The 50 most-cited articles in Environmental Science & Technology, 2017

Microplastics are a pollutant of environmental concern. Their presence in food destined for human consumption and in air samples has been reported. Thus, microplastic exposure via diet or inhalation could occur, the human health effects of which are unknown. The current review article draws upon cross-disciplinary scientific literature to discuss and evaluate the potential human health impacts of microplastics and outlines urgent areas for future research. Key literature up to September 2016 relating to accumulation, particle toxicity, and chemical and microbial contaminants was critically examined. Although microplastics and human health is an emerging field, complementary existing fields indicate potential particle, chemical and microbial hazards. If inhaled or ingested, microplastics may accumulate and exert localized particle toxicity by inducing or enhancing an immune response. Chemical toxicity could occur due to the localized leaching of component monomers, endogenous additives, and adsorbed environmental pollutants. Chronic exposure is anticipated to be of greater concern…

Plastic litter is widely acknowledged as a global environmental threat, and poor management and disposal lead to increasing levels in the environment. Of recent concern is the degradation of plastics from macro- to micro- and even to nanosized particles smaller than 100 nm in size. At the nanoscale, plastics are difficult to detect and can be transported in air, soil, and water compartments. While the impact of plastic debris on marine and fresh waters and organisms has been studied, the loads, transformations, transport, and fate of plastics in terrestrial and subsurface environments are largely overlooked. In this Critical Review, we first present estimated loads of plastics in different environmental compartments. We also provide a critical review of the current knowledge vis-à-vis nanoplastic (NP) and microplastic (MP) aggregation, deposition, and contaminant cotransport in the environment. Important factors that affect aggregation and deposition in natural subsurface environments are identified and critically analyzed. Factors affecting contaminant sorption onto plastic debris…

More than 3000 per- and polyfluoroalkyl substances (PFASs) are, or have been, on the global market, yet most research and regulation continues to focus on a limited selection of rather well-known long-chain PFASs, particularly perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and their precursors. Continuing to overlook the vast majority of other PFASs is a major concern for society. We provide recommendations for how to proceed with research and cooperation to tackle the vast number of PFASs on the market and in the environment.

It is important to understand the fragmentation processes and mechanisms of plastic litter to predict microplastic production in the marine environment. In this study, accelerated weathering experiments were performed in the laboratory, with ultraviolet (UV) exposure for up to 12 months followed by mechanical abrasion (MA) with sand for 2 months. Fragmentation of low-density polyethylene (PE), polypropylene (PP), and expanded polystyrene (EPS) was evaluated under conditions that simulated a beach environment. PE and PP were minimally fragmented by MA without photooxidation by UV (8.7 ± 2.5 and 10.7 ± 0.7 particles/pellet, respectively). The rate of fragmentation by UV exposure duration increased more for PP than PE. A 12-month UV exposure and 2-month MA of PP and PE produced 6084 ± 1061 and 20 ± 8.3 particles/pellet, respectively. EPS pellets were susceptible to MA alone (4220 ± 33 particles/pellet), while the combination of 6 months of UV exposure followed by 2 months of MA produced 12,152 ± 3276 particles/pellet. The number of fragmented polymer particles produced by UV exposure…

A substantial fraction of marine plastic debris originates from land-based sources and rivers potentially act as a major transport pathway for all sizes of plastic debris. We analyzed a global compilation of data on plastic debris in the water column across a wide range of river sizes. Plastic debris loads, both microplastic (particles <5 mm) and macroplastic (particles >5 mm) are positively related to the mismanaged plastic waste (MMPW) generated in the river catchments. This relationship is nonlinear where large rivers with population-rich catchments delivering a disproportionately higher fraction of MMPW into the sea. The 10 top-ranked rivers transport 88–95% of the global load into the sea. Using MMPW as a predictor we calculate the global plastic debris inputs form rivers into the sea to range between 0.41 and 4 × 10 6 t/y. Due to the limited amount of data high uncertainties were expected and ultimately confirmed. The empirical analysis to quantify plastic loads in rivers can be extended easily by additional potential predictors other than MMPW, for example, hydrological…

Recent studies suggest size-selective removal of small plastic particles from the ocean surface, an observation that remains unexplained. We studied one of the hypotheses regarding this size-selective removal: the formation of a biofilm on the microplastics (biofouling). We developed the first theoretical model that is capable of simulating the effect of biofouling on the fate of microplastic. The model is based on settling, biofilm growth, and ocean depth profiles for light, water density, temperature, salinity, and viscosity. Using realistic parameters, the model simulates the vertical transport of small microplastic particles over time, and predicts that the particles either float, sink to the ocean floor, or oscillate vertically, depending on the size and density of the particle. The predicted size-dependent vertical movement of microplastic particles results in a maximum concentration at intermediate depths. Consequently, relatively low abundances of small particles are predicted at the ocean surface, while at the same time these small particles may never reach the ocean floor.…

In an era of graphene-based nanomaterials as the most widely studied two-dimensional (2D) materials for enhanced performance of devices and systems in numerous environmental applications, molybdenum disulfide (MoS 2 ) nanosheets stand out as a promising alternative 2D material with many excellent physicochemical, biological, and mechanical properties that differ significantly from those of graphene-based nanomaterials, potentially leading to new environmental phenomena and novel applications. This Critical Review presents the latest advances in the use of MoS 2 nanosheets for important water-related environmental applications such as contaminant adsorption, photocatalysis, membrane-based separation, sensing, and disinfection. Various methods for MoS 2 nanosheet synthesis are examined, and their suitability for different environmental applications is discussed. The unique structure and properties of MoS 2 nanosheets enabling exceptional environmental capabilities are compared with those of graphene-based nanomaterials. The environmental implications of MoS 2 nanosheets are…

