Occurrence In Aquatic Environment Research Articles

Construction a flow through catalytic ozonation system with activated sludge based ceramsite for enhanced ibuprofen removal

Emerging contaminants had drawn much attention due to their ubiquitous occurrence in aquatic environment, and their potential negative effects. In this study, a flow catalytic ozonation system with activated sludge based ceramsite was established, and its catalytic performance was evaluated for degradation of ibuprofen (IBU). Firstly, the proportion of activated sludge and fly ash was 1:1 based on Reliy model for successfully preparation of ceramsite which could catalyze ozone to completely remove IBU within 10 min, while degradation ratio was just 19.9 % in ozonation system. The effects of operational conditions including initial concentration of IBU, ozone dosage, hydraulic retention time, and pH were considered to further verify the applicability of the system. The prepared ceramsite could not only enhance ozone dissolution, but also promote the decomposition of ozone to produce more •OH, which was contributed by metal ions active sites and surface hydroxyl groups. And the contribution of •OH for IBU degradation was about 95.3 % indicating that the •OH played an important role in degradation. The inorganic ions except CO32−/HCO3− and phosphates had less effect on catalytic performances. Furthermore, the degradation products and possible pathways were proposed. The catalytic ozonation system could effectively control the toxicity of the treatment solution. This study not only provided new ideas for resource utilization, but also provided advisable practice application of heterogeneous catalysts for dealing with wastewater.

Impact of COVID-19 pandemic on microplastic occurrence in aquatic environments: A three-year study in Taihu Lake Basin, China

The impact of the Coronavirus Disease 2019 (COVID-19) pandemic on microplastic (MP) occurrence in aquatic environments deserves an in-depth study. In this study, the occurrence of MPs and environmental flux of plastics before (2019) and during (2020 and 2021) the pandemic were comparatively investigated in various aquatic compartments in the Taihu Lake Basin in China. The field-based investigations from 2019 to 2021 for Taihu Lake have shown that, at the onset of the outbreak, the MP abundance declined at a rate of 62.3 %, but gradually recovered to the pre-pandemic level. However, the amount of plastics being released into aquatic environments showed a declining trend in 2020 and 2021 compared to those in 2019, with decrease rates of 13.7 % and 15.8 %, respectively. Characterization analysis of MP particles and source apportionment framework implied that while the contributions of tire abrasion and domestic waste to MP occurrence were depleted owing to the reduction in human activity during the pandemic, weathering and fragmentation of retained plastics contributed to the recovery of stored MPs. This study provides insights into the anthropogenic influences on MP occurrence, and supports policymakers in managing and controlling plastic contamination in large freshwater systems in the “new normal” phase.

Microplastics and 17α Ethinylestradiol: How Do Different Aquatic Invertebrates Respond to This Combination of Contaminants?

The synthetic hormone 17α ethinyl estradiol (EE2) is a molecule widely used in female contraceptives and recognized as a contaminant of attention (Watch List) in the European Union due to its high consumption, endocrine effects and occurrence in aquatic environments. Its main source of introduction is domestic sewage where it can be associated with other contaminants such as microplastics (MPs). Due to their characteristics, they can combine with each other and exacerbate their isolated effects on biota. This study evaluated the combined effects of microplastics (MPs) and 17α ethinylestradiol (EE2) on two tropical estuarine invertebrate species: Crassostrea gasar and Ucides cordatus. Polyethylene particles were spiked with EE2 and organisms were exposed to three treatments, categorized into three groups: control group (C), virgin microplastics (MPs), and spiked microplastics with EE2 (MPEs). All treatments were evaluated after 3 and 7 days of exposure. Oysters exhibited changes in phase 2 enzymes and the antioxidant system, oxidative stress in the gills, and reduced lysosomal membrane stability after exposure to MPs and MPEs. Crabs exposed to MPs and MPEs after seven days showed changes in phase 1 enzymes in the gills and changes in phases 1 and 2 enzymes in the hepatopancreas, such as disturbed cellular health. The combined effects of microplastics and EE2 increased the toxicity experienced by organisms, which may trigger effects at higher levels of biological organization, leading to ecological disturbances in tropical coastal ecosystems.

