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The increasing presence of plastics in the environment has raised concerns about their potential impact, especially as carriers of heavy metals such as Cd, Ni, and Pb. However, the adsorption mechanism of heavy metals on microplastics remains poorly understood. In this study, we investigated the adsorption behavior of Cd, Ni, and Pb by polystyrene (PS) and polypropylene (PP) microplastics to better comprehend their interaction and potential environmental implications. Our results revealed that equilibrium adsorption of microplastics with different heavy metals was achieved within a 6-h contact time. The FTIR analysis findings, which suggest that physical interactions play a significant role in the adsorption of heavy metals onto microplastics, are further supported by the observed changes in surface morphology after adsorption. We explored the influence of solution pH, contact duration, and initial concentration on the adsorption capacity and found significant effects on the adsorption behavior. To model the adsorption process, we applied Langmuir and Freundlich adsorption isotherm models and observed that the Langmuir model better fit the experimental data. Furthermore, we compared the pseudo-first and pseudo-second-order kinetic models and found that the pseudo-second-order model provided a more accurate description of the adsorption kinetics. Notably, the adsorption percentages varied depending on the type of microplastic and experimental conditions. Overall, this study enhances our understanding of the adsorption mechanism of heavy metals on microplastics and provides valuable insights into their behavior in aquatic environments. These findings have implications for the development of effective strategies for mitigating pollution caused by microplastics and heavy metals in aquatic ecosystems.

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This study presents the first set of data on the removal of proton pump inhibitors (PPIs) and histamine H2 receptor antagonists (HRAs) and their transformation products in two Romanian wastewater treatment plants (WWTPs), as well as the impact of these organic pollutants on freshwater receiving effluents. The research investigated eight target pharmaceuticals and three metabolites using a newly developed and validated Liquid Chromatography - Mass Spectrometry (LC-MS/MS) method. The combined determination had a range of quantification limits varying from 0.13 ng/L to 0.18 ng/L for surface water and from 0.28 ng/L to 0.43 ng/L for wastewater. All analytes except cimetidine and 5-hydroxy-omeprazole were identified in water samples. The study found similar overall removal efficiencies for both WWTPs (43.2 % for Galati and 51.7 % for Ramnicu-Valcea). The research also showed that ranitidine and omeprazole could pose a low to high ecological risk to aquatic organisms. The findings suggest that the treatment stages used in the two Romanian WWTPs are insufficient to remove the target analytes completely, leading to environmental risks associated with the occurrence of pharmaceutical compounds in effluents and freshwater.

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Azole compounds are utilized to combat fungal infections in plants to protect them and also used for treating mycosis in humans. The LC-MS/MS method is a technique that combines liquid chromatography with tandem mass spectrometry for analysis of twelve azole compounds from wastewater (influent, effluent) and sewage sludge. The compounds were isolated from waste water using automatic extraction in the solid phase. Sludge samples were dried by lyophilization, after which they were subjected to ultrasound extraction with methanol. The quantification limits ranged from 0.3 ng/L (clotrimazole-CLO and prochloraz-PRO) to 1.5 ng/L (tetraconazole-TEB and penconazole-PEN), for wastewater samples and for sewage sludge, the LOQs ranged from 0.1 ng/g to 0.6 ng/g. High concentrations of climbazole-CLI (207-391 ng/L), tebuconazole (92-424 ng/L), and clotrimazole (6.9-93-ng/L) were observed in influent samples of the 8 urban wastewater treatment plants, followed by fluconazole (49.3-76.8 ng/L), and prochloraz (7.3-72 ng/L). The ∑Azoles had a maximum of 676 ng/L in the Galati effluent, followed by the Bucharest station 357 ng/L, and 345 ng/L in the Braila effluent. The highest value of the daily mass loading (input) level was observed for climbazole, 265 mg/day/1000 in Iasi station, followed by tebuconazole, 238 mg/day/1000 people in the Bucharest station, and 203 mg/day/1000 people for climbazole in the Targoviste station. The daily mass emission presented values between 0.7 and 247 mg/day/1000 people. The highest emissions were observed for climbazole, 247 mg/day/1000 people in Braila station; 174 mg/day/1000 people in the Iasi station and 129 mg/day/1000 people in the Bucharest station. The concentrations of climbazole detected in the effluent can present a high risk for the plants Lemna minor and Navicula pelliculosa. Clotrimazole may present a high risk to the plant Desmodesmus subspicatus and to the invertebrate Daphnia magna. PRO may present high risk to the invertebrate Mysidopsis Bahia.

