ACS ES&T water最新文献

This study aims to comprehensively characterize the occurrence and potential risks of organophosphate esters (OPEs), especially the novel OPEs and related compounds present in river waters. Using high-resolution mass spectrometry, we conducted a comprehensive analysis of OPE-related compounds in water samples (n = 90) from the Chaobai River in Beijing, China. Target screening detected 16 traditional OPEs with cumulative concentrations of 0.69–1315 ng/L in spring and 1.5–1218 ng/L in autumn water samples. Suspect and nontarget screening further identified 42 novel OPEs and related compounds, including 12 organophosphate triesters, 11 organophosphate diesters, 7 organophosphonates, 8 organothiophosphate esters, and 4 others. The semiquantified concentrations of these novel compounds make up, on average, 36% of all OPE-related compounds. Thereinto, 36 novel compounds were discovered in surface water for the first time. Downstream samples exhibited more complex OPE profiles and higher concentrations compared to upstream and reservoir samples, associated with varied watershed characteristics. Hazard assessment and risk-based prioritization revealed significant environmental concerns regarding certain chlorinated OPEs and novel compounds, such as bis((5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl) methyl phosphonate P,P’-dioxide, 2-ethylhexyl hydrogen (2-ethylhexyl)phosphonate, and dihexyl hydrogen phosphate. This study underscores the importance of a comprehensive analysis in understanding OPE-related contamination and risks in surface water.

Linear solvation energy relationship (LSER) models have traditionally been used to predict the adsorption of organic contaminants (OCs) on carbon-based adsorbents in pure water. However, predicting OC uptake on solids is strongly influenced by the chemistry of water, adsorbent characteristics, and operational conditions. Machine learning (ML)-assisted LSER models can be promising solutions as an efficient tool to investigate the fate and control of per- and polyfluoroalkyl substances (PFAS) in complex environmental settings. In this study, ML-assisted LSER models were investigated for the first time to predict PFAS adsorption on activated carbons in complex water matrices. The results showed that ML-assisted LSER models outperformed traditional LSER models, with improved prediction accuracy (R² = 0.13–0.80 vs R² < 0.1). Principal component regression (PCR) was later applied to further enhance the efficiency of the ML models, resulting in more robust and accurate predictions (R² = 0.65–0.99) through a strategic combination of ML techniques. These combined approaches provide valuable tools for investigating and controlling PFAS in environmental compartments, providing new insights into developing source-tracking strategies for managing PFAS.

High nitrogen levels in drinking water sources pose a public health threat and have drawn significant attention. In situ high-efficiency ecological restoration technology using polyhydroxyalkanoates (PHAs) can effectively enrich target microorganisms and enhance denitrification in water bodies. However, the mechanisms behind PHA-driven carbon metabolism, nitrogen transformation, and electron transfer in denitrification remain unclear. This study investigated Pseudomonas stutzeri using sodium acetate (NaAc) or sodium 3-hydroxybutyrate as the sole carbon source. The PHA group achieved superior nitrogen removal (171.44 mg/L N, 13.39 mg N/mg DNA) compared to the NaAc group (83.83 mg/L N, 7.98 mg N/mg DNA), driven by elevated NADH levels and an increased NADH/NAD+ ratio, facilitating electron transfer to denitrifying enzymes (i.e., Nap, Nir). The metabolic flux shifted, with the tricarboxylic acid (TCA) cycle decreasing 7.08-fold and the pentose phosphate pathway (PPP) increasing 2.53-fold, optimizing reducing equivalent production for nitrogen assimilation and denitrification. A potential mechanism for PHA-enhanced denitrification and new insights into how carbon substrates regulate microbial functions in denitrification were then proposed.