A high-efficient, low-cost, and eco-friendly catalyst is highly desired to activate peroxides for environmental remediation. Due to the potential synergistic effect between bimetallic oxides’ two different metal cations, these oxides exhibit superior performance in the catalytic activation of peroxymonosulfate (PMS). In this work, novel Mn 1.8 Fe 1.2 O 4 nanospheres were synthesized and used to activate PMS for the degradation of bisphenol A (BPA), a typical refractory pollutant. The catalytic performance of the Mn 1.8 Fe 1.2 O 4 nanospheres was substantially greater than that of the Mn/Fe monometallic oxides and remained efficient in a wide pH range from 4 to 10. More importantly, a synergistic effect between solid-state Mn and Fe was identified in control experiments with Mn 3 O 4 and Fe 3 O 4 . Mn was inferred to be the primary active site in the surface of the Mn 1.8 Fe 1.2 O 4 nanospheres, while Fe(III) was found to play a key role in the synergism with Mn by acting as the main adsorption site for the reaction substrates. Both sulfate and hydroxyl radicals were generated in the…

Plastics can be found in all ecosystems across the globe. This type of environmental pollution is important, even if its impact is not fully understood. The presence of small plastic particles at the micro- and nanoscales is of growing concern, but nanoplastic has not yet been observed in natural samples. In this study, we examined four size fractions (meso-, large micro-, small micro-, and nanoplastics) of debris collected in the North Atlantic subtropical gyre. To obtain the nanoplastic portion, we isolated the colloidal fraction of seawater. After ultrafiltration, the occurrence of nanoscale particles was demonstrated using dynamic light scattering experiments. The chemical fingerprint of the colloids was obtained by pyrolysis coupled with gas chromatography-mass spectrometry. We demonstrated that the signal was anthropogenic and attributed to a combination of plastics. The polymer composition varied among the size classes. At the micro- and nanoscales, polyvinyl chloride, polyethylene terephthalate, polystyrene and polyethylene were observed. We also observed changes in the…

Abstract Although mounting evidence suggests the ubiquity of microplastic in aquatic ecosystems worldwide, our knowledge of its distribution in remote environments such as Polar Regions and the deep sea is scarce. Here, we analyzed nine sediment samples taken at the HAUSGARTEN observatory in the Arctic at 2340–5570 m depth. Density separation by MicroPlastic Sediment Separator and treatment with Fenton’s reagent enabled analysis via Attenuated Total Reflection FTIR and μFTIR spectroscopy. Our analyses indicate the wide spread of high numbers of microplastics (42–6595 microplastics kg–1). The northernmost stations harbored the highest quantities, indicating sea ice as a possible transport vehicle. A positive correlation between microplastic abundance and chlorophyll a content suggests vertical export via incorporation in sinking (ice-) algal aggregates. Overall, 18 different polymers were detected. Chlorinated polyethylene accounted for the largest proportion (38%), followed by polyamide (22%) and polypropylene (16%). Almost 80% of the microplastics were ≤25 μm. The microplastic…

Aqueous film-forming foams (AFFFs), containing per- and polyfluoroalkyl substances (PFASs), are released into the environment during response to fire-related emergencies. Repeated historical applications of AFFF at military sites were a result of fire-fighter training exercises and equipment testing. Recent data on AFFF-impacted groundwater indicates that ∼25% of the PFASs remain unidentified. In an attempt to close the mass balance, a systematic evaluation of 3M and fluorotelomer-based AFFFs, commercial products, and AFFF-impacted groundwaters from 15 U.S. military bases was conducted to identify the remaining PFASs. Liquid chromatography quadrupole time-of-flight mass spectrometry was used for compound discovery. Nontarget analysis utilized Kendrick mass defect plots and a "nontarget" R script. Suspect screening compared masses with those of previously reported PFASs. Forty classes of novel anionic, zwitterionic, and cationic PFASs were discovered, and an additional 17 previously reported classes were observed for the first time in AFFF and/or AFFF-impacted groundwater. All 57…

Marine plastic debris is a global environmental problem. Surveys have shown that <5 mm plastic particles, known as microplastics, are significantly more abundant in surface seawater and on shorelines than larger plastic particles are. Nevertheless, quantification of microplastics in the environment is hampered by a lack of adequate high-throughput methods for distinguishing and quantifying smaller size fractions (<1 mm), and this has probably resulted in an underestimation of actual microplastic concentrations. Here we present a protocol that allows high-throughput detection and automated quantification of small microplastic particles (20-1000 μm) using the dye Nile red, fluorescence microscopy, and image analysis software. This protocol has proven to be highly effective in the quantification of small polyethylene, polypropylene, polystyrene, and nylon-6 particles, which frequently occur in the water column. Our preliminary results from sea surface tows show a power-law increase in small microplastics (i.e., <1 mm) with a decreasing particle size. Hence, our data help to resolve…

