Investigation of heavy metal mobility and availability by the BCR sequential extraction procedure: relationship between soil properties and heavy metals availability
Abstract:In this study, surface soil and corn cob samples were collected from 15 different agricultural fields of Çanakkale, Turkey. These samples were analysed to determine the concentration of Cd, Cu, Mn, Ni, Pb and Zn. BCR sequential extraction was used to extract the binding forms of the metals in the soil samples. At the same time, a wet digestion method was used to determine the total concentration of heavy metals in soil and corn grain samples. The metal concentrations in the extracted phase were measured with f… Show more
“…19 When these chemical elements are introduced into the environment by human activity they show greater mobility, and are associated with other sediment fractions such as carbonates, organic matter, oxides, hydroxides and sulfides. 17,20,21 The evaluation of these chemical fractions is possible when using sequential extraction methods. [22][23][24] The methods most commonly used are the Tessier 25 and BCR, 26,27 proposed by the European Community Bureau of Reference.…”
, the Fundão dam ruptured which caused the spill of a large quantity of tailings from the extraction of iron ores to the Gualaxo do Norte, Carmo and Doce Rivers. Seven months prior to the rupture, our group had collected water and sediment samples at 13 points along the Tripuí Creek and the entire length of the Carmo River. Six months after deposition of the mud, new samples were collected in the Carmo River. Thus, the present study sought to evaluate the concentrations of trace elements in the waters and their distribution and mobility in sediment by BCR sequential extraction before and after the deposition of the tailings mud. Arsenic concentrations in the water samples were between 10.4 and 50.4 µg L -1 , which exceeded 10 ug L -1 (maximum limit permitted by Brazilian environmental regulations for water destined for human consumption) . The tailing mud layer on the sediments caused concentration increases of As (20%), Cd (13%), Co (5%), Cr (9%), Cu (11%), Ni (4%), Pb (7%) and Zn (19%) in the easily remobilized fractions. The presence of the elements in these fractions was indicative of high ecotoxicological risk and potential harm to the health of the local population.
“…19 When these chemical elements are introduced into the environment by human activity they show greater mobility, and are associated with other sediment fractions such as carbonates, organic matter, oxides, hydroxides and sulfides. 17,20,21 The evaluation of these chemical fractions is possible when using sequential extraction methods. [22][23][24] The methods most commonly used are the Tessier 25 and BCR, 26,27 proposed by the European Community Bureau of Reference.…”
, the Fundão dam ruptured which caused the spill of a large quantity of tailings from the extraction of iron ores to the Gualaxo do Norte, Carmo and Doce Rivers. Seven months prior to the rupture, our group had collected water and sediment samples at 13 points along the Tripuí Creek and the entire length of the Carmo River. Six months after deposition of the mud, new samples were collected in the Carmo River. Thus, the present study sought to evaluate the concentrations of trace elements in the waters and their distribution and mobility in sediment by BCR sequential extraction before and after the deposition of the tailings mud. Arsenic concentrations in the water samples were between 10.4 and 50.4 µg L -1 , which exceeded 10 ug L -1 (maximum limit permitted by Brazilian environmental regulations for water destined for human consumption) . The tailing mud layer on the sediments caused concentration increases of As (20%), Cd (13%), Co (5%), Cr (9%), Cu (11%), Ni (4%), Pb (7%) and Zn (19%) in the easily remobilized fractions. The presence of the elements in these fractions was indicative of high ecotoxicological risk and potential harm to the health of the local population.
“…Wastes usually result in the growth of disease-causing microorganisms and accumulation of heavy metals which can impact negatively on the environment. Leachates resulting from dumpsites constitute a significant source of pollution from heavy metal impacting on both aquatic and terrestrial environments (Sungur et al, 2014). This can be detrimental to human health, crop and soils (Bahnasawy et al, 2011;Balkhair and Ashraf, 2016).…”
“…For instance, depending on processes, absolute concentrations in the dissolved phase that commonly is associated with higher toxicity may or may not become high, even if suspended loads of metals in non-acidic systems frequently are high (Tarras-Wahlberg et al 2000). Additionally, speciation studies focusing on the large-scale transport of metals in hydrological systems remain rare (Pandey et al 2014;Sungur et al 2014). Thus, a relatively large number of combinations of water-metal systems exist that have not been evaluated with regard to model performance.…”
Section: Materials Mobilization Via Bank and Bed Erosion Undermentioning
The speciation of metals in aqueous systems is central to understanding their mobility, bioavailability, toxicity and fate. Although several geochemical speciation models exist for metals, the equilibrium conditions assumed by many of them may not prevail in field-scale hydrological systems with flowing water. Furthermore, the dominant processes and/or process rates in non-acidic systems might differ from well-studied acidic systems. We here aim to increase knowledge on geochemical processes controlling speciation and transport of metals under nonacidic river conditions. Specifically, we evaluate the predictive capacity of a speciation model to novel measurements of multiple metals and their partitioning, under highpH conditions in mining zones within the Lake Baikal basin. The mining zones are potential hotspots for increasing metal loads to downstream river systems. Metals released from such upstream regions may be transported all the way to Lake Baikal, where increasing metal contamination of sediments and biota has been reported. Our results show clear agreement between speciation predictions and field measurements of Fe, V, Pb and Zn, suggesting that the partitioning of these metals mainly was governed by equilibrium geochemistry under the studied conditions. Systematic over-predictions of dissolved Cr, Cu and Mo by the model were observed, which might be corrected by improving the adsorption database for hydroxyapatite because that mineral likely controls the solubility of these metals. Additionally, metal complexation by dissolved organic matter is a key parameter that needs continued monitoring in the Lake Baikal basin because dependable predictions could not be made without considering its variability. Finally, our investigation indicates that further model development is needed for accurate As speciation predictions under non-acidic conditions, which is crucial for improved health risk assessments on this contaminant.
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