Alkylated polycyclic aromatic hydrocarbons (PAHs) are abundant constituents of many PAH mixtures and contribute to risk at contaminated sites. Despite their abundance, the movement of alkylated PAHs remains understudied relative to unsubstituted PAHs. In the present study, passive sampling devices were deployed in the air, water, and sediments at 11 locations across multiple seasons to capture spatial and temporal variability in the abundance and movement of alkylated PAHs at a Brownsfield creosote site in Oregon, USA. Freely dissolved concentrations of 18 alkyl homologous series were quantified by gas chromatography-triple quadrupole mass spectrometry. Alkylated PAHs were consistently more abundant than unsubstituted PAHs in all sampled media (sum PAH and APAH concentrations 43–96% alkyl PAHs). Models of diffusive and advective flux revealed abundant 2 and 3-ring alkyl PAHs exhibited seasonal differences in movement, particularly across the air–water interface. The novel application of these methods to freely dissolved alkylated PAH homologues revealed that, in many instances, alkylated PAHs, particularly C3 and C4 homologues, moved in the opposite direction as unsubstituted PAHs across both the air–water and sediment-water interfaces. These findings reinforce the need to characterize alkylated PAHs and seasonal variability and can inform future sampling at contaminated sites.

The present study demonstrates alkylated PAHs exhibit transport dynamics dissimilar to unsubstituted PAHs, demonstrating the importance of directly measuring APAHs.

Alkylated polycyclic aromatic hydrocarbons (PAHs) are abundant constituents of many PAH mixtures and contribute to risk at contaminated sites. Despite their abundance, the movement of alkylated PAHs remains understudied relative to unsubstituted PAHs. In the present study, passive sampling devices were deployed in the air, water, and sediments at 11 locations across multiple seasons to capture spatial and temporal variability in the abundance and movement of alkylated PAHs at a Brownsfield creosote site in Oregon, USA. Freely dissolved concentrations of 18 alkyl homologous series were quantified by gas chromatography-triple quadrupole mass spectrometry. Alkylated PAHs were consistently more abundant than unsubstituted PAHs in all sampled media (sum PAH and APAH concentrations 43-96% alkyl PAHs). Models of diffusive and advective flux revealed abundant 2 and 3-ring alkyl PAHs exhibited seasonal differences in movement, particularly across the air-water interface. The novel application of these methods to freely dissolved alkylated PAH homologues revealed that, in many instances, alkylated PAHs, particularly C3 and C4 homologues, moved in the opposite direction as unsubstituted PAHs across both the air-water and sediment-water interfaces. These findings reinforce the need to characterize alkylated PAHs and seasonal variability and can inform future sampling at contaminated sites.

Residential water heating represents an important nexus of energy/water conservation, waterborne disease, hygiene, and consumer preference. Here, we examine attributes of two off-the-shelf 151-L tank water heaters, one with hot water recirculation (recirculating) and another without recirculation (standard), compared to a tankless on-demand heater (on-demand). Energy efficiency decreased in the order on-demand > standard > continuous recirculation. However, the electric on-demand water heater repeatedly malfunctioned and could not consistently achieve target temperatures >48 °C. At a temperature setting of 48 °C, the volume of water in the pipe and tank within a temperature range at very high risk for Legionella growth (38–47 °C) decreased from recirculating (150 L) > standard (40 L) > on-demand (∼0.47 L). However, at a temperature setting of 66 °C, the standard tank was stratified, and the bottom 13 L fell within the very high-risk temperature range, whereas the recirculating tank system maintained 100% of its volume >55 °C, which is not suitable for Legionella growth. Addition of insulation was found to markedly increase the temperature throughout the tank. In the standard tank set at 66 °C with insulation, no volume was maintained within the very high-risk range. Insulation can holistically increase energy efficiency and reduce health risks at a sufficiently elevated temperature setting.

Through head-to-head laboratory testing, water heater configuration and temperature setting conditions are identified to maximize energy savings while minimizing potential for Legionella growth.

Residential water heating represents an important nexus of energy/water conservation, waterborne disease, hygiene, and consumer preference. Here, we examine attributes of two off-the-shelf 151-L tank water heaters, one with hot water recirculation (recirculating) and another without recirculation (standard), compared to a tankless on-demand heater (on-demand). Energy efficiency decreased in the order on-demand > standard > continuous recirculation. However, the electric on-demand water heater repeatedly malfunctioned and could not consistently achieve target temperatures >48 °C. At a temperature setting of 48 °C, the volume of water in the pipe and tank within a temperature range at very high risk for Legionella growth (38-47 °C) decreased from recirculating (150 L) > standard (40 L) > on-demand (∼0.47 L). However, at a temperature setting of 66 °C, the standard tank was stratified, and the bottom 13 L fell within the very high-risk temperature range, whereas the recirculating tank system maintained 100% of its volume >55 °C, which is not suitable for Legionella growth. Addition of insulation was found to markedly increase the temperature throughout the tank. In the standard tank set at 66 °C with insulation, no volume was maintained within the very high-risk range. Insulation can holistically increase energy efficiency and reduce health risks at a sufficiently elevated temperature setting.