Abstract Air pollution affects billions of people worldwide, yet ambient pollution measurements are limited for much of the world. Urban air pollution concentrations vary sharply over short distances (≪1 km) owing to unevenly distributed emission sources, dilution, and physicochemical transformations. Accordingly, even where present, conventional fixed-site pollution monitoring methods lack the spatial resolution needed to characterize heterogeneous human exposures and localized pollution hotspots. Here, we demonstrate a measurement approach to reveal urban air pollution patterns at 4–5 orders of magnitude greater spatial precision than possible with current central-site ambient monitoring. We equipped Google Street View vehicles with a fast-response pollution measurement platform and repeatedly sampled every street in a 30-km2 area of Oakland, CA, developing the largest urban air quality data set of its type. Resulting maps of annual daytime NO, NO2, and black carbon at 30 m-scale reveal stable, persistent pollution patterns with surprisingly sharp small-scale variability…

Microplastic fibers make up a large proportion of microplastics found in the environment, especially in urban areas. There is good reason to consider synthetic textiles a major source of microplastic fibers, and it will not diminish since the use of synthetic fabrics, especially polyester, continues to increase. In this study we provide quantitative data regarding the size and mass of microplastic fibers released from synthetic (polyester) textiles during simulated home washing under controlled laboratory conditions. Consideration of fabric structure and washing conditions (use of detergents, temperature, wash duration, and sequential washings) allowed us to study the propensity of fiber shedding in a mechanistic way. Thousands of individual fibers were measured (number, length) from each wash solution to provide a robust data set on which to draw conclusions. Among all the variables tested, the use of detergent appeared to affect the total mass of fibers released the most, yet the detergent composition (liquid or powder) or overdosing of detergent did not significantly influence…

Microplastics are widespread contaminants in terrestrial environments but comparatively little is known about interactions between microplastics and common terrestrial contaminants such as zinc (Zn). In adsorption experiments fragmented HDPE bags c. one mm 2 in size showed similar sorption characteristics to soil. However, when present in combination with soil, concentrations of adsorbed Zn on a per mass basis were over an order of magnitude lower on microplastics. Desorption of the Zn was minimal from both microplastics and soil in synthetic soil solution (0.01 M CaCl 2 ), but in synthetic earthworm guts desorption was higher from microplastics (40–60%) than soil (2–15%), suggesting microplastics could increase Zn bioavailability. Individual Lumbricus terrestris earthworms exposed for 28 days in mesocosms of 260 g moist soil containing 0.35 wt % of Zn-bearing microplastic (236–4505 mg kg –1 ) ingested the microplastics, but there was no evidence of Zn accumulation, mortality, or weight change. Digestion of the earthworms showed that they did not retain microplastics in their gut.…

The vast, diverse universe of organic pollutants is a formidable challenge for environmental sciences, engineering, and regulation. Nontarget screening (NTS) based on high resolution mass spectrometry (HRMS) has enormous potential to help characterize this universe, but is it ready to go for real world applications? In this Feature article we argue that development of mass spectrometers with increasingly high resolution and novel couplings to both liquid and gas chromatography, combined with the integration of high performance computing, have significantly widened our analytical window and have enabled increasingly sophisticated data processing strategies, indicating a bright future for NTS. NTS has great potential for treatment assessment and pollutant prioritization within regulatory applications, as highlighted here by the case of real-time pollutant monitoring on the River Rhine. We discuss challenges for the future, including the transition from research toward solution-centered and robust, harmonized applications.

Metal-free carbonaceous materials, including nitrogen-doped graphene and carbon nanotubes, are emerging as alternative catalysts for peroxymonosulfate (PMS) activation to avoid drawbacks of conventional transition metal-containing catalysts, such as the leaching of toxic metal ions. However, these novel carbocatalysts face relatively high cost and complex syntheses, and their activation mechanisms have not been well-understood. Herein, we developed a novel nitrogen-doped carbonaceous nanosphere catalyst by carbonization of polypyrrole, which was prepared through a scalable chemical oxidative polymerization. The defective degree of carbon substrate and amount of nitrogen dopants (i.e., graphitic nitrogen) were modulated by the calcination temperature. The product carbonized at 800 °C (CPPy-F-8) exhibited the best catalytic performance for PMS activation, with 97% phenol degradation efficiency in 120 min. The catalytic system was efficient over a wide pH range (2–9), and the reaction of phenol degradation had a relatively low activation energy (18.4 ± 2.7 kJ mol –1 ). The…

Food losses and food waste (FLW) have become a global concern in recent years and emerge as a priority in the global and national political agenda (e.g., with Target 12.3 in the new United Nations Sustainable Development Goals). A good understanding of the availability and quality of global FLW data is a prerequisite for tracking progress on reduction targets, analyzing environmental impacts, and exploring mitigation strategies for FLW. There has been a growing body of literature on FLW quantification in the past years; however, significant challenges remain, such as data inconsistency and a narrow temporal, geographical, and food supply chain coverage. In this paper, we examined 202 publications which reported FLW data for 84 countries and 52 individual years from 1933 to 2014. We found that most existing publications are conducted for a few industrialized countries (e.g., the United Kingdom and the United States), and over half of them are based only on secondary data, which signals high uncertainties in the existing global FLW database. Despite these uncertainties, existing data…