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The perfluoroalkyl substances (PFAS) represent a persistent class of synthetic chemicals that spread in the environment as a result of industrialization. Due to their bioaccumulative and endocrine disruption implications, these chemicals can affect food quality and human health, respectively. In the present study, the bioconcentration and biotransformation of perfluorooctanoic acid (PFOA) in common carp (Cyprinus carpio) were evaluated in a biphasic system (exposure and depuration). Carp were continuously exposed, under laboratory conditions, to 10 (Experiment 1) and 100 (Experiment 2) µg/L PFOA for 14 weeks, followed by a wash out period of 3 weeks. Fish organs and tissues were collected at 8, 12, 14 weeks of exposure and at week 17, after the depuration period. The results obtained from the LC-MS/MS analysis showed the presence of PFOA in all studied organs. The highest values of PFOA were identified in the gallbladder (up to 2572 ng/g d.w.) in Experiment 1 and in the gallbladder (up to 18,640 ng/g d.w.) and kidneys (up to 13,581 ng/g d.w.) in Experiment 2. The average BCF varied between 13.4 and 158 L/Kg in Experiment 1 and between 5.97 and 80.3 L/Kg in Experiment 2. Four biotransformation products were identified and quantified in all organs, namely: PFBA, PFPeA, PFHxA, and PFHpA. PFBA was proven to be the dominant biotransformation product, with the highest values being determined after 8 weeks of exposure in the kidney, gallbladder, brain, liver, and gonads in both experiments. Because freshwater fish are an important food resource for the human diet, the present study showed the fishes' capacity to accumulate perfluoroalkyl substances and their metabolites. The study revealed the necessity of monitoring and risk studies of new and modern synthetic chemicals in aquatic resources.

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Organophosphate ester flame retardants (OPFRs) are ubiquitous organic pollutants in the environment and present an important preoccupation due to their potential toxicity to humans and biota. They can be found in various sources, including consumer products, building materials, transportation industry, electronic devices, textiles and clothing, and recycling and waste management. This paper presents the first survey of its kind in Romania, investigating the composition, distribution, possible sources, and environmental risks of OPFRs in five wastewater treatment plants (WWTPs) and the rivers receiving their effluents. Samples from WWTPs and surface waters were collected and subjected to extraction processes to determine the OPFRs using liquid chromatography with mass spectrometric detection. All the target OPFRs were found in all the matrices, with the average concentrations ranging from 0.6 to 1422 ng/L in wastewater, 0.88 to 1851 ng/g dry weight (d.w.) in sewage sludge, and 0.73 to 1036 ng/L in surface waters. The dominant compound in all the cases was tri(2-chloroisopropyl) phosphate (TCPP). This study observed that the wastewater treatment process was inefficient, with removal efficiencies below 50% for all five WWTPs. The environmental risk assessment indicated that almost all the targeted OPFRs pose a low risk, while TDCPP, TCPP, and TMPP could pose a moderate risk to certain aquatic species. These findings provide valuable information for international pollution research and enable the development of pollution control strategies.

