Fabiana Soares dos Santos

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.

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.

Resposta antioxidante, formação de fitoquelatinas e composição de pigmentos fotoprotetores em Brachiaria decumbens Stapf submetida à contaminação com Cd e Zn

-1 of Cd and 500 and 2000 mmol L -1 of Zn. Metal content of shoots and roots was determined, as well as alterations in photosynthetic and photoprotective pigments, antioxidant metabolites and phytochelatin synthesis. Plants concentrated elevated levels of Cd and Zn, especially in roots. Zinc exposure negatively affected chlorophyll and β-carotene content, whereas the highest dose of Cd reduced VAZ cycle pigments and tocopherol levels in plant shoots. Cadmium was the maximum inducer of the phytochelatin synthesis pathway.

Concentração de metais pesados em espécies arbóreas utilizadas para revegetação de área contaminada

RESUMO - O objetivo deste trabalho foi avaliar o potencial das especies arboreas Cordia africana Lam., Mimosa caesalpineafolia Benth., Acacia angustissima (Mill.) Ktze. e Anadenanthera colubrina (Vell.) Brenan na fitoestabiliz acao de metais pesados presentes em um substrato contaminado. Foram selecionados, aleatoriamente, quatro exemplares de cada especie para realizacao do estudo. Amostras de substrato na projecao da copa de cada exemplar arboreo foram coletadas nas profundidades de 0-10; 10-30 e 30-50 cm, para determinacao da concentracao pseudototal e fracionamento quimico de metais pesados. De cada individuo, foram coletados dados referentes a profundidade das raizes, DAP (diâmetro a altura do peito), diâmetro de copa e altura das plantas. Amostras de folha, caule, casca e raiz foram coletadas para determinacao dos metais pesados zinco (Zn), manganes (Mn), cadmio (Cd), chumbo (Pb) e cobre (Cu) nas diferentes partes da planta. A concentracao de Cd no substrato foi acima do valor de investigacao definido pelo CONAMA (3,0 mg kg -1 ), evidenciando contaminacao com esse elemento. Os maiores teores dos metais pesados foram encontrados na fracao residual (F5), indicando baixa disponibilidade destes elementos no substrato. Com relacao ao Cd, elevadas concentracoes tambem foram encontradas na fracao trocavel F2, considerada uma fracao em que os contaminantes se apresentam com certa mobilidade e biodisponibilidade. As especies vegetais estudadas apresentaram desenvolvimento dentro dos padroes normais, mostrando tolerância a areas contaminadas com Cd, que tendeu a se acumular nas raizes das plantas, com excecao da Cordia - africana. Palavras-chave: Arborizacao. Revegetacao. Solos-descontaminacao.

Remediação de solos tratados com lodo rico em zinco

This research had as objectives: to study the alterations in the distribution of Zn in different chemical carbonates fractions of soil treated with sewage sludge, caused by the application of carbonates, oxides and phosphates to determine the efficiency of these products in the contention of this element; and to evaluate the solubility reduction through the use of hyper accumulator plant. Industrial sewage sludge was applied in samples of surface layer of a Yellow Red Latossol and Yellow Red Argissol. The addition of CaCO3 caused chemical immobilization of Zn due to association of these elements with more stable chemical fractions. The FeCl3 + EDTA caused dissolution of Zn compounds and dessorption of these elements quelated by surface functional groups. The KH2PO4 did not alter the distribution of Zn in the different chemical forms in the soils. The Zn concentrated, mainly in the roots, which behaved as a natural filter, limiting the flux of these elements to the aerial part. In both soils, CaCO3 caused the smallest concentration of Zn in the root and aerial part. The addition of FeCl3+EDTA promoted the increase of Zn levels in the plant.