Poor air quality is globally the largest environmental health risk. Epidemiological studies have uncovered clear relationships of gaseous pollutants and particulate matter (PM) with adverse health outcomes, including mortality by cardiovascular and respiratory diseases. Studies of health impacts by aerosols are highly multidisciplinary with a broad range of scales in space and time. We assess recent advances and future challenges regarding aerosol effects on health from molecular to global scales through epidemiological studies, field measurements, health-related properties of PM, and multiphase interactions of oxidants and PM upon respiratory deposition. Global modeling combined with epidemiological exposure-response functions indicates that ambient air pollution causes more than four million premature deaths per year. Epidemiological studies usually refer to PM mass concentrations, but some health effects may relate to specific constituents such as bioaerosols, polycyclic aromatic compounds, and transition metals. Various analytical techniques and cellular and molecular assays are…

Sludge aggregation and biofilm formation are the most effective approaches to solve the washout of anammox microorganisms. In this study, the structure and composition of EPS (extracellular polymeric substances) were investigated to elucidate the factors for the anammox aggregation property. Anammox sludge taken from 18 lab-scale and pilot-scale reactors treating different types of wastewater was analyzed using EEM-PARAFAC (excitation-emission matrix and parallel factor analysis), FTIR (Fourier transform infrared spectroscopy) and real-time PCR combined with multivariate statistical analysis. The results showed that slime and TB-EPS (tightly bound EPS) were closely related with water quality and sludge morphology, and could be used as the indicators for anammox microbial survival ability and microbial aggregate morphology. Furthermore, slime secreted from anammox bacterial cells may be exhibited higher viscosity to the sludge surface and easily formed the gel network to aggregate. Large amounts of hydrophobic groups of protein in TB-EPS promoted the microbial aggregation. The…

The content of microplastics (MP) in the environment is constantly growing. Since the environmental relevance, particularly bioavailability, rises with decreasing particle size, the knowledge of the MP proportion in habitats and organisms is of gaining importance. The reliable recognition of MP particles is limited and underlies substantial uncertainties. Therefore spectroscopic methods are necessary to ensure the plastic nature of isolated particles, determine the polymer type and obtain particle count related quantitative data. In this study Curie-Point pyrolysis-gas chromatography-mass spectrometry combined with thermochemolysis is shown to be an excellent analytical tool to simultaneously identify and optionally quantify MP in environmental samples on a polymer specific mass related trace level. The method is independent of any mechanical preselection or particle appearance. For this purpose polymer characteristic pyrolysis products and their indicative fragment ions were used to analyze eight common types of plastics. Further aspects of calibration, recoveries, and potential…

The UV/chlorine process is an emerging advanced oxidation process (AOP) used for the degradation of micropollutants. However, the radical chemistry of this AOP is largely unknown for the degradation of numerous structurally diverse micropollutants in water matrices of varying quality. These issues were addressed by grouping 34 pharmaceuticals and personal care products (PPCPs) according to the radical chemistry of their degradation in the UV/chlorine process at practical PPCP concentrations (1 μg L –1 ) and in different water matrices. The contributions of HO • and reactive chlorine species (RCS), including Cl •, Cl 2 •–, and ClO •, to the degradation of different PPCPs were compound specific. RCS showed considerable reactivity with olefins and benzene derivatives, such as phenols, anilines, and alkyl-/alkoxybenzenes. A good linear relationship was found between the RCS reactivity and negative values of the Hammett ∑σ p + constant for aromatic PPCPs, indicating that electron-donating groups promote the attack of benzene derivatives by RCS. The contribution of HO •, but not…

Black carbon (BC) is ubiquitous in the environments and participates in various biogeochemical processes. Both positive and negative effects of BC (especially biochar) on the ecosystem have been identified, which are mainly derived from its diverse physicochemical properties. Nevertheless, few studies systematically examined the linkage between the evolution of BC molecular structure with the resulted BC properties, environmental functions as well as potential risk, which is critical for understanding the BC environmental behavior and utilization as a multifunctional product. Thus, this review highlights the molecular structure evolution of BC during pyrolysis and the impact of BC physicochemical properties on its sorption behavior, stability, and potential risk in terrestrial and aqueous ecosystems. Given the wide application of BC and its important role in biogeochemical processes, future research should focus on the following: (1) establishing methodology to more precisely predict and design BC properties on the basis of pyrolysis and phase transformation of biomass; (2)…

To estimate PM 2.5 concentrations, many parametric regression models have been developed, while nonparametric machine learning algorithms are used less often and national-scale models are rare. In this paper, we develop a random forest model incorporating aerosol optical depth (AOD) data, meteorological fields, and land use variables to estimate daily 24 h averaged ground-level PM 2.5 concentrations over the conterminous United States in 2011. Random forests are an ensemble learning method that provides predictions with high accuracy and interpretability. Our results achieve an overall cross-validation (CV) R 2 value of 0.80. Mean prediction error (MPE) and root mean squared prediction error (RMSPE) for daily predictions are 1.78 and 2.83 μg/m 3, respectively, indicating a good agreement between CV predictions and observations. The prediction accuracy of our model is similar to those reported in previous studies using neural networks or regression models on both national and regional scales. In addition, the incorporation of convolutional layers for land use terms and nearby PM 2.5…

