Presence Of Multiple Contaminants Research Articles

Improving the detection accuracy of the dual SERS aptasensor system with uncontrollable SERS “hot spot” using machine learning tools

BackgroundSimultaneous detection of food contaminants is crucial in addressing the collective health hazards arising from the presence of multiple contaminants. However, traditional multi-competitive surface-enhanced Raman scattering (SERS) aptasensors face difficulties in achieving simultaneous accurate detection of multiple target substances due to the uncontrollable SERS “hot spots”. In this study, using chloramphenicol (CAP) and estradiol (E2) as two target substances, we introduced a novel approach that combines machine learning methods with a dual SERS aptasensor, enabling simultaneous high-sensitivity and accurate detection of both target substances. ResultsThe strategy effectively minimizes the interference from characteristic Raman peaks commonly encountered in traditional multi-competitive SERS aptasensors. For this sensing system, the Au@4-MBA@Ag nanoparticles modified with sulfhydryl (SH)-CAP aptamer and Au@DTNB@Ag NPs modified with sulfhydryl (SH)-E2 aptamer were used as signal probes. Additionally, Fe3O4@Au nanoflowers integrated with SH-CAP aptamer complementary DNA and SH-E2 aptamer complementary DNA were used as capture probes, respectively. When compared to linear regression random forest, and support vector regression (SVR) models, the proposed artificial neural network (ANN) model exhibited superior precision, demonstrating R2 values of 0.963, 0.976, 0.991, and 0.970 for the training set, test set, validation set, and entire dataset, respectively. Validation with ten spectral groups reported an average error of 244 μg L−1. SignificanceThe essence of our study lies in its capacity to address a persistent challenge encountered by traditional multiple competitive SERS aptasensors – the interference generated by uncontrollable SERS “hot spots” that hinders simultaneous quantification. The accuracy of the predictive model for simultaneous detection of two target substances was significantly improved using machine learning tools. This innovative technique offers promising avenues for the accurate and high-sensitive simultaneous detection of multiple food and environmental contaminants.

Effects of Tebuconazole on the Earthworm Dendrobaena veneta: Full Life Cycle Approach

Tebuconazole (TEB), a widely used triazole fungicide, is effective against soil-borne and foliar fungal pathogens. Toxicants can exhibit varying effects depending on the life stage of organisms, although standard toxicity tests typically focus on adult individuals. This study aimed to assess TEB’s potential adverse effects on the earthworm Dendrobaena veneta throughout its life cycle. Effects were evaluated by exposing cocoons to varying TEB concentrations, monitoring hatching, newly hatched juvenile mass, and growth to adulthood. A reproduction test assessed impacts on adults, offering insights into how these results compared with cocoon exposure findings. Results revealed that TEB delayed hatching at concentrations of 25, 50, and 100 mg/kg by 6, 8, and 15.5 days, respectively. Newly hatched juveniles exhibited a 15.96% (50 mg/kg) and 27.37% (100 mg/kg) reduction in body mass compared to controls, with no subsequent compensation during growth. Results from the reproduction tests showed no adverse effects on adult survival, but the effects are observed on juveniles, indicating a higher sensitivity of this developmental stage. While several adverse effects were observed, it is important to note that these occurred at concentrations exceeding recommended application rates. TEB appears safe for earthworms when used correctly, but the presence of multiple contaminants and stressors warrants consideration.

Multiple Organic Contaminants Determination Including Multiclass of Pesticides, Polychlorinated Biphenyls, and Brominated Flame Retardants in Portuguese Kiwano Fruits by Gas Chromatography

Global production of exotic fruits has been growing steadily over the past decade and expanded beyond the originating countries. The consumption of exotic and new fruits, such as kiwano, has increased due to their beneficial properties for human health. However, these fruits are scarcely studied in terms of chemical safety. As there are no studies on the presence of multiple contaminants in kiwano, an optimized analytical method based on the QuEChERS for the evaluation of 30 multiple contaminants (18 pesticides, 5 polychlorinated biphenyls (PCB), 7 brominated flame retardants) was developed and validated. Under the optimal conditions, satisfactory extraction efficiency was obtained with recoveries ranging from 90% to 122%, excellent sensitivity, with a quantification limit in the range of 0.6 to 7.4 µg kg-1, and good linearity ranging from 0.991 to 0.999. The relative standard deviation for precision studies was less than 15%. The assessment of the matrix effects showed enhancement for all the target compounds. The developed method was validated by analyzing samples collected from Douro Region. PCB 101 was found in trace concentration (5.1 µg kg-1). The study highlights the relevance of including other organic contaminants in monitoring studies in food samples in addition to pesticides.

