Excessive nitrogen and phosphorus inputs have long been regarded as the primary drivers of algal blooms. However, as blooms become increasingly widespread, microelements such as iron and manganese (Mn) have attracted increasing attention for their regulatory roles in algal growth. As an essential micronutrient for algal development, Mn exhibits substantial variability in aquatic environments, which points to its potential involvement in algal blooms. Herein, this study investigated the regulatory mechanism of Mn on algal growth and the feedback effect of algae on the biogeochemistry of Mn by manipulating Mn concentrations. The results revealed that Mn was involved in multiple metabolic pathways in Microcystis aeruginosa, including carbon, nitrogen, sulfur, and iron metabolism. Mn deficiency inhibited electron transport, nitrogen assimilation, and the tricarboxylic acid cycle, while genes related to ferroptosis, fatty acid, and pyruvate metabolism were upregulated. Notably, Mn levels significantly affected the composition and chemical characteristics of algal organic matter, leading to increased photoreactivity at higher concentrations. Additionally, protein-mediated Mn complexation enabled Mn to temporarily persist as protein complexes both intracellularly and extracellularly, whose subsequent release facilitated the indirect phototransformation of pollutants. These findings offer new insights into the relationship between algal bloom and Mn in eutrophic waters.

Algal organic matter (AOM) originates from algal metabolism or the decomposition and release of intracellular substances, constituting a primary component of natural dissolved organic matter in eutrophic water with algal blooms. Recently, researches have increasingly focused on the high reactivity of AOM in complexation, photosensitization, and electron transfer processes. AOM has been suggested as a key player in the fate of contaminants and the biogeochemical cycle of aquatic environments. However, the understanding of the migration and transformation of AOM and its association with water eutrophication remains fragmentary. This study systematically reviewed the photosensitivity, bioavailability, and heterogeneity in molecular characteristics of AOM. It summarized the relationships between AOM and the macro- and micronutrients essential for maintaining normal physiological functions of algae during eutrophic algal blooms. Specifically, the constituents and physicochemical attributes of AOM are closely correlated with the algal species, growth stages, and nutrients. AOM can modulate nitrogen and phosphorus fluxes in sediments and the cycling of iron and manganese, thereby providing conditions for the sustainable algal blooms. Moreover, the contaminant assimilative capacity of eutrophic waters is enhanced due to photosensitization and redox conversion of micronutrients, which are regulated by AOM. The investigation on the properties and environmental behavior of AOM is expected to further clarify the causes of lake eutrophication and internal cycling mechanisms, aiding the integrated management of lake environments.

Microbial-derived extracellular polymeric substances (EPS) and iron minerals are ubiquitous in aquatic environments, and they can influence the fate of organic micropollutants such as 17α-ethinylestradiol (EE2). However, the interactions between EPS and iron minerals, and their influence on EE2 photodegradation, are seldom addressed in the literature. This study explored the effects of EPS derived from different aerobic or anaerobic microbials on the reductive dissolution of ferrihydrite (Fhy) and subsequent EE2 photodegradation, with emphasis on the impact of Fe-EPS complexes formation. In the dark, EPS could promote the reductive dissolution of Fhy via ligand-metal charge transfer, accompanied by Fe(III)-EPS complexes formation. Irradiation could further enhance such a dissolution process. Dissolved iron could accelerate the photolysis of protein and humic substances, triggering Maillard-like reactions that form the unsaturated medium- or high-molecular-weight polymers. The aerobic-EPS containing more proteins and humic substances photodegraded EE2 more effectively than anaerobic-EPS, with the triplet excited state playing a crucial role. In contrast, Fhy inhibited EPS-mediated EE2 photodegradation via light-shielding effect or photosensitizers oxidative decomposition. The information obtained in this research would contribute to the understanding of photochemistry involving EPS, iron minerals, and steroid estrogens, providing new insights into their environmental behavior.

