The Transformation Mechanism and Environmental Effects of Emerging Pollutants

A special issue of Toxics (ISSN 2305-6304). This special issue belongs to the section "Emerging Contaminants".

Deadline for manuscript submissions: closed (31 August 2022) | Viewed by 7615

Special Issue Editors


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Guest Editor
School of Environment, Nanjing University, Nanjing 210093, China
Interests: organic pollutants; advanced oxidation; photochemical transformation; photocatalysis; theoretical calculation
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
School of Environment, Nanjing University, Nanjing, China
Interests: advanced oxidation techniques; photocatalysis; ozonation; environmental theoretical chemistry; QSAR
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Various emerging pollutants are being detected in the natural environment, and thus understanding their biological toxicity and other related environmental effects has become the focus of researchers’ concern. Since they may cause great harms to organisms and even humans, great efforts have been devoted to removing these pollutants from the environment. Given this, evaluating the transformations of these pollutants during various treatment processes, including the exploration of reaction kinetics and mechanisms, the identification of intermediate products, and the toxicity assessment of reaction solutions, is a hot research topic that is becoming one of the frontier fields of environmental chemistry.

We are pleased to invite you to submit related research and review papers to this Special Issue. Please make your contributions to spread knowledge on the transformation mechanisms and environmental effects of emerging pollutants to scientific researchers all over the world, and improve the public understanding of toxic substances.

This Special Issue aims to: 1) Propose the transformation mechanisms of pollutants in water, soil, and gas media with experimental measurements based on modern analytical techniques and molecular-structure-based theoretical calculations. Especially, researchers are encouraged to conduct combined theoretical and experimental studies for the explanation of experimental phenomena and degradation mechanisms. 2) Reveal the underlying molecular mechanism for the activity of toxic substances and predict the properties of structurally similar compounds with quantitative structure–activity relationship (QSAR) models obtained through the comprehensive study of a certain series of compounds.

In this Special Issue, original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

  • Environmental Chemistry;
  • Environmental Toxicology.

We look forward to receiving your contributions.

Dr. Ruijuan Qu
Prof. Dr. Zunyao Wang
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • emerging pollutants
  • degradation
  • kinetics
  • intermediate products
  • reaction mechanisms
  • theoretical calculation
  • quantitative structure–activity relationship (QSAR)
  • toxicity assessment

Published Papers (3 papers)

