Photocatalytic Degradation of Selected Organophosphorus Pesticides Using Titanium Dioxide and UV Light

The photocatalytic degradation of five selected organophosphorus pesticides (OPPs), azinphos methyl, azinphos ethyl, disulfoton, dimethoate, and fenthion, has been investigated using TiO2 (photocatalyst) and UV irradiation. The addition of H2O2 (oxidant agent) into the illuminated aquatic suspensions was also surveyed. The degradation kinetics was studied under different experimental conditions such as pesticides’ and catalyst’s concentration. Experiments were performed in a Pyrex UV laboratory-constructed photoreactor equipped with 4 × 18 W low-pressure Hg lamps emitting at 365 nm (maximum intensity 14.5 mW cm−2 at distance 15 cm). The concentration of pesticides was determined by GC-NPD means. The extent of pesticide mineralization was assessed through TOC measurements. The results demonstrated that photolysis of target organophosphates in the absence of catalyst or oxidant is a slow process resulting in incomplete mineralization. Contradictory, studied pollutants were effectively degraded in the presence of TiO2; evolution of inorganic heteroatoms (SO42−, PO43−, NO2−, NO3−, and NH4+) as final products provided evidence that pesticide deterioration occurred. The photolysis efficiencies decreased in the order: disulfoton > azinphos ethyl > azinphos methyl > fenthion > dimethoate. Furthermore, a synergistic effect was observed with the addition of H2O2 in the pesticide-TiO2 suspensions. In all cases examined, reduction process appeared to follow pseudo first-order kinetics (Langmuir-Hinshelwood model). In conclusion, both catalytic systems investigated (UV-TiO2 and UV-TiO2-H2O2) have good potential for small-scale applications

Effects on the Photosynthetic Activity of Algae after Exposure to Various Organic and Inorganic Pollutants: Review

Algal studies remain necessary for risk assessment and their utility in ecotoxicology is the evaluation of lethal and sub-lethal toxic effects of potential toxicants on inhabitants of several ecosystems. Effects on algal photosynthetic apparatus caused by various chemical species have been extensively studied. The present chapter summarizes the published data concerning the toxicity of various organic and inorganic pollutants such as oils, pesticides, antifoulants and metals on photosynthesis of aquatic primary producers. Biochemical mode of action resulting in the disruption of photosynthesis depends on the chemical’s nature and the characteristics of the exposed microorganism. Observed differences in response and sensitivity by different species to the same toxicant were attributed to several algal characteristics including photosynthetic capacity, pigment type, cellular lipid and protein content, and cell size. Single species bioassays either for one chemical alone or in mixture have been well reported and tolerance of both marine and freshwater water-column phytoplaktonic species has been examined. Adequate published information on multispecies tests (communities) in laboratory and field studies exists. However, risk assessment on photosynthesis of microbenthic periphyton is inadequate, though it is essential especially for hydrophobic organic molecules. Further studies are required to evaluate the adverse effects of metabolites on aquatic microalgae

Toxic Effects of the Organophosphorus Insecticide Fenthion on Growth and Chlorophyll Production Activity of Unicellular Marine Microalgae Tetraselmis suecica: Comparison between Observed and Predicted Endpoint Toxicity Data

This chapter provides the results of a laboratory ecotoxicological study conducted to assess the acute toxicity of the organophosphorus pesticide fenthion toward the marine microalgal species Tetraselmis suecica. Bioassays were performed, and algal densities and chlorophyll pigments fractions were measured in the exponential phase after 96 h of exposure to fenthion. Two quantitative structure activity relationships (QSARs) were used to estimate the toxicity of 13 primary metabolites and degradation products of fenthion toward the selected organism; the first was based on the use of the n-octanol/water partition coefficient, whereas the second was based on the solubility of the compound in water. Results revealed that fenthion can have marked effects on the growth and photosynthesis of the target primary producers of marine ecosystems T. suecica. The parent pesticide toxicant was found not toxic to the tested algal species up to 1.00 mg L−1, while higher treatment concentrations not only affected algal densities and significantly decreased specific growth rate values (μ) (p < 0.05) but also decreased the contents of photosynthetic pigments. The comparison between the observed and the predicted toxicity values of the parent compound fenthion indicated that the predictive capability of the QSARs applied can be considered highly satisfactory. Consequently, both QSAR models were used for the prediction of toxicity data of fenthion’s principal metabolites and degradation products

Is the United States Claims Court Constitutional?

This article will deal with two major constitutional problems that have resulted from the creation of the Claims Court. The first issue is the constitutionality of the appointment of existing Court of Claims Commissioners to be judges on the Claims Court during a four-year transition period. By legislatively designating the persons who are to serve as judges on the new court, Congress has usurped the presidential appointment power. The second issue relates to the constitutional status of the Claims Court. The Court of Claims which it replaces was created under article III of the Constitution, and the judges on it were therefore entitled to life tenure and salaries that could not be reduced during their terms in office. The new Claims Court, on the other hand, is designated by Congress as an article I court; the judges are to be appointed for only fifteen year terms, and their salaries are subject to control by Congress. The new court exercises full judicial authority, however, and has jurisdiction over cases of national importance in which the government of the United States has a great financial stake. Although the analysis of this issue is far from simple, this author concludes that Congress has exceeded its constitutional authority by failing to comply with the requirements of article III of the Constitution in establishing the Claims Court

Perpetrating Cyber Dating Abuse: A Brief Report on the Role of Aggression, Romantic Jealousy and Gender

There is increasing evidence that the use of elec-tronic communication technology (ECT) is being integrated into romantic relationships, which can be used as a medium to control a romantic partner. Most research focuses on the vic-tims of cyber dating abuse, however, we focused on the factors that predict perpetration of cyber dating abuse. We explored whether aggression (verbal aggression, physical aggression, anger and hostility), romantic jealousy (emotional, cognitive and behavioral jealousy), and gender predicted perpetration of cyber dating abuse (n = 189). We found that hostility, behav-ioral jealousy and gender significantly predicted perpetration of cyber dating abuse. The findings of this study contribute to our understanding of the psychological factors that drive cyber dating abuse in romantic relationships

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 June 2021 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