Natural organic matter, also named ‘humic substances’, refers mainly to dead, partly macromolecular, organic compounds occurring in waters, soils, sediments and organic waste. Natural organic matter represents a major global carbon pool influencing many processes such as climate change, food production and environmental pollution, yet its molecular structure, dynamics and fate are poorly known. Here we the compare methods for the analysis of natural organic matter, such as nuclear magnetic resonance, ultraviolet–visible spectroscopy, fluorescence spectroscopy, Fourier transform-infrared spectroscopy, size exclusion chromatography, and mass spectrometry. We detail principal component analysis, principal coordinate analysis, hierarchical cluster analysis, parallel factor analysis, two-dimensional correlation analysis, and advanced coupled matrix tensor factorization.

The limited effectiveness of conventional water treatment processes for the remediation of per- and polyfluoroalkyl substances (PFAS) contaminated water has triggered intense investigation into alternative advanced and novel technologies. We employed high frequency ultrasound irradiation to mineralize a number of legacy and emerging PFAS. The produced fluoride ion concentrations increased linearly with reaction time regardless of experimental conditions for ten PFAS species (including perfluoroalkyl carboxylic acid (PFCAs), ether-based PFCAs, and sulfonates PFAS), at concentrations up to 50 mu M, with the use of landfill leachate as a background matrix, or in the presence of inorganic salts or other constituents such as alcohols and different sparging gases. Pyrolysis at or near the gas-liquid interface or within gas phase is proposed as the major pathway for PFAS mineralization. Based on identified products for GenX species (HFPO-DA, and its homologues HFPO-TA and HFPO-TeA), we propose the initial degradation occurs via homolytic cleavage of weaker C-O bonds, with contributions from HO center dot and H center dot in subsequent reactions. The minor products suggest the involvement of C-C cleavage pathways as well as the production and participation of other radical species. Fluorine mass balance at three hours of ultrasound treatment showed degradation of 49.6 % of 10 mu M HFPO-TeA with 87.4 % being fully converted into fluoride ion. The results demonstrate (1) ultrasonic irradiation leads to effective mineralization of PFAS concentrates over a broad range of water quality conditions; and (2) significant mineralization of PFAS with minimal fluoro-organic products could be achieved under appropriate conditions.

The dissolved organic matter in initial rainwater (RDOM), including soil-dissolved organic matter (SDOM) and water-soluble organic matter (WSOM) in the atmosphere, can potentially mediate the migration and transformation of contaminants in natural water. However, researches on its sources, characteristics, and impact of environmental factors are limited. This study aims to investigate the main sources of RDOM and its properties influenced by environmental factors (such as light exposure and temperature variation). The results revealed that RDOM was mainly composed of SDOM. Temperature (–5°C, −20°C, temperature alternating, 40°C, 50°C, 60°C) induced the variation of SDOM components, altering its fluorescence characteristics, aromatic components, and hydrophobicity. And high temperature showed a more pronounced effect on SDOM components. However, temperature fluctuations had different impacts on the SDOM-mediated photodegradation of bisphenol A (BPA). Among them, only SDOM that had undergone freeze-thaw cycles exhibited a promotive effect on the photodegradation of BPA, with the most significant effect observed at −20°C. Illumination (ultraviolet light (UV) and natural light (NL)) consumed the chromophoric groups of SDOM, disrupted its intricate electron transfer structure, and reduced the production of •OH and Triplet-state dissolved organic matter (3DOM∗). So, illumination, especially UV, significantly weakened its mediating effect on the photodegradation of BPA. Based on these findings above, RDOM through temperature increase and illumination potentially leads to an inhibition of the degradation rate of organic pollutants. Conversely, RDOM may exhibit an enhanced ability following a freeze-thaw process. This study is crucial for elucidating the environmental effects of RDOM.

Reductive dissolution of manganese oxide (MnOx) is a major process that improves the availability of manganese in natural aquatic environments. The extracellular organic matter (EOM) secreted by algae omnipresent in eutrophic waters may affect MnOx dissolution thus the fate of organic micropollutants. This study investigates the mechanisms of MnOx reductive dissolution mediated by EOM and examines the effects of this process on 17α-ethinylestradiol degradation. The influences of EOM concentration (1.0-20.0 mgC/L) and pH (6.0-9.0) in both dark and irradiated conditions were assessed. In the dark, EOM was found to facilitate MnOx reductive dissolution via the ligand-to-metal charge transfer (LMCT). The dissolution was further enhanced under irradiation, with the participation of superoxide ions (O2•-). Higher EOM concentrations increased the contents of available reducing substances and O2•-, accelerating the reductive dissolution. Higher pH slowed the photoreductive dissolution rates, while O2•--mediated reduction became more important. Polyphenols and highly unsaturated carbon and phenolic formulas in EOM were found to drive the reductive dissolution. Soluble reactive Mn(III) formed through reductive dissolution of MnOx effectively removed 17α-ethinylestradiol in solution. Overall, the findings regarding the mechanisms behind reductive dissolution of MnOx have broad implications for Mn geochemical cycles and organic micropollutant fate.