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This study investigated the occurrence and transport of four isothiazolinone-type biocides from commercial products to wastewater treatment plants (influents, sludges, and effluents) and to natural emissaries (upstream and downstream the wastewater treatment plants) in Romania. All four biocides were determined in personal care and household products, with the highest concentration of 76.4 µg/L OIT (2-octyl-4-isothiazolin-3-one). For environmental samples, three of the four isothiazolinones were determined, CMI (5-chloro-2-methyl-4-isothiazolin-3-one) being the prominent compound for water samples. The maximum concentration of 84.0 µg/L in influent, 122 µg/L upstream, and 144 µg/L downstream the wastewater treatment plants were obtained for CMI. Unlike water samples, in the sewage sludge samples, OIT proved to be the dominant compound, with concentration up to 5.80 µg/g d.w. The extremely high levels of isothiazolinone determined in different WWTPs from Romania may be due to the COVID-19 pandemic situation, during which a much larger amount of cleaning, hygiene, and personal care products was used. The isothiazolinone-type biocides were readily removed from the influents of the five WWTPs, with the mean removal rate up to 67.5%. The mean mass loading value for the targeted biocides based on influent was 20.4 µg/day/1000 people, while the average environmental emissions were 6.93 µg/day/1000 people for effluents. The results obtained for riverine water combine with statistical analysis showed that the anthropogenic activities are the major contamination sources of the surface waters. Preliminary ecological risk evaluation showed that BIT (1,2-benzisothiazol-3(2H)-one), OIT, and CMI could pose a very high risks to different aquatic species living in the receiving aquatic environments.

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Absorbable organic halogens (AOX) are a global parameter which refers to a group of chemical compounds that contain one or more chlorine, bromine or iodine atoms in their molecule and can easily adsorb on activated carbon. The global concern related to the occurrence of the AOX compounds in the environment is due to their toxic and mutagenic effects on aquatic organisms and their potential role as inhibitors of microorganism growth, even at AOX low concentrations. The purpose of this study was to analyze the presence, occurrence and composition of absorbable organic halogens in wastewater and sewage sludge. In addition, their genotoxicity effect on the environment was tested on a bacterial biological model. Daily mass loading, mass emission and fate of AOX parameter were investigated in two wastewater treatment plants (wastewater and sewage sludge samples) from Romania, Galati and Iasi. Their AOX daily mass loadings (151 and 55.4 g/day/1000people) and mass emissions into the environment (47.8 and 23.5 g/day/1000 people) for both locations were correlated with the concentration level of volatile organic compounds, chlorophenols, organochlorine pesticides and polychlorinated biphenyls from both wastewater and sewage sludge, respectively. Concentration levels of detected halogenated organic compounds (regulated by current standards) accounted only for a small percentage (3.70-14.5%) from the total AOX amount. An exception was observed in the case of dehydrated sludge samples where the identified compounds accounted for 80% of the AOX content from Iasi WWTP and 53% for Galati. Evaluating the genotoxic activity of AOX in sludge samples showed that genotoxicity was not induced up to 100 µg/mL dehydrated sludge.

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This study presents an adsorbent material (activated carbon) used in the treatment of wastewater with the role of removing ibuprofen, acetaminophen, diclofenac and ketoprofen pollutants. The wastewater treatment efficiencies of the activated carbon were systematically investigated using adsorption kinetics. The parameters studied were: pH (4 and 6 values of pH), initial concentration of wastewater (1, 5, and 10 mg/L), contact time (10 min), adsorbent quantity (0.1, 0.5, and 1 g), and isotherm models (Langmuir and Freundlich). The highest wastewater treatment efficiency was obtained at the 6 pH value. The determination of four anti-inflammatory drugs, frequently monitored in wastewater, was performed by a simple and fast method using the HPLC-technique-type DAD (diode array detector). The method was linear when the concentration ranged between 0.5 and 20 m/L for all compounds. The equilibrium concentration was obtained after 8 min. The octanol/water coefficient influenced the removal efficiency of the four drugs by the adsorbent material (activated carbon). The dose of activated carbon (0.1 to 1 g) significantly influenced the efficiency of wastewater treatment, which increased considerably when the dose of the adsorbent material increased. Using 1 g of the adsorbent material for the treatment of wastewater containing 1 mg/L initial concentration of pollutant compounds, the efficiencies were 98% for acetaminophen, 92% for diclofenac, 88% for ketoprofen and 96% for ibuprofen.