Soluble transition metals in particulate matter (PM) can generate reactive oxygen species in vivo by redox cycling, leading to oxidative stress and adverse health effects. Most metals, such as those from roadway traffic, are emitted in an insoluble form, but must be soluble for redox cycling. Here we present the mechanism of metals dissolution by highly acidic sulfate aerosol and the effect on particle oxidative potential (OP) through analysis of size distributions. Size-segregated ambient PM were collected from a road-side and representative urban site in Atlanta, GA. Elemental and organic carbon, ions, total and water-soluble metals, and water-soluble OP were measured. Particle pH was determined with a thermodynamic model using measured ionic species. Sulfate was spatially uniform and found mainly in the fine mode, whereas total metals and mineral dust cations were highest at the road-side site and in the coarse mode, resulting in a fine mode pH < 2 and near neutral coarse mode. Soluble metals and OP peaked at the intersection of these modes demonstrating that sulfate plays a key…

Microplastic pollution in inland waters is receiving growing attentions. Reservoirs are suspected to be particularly vulnerable to microplastic pollution. However, very limited information is currently available on pollution characteristics of microplastics in reservoir ecosystems. This work studied the distribution and characteristics of microplastics in the backwater area of Xiangxi River, a typical tributary of the Three Gorges Reservoir. Microplastics were detected in both surface water and sediment with concentrations ranging from 0.55 × 105 to 342 × 105 items km–2 and 80 to 864 items m–2, respectively. Polyethylene, polypropylene, and polystyrene were identified in surface water, whereas polyethylene, polypropylene, and polyethylene terephthalate, and pigments were observed in sediment. In addition, microplastics were also detected in the digestion tracts of 25.7% of fish samples, and polyethylene and nylon were identified. Redundancy analysis indicates a weak correlation between microplastics and water quality variables but a negative correlation with water level of the…

Micro-Fourier transform infrared (micro-FTIR) spectroscopy and Raman spectroscopy enable the reliable identification and quantification of microplastics (MPs) in the lower micron range. Since concentrations of MPs in the environment are usually low, the large sample volumes required for these techniques lead to an excess of coenriched organic or inorganic materials. While inorganic materials can be separated from MPs using density separation, the organic fraction impedes the ability to conduct reliable analyses. Hence, the purification of MPs from organic materials is crucial prior to conducting an identification via spectroscopic techniques. Strong acidic or alkaline treatments bear the danger of degrading sensitive synthetic polymers. We suggest an alternative method, which uses a series of technical grade enzymes for purifying MPs in environmental samples. A basic enzymatic purification protocol (BEPP) proved to be efficient while reducing 98.3 ± 0.1% of the sample matrix in surface water samples. After showing a high recovery rate (84.5 ± 3.3%), the BEPP was successfully applied…

Understanding the chemistry of hydrogen peroxide (H 2 O 2 ) decomposition and hydroxyl radical (•OH) transformation on the surface molecular level is a great challenge for the application of heterogeneous Fenton system in the fields of chemistry, environmental, and life science. We report in this study a conceptual oxygen vacancy associated surface Fenton system without any metal ions leaching, exhibiting unprecedented surface chemistry based on the oxygen vacancy of electron-donor nature for heterolytic H 2 O 2 dissociation. By controlling the delicate surface structure of catalyst, this novel Fenton system allows the facile tuning of •OH existing form for targeted catalytic reactions with controlled reactivity and selectivity. On the model catalyst of BiOCl, the generated •OH tend to diffuse away from the (001) surface for the selective oxidation of dissolved pollutants in solution, but prefer to stay on the (010) surface, reacting with strongly adsorbed pollutants with high priority. These findings will extend the scope of Fenton catalysts via surface engineering and consolidate…

Bisphenol A (BPA), a chemical incorporated into plastics and resins, has estrogenic activity and is associated with adverse health effects in humans and wildlife. Similarly structured BPA analogues are widely used but far less is known about their potential toxicity or estrogenic activity in vivo. We undertook the first comprehensive analysis on the toxicity and teratogenic effects of the bisphenols BPA, BPS, BPF, and BPAF in zebrafish embryo-larvae and an assessment on their estrogenic mechanisms in an estrogen-responsive transgenic fish Tg(ERE:Gal4ff)(UAS:GFP). The rank order for toxicity was BPAF > BPA > BPF > BPS. Developmental deformities for larval exposures included cardiac edema, spinal malformation, and craniofacial deformities and there were distinct differences in the effects and potencies between the different bisphenol chemicals. These effects, however, occurred only at concentrations between 1.0 and 200 mg/L which exceed those in most environments. All bisphenol compounds induced estrogenic responses in Tg(ERE:Gal4ff)(UAS:GFP) zebrafish that were inhibited by…

A closed-loop process to recover lithium carbonate from cathode scrap of lithium-ion battery (LIB) is developed. Lithium could be selectively leached into solution using formic acid while aluminum remained as the metallic form, and most of the other metals from the cathode scrap could be precipitated out. This phenomenon clearly demonstrates that formic acid can be used for lithium recovery from cathode scrap, as both leaching and separation reagent. By investigating the effects of different parameters including temperature, formic acid concentration, H 2 O 2 amount, and solid to liquid ratio, the leaching rate of Li can reach 99.93% with minor Al loss into the solution. Subsequently, the leaching kinetics was evaluated and the controlling step as well as the apparent activation energy could be determined. After further separation of the remaining Ni, Co, and Mn from the leachate, Li 2 CO 3 with the purity of 99.90% could be obtained. The final solution after lithium carbonate extraction can be further processed for sodium formate preparation, and Ni, Co, and Mn precipitates are…