Photosensitizer-mediated abiotic oxidation of Mn(II) can yield soluble reactive Mn(III) and solid Mn oxides. In eutrophic water systems, the ubiquitous algal extracellular organic matter (EOM) is a potential photosensitizer and may have a substantial impact on the oxidation of Mn(II). Herein, we focused on investigating the photochemical oxidation process from Mn(II) to solid Mn oxide driven by EOM. The results of irradiation experiments demonstrated that the generation of Mn(III) intermediate was crucial for the successful photo oxidization of Mn(II) to solid Mn oxide mediated by EOM. EOM can serve as both a photosensitizer and a ligand, facilitating the formation of the Mn(III)-EOM complex. The complex exhibited excellent efficiency in removing 17α-ethinylestradiol. Furthermore, the complex underwent decomposition as a result of reactions with reactive intermediates, forming a solid Mn oxide. The presence of nitrate can enhance the photochemical oxidation process, facilitating the conversion of Mn(II) to Mn(III) and then to solid Mn oxide. This study deepens our grasp of Mn(II) geochemical processes in eutrophic water and its impact on organic micropollutant fate.

BackgroundChildren are vulnerable to environmental exposure of contaminants due to their small size, lack of judgement skills, as well as their proximity to dust, soil, and other environmental sources. A better understanding about the types of contaminants that children are exposed to or how their bodies retain or process these compounds is needed.ObjectiveIn this study, we have implemented and optimized a methodology based on non-targeted analysis (NTA) to characterize chemicals in dust, soil, urine, and in the diet (food and drinking water) of infant populations.MethodsTo evaluate potential toxicological concerns associated with chemical exposure, families with children between 6 months and 6 years of age from underrepresented groups were recruited in the greater Miami area. Samples of soil, indoor dust, food, water, and urine were provided by the caregivers, prepared by different techniques (involving online SPE, ASE, USE, QuEChERs), and analyzed by liquid chromatography-high resolution mass spectrometry (LC-HRMS). Data post-processing was performed using the small molecule structure identification software, Compound Discoverer (CD) 3.3, and identified features were plotted using Kendrick mass defect plot and Van Krevelen diagrams to show unique patterns in different samples and regions of anthropogenic compound classifications.ResultsThe performance of the NTA workflow was evaluated using quality control standards in terms of accuracy, precision, selectivity, and sensitivity, with an average of 98.2%, 20.3%, 98.4% and 71.1%, respectively. Sample preparation was successfully optimized for soil, dust, water, food, and urine. A total of 30, 78, 103, 20 and 265 annotated features were frequently identified (detection frequency >80%) in the food, dust, soil, water, and urine samples, respectively. Common features detected in each matrix were prioritized and classified, providing insight on children's exposure to organic contaminants of concern and their potential toxicities.Impact statementCurrent methods to assess the ingestion of chemicals by children have limitations and are generally restricted by specific classes of targeted organic contaminants of interest. This study offers an innovative approach using non-targeted analysis for the comprehensive screening of organic contaminants that children are exposed to through dust, soil, and diet (drinking water and food).