In this study, we propose a combined process consisting of loose nanofiltration (LNF), mainly functioning to remove natural organic matter (NOM) while largely preserving mineral salts, and a subsequent ozonation or activated carbon adsorption, applied mainly to remove organic micropollutants (OMPs), under expectedly greatly reduced competing effects from the residual NOM of lowered concentration. Six LNF and one conventional NF membrane were adopted in an attempt to more comprehensively investigate the influence of residual NOM. All NF membranes had high rejections (∼90%) of humic- and fulvic-like substances, while those with a larger molecular weight cutoff (MWCO) had lower rejections of soluble microbial products and protein-like substances, to below 50%. This characteristic benefits the subsequent ozonation treatment, with a greatly reduced ozone decay rate (by >80%) and a lower total organic carbon-specific decay rate than that in feedwater. The preferred removal of humic- and fulvic-like substances by LNF membranes also benefits the removal of OMPs, especially those of high hydrophobicity, by granular activated carbon (GAC) adsorption. The residual NOM could hardly be adsorbed by GAC, with a greatly reduced adsorption amount onto the adsorbents (by >90%) compared to that in feedwater, thus leaving sufficient adsorption sites for OMP removal. A combination process based on loose nanofiltration was used to maximize the benefits of each unit, resulting in the simultaneous high removal of NOM and OMPs.

A homologous series of amino methylenephosphonate-based nonalpha aliphatic linear amino acids (LAAs) were developed. These new phosphonated linear amino acids, known as PLAAs (HOOC-(CH₂)_n-N-(PO₃H₂)₂), include phosphonated derivatives of glycine (PLAA-C2,n= 1), β-alanine (PLAA-C3,n= 2), γ-aminobutyric acid (PLAA-C4,n= 3), 5-aminovaleric acid (PLAA-C5,n= 4), and ε-aminocaproic acid (PLAA-C6,n= 5). The performance of these PLAAs as scale inhibitors was evaluated against calcium sulfate, calcium carbonate, and barium sulfate under oilfield dynamic conditions (approximately 80 bar and 100 °C) and compared with the commercial inhibitor Hydrodis-SI. The study also investigated their thermal stability and calcium compatibility. Notably, PLAAs with shorter chains between the carboxylic acid group and aminomethylenephosphonate moiety, such as PLAA-C2, PLAA-C3, and PLAA-C4, showed the highest inhibition efficiency for calcite scale. Furthermore, the PLAAs demonstrated superior thermal stability compared to Hydrodis-SI, particularly at 130 °C for 7 days, with no loss in inhibition performance. However, all tested inhibitors, exhibited poor performance against barium sulfate (Barite) due to an insufficient number of phosphonate groups in their backbone. PLAAs also showed good calcium compatibility, with PLAA-C4 and PLAA-C5 standing out for their exceptional compatibility across various saturations and Ca²⁺ concentrations.

To achieve rapid and accurate classification and identification of different microalgae species, we developed the M-YOLO v8s model based on the YOLO v8s model, replacing the C2F module with the C2F_Faster module in the backbone to achieve a lighter network structure and efficient feature extraction, and Focal-SIoU loss was introduced to enhance the stability of the model. SRGAN was employed to process the microalgae images captured by a microscope to increase the diversity of the data set before training to improve the robustness of the model. The detection accuracy and speed of M-YOLO version 8 were significantly improved, while the complexity was reduced. The precision increased from 98.5 to 98.9%, and the recall was 99.1%. Furthermore, Params decreased from 11.13 to 8.31 million and FLOPs decreased from 28.4 to 21.4 billion, indicating that fewer computing resources are required. The improved M-YOLO v8s model is crucial for the early warning and prevention of harmful algal blooms.