Pharmaceutical Contaminants in Wastewater and Receiving Water Bodies of South Africa: A Review of Sources, Pathways, Occurrence, Effects, and Geographical Distribution

The focus of this review article was to outline the sources, pathways, effects, occurrence, and spatial distribution of the most prescribed pharmaceuticals in wastewater and receiving waters of South Africa. Google Scholar, Web of Science, and Scopus were used to gather data from different regions. A zone-wise classification method was used to determine the spatial distribution and data deficiencies in different regions of South Africa. This review revealed that over 100 pharmaceutical compounds have been reported in South Africa’s various water sources and wastewater, with most studies and highest concentrations being documented in Gauteng and Kwa-Zulu Natal. The pharmaceutical concentration in water samples ranged from ng/L to µg/L. Aspirin, ketoprofen, diclofenac, ibuprofen, naproxen, erythromycin, tetracycline, sulfamethoxazole, acetaminophen, streptomycin, ciprofloxacin, ampicillin, carbamazepine, atenolol, pindolol, efavirenz, and zidovudine residues were among the frequently detected pharmaceutical residues in water bodies and wastewaters of South Africa. Based on the spatial distribution data, Gauteng has the highest number of pharmaceuticals (108) detected in waste and surface water, with the Northern Cape having no monitoring evidence. Therefore, to precisely ascertain the geographical distribution of pharmaceutical contaminants in South Africa, this review recommends that further research be carried out to track their occurrence in aquatic environments and WWTP, especially in isolated regions like Limpopo.

Embryonic Exposure to the Benzotriazole Ultraviolet Stabilizer 2-(2H-benzotriazol-2-yl)-4-methylphenol Decreases Fertility of Adult Zebrafish (Danio rerio).

Benzotriazole ultraviolet stabilizers (BUVSs) are emerging contaminants of concern. They are added to a variety of products, including building materials, personal care products, paints, and plastics, to prevent degradation caused by ultraviolet (UV) light. Despite widespread occurrence in aquatic environments, little is known regarding the effects of BUVSs on aquatic organisms. The aim of the present study was to characterize the effects of exposure to 2-(2H-benzotriazol-2-yl)-4-methylphenol (UV-P) on the reproductive success of zebrafish (Danio rerio) following embryonic exposure. Embryos were exposed, by use of microinjection, to UV-P at <1.5 (control), 2.77, and 24.25 ng/g egg, and reared until sexual maturity, when reproductive performance was assessed, following which molecular and biochemical endpoints were analyzed. Exposure to UV-P did not have a significant effect on fecundity. However, there was a significant effect on fertilization success. Using UV-P-exposed males and females, fertility was decreased by 8.75% in the low treatment group and by 15.02% in the high treatment group relative to control. In a reproduction assay with UV-P-exposed males and control females, fertility was decreased by 11.47% in the high treatment group relative to the control. Embryonic exposure to UV-P might have perturbed male sex steroid synthesis as indicated by small changes in blood plasma concentrations of 17β-estradiol and 11-ketotestosterone, and small statistically nonsignificant decreases in mRNA abundances of cyp19a1a, cyp11c1, and hsd17b3. In addition, decreased transcript abundances of genes involved in spermatogenesis, such as nanos2 and dazl, were observed. Decreases in later stages of sperm development were observed, suggesting that embryonic exposure to UV-P impaired spematogenesis, resulting in decreased sperm quantity. The present study is the first to demonstrate latent effects of BUVSs, specifically on fish reproduction. Environ Toxicol Chem 2024;43:385-397. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Aqueous oxidation of bisphenol analogues by ozone: Relevance of substituents on reactivity