Per- and polyfluoroalkyl substances (PFAS) are a group of anthropogenic pollutants that are found ubiquitously in surface and drinking water supplies. Due to their persistent nature, bioaccumulative potential, and significant adverse health effects associated with low concentrations, they pose a concern for human and environmental exposure. With the advances in high-resolution mass spectrometry (HRMS) methods, there has been an increasing number of non-targeted analysis (NTA) approaches that allow for a more comprehensive characterization of total PFAS present in environmental samples. In this study, we have developed and compared NTA workflows based on an online solid phase extraction- liquid chromatography high resolution mass spectrometry (online SPE-LC-HRMS) method followed by data processing using Compound Discoverer and FluoroMatch for the screening of PFAS in drinking waters from populated counties in South Florida, as well as in surface waters from Biscayne Bay, Key west, and Everglades canals. Tap water showed the highest number of PFAS features, indicating a poor removal of these chemicals by water treatment or perhaps the breakdown of PFAS precursors. The high number of PFAS features identified only by CD and FluoroMatch emphasizes the complementary aspects of these data processing methods. A Semi-quantitation method for NTA (qNTA) was proposed using a global calibration curve based on existing native standards and internal standards, in which concentration estimates were determined by a regression-based model and internal standard (IS) response factors. NTA play a crucial role in the identification and prioritization of non-traditionally monitored PFAS, needed for the understanding of the toxicological and environmental impact, which are largely underestimated due to the lack of such information for many PFAS.

Algal extracellular organic matter (EOM), a major fraction of the dissolved organic matter found in eutrophic plateau lakes, can act as a photosensitizer to drive the abiotic oxidation of Mn(II). This process has the potential to generate reactive Mn(III) and influence the fate of organic pollutants. In this study, the photodegradation of 17α-ethinylestradiol (EE2) in the presence of Mn(II) and EOM was investigated with emphasis on the photogeneration mechanism of Mn(III). The results indicated that Mn(II) can accelerate EE2 photodegradation in EOM solution owing to the photogeneration of reactive Mn(III), and the enhancement was greater at higher Mn(II) concentrations. The generation of reactive Mn(III) was mainly attributable to the action of superoxide radical generated by photosensitization of EOM. In addition, the photodegradation of EE2 was slower at higher pH, possibly because of the deactivation of Mn(III) under alkaline conditions. Single-electron transfer was an indispensable process in the photodegradation. The differences in fluorophore content, pH, and NO3- concentrations are all important determinants for EE2 photodegradation in natural waters. The information obtained in this research would contribute to the understanding of reactions between Mn(II) and EOM, and provide new insights into the behaviors of reactive Mn(III) in eutrophic water irradiated by sunlight.

17α-ethinylestradiol (EE2), a synthetic endocrine-disrupting chemical, can degrade in natural waters where humic acids (HA) and dissolved iron (DFe) are present. The iron is mostly bound in Fe(III)-HA complexes, the formation process of Fe(III)-HA complexes and their effect on EE2 degradation were explored in laboratory experiments. The mechanism of ferrihydrite facilitated by HA was explored with results indicating that HA facilitated the dissolution of ferrihydrite and the generation of Fe(III)-HA complexes with the stable chemical bonds such as C-O, CO in neutral, alkaline media with a suitable Fe/C ratio. 1O2, •OH, and 3HA* were all found to be important in the photodegradation of EE2 mediated by Fe(III)-HA complexes. Fe(III)-HA complexes could produce Fe(II) and hydrogen peroxide (H2O2) to create conditions suitable for photo-Fenton reactions at neutral pH. HA helped to maintain higher dissolved iron concentrations and alter the Fe(III)/Fe(II) cycling. The natural EE2 photodegradation pathway elucidated here provides a theoretical foundation for investigating the natural transformation of other trace organic contaminants in aquatic environments.

