scholarly journals Phytoextraction and fractionation of heavy metals in soil after multiple applications of natural chelants

2008 ◽  
Vol 65 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Évio Eduardo Chaves de Melo ◽  
Clístenes Williams Araújo do Nascimento ◽  
Adriana Maria de Aguiar Accioly ◽  
Ana Cristiane Queiroz Santos
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Organic Acids ◽  
Water Soluble ◽  
Low Molecular Weight ◽  
Velvet Bean ◽  
Polluted Soils ◽  
Metal Concentrations ◽  
Synthetic Agents ◽  
Assisted Phytoextraction

Chelate-assisted phytoextraction of heavy metals is a promising approach to clean up polluted soils. However, the most successful chelants tested so far are synthetic agents that barely degrade in soil, increasing the metal leaching risks. Natural organic acids have been proposed to enhance phytoextraction due to their higher biodegradability, but they can also be a drawback for efficient phytoextraction. This work was carried out to compare the effectiveness of multiple applications of citric and gallic acids on the availability in soil and accumulation of Cd, Pb, Cu, and Zn by velvet bean (Stizolobium aterrimum) plants. The organic acids were added as follows: 5 mmol kg-1 in the 28th cultivation day; two doses of 5 mmol kg-1 at the 28th and 31st day; and three applications at the same rate at the 28th, 31st, and 34th day of velvet bean cultivation. Soil samples were sequentially extracted and soil solution metal concentrations assessed. Neither citric acid nor gallic acid was efficient for metals phytoextraction. In general, low molecular weight organic acids (LMWOA) application increased the metal concentrations in the water soluble and exchangeable fractions. Zinc and Cu were retained mostly in the organic matter fraction. Zn was remobilized from the organic matter fraction through LMWOA application into the water soluble and exchangeable fractions. LMWOA mobilized Pb and Cu from iron oxides, but such an increase in solubility was not high enough to affect phytoextraction.

scholarly journals The Role of the Humic Substances in the Fractioning of Heavy Metals in Rodrigo de Freitas Lagoon, Rio de Janeiro - Brazil

2013 ◽  
Vol 85 (4) ◽  
pp. 1289-1301 ◽  
Author(s):  
ESTEFAN M. DA FONSECA ◽  
JOSE A. BAPTISTA NETO ◽  
JOHN MCALISTER ◽  
BERNARD SMITH ◽  
MARCOS A. FERNANDEZ ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Rio De Janeiro ◽  
Water Soluble ◽  
Metal Partitioning ◽  
Fine Grain ◽  
Soluble Phase ◽  
The City ◽  
South Zone

One of the main results of the processes related to urbanization is the contamination of the adjacent water bodies. Inserted in this context, the Rodrigo de Freitas lagoon is situated in the south zone of the city of Rio de Janeiro. This ecosystem receives several inputs containing all sorts of pollutants, including heavy metals. The present work aimed to study the partitioning of heavy metals in the sediments of Rodrigo de Freitas and the influence of organic matter in this fractionation dynamic. The results of these analyses presented the contents of organic matter as an important metal-capturing agent. Fractionation of organic matter resulted in a predominance of humine. Heavy metal partitioning showed that the metals bound by the water-soluble phase have no significant concentrations. Special features such as, reducing sediment, high levels of organic matter and fine grain size have transformed this ecosystem in an effective deposit of pollutants, where heavy metals are not available in easily reactive fractions.

Water-soluble low-molecular-weight organic acids in automorphic loamy soils of the tundra and taiga zones

2013 ◽  
Vol 46 (6) ◽  
pp. 654-659 ◽  
Author(s):  
E. V. Shamrikova ◽  
I. V. Gruzdev ◽  
V. V. Punegov ◽  
F. M. Khabibullina ◽  
O. S. Kubik
Keyword(s):  
Molecular Weight ◽  
Organic Acids ◽  
Water Soluble ◽  
Low Molecular Weight

Photoformation of Low-Molecular-Weight Organic Acids from Brown Water Dissolved Organic Matter

2003 ◽  
Vol 37 (18) ◽  
pp. 4190-4198 ◽  
Author(s):  
Thomas Brinkmann ◽  
Philip Hörsch ◽  
Daniel Sartorius ◽  
Fritz H. Frimmel
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Organic Acids ◽  
Low Molecular Weight

scholarly journals Organic acids effects on desorption of heavy metals from a contaminated soil

2006 ◽  
Vol 63 (3) ◽  
pp. 276-280 ◽  
Author(s):  
Clístenes Williams Araújo do Nascimento
Keyword(s):  
Heavy Metals ◽  
Molecular Weight ◽  
Citric Acid ◽  
Organic Acids ◽  
Low Molecular Weight ◽  
High Biomass ◽  
High Concentration ◽  
Accumulation Of Metals ◽  
Pb Concentration ◽  
Oxalic Acids

Phytoremediation of heavy metals is a biotechnology that extracts metals from soils and transfer them to plant. As hyperaccumulator species have demonstrated low potential for commercial phytoextraction, synthetic chelates have been successfully used to induce accumulation of metals by high-biomass plants. However, they pose serious environmental drawbacks regarding excessive amount of metals solubilized. In search for synthetic chelate-alternatives, this paper evaluate the performance of DTPA, EDTA, citric acid, oxalic acid, vanillic acid, and gallic acid in desorbing Cd, Pb, Zn, Cu, and Ni from soil. DTPA and EDTA were highly effective in desorbing Cd, Pb, Zn, Cu, and Ni from soil. However, the excessively high concentration of metals brought in solution by such chelates limits their application in the field. Citric and oxalic acids desorbed substantial quantities of Zn, Cu, and Ni if applied at 10 or 20 mmol kg-1. At the 20 mmol kg-1 dose, vanillic and gallic acids solubilized significant amounts of Zn, Ni, and Cd from soil. None of the tested low molecular weight organic acids substantially increased the Pb concentration in soil solution.