Response Mechanisms of Plants to Heavy Metal Pollution: Possibility of Using Macrophytes for Remediation of Contaminated Aquatic Environments

Water contamination by heavy metals is a growing concern among public officials and citizens due to their high potential toxicity to living things and the environment. Macrophytes have been studieds for use in a cleaning up polluted water bodies, due to their favorable characteristics. The various species can respond differently to environments contaminated with heavy metals. They can be sensitive, showing symptoms of toxicity and intolerant of high contamination levels, or tolerant, using extra or intracellular mechanisms to allow them to grow in the presence of these contaminants. In this review, we present the main mechanisms used by plants in response to contamination by heavy metals.

Comportamento da Cordia africana Lam. cultivada em solo contaminado por metais pesados e tratado com materiais amenizantes

This study aimed to evaluate the remediation of two soils contaminated with heavy metals from soil excavations, located near the port of Itaguai, through the techniques of chemical immobilization and phytostabilization using the species Cordia africana. The data were collected in the ore courtyard from ‘Companhia Siderugica Nacional’ (CSN), in the port of Itaguai, Rio de Janeiro state. In order to reduce the solubility of heavy metals present in these substrates, two industrial waste products produced by CSN were used as ameliorating products, the steelmaking slag and the mill scale, in different concentrations. The plant species was considered with potential to be used in programs of phytostabilization, due to its heavy metal tolerance studied and to high accumulation of such elements in roots and stem. In the substrate of low combination, the lowest accumulation of zinc and cadmium in stems and leaves occurred with the use of 4% of soothing. In the substrate of high accumaltion it was 6%.

Synthesis of zeolites with different chemical and textural properties for metal ions removal from aqueous solutions

In this study β-zeolite, ferrierite and partially delaminated PREFER (precursor of ferrierite) zeolites with several chemical and textural properties were synthesized for the removal of zinc and lead ion metals from their respective solutions. Adsorption experiments involving the suspension of tiny amounts of these solids in aqueous solutions containing either Zn2+ or Pb2+ showed that the removal of these metals at a considerable extent may be attained. Among the studied materials, β-zeolite displayed the better performance in metal ion removal, which may be ascribed to its higher aluminum content, surface area and external surface area, that allows a greater density and availability of ion adsorption active sites. Kinetic data from a pseudo-second-order model indicate that the chemical interaction among metal ions and active sites is the rate-limiting step. Furthermore, the better performance of the β-zeolite displayed in reusability testing makes it a potential adsorbent for future applications in the treatment of effluents containing toxic metals.

Numerical study of the influence of electrode arrangements in electrokinetic remediation technique

The effectiveness of electrokinetic remediation for soils depends on several factors such as the arrangement and shape of electrodes. This paper presents a numerical study on external electrostatic field generated by seven different electrode configurations in any unbounded two-dimensional domain. The boundary condition at infinity for the voltage is approximated by the iterative algorithm that expands the domain till the limit of the specified tolerance (threshold value). The numerical results indicate that there is no unique configuration with larger effective area for all spacings between the oppositely charged electrodes. In addition, the configuration with the smallest inactive electric field strength spots for all spacings between the electrodes is not unique. Moreover, the voltage profile for all electrode configurations is nonlinear, and the external electric field strength varies widely near the electrodes. Only in the intermediate region between the electrodes the external electric field strength approaches a constant value.

Escória de aciaria na redução da solubilidade e lixiviação de manganês em áreas contaminadas

Steelmaking slag is a waste of steel production and has owned corrective soil acidity and may consequently reduce the mobility of trace elements. The research aimed the capacity of industrial waste steelmaking slag to reduce the solubility and lixiviation of Mn in contaminated soil. In the Soil Pollution Laboratory of the UFRRJ (Seropedica-RJ), leaching experiments were carried using three different residues contaminated with Mn, and two doses of the inertizant residues steelmaking slag. In the columns were applied a known and constant volume of water, established to simulate the maximum precipitation occurred in the last 17 years, in the region where the residue was collected. The highest dose of steelmaking slag (6%) reduced the Mn solubility below the maximum allowed by ABNT, for G1, G2 and Ge, and the treatment with 6% steelmaking slag + barriers chemical was the most effective in reducing the leaching of Mn in all groups. Therefore, the results showed the efficiency of steelmaking slag in the reduction of Mn solubility and lixiviation in all residues.