In recent years, bisphenol A has been progressively replaced by other bisphenol analogues, leading to an increase of their occurrence in aquatic environments. However, limited data is available regarding their removal through oxidation treatments, such as ozonation. In this work, the reactivity of ozone with seven novel bisphenol A substitutes (bisphenol E, bisphenol B, bisphenol AF, bisphenol C, bisphenol AP, bisphenol Z and bisphenol C-Cl) was studied over a wide range of pH by competition kinetics. The second-order rate constants of ozone were determined for their protonated species (k1, k2 and k3), together with their pH-dependent reactivity profile. High and similar reactivity of ozone with all bisphenols was distinguished at basic pH (k3 = 8.83×108 - 1.39×109 M−1 s−1). This reactivity decreased at neutral pH, although it remained comparable for all bisphenols (kapp = 2×106 - 5×106 M−1 s−1). In contrast, the even lower reactivity observed at acidic pH exhibited significant variations between them (k1 = 1.54×102 - 1.22×105 M−1 s−1), due to the influence of the different functional groups, as their behaviour as electron-donating or electron-withdrawing moieties strongly govern their reactivity with ozone. Additionally, the oxidation products resulting from the reaction of ozone with bisphenols at neutral pH were also assessed. The generation of catechol derivatives was suggested as the primary degradation pathway for the majority of bisphenols. Other oxidation products were also commonly detected, such as ortho-quinone derivatives, ring opening products and simple phenolic fragments.

Analysis of ultrashort-chain and short-chain (C1 to C4) per- and polyfluorinated substances in potable and non-potable waters

Ultrashort-chain (USC) per- and polyfluoroalkyl substances (PFAS) are small and very polar compounds with carbon chain lengths of less than C4. Their ubiquitous occurrence in aquatic environments has become a major concern in parallel to long chain PFAS contamination. The high polarity of USC PFAS challenges current analytical practices based on reversed-phase liquid chromatography due to insufficient chromatographic retention. In this study, a fast and reliable LC-MS/MS method was developed for the analysis of C1 to C4 PFAS including trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), perfluorobutanoic acid (PFBA), trifluoromethanesulfonic acid, perfluoroethanesulfonic acid, perfluoropropanesulfonic acid, and perfluorobutanesulfonic acid utilizing a hybrid HILIC/ion exchange column. Three different water samples (tap water, bottled spring water, sewage treatment wastewater) were chosen for method validation to demonstrate the applicability of developed analytical method for the measurement of C1 to C4 PFAS in both potable and non-potable waters. A direct injection workflow was evaluated by accuracy and precision analysis of fortified water samples. Accurate quantification was achieved using calibration standards prepared in reverse osmosis water at the range of 20 to 800 ng/L for TFA, 5.0 to 800 ng/L for PFPrA and PFBA, and 2.5 to 800 ng/L for sulfonic acid PFAS. The average recoveries of fortified samples among three water samples were from 86.6% to 107%, and the relative standard deviation ranged from 1.62% to 10.7%. Additional drinking waters and wastewaters collected from various source waters were tested to further demonstrate that the established workflow is suitable for accurate quantification of C1 to C4 PFAS in a variety of water matrices.

Effects of Commercial Sunscreens on Survival, Reproduction and Embryonic Development of the Aquatic Snail Biomphalaria glabrata (SAY, 1818).

Over the past few years, there has been a significant increase in the use of sunscreens. Consequently, the occurrence in aquatic environments of ultraviolet filters has also increased. The present study aims to evaluate the toxicity of two commercial sunscreens to the aquatic snail Biomphalaria glabrata. Acute assays were performed with adult snails exposed to solutions of the two products in synthetic soft water. Reproduction and development assays were carried out, involving individual adult and egg masses exposure to assess fertility and embryonic development. Sunscreen A showed a LC50-96h of 6.8g/L and reduction in number of eggs and egg masses per individual in the concentration of 0.3g/L. Sunscreen B presented higher malformation rates in 0.4g/L with 63% of malformed embryos. Results indicate that the formulation used in sunscreens is an important factor in aquatic toxicity and needs to be evaluated before the final product is commercialized.

