ACS ES&T water最新文献

Fluoroquinolones, a class of antibiotics, have been detected in various aquatic environments, including those experiencing freeze–thaw cycles. This study investigated the adsorption of ciprofloxacin (CIP) in frozen (−21 °C) and aqueous (25 °C) solutions under varying pH levels, electrolyte types, and ionic strengths. CIP sorption on goethite was found to be transient, as freezing re-establishes equilibrium, nearly doubling CIP loadings at acidic to circumneutral pH values. The original equilibrium was restored by thawing. Our investigation reveals that ion pairs, formed between the positively charged piperazine group of CIP and anions (Cl^–, Br^–, and NO₃^–), create a charge-shielding effect, explaining the transient nature of CIP sorption equilibrium at goethite-water interfaces. In situ ATR-FTIR observations and model predictions further confirm the significant role of ion-paired surface complexes in transient CIP sorption. The transience of CIP sorption equilibrium in frozen and aqueous solutions is attributed to the local concentrations of anions, which undergo freeze-concentration into liquid intergrain boundaries and dilution by reversible ice nucleation and thawing. As the interaction between the hydrosphere and cryosphere intensifies with climate change, these findings have significant implications for evaluating the fate of contaminants in both terrestrial and aquatic environments.

Here, we present the first systematic and comprehensive analysis of the biochemical and transcriptomic characteristics of Microlunatus phosphovorus NM-1 with glucose and amino acids as carbon sources for enhanced biological phosphorus removal (EBPR). Glucose-induced the highest P release rate, followed by aspartate and glutamate. Its anaerobic P release and glucose uptake and aerobic P uptake kinetics exceeded those of Tetrasphaera and Candidatus Accumulibacter (with acetate). Anaerobic glucose uptake and activation were achieved via the phosphoenolpyruvate-dependent phosphotransferase system and bifunctional glucokinases, contributing to its exceptionally high glucose uptake rates. Aspartate and glutamate uptake was driven by proton motive force. Glucose and those amino acids were mainly stored as glycogen. Novel pathways (beta-oxidation and fatty acid biosynthesis) were encoded by NM-1 for polyhydroxyalkanoate generation. Transcriptomic analysis revealed significantly transcribed genes in the glyoxylate cycle in anaerobic glucose metabolism. Glutamate and aspartate were deaminized and routed into the TCA cycle for glycogen and polyhydroxyvalerate generation. Two low-affinity phosphate transporter genes were distinctly transcribed in the anaerobic and aerobic phases, benefiting enhanced P release and uptake. Collectively, this study provides a comprehensive understanding of the glucose and amino acid metabolism of NM-1, benefiting an improved description and modeling of the M. phosphovorus-mediated EBPR process.

Residents and their pets may experience aesthetic or health concerns resulting from elevated copper in their drinking water. The United States Environmental Protection Agency Lead and Copper Rule focuses on addressing systemwide corrosion issues, but gaps in the rule leave some municipal water consumers and residents with private well water vulnerable to high cuprosolvency. We developed guidance to aid residents in understanding, detecting, and addressing cuprosolvency issues in their drinking water. Three types of at-home test kits for copper and one for pH were determined to be accurate enough (R² > 0.9 (lab, based on average values from n = 5 replicates each) and >0.7 (field)) to detect concerns related to high cuprosolvency and inform selection of intervention options. Case study results indicate that, although water treatments such as increasing pH on-site may be effective, long-term treatment (>36 weeks or permanently) may be needed to maintain reductions in cuprosolvency. A decision tree is provided to help residents and citizen scientists navigate these concerns for both public water systems and private wells.

This work addresses gaps in the LCR by developing guidance to help residents detect and address elevated copper in their drinking water.

