scholarly journals Preliminary Investigation concerning Metals Bioavailability in Waters of Aries River Catchment by Using the Diffusive Gradients in Thin Films Technique

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Marin Senila ◽  
Erika Andrea Levei ◽  
Lacrimioara Ramona Senila ◽  
Marius Roman
Keyword(s):  
Thin Films ◽  
Preliminary Investigation ◽  
Low Flow ◽  
Metal Species ◽  
Dissolved Metals ◽  
Metal Concentrations ◽  
River Catchment ◽  
Mining Areas ◽  
Diffusive Gradients ◽  
Very High

The paper presents the metals content and bioavailability in waters of Aries River catchment, Romania. Concentration of labile dissolved metal species measured by diffusive gradients in thin films technique (DGT), metals in colloidal and in particulate phases, and also general physical-chemical indicators of water were determined. Very high total metal concentrations were found in the tributaries that drain the mining areas. However, the influence of the polluted tributaries on the Aries River water quality was moderate, as a consequence of the tributaries low flow rate compared with that of the Aries River. Using the DGT technique the bioavailable metals fractions expressed as % of total dissolved metals concentrations were found to be 28–88% for Cu, 43–72% for Zn, 73–85% for Fe, and 33–70% for Mn. Depending on the used method for dissolved metals determination the classification of waters according to quality classes may differ. Excluding the colloidal metal fractions, DGT measures only truly dissolved metal concentrations. In cases with very high metal contamination the differences between total dissolved and DGT-labile concentrations are unimportant for waters classification. However, where the metals concentration is near the thresholds values the determination method is very important.

scholarly journals Forced Biomineralization: A Review

Biomimetics ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 46
Author(s):  
Hermann Ehrlich ◽  
Elizabeth Bailey ◽  
Marcin Wysokowski ◽  
Teofil Jesionowski
Keyword(s):  
Environmental Conditions ◽  
Metal Ion ◽  
Toxic Metal ◽  
Dissolved Metals ◽  
Metal Concentrations ◽  
Ion Concentrations ◽  
Wide Range ◽  
Aqueous Environments ◽  
Protective Structures ◽  
Very High

Biologically induced and controlled mineralization of metals promotes the development of protective structures to shield cells from thermal, chemical, and ultraviolet stresses. Metal biomineralization is widely considered to have been relevant for the survival of life in the environmental conditions of ancient terrestrial oceans. Similar behavior is seen among extremophilic biomineralizers today, which have evolved to inhabit a variety of industrial aqueous environments with elevated metal concentrations. As an example of extreme biomineralization, we introduce the category of "forced biomineralization," which we use to refer to the biologically mediated sequestration of dissolved metals and metalloids into minerals. We discuss forced mineralization as it is known to be carried out by a variety of organisms, including polyextremophiles in a range of psychrophilic, thermophilic, anaerobic, alkaliphilic, acidophilic, and halophilic conditions, as well as in environments with very high or toxic metal ion concentrations. While much additional work lies ahead to characterize the various pathways by which these biominerals form, forced biomineralization has been shown to provide insights for the progression of extreme biomimetics, allowing for promising new forays into creating the next generation of composites using organic-templating approaches under biologically extreme laboratory conditions relevant to a wide range of industrial conditions.

Prediction of Zinc and Cadmium Phytoavailability Within a Contaminated Agricultural Site using DGT

2006 ◽  
Vol 3 (1) ◽  
pp. 61 ◽  
Author(s):  
Jean-Yves Cornu ◽  
Laurence Denaix
Keyword(s):  
Thin Films ◽  
Human Health ◽  
Metal Contamination ◽  
Predictive Tool ◽  
Metal Concentrations ◽  
Wide Range ◽  
Agricultural Site ◽  
Diffusive Gradients ◽  
Metal Phytoavailability ◽  
Cultivated Soils

Environmental Context.In some agricultural areas, soils are contaminated by trace elements. This contamination of cultivated soils may constitute a serious problem for human health through the accumulation of metals in the edible parts of crops. In order to assess the risk for human health associated with metal contamination of soil, we need to develop simple tools like Diffusive Gradients in Thin Films (DGT) for predicting crop metal accumulation. The present study focuses on an agricultural site contaminated with fallout from industrial dust and reveals that DGT could be a predictive tool of zinc accumulation in lettuce. Abstract.Risk assessment of metal contamination in cultivated soils needs to address metal phytoavailability. The technique of diffusive gradients in thin films (DGT) has been shown to be a promising tool to assess metal phytoavailability in a wide range of soils. The present study has examined the ability of the DGT method to predict metal phytoavailability within a contaminated agricultural site. Lettuce (Lactuva sativa cv Appia) was grown in nine metal-contaminated soils differing mainly by their pH. Metal concentrations (Zn, Cd) in plant shoots were compared with total soil metal concentrations and free ion metal concentrations in soil pore waters, and effective concentrations, CE, measured by DGT. Plant Zn concentrations were highly related to CE, suggesting DGT can be a sensitive tool able to assess Zn phytoavailability within mildly contaminated agricultural soils. Plant Cd concentrations were less closely related to CE, signifying that processes other than Cd re-supply from the solid phase may occur during soil–plant transfer of Cd.