Recognition, possible source, and risk assessment of organic pollutants in surface water from the Yongding River Basin by non-target and target screening

Organic pollutants in aquatic environment could have important implications on pollution stress on aquatic organisms and even on the risk of human exposure. Thus, revealing their occurrence in aquatic environment is essential for water quality monitoring and ecological risk purposes. In this study, a comprehensive two-dimensional gas chromatography connected with time-of-flight mass spectrometry (GC × GC-TOF-MS) was applied, to enable non-target and target analysis of pollutants in the Yongding River Basin. Based on the isotopic patterns, accurate masses and standard substances, certain environmental contaminants were tentatively identified which including polycyclic aromatic hydrocarbon (PAHs), organochlorine pesticides (OCPs), phenols, amines, etc. The compounds with the highest concentration were naphthalene (109.0 ng/L), 2,3-benzofuran (51.5 ng/L) and 1,4-dichlorobenzene (35.9 ng/L) in Guishui River. Wastewater treatment plants (WWTPs) discharges were a main source of pollutants in Yongding River Basin, as the types of compounds screened in the downstream river were relatively similar to those from WWTPs. According to the target analysis, a number of pollutants were selected due to the acute toxicity and cumulative discharge from WWTPs and downstream rivers. Three PAHs (naphthalene, Benzo(b)fluoranthene and pyrene) homologues showed moderate risk to fish and H. Azteca in Yongding River Basin, while the rest of the measured chemicals showed low ecological impact across the entire study area based on the risk assessment. The results are helpful for understanding the necessity of high-throughput screening analysis for assessing water quality of rivers and the discharge emissions of pollutants from WWTPs to the river environment.

Untargeted Metabolomics Reveals Antidepressant Effects in a Marine Photosynthetic Organism: The Diatom Phaeodactylum tricornutum as a Case Study.

The increased use of antidepressants, along with their increased occurrence in aquatic environments, is of concern for marine organisms. Although these pharmaceutical compounds have been shown to negatively affect marine diatoms, their mode of action in these non-target, single-cell phototrophic organisms is yet unknown. Using a Fourier-transform ion cyclotron-resonance mass spectrometer (FT-ICR-MS) we evaluated the effects of fluoxetine in the metabolomics of the model diatom Phaeodactylum tricornutum, as well as the potential use of the identified metabolites as exposure biomarkers. Diatom growth was severely impaired after fluoxetine exposure, particularly in the highest dose tested, along with a down-regulation of photosynthetic and carbohydrate metabolisms. Notably, several mechanisms that are normally down-regulated by fluoxetine in mammal organisms were also down-regulated in diatoms (e.g., glycerolipid metabolism, phosphatidylinositol signalling pathway, vitamin metabolism, terpenoid backbone biosynthesis and serotonin remobilization metabolism). Additionally, the present work also identified a set of potential biomarkers of fluoxetine exposure that were up-regulated with increasing fluoxetine exposure concentration and are of high metabolic significance following the disclosed mode of action, reinforcing the use of metabolomics approaches in ecotoxicology.

Occurrence and distribution of triclosan and its transformation products in Taihu Lake, China.

The transformation products of triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) may be more persistent and toxic than their parent compound, yet their occurrence in aquatic environments is poorly understood. In this study, we identified three transformation products in sediment samples from Taihu Lake and compared their concentrations with the parent compound triclosan. Triclosan in Taihu Lake was at low level, ranging from 0.086 to 1.1 ng/L in surface water and 0.0058-8.3 ng/g in sediments. The three detected transformation products included methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives. Those transformation products constituted 0.73-87.5% of the total triclosan (total triclosan is the sum of triclosan, methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives on a molar basis), indicating that the ecological risk of transformation products should be considered in addition to the parent compound. Different transformation products had distinct spatial distributions. Chlorinated triclosan derivatives had the highest concentration in samples from the northwest region (0.016-0.21 ng/g) of the lake and were positively correlated with triclosan, which may indicate the possible transformation from triclosan to chlorinated triclosan derivatives. Methyl triclosan and methyl chlorinated triclosan derivatives were generally higher in samples from the center of the lake (0.22-0.28 ng/g for methyl triclosan and 0.017-0.021 ng/g for methyl chlorinated triclosan derivatives, respectively), indicating the possible occurrence of in situ microbial methylation of triclosan and chlorinated triclosan derivatives and the accumulation of those methylated analogues in Taihu Lake.