Quantitative digestion of fresh herbage by sheep:V. The digestion of four herbages and prediction of sites of digestion

1979 ◽  
Vol 92 (3) ◽  
pp. 605-616 ◽  
Author(s):  
M. J. Ulyatt ◽  
A. R. Egan
Keyword(s):  
Organic Matter ◽  
Small Intestine ◽  
Organic Acids ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Crude Protein ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Water Soluble Carbohydrate ◽  
Dietary Origin

SUMMARYThe extents and sites of digestion of organic matter (OM), and its constituent watersoluble carbohydrates, organic acids, pectin, cellulose, hemicellulose and crude protein have been studied in sheep prepared with re-entrant duodenal cannulas and fed four fresh herbage diets, Ruanui perennial ryegrass, Tama Westerwolds ryegrass, Pitau white clover and Fakir sainfoin, at each of two levels of intake.The water-soluble carbohydrate, organic acids and pectin of all diets were almost completely digested within the rumen. Some 10% of water soluble carbohydrate reached the duodenum on each diet, though this may not have been of dietary origin. Only on legume diets, where pectin concentration was higher, did measurable amounts of pectin reach the intestine, accounting for some 5% of the pectin.Hemicellulose and cellulose digestibilities differed between diets, being lowest for sainfoin, and next lowest for clover. Between 79 and 94% of digestible hemicellulose was digested in the stomach, but diet and intake had no significant effect on this partition. Of the digestible cellulose, 87–97% was digested in the stomach.Digestibility of N was lowest for sainfoin and highest for Tama ryegrass. There were no significant differences between herbage species or intake in the percentage of digested N digested in the stomach or intestines. The tannin contained in sainfoin had no effect on nitrogen digestion.Data from this and other studies reported in the literature were examined as a basis for establishing prediction equations whereby the partition of digestion of the major carbohydrate and nitrogenous constituents in stomach and intestines might be estimated from data obtainable from standard digestibility trials. Regressions were developed for predicting the amounts of OM, cellulose, and hemicellulose digested in the stomach. There are not yet enough suitable data available to predict the amount of nitrogen entering the small intestine.

Generation of water-soluble organic acids from kerogen during hydrous pyrolysis: implications for porosity development

1987 ◽  
Vol 51 (362) ◽  
pp. 495-503 ◽  
Author(s):  
T. I. Eglinton ◽  
C. D. Curtis ◽  
S. J. Rowland
Keyword(s):  
Gas Chromatography ◽  
Organic Acids ◽  
Oil Field ◽  
Water Soluble ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Molecular Weight ◽  
Secondary Porosity ◽  
Hydrous Pyrolysis ◽  
Kerogen Type ◽  
Artificial Maturation

AbstractConcentrations of organic acids ranging up to several thousand parts per million have previously been found in oil-field waters. These acids are of interest because of their potential to enhance porosity by the dissolution of carbonates and aluminosilicates. They are believed to be generated from organic geopolymers (kerogen) in the late-diagenetic-early-catagenetic stage of thermal maturation.During the course of artificial maturation experiments in which kerogens of varying type were heated in the presence of water (so-called ‘hydrous pyrolysis’) and different minerals, the distribution and abundance of low molecular weight water-soluble acids were determined by gas chromatography and gas chromatography-mass spectrometry. Preliminary results suggest that significant quantities of mono- and di-carboxylic acids are produced during hydrous pyrolysis. The amounts and types of acid appear to vary as a function of kerogen type, maturity and mineralogy. Implications of these findings regarding the development of secondary porosity are discussed.

Pollutant monitoring in sludge treatment wetlands

2011 ◽  
Vol 64 (7) ◽  
pp. 1558-1565 ◽  
Author(s):  
E. Peruzzi ◽  
G. Masciandaro ◽  
C. Macci ◽  
S. Doni ◽  
B. Ceccanti
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Organic Compounds ◽  
Wastewater Treatment Plants ◽  
Land Application ◽  
Water Soluble ◽  
Sludge Stabilization ◽  
Organic Matter Stabilization ◽  
Urban Wastewater Treatment ◽  
Toxic Organic Compounds

Phragmites australis for sludge dewatering and stabilization processes have been widely proved. The presence of reeds, indeed, efficiently allows solids dewatering and organic matter stabilization in order to obtain a stabilised product that can be suitable for land application, even if its environmental impact has to be considered. The actual revision of the European Union's Working Document on Sludge (2000), in fact, seems to be addressed to detect two principal categories of pollutants in sludge for agricultural use: heavy metals and toxic organic compounds. In this study are presented results about sludge stabilization and monitoring of heavy metal fractionation and organic compounds in four urban wastewater treatment plants managed by Acque S.p.A., (Tuscany, Italy). To evaluate the process of sludge stabilization parameters were determined that highlight the biochemical and chemico-structural properties of sludge organic matter. The results showed that stabilization of the sludge over time occurred as shown by the low content of water soluble carbon and dehydrogenase activity, and by the re-synthesis of humic-like matter highlighted by the pyrolytic indices of mineralization and humification. Results about fractionation showed that heavy metals were retained in fractions related to the stabilized organic matter. Moreover, toxic organic compounds showed a drastic reduction at the end of the monitoring period.

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