Microbial Biotechnology and Bioremediation

Microbial biotechnology is a rapidly growing field that leverages the abilities of microorganisms for practical applications. From producing biofuels to removing pollutants, microorganisms play a crucial role in shaping our world. Bioremediation is one of the most promising applications of microbial biotechnology, using microorganisms to clean up contaminated sites and restore ecosystems. The impact of human activities has led to widespread pollution, and traditional methods of remediation are often expensive, time-consuming, and not environmentally friendly. Microbial biotechnology offers a sustainable and cost-effective alternative.
 
 Bioremediation can be performed using indigenous microorganisms or by introducing specific strains of microorganisms that are capable of breaking down contaminants. These microorganisms use the pollutants as a source of energy and nutrients, transforming them into harmless substances. This process not only cleans up the site, but it also helps to restore the natural ecosystem and biodiversity. The field of microbial biotechnology has made significant progress in recent years, with advancements in molecular biology and genomics enabling a deeper understanding of microorganisms and their capabilities. The development of new bioremediation techniques has allowed for the efficient removal of a wide range of contaminants, including heavy metals, oil and other petroleum products, and toxic organic compounds. These techniques have proven to be effective in treating contaminated soil, groundwater, and surface water [1].
 
 However, the implementation of bioremediation techniques is not without its challenges. One of the biggest challenges is identifying the most effective strains of microorganisms for a specific contamination site. The environmental conditions, such as pH, temperature, and nutrient levels, can have a significant impact on the efficacy of bioremediation. Furthermore, the presence of multiple contaminants can complicate the process, requiring the use of multiple strains of microorganisms. Despite these challenges, the benefits of bioremediation, including sustainability and cost-effectiveness, make it a promising solution for cleaning up contaminated sites.
 
 The impact of microbial biotechnology and bioremediation goes beyond just environmental remediation. By leveraging the abilities of microorganisms, we can also contribute to the development of new and innovative technologies. For example, biorefineries are being developed to produce biofuels, bioplastics, and other bioproducts using sustainable processes. This not only helps to reduce the reliance on fossil fuels, but it also helps to reduce greenhouse gas emissions and promote sustainable development.
 
 Microbial biotechnology and bioremediation are critical fields that offer solutions to some of the biggest environmental challenges facing our world. With continued investment and research, we can develop and implement more effective and sustainable bioremediation techniques. These techniques will play a key role in cleaning up contaminated sites, restoring ecosystems, and promoting sustainable development. It is our hope that the benefits of microbial biotechnology and bioremediation will be recognized and supported by governments, organizations, and the public, allowing us to make a positive impact on our world.

Early Exposure to Environmental Pollutants: Imidacloprid Potentiates Cadmium Toxicity on Zebrafish Retinal Cells Death.

In the present study, we analyzed the combination of non-toxic concentrations per se, of Cd and a pesticide the imidacloprid (IMI) (10 and 50 μM for Cd and 195 μM for IMI), to highlight early developmental toxicity and possible damage to retinal cells. Co-exposure to Cd and IMI showed a toxic effect in zebrafish larval development, with lowered degrees of survival and hatching, and in some cases the induction of structural alterations and edema. In addition, co-exposure to 50 and 195 μM, respectively, for Cd and IMI, also showed increased apoptosis in eye cells, accompanied by up regulation of genes associated with antioxidant markers (cat, sod1, nrf2 and ho-1). Thus, the present study aims to highlight how the presence of multiple contaminants, even at low concentrations, can be a risk factor in a model of zebrafish (Danio rerio). The presence of other contaminants, such as IMI, can cause an enhancement of the toxic action of Cd on morphological changes in the early life stage of zebrafish, but more importantly disrupt the normal development of the retina, eventually triggering apoptosis.

Bacterial community assemblages in sediments under high anthropogenic pressure at Ichkeul Lake/Bizerte Lagoon hydrological system, Tunisia

