si in plant protection, with the Fr/FFr ratio as the variable recommended for identification of temporal changes in plants.

“…This variability among species were also observed in plants such as leucaena, sesbania (Melo, 2006), oats, ryegrass, peanuts and Stylosanthes (Melo et al, 2009). …”

Section: Arsenic Concentrations and Contents In Different Plant Organsmentioning

confidence: 74%

“…The symptoms of As toxicity are purplish basal leaves, with internerval chlorosis followed by necrosis (Gardea-Torresdey et al, 2005;Melo et al, 2009). These symptoms were not observed in the plants of E. urophylla submitted to As concentrations lower than 400 mg dm -3 , or in the plants of E. citriodora submitted to any of the As concentrations applied to the soil.…”

Section: Resultsmentioning

confidence: 99%

Behavior of Eucalyptus urophylla and Eucalyptus citriodora Seedlings Grown in Soil Contaminated by Arsenate

Melo

Dias

Assis

2016

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Persistent areas of tailings and deposits from coal and gold mining may present high levels of arsenic (As), mainly in the arsenate form, endangering the environment and human health. The establishment of vegetation cover is a key step to reclaiming these environments. Thus, this study aimed to evaluate the potential of Eucalyptus urophylla and E. citriodora seedlings for use in phytoremediation programs of arsenate-contaminated areas. Soil samples were incubated at increasing rates (0, 50, 100, 200 and 400 mg dm -3 ) of arsenic (arsenate form, using Na 2 HAsO 4 ) for 15 days. The seedlings were produced in a substrate (vermiculite + sawdust) and were transplanted to the pots with soil three months after seed germination. The values of plant height and diameter were taken during transplanting and 30, 60 and 90 days after transplanting. In the last evaluation, the total leaf area and biomass of shoots and roots were also determined. The values of available As in soil which caused a 50 % dry matter reduction (TS 50% ), the As translocation index (TI) from the roots to the shoot of the plants, and its bioconcentration factor (BF) were also calculated. Higher levels of arsenate in the soil significantly reduced the dry matter production of roots and shoots and the height of both species, most notably in E. urophylla plants. The highest levels of As were found in the root, with higher values for E. citriodora (ranging from 253.86 to 400 mg dm -3). The TI and BF were also reduced with As doses, but the values found in E. citriodora were significantly higher than in E. urophylla. E. citriodora plants presented a higher capacity to tolerate As and translocate it to the shoot than E. urophylla. Although these species cannot be considered as hyperaccumulators of As, E. citriodora presented the potential to be used in phytoremediation programs in arsenate-contaminated areas due to the long-term growth period of this species.