Peracetic acid (PAA) is a widely used disinfectant, and combined UV light with PAA (i.e., UV/PAA) can be a novel advanced oxidation process for elimination of water contaminants. This study is among the first to evaluate the photolysis of PAA under UV irradiation (254 nm) and degradation of pharmaceuticals by UV/PAA. PAA exhibited high quantum yields (Φ 254 nm = 1.20 and 2.09 mol·Einstein –1 for the neutral (PAA 0 ) and anionic (PAA – ) species, respectively) and also showed scavenging effects on hydroxyl radicals ( k • OH/PAA 0 = (9.33 ± 0.3) × 10 8 M –1 ·s –1 and k • OH/PAA – = (9.97 ± 2.3) × 10 9 M –1 ·s –1 ). The pharmaceuticals were persistent with PAA alone but degraded rapidly by UV/PAA. The contributions of direct photolysis, hydroxyl radicals, and other radicals to pharmaceutical degradation under UV/PAA were systematically evaluated. Results revealed that • OH was the primary radical responsible for the degradation of carbamazepine and ibuprofen by UV/PAA, whereas CH 3 C(═O)O • and/or CH 3 C(═O)O 2 • contributed significantly to the degradation of naproxen and…

Composting is an efficient way to convert organic waste into fertilizers. However, waste materials often contain large amounts of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) that can reduce the efficacy of antibiotic treatments when transmitted to humans. Because conventional composting often fails to remove these compounds, we evaluated if hyperthermophilic composting with elevated temperature is more efficient at removing ARGs and MGEs and explored the underlying mechanisms of ARG removal of the two composting methods. We found that hyperthermophilic composting removed ARGs and MGEs more efficiently than conventional composting (89% and 49%, respectively). Furthermore, the half-lives of ARGs and MGEs were lower in hyperthermophilic compositing compared to conventional composting (67% and 58%, respectively). More-efficient removal of ARGs and MGEs was associated with a higher reduction in bacterial abundance and diversity of potential ARG hosts. Partial least-squares path modeling suggested that reduction of MGEs played a key role in ARG removal in…

Advanced oxidation processes (AOPs), such as hydroxyl radical (HO • )- and sulfate radical (SO 4 •– )-mediated oxidation, are alternatives for the attenuation of pharmaceuticals and personal care products (PPCPs) in wastewater effluents. However, the kinetics of these reactions needs to be investigated. In this study, kinetic models for 15 PPCPs were built to predict the degradation of PPCPs in both HO • - and SO 4 •- -mediated oxidation. In the UV/H 2 O 2 process, a simplified kinetic model involving only steady state concentrations of HO • and its biomolecular reaction rate constants is suitable for predicting the removal of PPCPs, indicating the dominant role of HO • in the removal of PPCPs. In the UV/K 2 S 2 O 8 process, the calculated steady state concentrations of CO 3 •– and bromine radicals (Br •, Br 2 •– and BrCl •– ) were 600-fold and 1–2 orders of magnitude higher than the concentrations of SO 4 •–, respectively. The kinetic model, involving both SO 4 •– and CO 3 •– as reactive species, was more accurate for predicting the removal of the 9 PPCPs, except for salbutamol and…

Recycling of livestock manure in agroecosystems to partially substitute synthetic fertilizer nitrogen (N) input is recommended to alleviate the environmental degradation associated with synthetic N fertilization, which may also affect food security and soil greenhouse gas (GHG) emissions. However, how substituting livestock manure for synthetic N fertilizer affects crop productivity (crop yield; crop N uptake; N use efficiency), reactive N (Nr) losses (ammonia (NH 3 ) emission, N leaching and runoff), GHG (methane, CH 4; and nitrous oxide, N 2 O; carbon dioxide) emissions and soil organic carbon (SOC) sequestration in agroecosystems is not well understood. We conducted a global meta-analysis of 141 studies and found that substituting livestock manure for synthetic N fertilizer (with equivalent N rate) significantly increased crop yield by 4.4% and significantly decreased Nr losses via NH 3 emission by 26.8%, N leaching by 28.9% and N runoff by 26.2%. Moreover, annual SOC sequestration was significantly increased by 699.6 and 401.4 kg C ha –1 yr –1 in upland and paddy fields,…

Iron-based materials used in water treatment and groundwater remediation-especially micro- and nanosized zerovalent iron (nZVI)-can be more effective when modified with lower-valent forms of sulfur (i.e., "sulfidated"). Controlled sulfidation for this purpose (using sulfide, dithionite, etc.) is the main topic of this review, but insights are derived by comparison with related and comparatively well-characterized processes such as corrosion of iron in sulfidic waters and abiotic natural attenuation by iron sulfide minerals. Material characterization shows that varying sulfidation protocols (e.g., concerted or sequential) and key operational variables (e.g., S/Fe ratio and sulfidation duration) result in materials with structures and morphologies ranging from core-shell to multiphase. A meta-analysis of available kinetic data for dechlorination under anoxic conditions, shows that sulfidation usually increases dechlorination rates, and simultaneously hydrogen production is suppressed. Therefore, sulfidation can greatly improve the efficiency of utilization of reducing equivalents for…