Bacterial communities inhabiting sediments in coastal areas endure the effect of strong anthropogenic pressure characterized by the presence of multiple contaminants. Understanding the effect of pollutants on the organization of bacterial communities is of paramount importance in order to unravel bacterial assemblages colonizing specific ecological niches. Here, chemical and molecular approaches were combined to investigate the bacterial communities inhabiting the sediments of the Ichkeul Lake/Bizerte Lagoon, a hydrological system under anthropogenic pressure. Although the microbial community of the Ichkeul Lake sediment was different to that of the Bizerte Lagoon, common bacterial genera were identified suggesting a lake-lagoon continuum probably due to the hydrology of the system exchanging waters according to the season. These genera represent bacterial "generalists" maintaining probably general biogeochemical functions. Linear discriminant analysis effect size (LEfSe) showed significant differential abundance distribution of bacterial genera according to the habitat, the pollution type and level. Further, correlation analyses identified specific bacterial genera which abundance was linked with pesticides concentrations in the lake, while in the lagoon the abundance of specific bacterial genera was found linked with the concentrations of PAHs (Polycyclic aromatic hydrocarbons) and organic forms of Sn. As well, bacterial genera which abundance was not correlated with the concentrations of pollutants were identified in both lake and lagoon. These findings represent valuable information, pointing out specific bacterial genera associated with pollutants, which represent assets for developing bacterial tools for the implementation, the management, and monitoring of bioremediation processes to mitigate the effect of pollutants in aquatic ecosystems.

Technetium and iodine aqueous species immobilization and transformations in the presence of strong reductants and calcite-forming solutions: Remedial action implications

At the Hanford Site in southeastern Washington, discharge of radionuclide laden liquid wastes resulted in vadose zone contamination, providing a continuous source of these contaminants to groundwater. The presence of multiple contaminants (i.e., 99Tc and 129I) increases the complexity of finding viable remediation technologies to sequester contaminants in situ and protect groundwater. Although previous studies have shown the efficiency of zero valent iron (ZVI) and sulfur modified iron (SMI) in reducing mobile Tc(VII) to immobile Tc(IV) and iodate incorporation into calcite, the coupled effects from simultaneously using these remedial technologies have not been previously studied. In this first-of-a-kind laboratory study, we used reductants (ZVI or SMI) and calcite-forming solutions to simultaneously remove aqueous Tc(VII) and iodate via reduction and incorporation, respectively. The results confirmed that Tc(VII) was rapidly removed from the aqueous phase via reduction to Tc(IV). Most of the aqueous iodate was transformed to iodide faster than incorporation into calcite occurred, and therefore the I remained in the aqueous phase. These results suggested that this remedial pathway is not efficient in immobilizing iodate when reductants are present. Other experiments suggested that iodate removal via calcite precipitation should occur prior to adding reductants for Tc(VII) removal. When microbes were included in the tests, there was no negative impact on the microbial population but changes in the makeup of the microbial community were observed. These microbial community changes may have an impact on remediation efforts in the long-term that could not be seen in a short-term study. The results underscore the importance of identifying interactions between natural attenuation pathways and remediation technologies that only target individual contaminants.

Water Sources Diagram in Multiple Contaminant Processes: Maximum Reuse

Water scarcity, rising energy costs, and stricter regulations on disposal of industrial effluents have forced a focus on the water usage in process plants. In this context, the development of methodologies to analyze the possibility of water reuse in industrial processes, considering the presence of multiple contaminants, has became an important issue for process engineers. There are a great variety of methods to deal with this problem, and they can be divided in two groups: algorithmic methods and mathematical programming methods. The problem with multiple contaminants becomes more complex, and the available algorithmic procedures are sometimes cumbersome; the methodologies based on mathematical programming present complex formulation and solving algorithms. This paper presents an extension of the algorithmic procedure water source diagram (WSD) to multiple contaminant processes. The proposed extended WSD procedure synthesizes water mass exchange networks for multiple contaminant processes, focusing on w...

Special Issue on Contaminant Mixtures: Fate, Transport, and Remediation

The fate and transport of mixed contaminants in subsurface environments can be quite complex because of various physical, chemical, and biological processes. In-depth understanding of geochemistry that influences the distribution, speciation, and transport is needed to understand the risk and develop remedial strategies. Joo et al. performed batch experiments to evaluate the sorption of six nonpolar and six polar organic compounds as mixtures to both hydrophilic mineral surfaces [uncoated, iron (hydr) oxide-coated, and aluminum (hydr)oxide-coated sands] and humic acid–mineral complexes with different fractions of organic carbon. The mixture effects on sorption of the nonpolar compounds were found to be not significant, whereas they were found to be significant for polar compounds depending on the mixture compositions and the type of sorbent. This implies the need for accurately quantifying and modeling mixture effects on fate and transport of multiple organic contaminants present at the site. Poly and Sreedeep performed batch sorption experiments and found that the presence of multiple contaminants affect the sorption of individual contaminants. The contaminant fate prediction based on linear isotherm is influenced by the range of concentration for single and multiple contaminants. For lower ranges of concentration, the contaminant fate prediction based on the Freundlich isotherm is greater than that of Langmuir, and vice versa for higher concentration range. Further, the difference in contaminant fate prediction based on Freundlich and Langmuir nonlinear isotherms decreases with an increase in concentration. The fate and transport parameters of soils vary in space because of soil heterogeneity, and such conditions require transport modeling using stochastic approaches. Nezhad and Javadi present an advective and diffusive-dispersive contaminant transport, using a stochastic finite-element approach. The need for expanding such approaches to multiple contaminant conditions is warranted.