Toxicity of bisphenol A and its structural congeners to microalgae Chlorella vulgaris and Desmodesmus armatus

Bisphenol A and its structural congeners are increasingly recognized as emerging contaminants with toxic and estrogenic potential that have been widely used in many consumer products. Due to their widespread occurrence in aquatic environment, they could pose risks to the primary producers, such as microalgae. Therefore, the objective of this study was to examine the toxicity of bisphenol A, its six structural congeners, and their mixture towards the green algae Chlorella vulgaris and Desmodesmus armatus. Bisphenol A (average 14 days, EC50: 42.29 mg L−1) exhibited less harmful effect than structural congeners, such as bisphenol AF, bisphenol G, bisphenol X for C. vulgaris (average 14 days, EC50: 22.39 mg L−1) and bisphenol AF, bisphenol G, bisphenol M, bisphenol X for D. armatus (average 14 days, EC50: 27.16 mg L−1), respectively. Moreover, exposure to combined bisphenol A and its structural congeners leads to synergistic effects. Thus, the increased adverse effect caused by complex chemical mixture poses a greater risk to microalgae. The order of toxic effect (14 days, EC50) of individual and combined structural congeners was: bisphenol G > bisphenol X > mixture > bisphenol AF > bisphenol A > bisphenol Y > bisphenol M > bisphenol P for C. vulgaris and mixture > bisphenol G > bisphenol X > bisphenol M > bisphenol AF > bisphenol A > bisphenol Y > bisphenol P for D. armatus, respectively. This is the first time that the toxicity of structural congeners of bisphenol A and its mixture to microalgae is described. Furthermore, these results were conducted to assess potential ecological risk of these compounds in the aquatic environment.

Ecotoxicity of losartan potassium in aquatic organisms of different trophic levels

The intensive use of the antihypertensive losartan potassium (LOS) has culminated in its high occurrence in aquatic environments. However, insufficient studies had investigated its effects in non-target organisms. In this study, ecotoxicity of LOS was assessed in aquatic organisms from distinct trophic levels (Desmodesmus subspicatus, Daphnia magna, and Astyanax altiparanae). Genotoxicity was assessed by the comet assay in D. magna and A. altiparanae, and biochemical biomarkers for the fish. LOS was more toxic to D. subspicatus (EC50(72h) = 27.93 mg L−1) than D. magna (EC50 = 303.69 mg L−1). Subsequently, this drug showed to induce more DNA damage in D. magna than A. altiparanae, when exposed to 2.5 mg L−1. No significant stress responses were observed by the fish biomarkers, suggesting that higher trophic levels organisms are more tolerant to LOS toxicity. LOS showed relatively low toxic potential for a short period of exposure, but with different patterns of toxicity for the organisms from distinct trophic levels, contributing to further risk assessment of LOS.

Perfluorooctane Sulfonate in US Ambient Surface Waters: A Review of Occurrence in Aquatic Environments and Comparison to Global Concentrations

Perfluorooctane sulfonate (PFOS) is one of the dominant perfluoroalkyl substances (PFAS) detected in aquatic ecosystems. It has been used in a wide range of industrial and consumer products for decades. The unique properties of PFOS, including its stability and resistance to degradation, have made it highly persistent in the aquatic environment. Because of its persistence, potential toxicity, and occurrence in aquatic ecosystems, interest in PFOS has increased in recent decades. Despite this interest, current information on the environmental distribution of PFOS in ambient surface waters of the United States is fairly limited. This critical review summarizes the currently available literature on PFOS occurrence in surface waters across the United States and highlights existing data gaps. Available data are largely from a handful of study areas with known PFAS manufacturing or industrial uses, with much of the data collected from freshwater systems in eastern states and the upper Midwest. Measured PFOS concentrations in surface waters vary widely, over 8 orders of magnitude, with the highest concentrations occurring downstream from manufacturing and industrial use plants, areas near aqueous film-forming foam-use sites, and sites where PFOS precursors were used in textile treatment. Non-point source-related occurrences are highest near urbanized areas with high population densities. Current data illustrate the occurrence of PFOS in surface waters across multiple US states. Additional data are needed to better understand PFOS occurrence in US aquatic ecosystems, particularly in estuarine and marine systems and where monitoring data are not available (e.g., southwestern, central, and western United States). Additional PFOS occurrence data would provide valuable information on potential spatial and temporal variability in surface waters and possible risks posed to aquatic ecosystems. Environ Toxicol Chem 2021;40:2425-2442. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

