Marcio Osvaldo Lima Magalhães

Chemical amendment and phytostabilization of an industrial residue contaminated with Zn and Cd

A fitoestabilizacao de solos contaminados com metais pesados e considerada uma boa alternativa para reduzir a erosao e dispersao de contaminantes no ambiente. Foi conduzido um experimento em casa-de-vegetacao com o objetivo de avaliar a contencao quimica (silicato de calcio e lodo do biodigestor de uma cervejaria) e a fitorremediacao pela Brachiaria decumbens, de um residuo industrial contaminado com Zn e Cd, utilizando vasos de 30 L. Os tratamentos foram: residuo industrial (testemunha); residuo industrial + 20% lodo; residuo industrial + silicato de calcio (2%; 3%); (residuo industrial + 20% lodo) + silicato de calcio (2,5%; 4%). Apos estabilizacao do pH, foram cultivados nos tratamentos plantas de B. decumbens, visando avaliar o potencial de tolerância a elevadas concentracoes de Zn e Cd presentes no residuo industrial. No plantio e colheita das plantas foram retiradas amostras dos diferentes tratamentos para determinacao do pH e extracoes simples com agua, nitrato de sodio, acido acetico e DTPA. A partir das concentracoes de Zn e Cd obtidas nas extracoes, foram estimadas, atraves das diferencas nas quantidades extraiveis, as concentracoes de Zn e Cd nas provaveis formas quimicas. A adicao de residuos industriais, alcalino e orgânico, provocou reducao nas percentagens de Zn e Cd nas fracoes soluvel e trocavel, e predominância dos mesmos em fracoes quimicas mais estaveis como complexados e precipitados. A B. decumbens apresentou tolerância ao Zn e Cd presentes no residuo industrial apos tratamento de contencao quimica.

Effect of variations in the redox potential of Gleysol on barium mobility and absorption in rice plants.

Two assays were designed to obtain information about the influence of redox potential variations on barium mobility and bioavailability in soil. One assay was undertaken in leaching columns, and the other was conducted in pots cultivated with rice (Oryza sativa) using soil samples collected from the surface of Gleysol in both assays. Three doses of barium (100,300 mg kg(-1) and 3000 mg kg(-1)-soil dry weight) and two redox potential values (oxidizing and reducing) were evaluated. During the incubation period, the redox potential (Eh) was monitored in columns and pots until values of -250 mV were reached. After the incubation period, geochemical partitioning was conducted on the barium using the European Communities Bureau of Reference (BCR) method. Rainfall of 200 mm d(-1) was simulated in the columns and in the planting of rice seedlings in the pots. The results of the geochemical partitioning demonstrated that the condition of reduction favors increased barium concentrations in the more labile chemical forms and decreased levels in the chemical forms related to oxides. The highest barium concentrations in leached extracts (3.36 mg L(-1)) were observed at the highest dose and condition of reduction at approximately five times above the drinking water standard. The high concentrations of barium in the soil did not affect plant dry matter production. The highest levels and accumulation of barium in roots, leaves, and grains of rice were found at the highest dose and condition of reduction. These results demonstrate that reduction leads to solubilization of barium sulfate, thereby favoring greater mobility and bioavailability of this element.

Potencial de duas espécies de eucalipto na fitoestabilização de solo contaminado com zinco

With the aim of assessing the phytoremediation process to improve the soil contamination with zinc, it was used Eucalyptus urophylla and Eucalyptus saligna with slag from steelmaking and scales from hot-strip mills. The experiment was conducted in a greenhouse at the Universidade Federal Rural do Rio de Janeiro, using a soil contaminated with zinc, collected in an area near the ore yard at Itaguai harbor as well at the local of disposition of hazardous waste of Mercantil and Industrial Inga Co. at Itaguai-RJ. The substrate was treated with two inertizing agents: industrial waste with alkaline caracteristics (steelmaking slag) in 4 and 6% doses and another one with high content of iron oxide used as adsorption material (hot-strip mill scale) at single dose of 1%. After seedling transplant, the substrate was collected in order to determine pH and zinc fractionation in its different chemicals forms. It was verified that the not treated substrate showed high zinc content in bioavaiable fractions. This caused a reduction in the Zinc concentration in the water-soluble and exchangable forms and increase in more stable phases. The smallest dose of steelmaging slag was sufficient to cause a reduction of zinc concentrations solutions and this effect was showed clearly in the plant development, while the highest dose of steelmaging slag promote higher development in the species. The specie that obtained better development was E./ urophylla, that one showing higher zinc content was E. saligna.

Mobilidade de bário em solo tratado com sulfato de bário sob condição de oxidação e redução

In order to evaluate possible solubility of BaSO4 in soils under reducing conditions, column leaching assay was settled down, where the soil received three doses of BaSO4 (100, 300 and 3000 mg kg-1) at two humidities. After reaching an Eh of -200 mV rainfall of 200 mm per day-1 was simulated. The condition of reduction led to the increased levels of barium in the fractions of higher lability and the highest levels of barium in the leachate extract, which were above the potability standards. Only 0.05% of barium in the column that received the highest dose was removed by leaching.

Desempenho de duas espécies de eucalipto em solo com elevados teores de Mn

Currently, there is considerable interest in developing strategies that are efficient and durable in the remediation of soils contaminated with heavy metals. This study aimed to evaluate the development of Eucalyptus urophylla and Eucalyptus saligna grown in contaminated substrate with Mn collected in the area near the Port of Itaguai and location of disposal of hazardous waste of Cia Mercantil and Industrial Inga in Itaguai. The substrate was treated with two industrial waste, with a characteristic alkaline (slag of melt shop) and another with high content of iron oxide (lamination of scale). It was found that the untreated substrate, had a high content of Mn in fractions phytoavailable, being these values toxic to the species. The treatments caused a reduction in the concentrations of Mn in solution and exchangeable (fractions phytoavailable) and increase in more stable phases. The lowest dose of slay of melt shop was enough to decrease the concentrations of Mn in solution, and this effect is evidenced by the development of plants and in the higher dose of slay of melt shop the growth of studied species was more. Eucalyptus urophylla showed greater development and greater extraction of this element.

Use of Cordia Africana in the Phytostabilization of Substrates from Excavations of the Ore Courtyard at the Port of Itaguai, Brazil

The objective of this study was to evaluate the phytostabilization of two substrates contaminated with heavy metals from excavations of the ore courtyard at the port of Itaguai, Brazil. Initially, an inventory of tree species located near the study area was performed to select species for phytostabilization. The species Cordia africana exhibited deeper roots, a larger diameter at chest height (DCH) and crown diameter, as well as higher concentrations of Zn, Cd, and Pb in the trunk, bark, and roots compared to the other investigated species. The tolerance of the selected species to the metals Zn, Cd, and Pb was subsequently assessed through a greenhouse test. The substrates used in the experiment also obtained from excavations at the ore courtyard and showed different levels of heavy metals, indicating either low contamination (Substrate 1) or high contamination (Substrate 2). Alkaline industrial waste steel slag (SS) was used as an amendment to reduce the solubility of heavy metals. Application of the amendment agent to the substrates reduced the bioavailability of heavy metals, favoring the growth of C. africana. This species presents potential for use in phytostabilization programs due to its tolerance for heavy metals and the observed higher accumulation of these metals in the roots and especially the trunk of this species compared to other vegetal parts.