Diffusive gradients in thin-films
Dotaz
Zobrazit nápovědu
Concentrations of Cd, Cu, Cr, Pb, Ni and Zn were monitored in the Svitava River (the Czech Republic) during April and September 2005. Total concentrations and total dissolved concentrations were obtained through regular water sampling, and the diffusive gradients in thin films technique (DGT) were used to gain information on the kinetically labile metal concentrations. Each measured concentration was compared with the corresponding average (bio)available concentration calculated from the mass of metal accumulated by the moss species Fontinalis antipyretica. The concentrations of Cd, Pb, Cr and Zn measured using DGT corresponded well with those obtained after the deployment of Fontinalis antipyretica moss bags in the Svitava River, but the concentrations of Cu and Ni did not. The calculated (bio)available Cu concentration correlated well with the total dissolved concentration of Cu, whereas no correlation was found to exist between the concentrations of Ni.
The aim of this study was to assess cadmium and copper uptake by radish (Raphanus sativus) and to test the capability of the diffusive gradient in thin films (DGT) technique to predict bioaccessibility of the metals for this plant. Radish plants were grown in pots filled with uncontaminated control and artificially contaminated soils differing in cadmium and copper contents. Metal concentrations in plants were compared with free ion metal concentrations in soil solution, and concentrations measured by DGT. Significant correlation was found between metal fluxes to plant and metal fluxes into DGT. Pearson correlation coefficient for cadmium was 0.994 and for copper 0.998. The obtained results showed that DGT offers the possibility of simple test procedure for soils and can be used as a physical surrogate for plant uptake.
The diffusive gradient in the film technique (DGT) is a new approach to the in-situ determinations of labile metal species in aquatic systems. The DGT device accumulates labile species from solution and therefore contamination problems associated with conventional collection and filtration procedures are eliminated. The technique employs a hydrogel layer to control the diffusive transport of metals to a cation-exchange resin, which is selective for free or weakly complexed metal ion species. This study deals with the use of a new resin based on the Spheron-Oxin® ion exchanger in the DGT technique. The resin with a selectivity for trace metal species higher than Chelex 100 could provide more information on metal speciation in aquatic systems. Its performance was tested for Cd, Cu, Ni and Pb under laboratory conditions. The new resin provides reliable results in the pH range 6-8, independently of ionic strength (25 mmol l-1- 0.6 mol l-1) and also in the presence of Mg(NO3)2 (10 µmol l-1 - 0.05 mol l-1). The effect of iminodiacetic acid, as a model competitive ligand on the metal uptake measured by DGT probe was also assessed.
The diffusive gradients in thin films technique (DGT) was used for the determination of bioavailable mercury in urban soils, and results were compared to the mercury accumulation by Pisum sativum L. (pea) parts (leaf, root, stem, blossom, legume, and green seed). The total mercury concentration in soil samples was ranged between 0.084 and 0.326 mg kg-1. The soil solutions contained 0.15%-0.20% of mercury present in soils. In the soil solution, 2.21%-3.45% of mercury was available for DGT units. The highest mercury content was determined in the leaf and root of the pea plant, and the lowest in the consumable part of the pea plant (green seed). Mercury concentration in the parts of the pea plant increased over time, alongside the growth of the plant. The effect of acid precipitation on mercury bioavailability was statistically non-significant (p = 0.53). Significant and positive correlations were found between mercury flux into DGT unit, and mercury flux into the root (r = 0.989), leaf (r = 0.985), and stem (r = 0.904) of the pea plant. The obtained results suggest that the DGT method could be used for description of the uptake of mercury by pea plant parts in non-contaminated and slightly contaminated soils.