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Research

14 pages, 1115 KiB  
Article
Predicting the Bioconcentration Factor in Fish from Molecular Structures
by Linda Bertato, Nicola Chirico and Ester Papa
Toxics 2022, 10(10), 581; https://doi.org/10.3390/toxics10100581 - 30 Sep 2022
Cited by 3 | Viewed by 2892
Abstract
The bioconcentration factor (BCF) is one of the metrics used to evaluate the potential of a substance to bioaccumulate into aquatic organisms. In this work, linear and non-linear regression QSARs were developed for the prediction of log BCF using different computational approaches, and [...] Read more.
The bioconcentration factor (BCF) is one of the metrics used to evaluate the potential of a substance to bioaccumulate into aquatic organisms. In this work, linear and non-linear regression QSARs were developed for the prediction of log BCF using different computational approaches, and starting from a large and structurally heterogeneous dataset. The new MLR-OLS and ANN regression models have good fitting with R2 values of 0.62 and 0.70, respectively, and comparable external predictivity with R2ext 0.64 and 0.65 (RMSEext of 0.78 and 0.76), respectively. Furthermore, linear and non-linear classification models were developed using the regulatory threshold BCF >2000. A class balanced subset was used to develop classification models which were applied to chemicals not used to create the QSARs. These classification models are characterized by external and internal accuracy up to 84% and 90%, respectively, and sensitivity and specificity up to 90% and 80%, respectively. QSARs presented in this work are validated according to regulatory requirements and their quality is in line with other tools available for the same endpoint and dataset, with the advantage of low complexity and easy application through the software QSAR-ME Profiler. These QSARs can be used as alternatives for, or in combination with, existing models to support bioaccumulation assessment procedures. Full article
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14 pages, 3314 KiB  
Article
Theoretical Calculation on the Reaction Mechanisms, Kinetics and Toxicity of Acetaminophen Degradation Initiated by Hydroxyl and Sulfate Radicals in the Aqueous Phase
by Mengmeng Xu, Junfang Yao, Simei Sun, Suding Yan and Jingyu Sun
Toxics 2021, 9(10), 234; https://doi.org/10.3390/toxics9100234 - 25 Sep 2021
Cited by 10 | Viewed by 1899
Abstract
The •OH and SO4•− play a vital role on degrading pharmaceutical contaminants in water. In this paper, theoretical calculations have been used to discuss the degradation mechanisms, kinetics and ecotoxicity of acetaminophen (AAP) initiated by •OH and SO4•−. [...] Read more.
The •OH and SO4•− play a vital role on degrading pharmaceutical contaminants in water. In this paper, theoretical calculations have been used to discuss the degradation mechanisms, kinetics and ecotoxicity of acetaminophen (AAP) initiated by •OH and SO4•−. Two significant reaction mechanisms of radical adduct formation (RAF) and formal hydrogen atom transfer (FHAT) were investigated deeply. The results showed that the RAF takes precedence over FHAT in both •OH and SO4•− with AAP reactions. The whole and branched rate constants were calculated in a suitable temperature range of 198–338 K and 1 atm by using the KiSThelP program. At 298 K and 1 atm, the total rate constants of •OH and SO4•− with AAP were 3.23 × 109 M−1 s−1 and 4.60 × 1010 M−1 s−1, respectively, considering the diffusion-limited effect. The chronic toxicity showed that the main degradation intermediates were harmless to three aquatic organism, namely, fish, daphnia, and green algae. From point of view of the acute toxicity, some degradation intermediates were still at harmful or toxic level. These results provide theoretical guidance on the practical degradation of AAP in the water. Full article
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20 pages, 1696 KiB  
Article
Potential Environmental Risk Characteristics of PCB Transformation Products in the Environmental Medium
by Minghao Li, Wei He, Hao Yang, Shimei Sun and Yu Li
Toxics 2021, 9(9), 213; https://doi.org/10.3390/toxics9090213 - 7 Sep 2021
Cited by 2 | Viewed by 2124
Abstract
The complementary construction of polychlorinated biphenyl (PCB) phytotoxicity and the biotoxicity 3D-QSAR model, combined with the constructed PCB environmental risk characterization model, was carried out to evaluate the persistent organic pollutant (POP) properties (toxicity (phytotoxicity and biotoxicity), bioconcentration, migration, and persistence) of PCBs [...] Read more.
The complementary construction of polychlorinated biphenyl (PCB) phytotoxicity and the biotoxicity 3D-QSAR model, combined with the constructed PCB environmental risk characterization model, was carried out to evaluate the persistent organic pollutant (POP) properties (toxicity (phytotoxicity and biotoxicity), bioconcentration, migration, and persistence) of PCBs and their corresponding transformation products (phytodegradation, microbial degradation, biometabolism, and photodegradation). The transformation path with a significant increase in environmental risks was analyzed. Some environmentally friendly PCB derivatives, exhibiting a good modification effect, and their parent molecules were selected as precursor molecules. Their transformation processes were simulated and evaluated for assessing the environmental risks. Some transformation products displayed increased environmental risks. The environmental risks of plant degradation products of the PCBs in the environmental media showed the maximum risk, indicating that the potential risks of the transformation products of the PCBs and their environmentally friendly derivatives could not be neglected. It is essential to further improve the ability of plants to degrade their transformation products. The improvement of some degradation products for environmentally friendly PCB derivatives indicates that the theoretical modification of a single environmental feature cannot completely control the potential environmental risks of molecules. In addition, this method can be used to analyze and evaluate environmentally friendly PCB derivatives to avoid and reduce the potential environmental and human health risks caused by environmentally friendly PCB derivatives. Full article
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