Occurrence, bioavailability and toxic effects of trace metals and organic contaminants in mangrove ecosystems: a review.

Environmental context The health of aquatic organisms depends on the distribution of the dissolved forms of chemical components (speciation) and their rates of interaction (dynamics). This review documents and explains progress made using the dynamic technique of diffusive gradients in thin-films (DGT) to meet these challenges of measuring directly chemical speciation and associated dynamics in natural waters. The relevance of these measurements to uptake by biota of chemical forms in soils, sediments and water is discussed with reference to this expanding literature. Abstract This review assesses progress in studies of chemical speciation using diffusive gradients in thin-films (DGT) by examining the contributions made by key publications in the last 20 years. The theoretical appreciation of the dynamic solution components measured by DGT has provided an understanding of how DGT measures most metal complexes, but excludes most colloids. These findings strengthen the use of DGT as a monitoring tool and provide a framework for using DGT to obtain in situ kinetic information. Generally, the capabilities of DGT as an in situ perturbation and measurement tool have yet to be fully exploited. Studies that have used DGT to investigate processes relevant to bioavailability have blossomed in the last 10 years, especially for soils, as DGT mimics the diffusion limiting uptake conditions that, under some conditions, characterise uptake by plants. As relationships between element accumulated by DGT and in plants depend on the plant species, soils studied, and the element and its chemical form, DGT is not an infallible predictive tool. Rather its strength comes from providing information on the labile species in the system, whether water, soil or sediment. Recent studies have shown good relationships between measurements of metals in periphyton and by DGT, and unified dose response curves have been obtained for biota in sediments when they are based on DGT measurements. Both these cases suggest that alternative approaches to the established ‘free ion’ approach may be fruitful in these media and illustrate the growing use of DGT to investigate environmental chemical processes.

Use of diffusive gradients in thin-films for studies of chemical speciation and bioavailability

The mobilization of toxic metals in soils strongly depends on their bounding in different geochemical fractions. However, the relations between soil properties and the vertical horizon-specific distribution of different geochemical fractions of cadmium (Cd), lead (Pb), and nickel (Ni) in various floodplain soil types are limited and have not been studied up to date. Therefore, seven soil profiles in three areas along the Elbe River, Germany, which represent the two soil groups Mollic Fluvisols and Eutric Gleysols, were selected to determine geochemical fractions of Cd, Pb, and Ni. A sequential extraction procedure which fractionate metals into the seven fractions: F1: soluble+exchangeable, F2: easily mobilizable, F3: bound to Mn oxides, F4: bound to soil organic matter, F5: occluded into amorphous Fe oxides, F6: occluded into crystalline Fe oxides, and F7: residual fraction was used. Concentrations of pseudo-total Cd, Ni, and Pb were exceeded the international trigger action values and governed mainly by soil organic carbon (SOC), cation exchange capacity, and Fe–Mn sesquioxides. The mobile fraction (∑F1–F2) was dominant for Cd, whereas Pb was mainly bounded in F4/F5, and Ni in F7/F6. Cadmium and Pb reveal a higher potential mobility (∑F1–F6) than Ni. The potential mobile fraction ranged from 90 % to 97 %, 44 % to 61 %, and 83 % to 92 % of the (pseudo)total Cd, Ni, and Pb, respectively. The Gleysols showed a higher mobile fraction and potential mobile fraction than Fluvisols. The mobile fraction of the metals correlated positively with clay, SOC, and total sulfur (St), and negatively with pH and Fe–Mn oxides. Our results indicate that the studied soils exhibit elevated concentrations of Cd, Ni, and Pb, as well as a high potential mobilization of these metals. Our findings suggest that a release of these toxic metals in floodplain soils should be considered due to an increased mobilization and the potential environmental risks such as uptake by plants, and thus, the transfer of these metals into the grassland and food chain, as well as transport via waters during periods of flooding.

Assessing the Mobilization of Cadmium, Lead, and Nickel Using a Seven-Step Sequential Extraction Technique in Contaminated Floodplain Soil Profiles Along the Central Elbe River, Germany

Phytostabilisation potential of giant reed for metals contaminated soil modified with complex organic fertiliser and fly ash: A field experiment.

