Potential Effects of Persistent Organic Contaminants on Marine Biota: A Review on Recent Research

Synthetic organic compounds belonging to different chemical classes and possessing diverse physicochemical properties are frequently present in marine environments. Microplastics, pharmaceuticals, pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) are contained in the list of persistent organic pollutants (POPs) that have been detected in the global marine system. Numerous ecotoxicological studies have revealed the direct and indirect effects of anthropogenic toxicants on marine biota. The present review presents the research that has been conducted during the period from 1 January 2016 to 30 June2021 concerning the lethal and sub-lethal impacts of selected organic-synthetic stressors on different plant and animal marine species, and summarizes the observed or predicted individual and combined effects after exposure to chemical mixtures of such contaminants. Future research needs dependent on the knowledge gaps that remain in the bibliography are also highlighted.

Novel magnetically retrievable In2O3/MoS2/Fe3O4 nanocomposite materials for enhanced photocatalytic performance

The current work involves synthesis of hybrid nanomaterial of In2O3/MoS2/Fe3O4 and their applications as photocatalysts for disintegration of esomeprazole under visible light illumination. The data emerged from various analyses testified to the successful construction of the desired nano-scaled hybrid photocatalyst. Tauc plot gave the band gap of In2O3/MoS2/Fe3O4 to be ~ 2.15 eV. Synergistic effects of the integrant components enabled efficacious photocatalytic performances of the nanocomposite. The nanohybrid photocatalyst In2O3/MoS2/Fe3O4 showed photodecomposition up to ~ 92.92% within 50 min. The current work realizes its objective of constructing metal oxide based hybrid nano-photocatalyst supported on MoS2 sheets for activity in the visible spectrum, which displayed remarkable capacity of disintegrating emerging persistent organic contaminants and are magnetically recoverable.

Enzyme Kinetics of Organic Contaminant Oxygenations

Enzymatic oxygenations initiate biodegradation processes of many organic soil and water contaminants. Even though many biochemical aspects of oxygenation reactions are well-known, quantifying rates of oxidative contaminant removal as well as the extent of oxygenation remains a major challenge. Because enzymes use different strategies to activate O2, reactions leading to substrate oxygenation are not necessarily limiting the rate of contaminant removal. Moreover, oxygenases react along unproductive pathways without substrate metabolism leading to O2 uncoupling. Here, we identify the critical features of the catalytic cycles of selected oxygenases that determine rates and extents of biodegradation. We focus most specifically on Rieske dioxygenases, a subfamily of mononuclear non-heme ferrous iron oxygenases, because of their ability to hydroxylate unactivated aromatic structures and thus initiate the transformation of the most persistent organic contaminants. We illustrate that the rate-determining steps in their catalytic cycles range from O2 activation to substrate hydroxylation, depending on the extent of O–O cleavage that is required for generating the reactive Fe-oxygen species. The extent of O2 uncoupling, on the other hand, is highly substrate-specific and potentially modulated by adaptive responses to oxidative stress. Understanding the kinetic mechanisms of oxygenases will be key to assess organic contaminant biotransformation quantitatively.

Synthesis and Characterization of Supported TiO2 Based Nano Catalysts and Application for the Removal of Water Contaminants

The occurrence of persistent organic contaminants. [...]