Bioaccumulation, Metabolism, and Biomarker Responses in Hyriopsis cumingii Exposed to 4‐Mono‐Chlorinated Dibenzothiophene

Polychlorinated dibenzothiophenes (PCDTs) are sulfur analogues of polychlorinated dibenzofurans with prevalent occurrence in aquatic environments and potential ecological risks. However, data on the behavior and toxicity of PCDTs in aquatic organisms remain scarce. In the present study, the bioaccumulation, metabolism, and oxidative damage of 4-mono-chlorinated dibenzothiophene (4-mono-CDT) in freshwater mussel (Hyriopsis cumingii) were investigated after exposure to 4-mono-CDT in semistatic water. The uptake rates, depuration rates, half-lives, and bioconcentration factors of 4-mono-CDT in hepatopancreas, gill, and muscle tissues ranged from 0.492 to 1.652 L d-1 g-1 dry weight, from 0.117 to 0.308 d-1 , from 2.250 to 5.924 d, and from 2.903 to 8.045 × 103 L kg-1 dry weight, respectively. A dechlorinated metabolite (dibenzothiophene) was detected in hepatopancreas tissue, indicating that dechlorination was the main metabolic pathway of 4-mono-CDT. As the exposure time increased, the activities of superoxide dismutase, catalase, and glutathione peroxidase were induced or inhibited in the different experimental groups. The malondialdehyde content increased with increasing 4-mono-CDT dose and exposure time. A higher concentration of 4-mono-CDT corresponded to a greater integrated biomarker response in each tissue and greater oxidative damage. The antioxidant enzymes in hepatopancreas were more sensitive to 4-mono-CDT than those in gill. The results provide useful information on the behavior and ecotoxicity of PCDTs in freshwater mussels. Environ Toxicol Chem 2021;40:1873-1882. © 2021 SETAC.

How Ulva lactuca can influence the impacts induced by the rare earth element Gadolinium in Mytilus galloprovincialis? The role of macroalgae in water safety towards marine wildlife

Rare earth elements (REEs) are gaining growing attention in environmental and ecotoxicological studies due to their economic relevance, wide range of applications and increasing environmental concentrations. Among REEs, special consideration should be given to Gadolinium (Gd), whose wide exploitation as a magnetic resonance imaging (MRI) contrast agent is enhancing the risk of its occurrence in aquatic environments and impacts on aquatic organisms. A promising approach for water decontamination from REEs is sorption, namely through the use of macroalgae and in particular Ulva lactuca that already proved to be an efficient biosorbent for several chemical elements. Therefore, the present study aimed to evaluate the toxicity of Gd, comparing the biochemical effects induced by this element in the presence or absence of algae. Using the bivalve species Mytilus galloprovincialis, Gd toxicity was evaluated by assessing changes on mussels’ metabolic capacity and oxidative status. Results clearly showed the toxicity of Gd but further revealed the capacity of U. lactuca to prevent injuries to M. galloprovincialis, mainly reducing the levels of Gd in water and thus the bioaccumulation and toxicity of this element by the mussels. The results will advance the state of the art not only regarding the effects of REEs but also with regard to the role of algae in accumulation of metals and protection of aquatic organisms, generating new insights on water safety towards aquatic wildlife and highlighting the possibility for resources recovery.