1,4-Dioxane is an emerging water contaminant that is likely to be carcinogenic to humans. Its treatment is challenging due to its high water solubility, low Henry’s law constant, and low partition coefficients. Adsorption has been widely studied for removing 1,4-dioxane. Although the adsorption kinetics and isotherms of several water pollutants have been widely studied, little is known about the adsorption kinetics of 1,4-dioxane. In this study, the kinetics of 1,4-dioxane adsorption by AmberSorb and Granular Activated Carbon (GAC) were investigated. A homogeneous surface diffusion model was developed to describe the adsorption of 1,4-dioxane in continuous-flow and batch systems. The external mass-transfer and internal diffusion coefficients of 1,4-dioxane for AmberSorb (1.79 × 10^–3 cm/min and 3.52 × 10^–4 cm²/min) were determined about five- and thirty-fold larger than that of their corresponding parameters for GAC. For both adsorbents, the adsorption was limited by the mass-transfer across the fluid film that covers the adsorbent and the adsorbent–adsorbate interaction at the adsorbent surface but not limited by the diffusion within the adsorbent. While the mass-transfer across the external fluid film affected the maximum 1,4-dioxane removal percentage and the adsorption rate, the isotherm parameters mainly controlled the adsorption capacity and adsorbent service life.

Adsorption of aqueous organic pollutants onto microplastics influences the exposure and risks of both the pollutants and microplastics. Experimental determination of the aqueous adsorption equilibrium constants (K_aq) that characterize the adsorption capacity of microplastics to pollutants is laborious and inefficient since the K_aq values rely on various combinations of conditions, such as pH, ionic strength, and particle sizes. Herein, molecular dynamics (MD) methods were established by comparing the MD-calculated K_aq values with the empirical values of 14 compounds adsorbed onto polyethylene (PE) microplastics having different particle sizes (10–250 μm) in pure water and seawater. Based on the data sets consisting of experimental and MD-calculated K_aq values, machine learning models were constructed. A gradient boosting decision tree (GBDT) model requires only easily obtainable Mordred descriptors for pollutants and desired conditions (particle sizes and ionic strength) to yield accurate results, with an external determination coefficient of 0.99. The GBDT model exhibits a great improvement over the previous one, as it incorporates multiple factors including ionic strength from pure water to seawater, dissociation species at different pH, and PE particle sizes with diameters ranging from nanometers to micrometers. This study paves a new way for high-throughput estimating K values for microplastics and pollutants at different environmental conditions.

Nanoplastics possess unique characteristics (e.g., high surface area/volume ratio) that enhance the adsorption of organic chemicals onto their surface. Their occurrence raises human health and ecotoxicological concerns, as pollutants bound to nanoplastics can have a larger effect than they would on their own. This study assessed the sorption of plant protection products (glyphosate and methyl parathion), an antidepressant (fluoxetine), a perfluorochemical (perfluorooctanoic acid [PFOA]), and a polycyclic aromatic hydrocarbon (phenanthrene) onto commercially available carboxylated polystyrene (PS) nanoplastics (NPs, 500 and 20 nm). Based on the calculated sorption coefficients (K_d, L/kg), the sequence of chemicals displaying the highest to lowest affinity toward PSNPs is fluoxetine > phenanthrene > methyl parathion > PFOA > glyphosate, with 20 nm PS showing a higher potential to sorb organic chemicals. Cationic (fluoxetine) and hydrophobic (phenanthrene) substances were more amenable to sorption, whereas negatively charged and more hydrophilic ones (i.e., PFOA and glyphosate) showed poor sorption. pH influenced sorption for all target chemicals except phenanthrene. Sorption capacity was further reduced in water spiked with natural organic matter and in tertiary-treated wastewater effluent. Overall, our work enhances the understanding of how representative organic chemicals sorb onto nanoplastics and provides quantitative information (i.e., K_d) on future simulations of nanoplastics’ fate and transport.

Biofilms in water distribution systems are complex and tenacious populations of microbes surrounded by a protective matrix that may lead to significant water-borne diseases due to contamination and compromised quality of water. To tackle this issue, several small-molecule-based antimicrobials and engineered nanomaterials were developed that show much promise in combating biofilms. Herein, organic carbon dots (LC-CDs) were successfully synthesized from Lantana camara leaf extract, which is an invasive plant, using a one-pot hydrothermal method, requiring no chemical modifications. These LC-CDs were found to be less toxic and exhibited antibacterial and antibiofilm properties, indicating their potential use to combat biofilms. While natural carbon dots have been extensively studied for bioimaging, their antibiofilm activity has not been widely explored. Our study explores the antibacterial activity of naturally derived carbon dots through the generation of reactive oxygen species, thereby expanding the industrial prospects of this system as an antibacterial and antibiofilm agent. The LC-CDs may serve as antibacterial and antibiofilm agents to facilitate clean water production.