Perfluoro-2-propoxypropanoic acid (PFPrOPrA), a free acid form of GenX, is a problematic perfluorinated alkyl substance (PFAS). Standard and advanced wastewater treatment methods are unable to effectively degrade PFAS due to its strong and unreactive C-F bonds. TiO2 photocatalytic, radiolytic, and ultrasonic irradiation (USI) methods were applied in an attempt to degrade PFPrOPrA. A bimolecular rate constant for the reaction of e(aq)(- )and GenX of (3.09 +/- 0.03) x 10(7) M-1. s(-1) was measured in a buffered aqueous solution by monitoring the transient signal of the hydrated electron as a function of GenX concentration. Corroborating this relatively slow rate constant, less than 2% GenX degradation was observed after 8 h of continuous Co-60 gamma radiolysis under a variety of conditions. TiO2 photocatalysis at 350 nm under alkali conditions showed minimal destruction of GenX without detectable levels of defluorination as measured by the production of fluoride ions. However, upon ultrasonic irradiation at 640 kHz and 396 W in an argon-saturated aqueous solution, greater than 80% of GenX was degraded within 60 min, yielding fluoride ions as the major product. We propose that the ultrasonic-induced degradation of GenX occurs primarily by pyrolysis. Computational methods were used to probe the energetics of the completing degradation pathways and possible pyrolytic products. The results demonstrate ultrasonic-induced pyrolysis is a promising process to mineralize GenX. The process can be accurately monitored and likely extended to mineralize a variety of perfluorinated and polyfluorinated substances. (C) 2022 American Society of Civil Engineers.

Per- and polyfluoroalkyl substances (PFAS) are persistent anthropogenic pollutants present in many environmental media worldwide due to their extensive uses in many industrial and commercial products combined with their high thermal and chemical stabilities. Its ubiquitous presence in surface and drinking water supply and significant adverse health effects observed in wildlife and humans, associated with its bioaccumulation potential, pose big concerns. In this study, we have developed and validated a semi-automated solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS/MS) for the determination of legacy and emerging short-chain PFAS substitutes in surface and tap water at low parts-per-trillion (ppt) levels in South Florida environments. Surface waters from Biscayne Bay and adjacent canals (n = 15) and tap waters from different counties (Miami-Dade, Broward, and Palm Beach County) (n = 21) were collected between October 2020 (wet season) and February 2021 (dry season). Total PFAS concentrations up to 242 ng L-1 (average of 168 ng L-1) were found in tap water from Grapeland Heights, which is the closest location to the Miami international airport that was sampled. The highest average total PFAS level of 106 ng L-1 was observed in surface water from the Biscayne Canal C-8 for the wet and dry season. In general, average total PFAS was higher in tap water (86.3 ng L-1) than in surface waters (46.3 ng L-1), whereas the most predominant and frequently detected PFAS were PFBA, PFBS, PFPeA, PFHxA, PFHxS, PFOA and PFOS. PFAS levels found could represent a high human health risk, and ecological risk based on PFOS levels above recommended thresholds are also noted. Such knowledge on PFAS occurrence, distribution and sources in South Florida will provide essential information for local and regional regulatory agencies related to water quality, further facilitating the development of guidelines and procedures for PFAS pollution control and reduction in Florida. (C) 2021 Elsevier B.V. All rights reserved.

In this research, we have developed and validated a modified version of the U.S.EPA method 506 using a liquid-liquid extraction method followed by gas-chromatography mass spectrometry analysis to assess the occurrence and spatial and seasonal variation of six phthalates (di(2-ethylhexyl) phthalate-DEHP, dibutyl phthalate-DBP, butyl benzyl phthalate-BBP, diethyl phthalate-DEP, dimethyl phthalate-DMP, and di-n-octyl phthalate-DOP) in surface and tap waters from South Florida, collected during the wet and dry seasons. The most frequently detected phthalate was DEHP, with concentrations up to 1.56 μg/L in surface water. Higher DEHP concentrations were observed in tap water during the wet season, which aligns with the higher temperature during the summer months facilitating leaching from plastic materials. Preliminary ecological and human health risk assessments suggested low hazard risk based on concentrations observed in tap and surface waters, respectively. PAEs could however still constitute a great concern to sensitive marine species, including early stages organisms and coral reefs.

Poly- and perfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants that have been the subject of several investigations worldwide due to their persistence and significant adverse health effects to humans and animals. In Florida, high PFAS levels have been detected in the ground water, surface water, soils and sediments near military bases, airports, and firefighting training facilities. Recently, a drinking water assessment conducted by the EWG has identified Miami, Florida as the U.S city with the third highest levels of PFAS among 44 locations assessed. This critical review presents a summary of the recent literature, databases, and investigations of PFAS contamination in Florida, focusing on PFAS occurrence, major sources and treatment methods. The major PFAS sources identified are divided into the usage of aqueous film forming foams (AFFF), landfills, and wastewater treatment plants. Despite the lack of comprehensive studies in Florida, toxicity concerns are also discussed. Major knowledge gaps and future research needs are considered. (C) 2020 Elsevier B.V. All rights reserved.