Assisted Washing for Heavy Metal and Metalloid Removal from Contaminated Dredged Materials

In the present study a chemical washing process was applied to dredged sea and river sediments. Five chelating agents (ethylenediaminetetraacetic, nitrilotriacetic, citric, [S,S]-ethylenediaminedisuccinic and oxalic acids), three surfactants (sodium dodecyl sulphate, cetylpyridinium chloride and saponin Q), as well as monobasic potassium phosphate were used as the extracting agents. The effect of sonication was also tested as a conditioning step to couple with chelant-based extraction. The extraction experiments were performed in both single and multiple washing stages. The results indicated that, for given experimental conditions, the remediation efficiency was strongly dependent on the specific contaminant under concern, with contaminant speciation and distribution in the solid matrix as well as affinity for the extracting agent playing a major role in the decontamination process. In this respect, the study also showed that in the presence of multiple contaminants the use of a single extraction agent is not sufficient to attain adequate quality levels for the treated sediment.

Carbon isotope fractionation during permanganate oxidation of chlorinated ethylenes (cDCE, TCE, PCE).

Permanganate oxidation of chlorinated ethylenes is an attractive technique to effect remediation of these important groundwater contaminants. Stable carbon isotope fractionation associated with permanganate oxidation of trichloroethylene (TCE), tetrachloroethylene (PCE), and cis-1,2-dichloroethylene (cDCE) has been measured, to study the possibility of applying stable carbon isotope analysis as a technique to assess the efficacy of remediation implemented by permanganate oxidation. Average carbon isotope fractionation factors of alphaTCE = 0.9786, alphaPCE = 0.9830, and alphacDCE = 0.9789 were obtained, although the fractionation factor for PCE may be interpreted to change from a value of 0.9779-0.9871 during the course of the reaction. The fractionation factors for all three compounds are quite similar, in contrast to the variation of fractionation factors vs degree of chlorination observed for other degradative processes, such as microbial dechlorination. This may be due to a common rate-determining step for permanganate oxidation of all three compounds studied. The large fractionation factors and the relative lack of dependence of the fractionation factors upon other environmental factors (e.g. oxidation rate, presence of multiple contaminants, incomplete oxidation, presence of chloride in solution) indicate that monitoring delta13C values of chlorinated ethylenes during oxidation with permanganate may be a sensitive, and potentially quantitative, technique to investigate the extent of degradation.

Use of bacterial biosensors to interpret the toxicity and mixture toxicity of herbicides in freshwater

The dose response relationship between seven commonly used herbicides and four luminescence-based bacterial biosensors was characterised. As herbicide concentration increased the light emitted by the test organism declined in a concentration dependent manner. These dose responses were used to compare the predicted vs. observed response of a biosensor in the presence of multiple contaminants. For the majority of herbicide interactions, the relationship was not additive but primarily antagonistic and sometimes synergistic. These biosensors provide a sensitive test and are able to screen a large volume and wide range of samples with relative rapidity and ease of interpretation. In this study biosensor technology has been successfully applied to interpret the interactive effects of herbicides in freshwater environments.

Comparative reproductive and developmental toxicology of PCBs in birds

The acute toxicity of PCBs to adult birds increases with increasing chlorination of the PCB mixture, and brain residues greater than 300 mg/kg are associated with mortality. Sublethal effects in adults include reduced parental attentiveness and abnormal reproductive behavior. PCBs cause a suite of developmental effects, including endocrine disruption, immunotoxicity and teratogenesis, rather than a specific etiology such as egg shell thinning. Possible polychlorinated dibenzofuran (PCDF) contamination in PCB mixtures may have been responsible for some of the reported toxic effects attributed to PCBs, such as edema. PCB concentrations causing embryo mortality range from 3.1 μg/kg for 3,3′,4,4′,5-pentachlorobiphenyl in chicken eggs to 30 mg/kg for total PCBs in double crested cormorant eggs. Dietary no adverse effect concentrations range from 0.5 ppm in the American kestrel to 50 ppm in the Japanese quail. Genetic differences related to expression of the aryl hydrocarbon (Ah) receptor, rather than toxicokinetics, may be the dominant factor determining reproductive toxicity of PCBs in birds. The assessment of potential injury to bird populations from PCBs is confounded by the presence of multiple contaminants in field-collected biota and environmental media.