Abstract In this study, we construct a surface Fenton system with hydroxylamine (NH2OH), goethite (α-FeOOH), and H2O2 (α-FeOOH–HA/H2O2) to degrade various organic pollutants including dyes (methyl orange, methylene blue, and rhodamine B), pesticides (pentachlorophenol, alachlor, and atrazine), and antibiotics (tetracycline, chloramphenicol, and lincomycin) at pH 5.0. In this surface Fenton system, the presence of NH2OH could greatly promote the H2O2 decomposition on the α-FeOOH surface to produce ·OH without releasing any detectable iron ions during the alachlor degradation, which was different from some previously reported heterogeneous Fenton counterparts. Moreover, the ·OH generation rate constant of this surface Fenton system was 102–104 times those of previous heterogeneous Fenton processes. The interaction between α-FeOOH and NH2OH was investigated with using attenuated total reflectance Fourier transform infrared spectroscopy and density functional theory calculations. The effective degradation of organic pollutants in this surface Fenton system was ascribed to the efficient…

There is limited knowledge regarding the adverse effects of wastewater-derived microplastics, particularly fibers, on aquatic biota. In this study, we examined the acute (48 h) and chronic (8 d) effects of microplastic polyester fibers and polyethylene (PE) beads on freshwater zooplankton Ceriodaphnia dubia. We also assessed the acute response of C. dubia to a binary mixture of microplastic beads and fibers for the first time. Acute exposure to fibers and PE beads both showed a dose-dependent effect on survival. An equitoxic binary mixture of beads and fibers resulted in a toxic unit of 1.85 indicating less than additive effects. Chronic exposure to lower concentrations did not significantly affect survival of C. dubia, but a dose-dependent effect on growth and reproduction was observed. Fibers showed greater adverse effects than PE beads. While ingestion of fibers was not observed, scanning electron microscopy showed carapace and antenna deformities after exposure to fibers, with no deformities observed after exposure to PE beads. While much of the current research has focused on…

Transformation and evolution mechanisms of nitrogen during algae pyrolysis were investigated in depth with exploration of N-containing products under variant temperature. Results indicated nitrogen in algae is mainly in the form of protein-N (∼90%) with some inorganic-N. At 400–600 °C, protein-N in algae cracked first with algae pyrolysis and formed pyridinic-N, pyrrolic-N, and quaternary-N in char. The content of protein-N decreased significantly, while that of pyrrolic-N and quaternary-N increased gradually with temperature increasing. Pyridinic-N and pyrrolic-N formation was due to deamination or dehydrogenation of amino acids; subsequently, some pyridinic-N converted to quaternary-N. Increasing temperature decreased amides content greatly while increased that of nitriles and N-heterocyclic compounds (pyridines, pyrroles, and indoles) in bio-oil. Amides were formed through NH 3 reacting with fatty acids, that underwent dehydration to form nitriles. Besides, NH 3 and HCN yields increased gradually. NH 3 resulted from ammonia-N, labile amino acids and amides decomposition, while…

Utilities incorporating the potable reuse of municipal wastewater are interested in converting from the UV/H 2 O 2 to the UV/free chlorine advanced oxidation process (AOP). The AOP treatment of reverse osmosis (RO) permeate often includes the de facto UV/chloramine AOP because chloramines applied upstream permeate RO membranes. Models are needed that accurately predict oxidant photolysis and subsequent radical reactions. By combining radical scavengers and kinetic modeling, we have derived quantum yields for radical generation by the UV photolysis of HOCl, OCl –, and NH 2 Cl of 0.62, 0.55, and 0.20, respectively, far below previous estimates that incorporated subsequent free chlorine or chloramine scavenging by the • Cl and • OH daughter radicals. The observed quantum yield for free chlorine loss actually decreased with increasing free chlorine concentration, suggesting scavenging of radicals participating in free chlorine chain decomposition and even free chlorine reformation. Consideration of reactions of • ClO and its daughter products (e.g., ClO 2 – ), not included in previous…

grams or thousand tonnes) of mercury (Hg) have been released by human activities up to 2010, 73% of which was released after 1850. Of this liberated Hg, 470 Gg were emitted directly into the atmosphere, and 74% of the air emissions were elemental Hg. Cumulatively, about 1070 Gg were released to land and water bodies. Though annual releases of Hg have been relatively stable since 1880 at 8 ± 2 Gg, except for wartime, the distributions of those releases among source types, world regions, and environmental media have changed dramatically. Production of Hg accounts for 27% of cumulative Hg releases to the environment, followed by silver production (24%) and chemicals manufacturing (12%). North America (30%), Europe (27%), and Asia (16%) have experienced the largest releases. Biogeochemical modeling shows a 3.2-fold increase in the atmospheric burden relative to 1850 and a contemporary atmospheric reservoir of 4.57 Gg, both of which agree well with observational constraints. We find that approximately 40% (390 Gg) of the Hg discarded to land and water must be sequestered at contaminated…