- MeSH
- biologická dostupnost MeSH
- hrách setý metabolismus MeSH
- kořeny rostlin metabolismus MeSH
- látky znečišťující půdu analýza farmakokinetika MeSH
- listy rostlin metabolismus MeSH
- metody MeSH
- půda chemie MeSH
- rtuť analýza farmakokinetika MeSH
- semena rostlinná metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Fish sauce is a popular seasoning liquid originating from southeastern Asian cuisine, consisting of fermented fish, salt and additional ingredients. Fish can contain high amounts of metals, some of which are hazardous for human health. Therefore, authorities responsible for food safety and quality should monitor the levels of these contaminants in fish and fish deviated products. In this work, the passive sampling technique of Diffusive Gradients in Thin-films (DGT) containing Chelex-100 and Purolite S924 resin gels, is used for the determination of dissolved mercury (Hg), cadmium (Cd) and lead (Pb) in fish sauce. The DGT performance test showed linear accumulation of Hg, Cd and Pb on the binding gels versus deployment time. A wide range of pH and salt concentration did not affect the performance of the DGT. The effective diffusion coefficients of Hg, Cd and Pb in diffusive gels were determined by applying a series of deployments in fish sauce solution. Besides the direct sampling with the DGT technique, fish sauce samples were also digested using a microwave oven. Analyses of DGT and microwave oven digested samples were performed with Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS). Both methods were then used for the analysis of fish sauces from local retail stores. Due to the preconcentration ability of DGT, lower detection limits of Hg, Cd and Pb could be achieved compared to the microwave digestion method. The DGT technique offers a more sensitive method for trace element analysis in complex food matrices.
- Publikační typ
- časopisecké články MeSH
The distribution of mercury in surface water and in sediment from Deûle River in Northern France was studied by application of conventional sampling methods and by diffusive gradients in thin films technique (DGT). Concentration of total dissolved mercury in surface water was 20.8 ± 0.8 ng l(-1). The particulate mercury concentration was 6.2 ± 0.6 µg g(-1). The particulate mercury was accumulated in sediment (9.9 ± 2.3 mg kg(-1)), and it was transformed by methylating bacteria to methylmercury, mainly in the first 2-cm layer of the sediment. Total dissolved concentration of mercury in sediment pore water obtained by application of centrifugation extraction was 17.6 ± 4.1 ng l(-1), and it was comparable with total dissolved pore water mercury concentration measured by DGT probe containing Duolite GT-73 resin gel (18.2 ± 4.3 ng l(-1)), taking the sediment heterogeneity and different principles of the applied methods into account. By application of two DGT probes with different resin gels specific for mercury, it was found that approximately 30% of total dissolved mercury in sediment pore water was present in labile forms easy available for biota. The resolution of mercury DGT depth profiles was 0.5 cm, which allows, unlike conventional techniques, to study the connection of the geochemical cycle of mercury with geochemical cycles of iron and manganese.
- MeSH
- chemické látky znečišťující vodu analýza MeSH
- monitorování životního prostředí metody MeSH
- rtuť analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Francie MeSH
The mercury bioaccumulation by common carp (Cyprinus carpio L.) tissues (gills, skin, eyes, scales, muscle, brain, kidneys, liver, and spleen) and the capability of the diffusive gradient in thin film (DGT) technique to predict bioavailability of mercury for individual carp's tissues were evaluated. Carp and DGT units were exposed to increasing concentrations of mercury (Hg2+: 0 μg L-1, 0.5 μg L-1, 1.5 μg L-1and 3.0 μg L-1) in fish tanks for 14 days. In the uncontaminated fish group, the highest mercury concentration was determined in the muscle tissues and, in fish groups exposed to mercury, the highest mercury concentration was determined in the detoxification (kidneys) and input (gills) organs. A strong and positive correlation between the rate of mercury uptake by the DGT technique and the rate of mercury accumulation by fish tissues (gills, skin, scales, and eyes) was observed.
- MeSH
- biologická dostupnost MeSH
- difuze MeSH
- kapři metabolismus MeSH
- kinetika MeSH
- ledviny chemie metabolismus MeSH
- rtuť analýza farmakokinetika MeSH
- svaly chemie metabolismus MeSH
- žábry chemie metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