scholarly journals Monitoring of Heavy Metal Pollution in Water and Sediments at the Mid-Black Sea Region by Using Passive Sampling Method Diffusive Gradients in Thin Films

2021 ◽  
Vol 9 (6) ◽  
pp. 1076-1086
Author(s):  
Arife Şimşek ◽  
Şule Sancak ◽  
Gülfem Bakan
Keyword(s):  
Thin Films ◽  
Heavy Metals ◽  
Heavy Metal ◽  
Black Sea ◽  
Passive Sampling ◽  
Sampling Method ◽  
Grab Sampling ◽  
Metal Concentrations ◽  
Water And Sediment ◽  
Diffusive Gradients

Determining the potential bioavailability of heavy metals, evaluating according to adapted regulations is essential to efficiently conserve our coastal and estuarine waters. In this study, it is aimed to determine the industrial pollution and various other pollution sources that the Black Sea Basin is exposed to by using DGT (Diffusive Gradients in Thin Films) method and grab (manuel) sampling method in water and sediment and to evaluate the existing pollution according to quality standards. In Samsun, seasonal samples were collected from five different sampling stations, namely Akkiraz Stream, Hıdırellez Stream, Organized Industrial Zone (OIZ) Channel, Şabanoğlu Stream and Selyeri Stream, which are selected from Tekkeköy region where industry is intensively active. In order to determine the heavy metal content in both water and sediment samples, the DGT method was chosen for passive sampling and the grab sampling method was used for active sampling, and the efficiency of the methods was evaluated. According to the results of the study, the heavy metal concentration in grab sampling for water samples in descending order Al> Fe> Zn> Pb> Ni> Cu; In the samples taken with DGT, they are listed as Al> Fe> Zn> Cu> Ni> Pb. There were significant relationships between the total metal concentrations of sediment (Csed) and water (Csu) in grab sampling and metal concentrations sediment (Csed-DGT) and water (Csu-DGT) measured by DGT. It was found that the sensitivity and performance of sampling with DGT was 2-10 times higher compared to grab sampling. The high resolution in situ DGT technique for the assessment and management of the potential release risk of heavy metals at the water-sediment interface is a complementary method that contributes to the standard grab sampling method.

scholarly journals Risk assessment of eight metals and their mixtures to aquatic biota in sediments with diffusive gradients in thin films (DGT): a case study in Pearl River intertidal zone

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Yang-Guang Gu
Keyword(s):  
Thin Films ◽  
Intertidal Zone ◽  
Sediment Toxicity ◽  
River Estuary ◽  
Pearl River ◽  
Aquatic Biota ◽  
Metal Concentrations ◽  
Metal Mixtures ◽  
Diffusive Gradients

Abstract Background The ecotoxicological risk posed by metals and their mixtures in sediments depends on their bioavailability. Many methods for evaluating the bioavailability of metals in sediments/soils are time-consuming and expensive, and frequently result in equivocal outcomes. The diffusive gradients in thin films (DGT) technique is a good measure of bioavailability for metals that can avoid the above drawbacks. Therefore, more effective approaches to this method should be developed that focus on metal bioavailability. No studies have been conducted using DGT to assess metal mixtures to aquatic biota in sediments. This study is therefore the first attempt to assess sediment toxicity of metals and their mixtures to aquatic biota based on the DGT technique. The intertidal zone of the Pearl River Estuary is selected as a case study. Results The bioavailable (DGT-labile) concentrations of metals range as follows (μg/L): Cd, 0.34–3.62; Pb, 1.35–1.92; Ni, 0.67–92.83; Cu, 0.74–10.30; Zn, 28.60–296.94; Co, 0.03–58.85; Fe, 7.23–4539.36; and Mn, 19.40–6626.83. The risk quotient (RQ), which is the ratio between the measured metal concentrations in the environment (MEC) and the predicted no-effect concentration (PNEC), is conducted to evaluate the single metal risk. The RQ based on summing up the MEC/PNEC ratios (RQMEC/PNEC) and the RQ based on sum of toxic units (RQSTU) are used to assess risk of metal mixture. TheRQ values of Cd, Pb, Ni, Cu, Zn, Fe, and Mn significantly exceed 1, indicating that the adverse effects of the metals are not negligible. Regarding the toxicity of metal mixtures, the values of RQMEC/PNEC and RQSTU are both between 62.45 and 743.48, revealing that the possible risk has already occurred in the study area. Conclusions The two methods of RQMEC/PNEC and RQSTU based on DGT-labile metal concentrations are effective and suitable to estimate the toxicity of metal mixtures in sediments.