Poly- and perfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants that have been the subject of several investigations worldwide due to their persistence and significant adverse health effects to humans and animals. In Florida, high PFAS levels have been detected in the ground water, surface water, soils and sediments near military bases, airports, and firefighting training facilities. Recently, a drinking water assessment conducted by the EWG has identified Miami, Florida as the U.S city with the third highest levels of PFAS among 44 locations assessed. This critical review presents a summary of the recent literature, databases, and investigations of PFAS contamination in Florida, focusing on PFAS occurrence, major sources and treatment methods. The major PFAS sources identified are divided into the usage of aqueous film forming foams (AFFF), landfills, and wastewater treatment plants. Despite the lack of comprehensive studies in Florida, toxicity concerns are also discussed. Major knowledge gaps and future research needs are considered.

Cetirizine, a second-generation antihistamine, has been detected in surface water and wastewater treatment eluent. The presence of Cetirizine and personal care products in the sources for drinking water is a serious concern. Cetirizine in aqueous media is readily degraded over a wide range of concentrations (4.3 to 65 mu mol/L) upon ultrasonic treatment at 640 KHz. When the concentration of CET was below 21.7 mu mol/L, more than 50 degrees A of the initial concentration was degraded within 12 min. The degradation is effectively modeled at individual concentrations by pseudo first order kinetics, however the rate constants varied from 0.148 to 0.025 min(-1) as a function of initial concentration. The degradation kinetics are effectively modeled by Langmuir-Hinshelwood heterogeneous kinetics. Application of the L = H model to the ultrasonic induced degradation of Cetirizine yields a reactivity constant, k(L-H-rxn) = 1.64 mu mol. L-1 . min(-1) and the partitioning constant, KL-H = 0.10 L/mu mol. Ultrasonically induced degradation of Cetirizine was faster under argon and oxygen saturated conditions compared to air saturation. Addition of an equimolar concentration of the hydroxyl radical scavenger, coumarin, during ultrasonic treatment lead to decreased degradation rates by 46 %, demonstrating that pyrolysis and hydroxyl radical oxidation significantly contribute to the degradation process. The primary degradation reaction products, 1-((4-chlorophenyl)(phenyl)methyl)piperazine, 2-(2-(piperazin-1-yeethoxy)acetic acid, 2-(4-((4-chlorophenyl)(phenyl)methyl)piperazin-1-yl)ethanol, and ortho, meta and para hydroxylation of the aromatic ring of CET were identified by LC-MS. Ultrasound induced remediation is a rapid and effective method for remediation of Cetirizine from water.

Diphenhydramine (DPH) the active ingredient in Benadryl, has been detected in streams, rivers and other surface water sources. As a bioactive compound, DPH impacts human health even at low concentrations. Ultrasonic irradiation at 640 kHz leads to the rapid degradation of DPH in aqueous solution. Radical scavenging experiments and detailed product studies indicate the DPH degradation involves direct pyrolysis and degradation reactions mediated by the hydroxyl radicals produced during cavitation. The degradation can be modeled by pseudo-first order kinetics yielding rate constants k of 0.210, 0.130, 0.082, 0.050, 0.035, 0.023 min(-1) at the initial concentrations of 2.8, 5.2, 13.9, 27.0, 61.0, 160.0 mu mol L-1, respectively. The degradation process follows the Langmuir-Hinshelwood (heterogeneous) model with a partition coefficient, KL-H = 0.06 mu mol.L-1 and reactivity constant k(r) = 1.96 mu mol min(-1).L-1. A competition kinetic study conducted employing the hydroxyl radical trap, coumarin, illustrates that DPH was degraded primarily by hydroxyl radical mediated processes. Computational studies employing Gaussian 09 basis set provide fundamental insight into the partitioning of the reaction pathways and the degradation mechanisms. The study demonstrates the ultrasonic degradation of DPH is rapid, follows simple kinetic expressions and is accurately modeled using computational methods. (C) 2018 Elsevier Ltd. All rights reserved.