The paper aims to assess the impacts of the hydropower plans, economic activities, flow dynamics, water quality, nutrient sediment, habitat fragmentation, and aquatics biodiversity of the river that influence the livelihoods of local fishermen. The two study areas of Sayabouly Province (Laos) and Hau River (Vietnam) were selected to conduct the study. The study explored the connection Mekong’s farmers and fishers have with their water resources and how the changes of water resources from the river affect the biodiversity of fishes and livelihoods, income, and food security and shape cultural worldviews. The study also reconnected the link between the natural resources and policies that rural people need to strengthen their livelihood strategies so they can thrive, provide food for themselves and urban populations, and ensure the environmental integrity of the Mekong basin for future generations. The changes in water quantity and quality, biodiversity, and fish production of the local communities in the Lower Mekong River have direct and indirect impacts on the livelihood of the communities. The study found the impacts of water quantity and quality on the livelihood of local communities through the impact on biodiversity and aquatic production. The findings contribute to the current knowledge gap by providing scientific information to policymakers to prevent the consequences of water insecurity on the natural ecosystem and the livelihood of local fishers and farmers in the study areas.

Quantitative microbial risk assessments (QMRAs) infrequently include pathogen and fecal marker decay. However, this necessitates the assumption that pathogens and indicators decay at similar rates or that decay prior to human exposure is negligible, which may misestimate the infection risks. Here, we created a QMRA model incorporating pathogen (Cryptosporidium, Giardia, Enterovirus, Rotavirus, Salmonella spp., Campylobacter jejuni, and E. coli O157:H7) and fecal indicator (HF183) decay to assess the impact of decay on the probability of gastrointestinal illness estimates in a recreational water QMRA model. Neglecting to account for pathogen decay rapidly resulted in an overestimation of risk; for example, not incorporating decay resulted in a statistically significant overestimation of risk after 30 min for Campylobacter jejuni and after 13 h for all pathogens. Substituting the fecal indicator HF183 decay rates for pathogen decay rates also rapidly resulted in a statistically significant over- or underestimation of risk. HF183 best represented the decay rate of Salmonella spp. but still resulted in an underestimation of risk after 13 h. Overall, including decay rates resulted in statistically different risk estimations on realistic time scales following pollution events, suggesting that QMRAs that neglect decay overestimate the probability of illness, and the indicator ratio approach could yield overestimations or underestimations depending on the difference between indicator and pathogen decay rate constants.

While numerous assessments of micropollutant exposure primarily focus on monitoring the water column, a growing body of research indicates that differences in micropollutant partitioning in other compartments require additional consideration for risk evaluation. This study investigated the partitioning of antibiotics, antiepileptics, antibacterials, and antidepressants and their metabolites in water, sediment, macroinvertebrates (gammarids), biofilm, and fish (spoonhead sculpin and longnose dace) found or exposed in replicate naturalized streams (Calgary, Alberta, Canada). All target micropollutants were detected in the water and sediment, and >5 substances were detected in the biotic matrices at concentrations between the limit of quantitation and 244 ± 16 ng/g_dw. Triclosan and triclocarban (antibacterials) were frequently detected in sediments, but very rarely in the water column. The solid–water partitioning (K_d) and organic carbon–water partitioning coefficients (K_oc) indicate that fluoxetine, norfluoxetine, and triclosan have a stronger affinity for sediments and/or organic matter (log K_d > 2.7, log K_oc > 1.5). More specifically, fluoxetine was found to be up to 10× higher in sediments, biofilm, and gammarids than other substances, whereas its concentration in the water column was very low or nondetectable. Finally, bottom-dwelling fish (spoonhead sculpin) were also found to have higher concentrations of fluoxetine and its metabolite than longnose dace.