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As environment emerging contaminants of anthropogenic origin, antidiabetic drugs are present in the range of high ng/L to ng/mL in the influent and the effluent of the waste water treatment plant (WWTP). The metformin compound is the most used hypoglycemic agent in the world. The aim of this study was to develop a new analytic method, based on solid phase extraction followed by liquid chromatography coupled with mass spectrometric detector (SPE-LC-MS/MS), for identification and quantification of 5 antidiabetic compounds (glibenclamide/glyburide, glimepiride, metformin, glipizide, guanyl urea, gliclazide) and one degradation product (guanyl urea). The investigated environmental samples were the influent and the effluent of four urbans WWTP's. By validating of the analytical method, it was obtained low LOQ's (0.2-4.5 ng/L), satisfactory recovery rates (53.6-116.8%), and corresponding performance parameters: inter-day precision (4.9-8.4%) and reproducibility (11.3-14.6%). The concentrations of antidiabetics were as follow in influent and effluent: metformin 76-2041ng/L and 2-206ng/L, gliclazide (14.1-42.4 ng/L, and 3.3-19.1), glipizide (7.5-11.2 ng/L and 6.5-10ng/L), guanyl urea (6.2-7.3 and 8.3-21.3 ng/L). The efficiency of elimination of the antidiabetics in WWTP's was maximum for metformin (67.6-98.5%), followed, by gliclazide (72.9-78.2%). The lowest elimination efficiency was calculated for glipizide (10.7-13.3%). The guanyl urea undergoes a formation process (74.5-84.2%) in effluent, from the metformin contained in influent.

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A new acidophilic iron-oxidizing strain (C25) belonging to the novel genus Acidithrix was isolated from pelagic iron-rich aggregates ('iron snow') collected below the redoxcline of an acidic lignite mine lake. Strain C25 catalysed the oxidation of ferrous iron [Fe(II)] under oxic conditions at 25 °C at a rate of 3.8 mM Fe(II) day(-1) in synthetic medium and 3.0 mM Fe(II) day(-1) in sterilized lake water in the presence of yeast extract, producing the rust-coloured, poorly crystalline mineral schwertmannite [Fe(III) oxyhydroxylsulfate]. During growth, rod-shaped cells of strain C25 formed long filaments, and then aggregated and degraded into shorter fragments, building large cell-mineral aggregates in the late stationary phase. Scanning electron microscopy analysis of cells during the early growth phase revealed that Fe(III)-minerals were formed as single needles on the cell surface, whereas the typical pincushion-like schwertmannite was observed during later growth phases at junctions between the cells, leaving major parts of the cell not encrusted. This directed mechanism of biomineralization at specific locations on the cell surface has not been reported from other acidophilic iron-oxidizing bacteria. Strain C25 was also capable of reducing Fe(III) under micro-oxic conditions which led to a dissolution of the Fe(III)-minerals. Thus, strain C25 appeared to have ecological relevance for both the formation and transformation of the pelagic iron-rich aggregates at oxic/anoxic transition zones in the acidic lignite mine lake.

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A simple, sensitive and reliable HPLC-FLD method for the routine determination of 4-nonylphenol, 4-NP and 4-tert-octylphenol, 4-t-OP content in water samples was developed. The method consists in a liquid-liquid extraction of the target analytes with dichloromethane at pH  3.0-3.5 followed by the HPLC-FLD analysis of the organic extract using a Zorbax Eclipse XDB C8 column, isocratic elution with a mixed solvent acetonitrile/water 65:35, at a flow rate of 1.0 mL/min and applying a column temperature of 40°C. The method was validated and then applied with good results for the determination of 4-NP and 4-t-OP in Ialomita River water samples collected each month during 2006. The concentration levels of 4-NP and 4-t-OP vary between 0.08-0.17 µg/L with higher values of 0.24-0.37 µg/L in the summer months for 4-NP, and frequently <0.05 µg/L but also between 0.06-0.09 µg/L with higher values of 0.12-0.16 µg/L in July and August for 4-t-OP and were strongly influenced by sesonial and anthropic factors. The method was also applied on samples collected over 2 years 2007 and 2008 from urban wastewaters discharged into sewage or directly into the rivers by economic agents located in 30 Romanian towns. Good results were obtained when the method was used for analysis of effluents discharged into surface waters by 16 municipal wastewater treatment plants, during the year 2008.

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