TOXIC EFFECT OF PHARMACEUTICALS WITH REFERENCE TO OXYTETRACYCLINE

Manufacturing and release of pharmaceuticals are increasing in different countries of the world especially in developing countries. The discharge from wastewater plant contains a wide range of classes of pharmaceuticals. Rapidly growing economy, aquaculture, and livestock industry has led to increased incidences of diseases and has increased the release of pharmaceuticals into natural environment which is affecting the biodiversity of hotspots adversely. This review mainly focuses on antibiotic oxytetracycline, its use, structure, occurrence in aquatic environments and other environmental compartments, lastly an overview of toxicity to fish is provided. The threats posed by these pharmaceuticals are evident from the studies showing their toxic effect on different aquatic organisms.

The Problem of Phthalate Occurrence in Aquatic Environment

This review has four major objectives: I) to present the problem of phthalate pollution, II) to highlight common techniques for quantification of phthalate compounds in &lt;br /&gt; water, III) to summarize current trends in determination of phthalates toxicity and point &lt;br /&gt; out the major adverse effects, and IV) to discuss and critically compare modern approaches in purification of phthalate-polluted water samples and thus reveal the further &lt;br /&gt; perspectives. Phthalates are organic compounds that are used extensively as additives in &lt;br /&gt; plastics and personal care products. They have high leaching potential and, therefore, &lt;br /&gt; they have been detected in various environments, including aquatic environments. Concentrations of phthalates in water are generally low, so their determination usually requires preconcentration. However, phthalates are compounds with very high hazardous &lt;br /&gt; potential. Related toxicity studies have been focused mainly on long-term exposures, and &lt;br /&gt; the results have shown that phthalates mainly affect the endocrine and reproductive systems. Therefore, phthalates have become a global concern. Their removal from the environment not only ensures environmental protection, but the protection of human health as well. Among various presented approaches for phthalates removal, anaerobic biodegradation has shown the highest potential for further developments because it is a promising technology for using wastewater as a source of green energy.

Literature Review: Global Neonicotinoid Insecticide Occurrence in Aquatic Environments

Neonicotinoids have been the most commonly used insecticides since the early 1990s. Despite their efficacy in improving crop protection and management, these agrochemicals have gained recent attention for their negative impacts on non-target species such as honeybees and aquatic invertebrates. In recent years, neonicotinoids have been detected in rivers and streams across the world. Determining and predicting the exposure potential of neonicotinoids in surface water requires a thorough understanding of their fate and transport mechanisms. Therefore, our objective was to provide a comprehensive review of neonicotinoids with a focus on their fate and transport mechanisms to and within surface waters and their occurrence in waterways throughout the world. A better understanding of fate and transport mechanisms will enable researchers to accurately predict occurrence and persistence of insecticides entering surface waters and potential exposure to non-target organisms in agricultural intensive regions. This review has direct implications on how neonicotinoids are monitored and degraded in aquatic ecosystems. Further, an improved understanding of the fate and transport of neonicotinoids aide natural resource practitioners in the development and implementation of effective best management practices to reduce the potential impact and exposure of neonicotinoids in waterways and aquatic ecosystems.

Toxicity evaluation and by-products identification of triclosan ozonation and chlorination

Triclosan (TCS) has attracted increasing concern due to its ubiquitous occurrence in aquatic environments as well as its potential adverse effects on human health. This study investigated the toxicity and transformation characteristics of triclosan ozonation and chlorination. The results showed that two hydroxylated by-products were formed via nucleophilic substitution during ozonation, while three chlorinated compounds were generated via electrophilic substitution during chlorination. The toxicity results demonstrated that the parent compound, triclosan, exhibited mild genotoxicity and anti-estrogenic activity. The chlorination of triclosan resulted in a 30-fold increase in anti-estrogenic activity owing to the generation of toxic polychlorinated transformation by-products. In addition, the chlorination by-products were found to be genotoxic like the parent compound. Fortunately, in contrast to chlorination, ozonation could mitigate the genotoxicity and anti-estrogenic activity of triclosan-containing water.