Soil electrokinetic remediation (ER) is an efficient technique to remove heavy metals from the complex soil matrix, however, this process needs a large amount of electricity input, which increases the cost and limits its application in remote agricultural fields. Microbial fuel cells (MFCs) are able to convert organic matter into electric current by using extracellular-respiring microbes. In this study, MFCs were designed and applied to electrokinetic removal of zinc (Zn) and cadmium (Cd) from a contaminated paddy soil. The current produced by three-chamber MFCs was ∼0.4Am−2 when loaded with the citric acid-amended soil. Replacement of the anion exchangeable membrane with nylon filter increased the transport rate of metal ions from the middle remediation chamber to the cathode chamber. After 78-day running, the systems with 300 Ω resistors removed 12 mg Zn and 0.7 mg Cd more than those without resistors, suggesting that the current produced by the MFCs could significantly facilitate metal removal. The BCR extraction methods were applied to characterize the metal fractionation after ER treatment. The results showed that most of the removed metals came from acid extractable and reducible fractions. This study provides evidences that MFCs could power the soil ER processes, but the removal efficiency needs to be improved before its application in contaminated fields.

Can electrokinetic removal of metals from contaminated paddy soils be powered by microbial fuel cells

This study assessed the effect of biosolids applied at rates, 0, 30, 45, and 60 Mg ha−1 on the chemical associations and bioavailability of Cu and Zn in soils from an important agricultural zone of the Metropolitan Region in Central Chile. Three methods were used to determine the bioavailability of Cu and Zn in soils: ryegrass (Lolium perenne) plants, diffusive gradients in thin films (DGT) technique, and Community Bureau of Reference (BCR) sequential extraction. The DGT effective concentration (C
 E) and sequential extract acid soluble fraction of the BCR extraction (most labile fraction of the soils, normally associated with bioavailability) were compared with total metal concentration in ryegrass plants as a means to compare the chemical and biological measures of bioavailability. Total Zn was higher in comparison to Cu for all treatments. Concentrations were within the limits set by the Chilean regulations for land-applied biosolids. Metals in the control soil were primarily found in the residual fraction of soils. Biosolids application generally decreased this fraction, with a subsequent increase observed mainly in the acid soluble fraction. The contents of Cu and Zn in ryegrass plants increased with increasing rates of biosolids. Comparison of the Cu and Zn content in ryegrass plants with C
 E, showed a good correlation for Zn. However, the C
 E for soil Cu was only related to plant Cu for some of the soils studied. Correlation between Zn in ryegrass plants and the labile fraction of Zn as measured by the sequential extraction was excellent, with correlation coefficients >0.9, while for Cu, correlation coefficients were lower.

Determination of the Bioavailable Fraction of Cu and Zn in Soils Amended with Biosolids as Determined by Diffusive Gradients in Thin Films (DGT), BCR Sequential Extraction, and Ryegrass Plant

https://doi.org/10.1016/j.aca.2022.339718

SARS-CoV-2 electrochemical immunosensor based on the spike-ACE2 complex

As a more efficient and effective way to address disease diagnosis and intervention, cutting-edge technologies, devices, therapeutic approaches, and practices have emerged within the personalized medicine concept depending on the particular patient's biology and the molecular basis of the disease. Personalized medicine is expected to play a pivotal role in assessing disease risk or predicting response to treatment, understanding a person's health status, and, therefore, health care decision-making. This work discusses electrochemical biosensors for monitoring multiparametric biomarkers at different molecular levels and their potential to elucidate the health status of an individual in a personalized manner. In particular, and as an illustration, we discuss several aspects of the infection produced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a current health care concern worldwide. This includes SARS-CoV-2 structure, mechanism of infection, biomarkers, and electrochemical biosensors most commonly explored for diagnostics, prognostics, and potentially assessing the risk of complications in patients in the context of personalized medicine. Finally, some concluding remarks and perspectives hint at the use of electrochemical biosensors in the frame of other cutting-edge converging/emerging technologies toward the inauguration of a new paradigm of personalized medicine. 

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Detection of COVID-19-related biomarkers by electrochemical biosensors and potential for diagnosis, prognosis, and prediction of the course of the disease in the context of personalized medicine

Viviana Vásquez

Papers

Determination of the Bioavailable Fraction of Cu and Zn in Soils Amended with Biosolids as Determined by Diffusive Gradients in Thin Films (DGT), BCR Sequential Extraction, and Ryegrass Plant

SARS-CoV-2 electrochemical immunosensor based on the spike-ACE2 complex

Detection of COVID-19-related biomarkers by electrochemical biosensors and potential for diagnosis, prognosis, and prediction of the course of the disease in the context of personalized medicine