Use of the diffusive gradients in thin films technique to evaluate (bio)available trace metal concentrations in river water

2007 ◽  
Vol 387 (6) ◽  
pp. 2239-2244 ◽  
Author(s):  
Pavel Diviš ◽  
Hana Dočekalová ◽  
Lukáš Brulík ◽  
Marek Pavliš ◽  
Petr Hekera
Keyword(s):  
Thin Films ◽  
Trace Metal ◽  
River Water ◽  
Metal Concentrations ◽  
Diffusive Gradients

scholarly journals Evaluation of the diffusion gradient in thin-films (DGT) technique for measuring trace metal concentrations in freshwaters

2021 ◽  
Author(s):  
Deborah Lynn Parent
Keyword(s):  
Thin Films ◽  
Metal Ions ◽  
Metal Concentration ◽  
Metal Species ◽  
Aquatic Environments ◽  
Organic Metal ◽  
Freshwater Lakes ◽  
Metal Concentrations ◽  
The Many

The recently developed Diffusion Gradient in Thin-films (DGT) technique is based on a simple device that accumulates metals in situ, over time in a Na resin gel. Metal ions diffuse through a hydrogel membrane and are rapidly bound by the resin. The many advantages associated with the DGT technique (simplicity, in situ technique, low detection limits, and ability to measure many metals) have lead to its rapid application in aquatic environments. Caveats have been recognized with the DGT technique when it is used in aquatic environments. These include: the ability of strongly complexed organic-metal molecules to diffuse through the hydrogel and become complexed by the resin gel, and in freshwater lakes with a low concentration of cations (Σ [cations] ≤ 2 × 10 -4 M), it is hypothesized that the diffusion coefficient of metal ions entering the DGT device increases. Both of these caveats overestimate the concentrations of labile inorganic metals in the deployment solution. The hypothesis that deploying DGT devices equipped with two different hydrogel formulations ("open" and "tight") will provide reasonable measurements of DGT-labile "organic" and "inorganic" concentrations of Mn, Cd and Pb was tested in the field. DGT devices were deployed in three lakes (Lake Tantare, Lake 8t. Joseph and Lake Memphremagog). To compare the responses of the DGT devices with the total dissolved metal concentration (< 0.20 um) of each lake, in situ dialysis samplers were deployed simultaneously. Overestimation of DGT-labile "inorganic" concentrations of Mn and Pb, and overestimation of DGT-labile "organic" Cd was observed when compared to the measured total dissolved metal concentrations in the lakes. The hypothesis that DGT devices equipped with a Ca form of the resin gel (as an alternative to the sodium based resin gel in the DGT device) will reasonably measure Mn, Cd and Pb labile metal concentrations in freshwater lakes with low cation concentrations was tested. DGT devices with the Ca form of the resin gel were deployed in Lake Tantare, Lake 8t. Joseph and Lake Memphremagog. Overestimation of DGT-labile metal concentrations of Mn, Cd and Pb were observed with the Ca resin gel in the lakes when compared to the measured total dissolved concentrations. The implication of these findings is that the DGT technique should not be used in freshwaters with low cation concentrations (Σ [cations] ≤ 2 × 10 -4 M), typical of lakes found in the Canadian environment, until the caveats of the technique have been resolved. Extreme caution should be used when drawing conclusions regarding the concentrations of inorganic and organic metal species, since it has been found the DGT devices with the two different hydrogel formulations overestimate the inorganic metal concentration relative to the organic metal concentration in aquatic environments.

scholarly journals Measurement of Electrical Properties of Superconducting YBCO Thin Films in the VHF Range

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3360
Author(s):  
Yakir Dahan ◽  
Eldad Holdengreber ◽  
Elichai Glassner ◽  
Oz Sorkin ◽  
Shmuel E. Schacham ◽  
...  
Keyword(s):  
Thin Films ◽  
Theoretical Model ◽  
Quality Factor ◽  
High Frequency ◽  
Unit Length ◽  
Superconducting Thin Films ◽  
Electrical Parameters ◽  
Very High Frequency ◽  
Production Constraints ◽  
Very High

A new measurement technique of electrical parameters of superconducting thin films at the Very High Frequency (VHF) range is described, based on resonators with microstrip (MS) structures. The design of an optimal resonator was achieved, based on a thorough theoretical analysis, which is required for derivation of the exact configuration of the MS. A theoretical model is presented, from which an expression for the attenuation of a MS line can be derived. Accordingly, simulations were performed, and an optimal resonator for the VHF range was designed and implemented. Production constraints of YBa2Cu3O7 (YBCO) limited the diameter of the sapphire substrate to 3″. Therefore, a meander configuration was formed to fit the long λ/4 MS line on the wafer. By measuring the complex input reflection coefficients of a λ/4 resonator, we extracted the quality factor, which is mainly affected by the dielectric and conductor attenuations. The experimental results are well fitted by the theoretical model. The dielectric attenuation was calculated using the quasi-static analysis of the MS line. An identical copper resonator was produced and measured to compare the properties of the YBCO resonator in reference to the copper one. A quality factor of ~6·105 was calculated for the YBCO resonator, three orders of magnitude larger than that of the copper resonator. The attenuation per unit length of the YBCO layer was smaller by more than five orders of magnitude than that of the copper.

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