Abstract The present study investigated the presence of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in river water collected in 2016 up- and downstream from a fluorochemical production plant, as well as in river water from control sites, in The Netherlands. Additionally, drinking water samples were collected from municipalities in the vicinity from the production plant, as well as in other regions in The Netherlands. The PFOA replacement chemical GenX was detected at all downstream river sampling sites with the highest concentration (812 ng/L) at the first sampling location downstream from the production plant, which was 13 times higher than concentrations of sum perfluoroalkylcarboxylic acids and perfluoroalkanesulfonates (∑PFCA+∑PFSA). Using high resolution mass spectrometry, 11 polyfluoroalkyl acids belonging to the C2nH2nF2nO2, C2nH2n+2F2nSO4 or C2n+1H2nF2n+4SO4 homologue series were detected, but only in downstream water samples. These emerging PFASs followed a similar distribution as GenX among the downstream sampling sites, suggesting the production plant…

Landfill leachate concentrate is a type of refractory organic wastewater with high environmental risk. Identification of refractory components and insights into the molecular transformations of the organics are essential for the development of efficient treatment process. In this report, molecular compositions of dissolved organic matter (DOM) in leachate concentrate, as well as changes after anaerobic/aerobic biodegradation and coagulation with salts, were characterized using electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). DOM in leachate concentrate were more saturated and less oxidized with more nitrogen and sulfur-containing substances (accounting for 50.0%), comparing with natural organic matter in Suwannee River. Selectivity for different classes of organics during biodegradation and coagulation processes was observed. Substances with low oxidation degree (O/C < 0.3) were more reactive during biodegradation process, leading to the formation of highly oxidized molecules (O/C > 0.5). Unsaturated (H/C < 1.0) and…

Ultrasound (US) was shown to activate persulfate (PS) providing an alternative activation method to base or heat as an in situ chemical oxidation (ISCO) method. The kinetics and mechanism of ultrasonic activation of PS were examined in aqueous solution using an in situ electron paramagnetic resonance (EPR) spin trapping technique and radical trapping with probe compounds. Using the spin trap, 5,5-dimethyl-1-pyrroline- N -oxide (DMPO), hydroxyl radical ( • OH) and sulfate radical anion (SO 4 •– ) were measured from ultrasonic activation of persulfate (US-PS). The yield of • OH was up to 1 order of magnitude greater than that of SO 4 •– . The comparatively high • OH yield was attributed to the hydrolysis of SO 4 •– in the warm interfacial region of cavitation bubbles formed from US. Using steady-state approximations, the dissociation rate of PS in cavitating bubble systems was determined to be 3 orders of magnitude greater than control experiments without sonication at ambient temperature. From calculations of the interfacial volume surrounding cavitation bubbles and using the…

Landfills are the final stage in the life cycle of many products containing per- and polyfluoroalkyl substances (PFASs) and their presence has been reported in landfill leachate. The concentrations of 70 PFASs in 95 samples of leachate were measured in a survey of U.S. landfills of varying climates and waste ages. National release of PFASs was estimated by coupling measured concentrations for the 19 PFASs where more than 50% of samples had quantifiable concentrations, with climate-specific estimates of annual leachate volumes. For 2013, the total volume of leachate generated in the U.S. was estimated to be 61.1 million m 3, with 79% of this volume coming from landfills in wet climates (>75 cm/yr precipitation) that contain 47% of U.S. solid waste. The mass of measured PFASs from U.S. landfill leachate to wastewater treatment plants was estimated to be between 563 and 638 kg for 2013. In the majority of landfill leachate samples, 5:3 fluorotelomer carboxylic acid (FTCA) was dominant and variations in concentrations with waste age affected total estimated mass. There were six PFASs…

Uranium is not only a strategic resource for the nuclear industry but also a global contaminant with high toxicity. Although several strategies have been established for detecting uranyl ions in water, searching for new uranium sensor material with great sensitivity, selectivity, and stability remains a challenge. We introduce here a hydrolytically stable mesoporous terbium(III)-based MOF material compound 1, whose channels are as large as 27 Å × 23 Å and are equipped with abundant exposed Lewis basic sites, the luminescence intensity of which can be efficiently and selectively quenched by uranyl ions. The detection limit in deionized water reaches 0.9 μg/L, far below the maximum contamination standard of 30 μg/L in drinking water defined by the United States Environmental Protection Agency, making compound 1 currently the only MOF material that can achieve this goal. More importantly, this material exhibits great capability in detecting uranyl ions in natural water systems such as lake water and seawater with pH being adjusted to 4, where huge excesses of competing ions are…

Lithium is a rare metal because of geographical scarcity and technical barrier. Recycling lithium resource from spent lithium ion batteries (LIBs) is significant for lithium deficiency and environmental protection. A novel approach for recycling lithium element as Li 2 CO 3 from spent LIBs is proposed. First, the electrode materials preobtained by mechanical separation are pyrolyzed under enclosed vacuum condition. During this process the Li is released as Li 2 CO 3 from the crystal structure of lithium transition metal oxides due to the collapse of the oxygen framework. An optimal Li recovery rate of 81.90% is achieved at 973 K for 30 min with a solid-to-liquid ratio of 25 g L –1, and the purity rate of Li 2 CO 3 is 99.7%. The collapsed mechanism is then presented to explain the release of lithium element during the vacuum pyrolysis. Three types of spent LIBs including LiMn 2 O 4, LiCoO 2, and LiCo x Mn y Ni z O 2 are processed to prove the validity of in situ recycling Li 2 CO 3 from spent LIBs under enclosed vacuum condition. Finally, an economic assessment is taken to prove that…

99 Tc is one of the most problematic radioisotopes in used nuclear fuel owing to its combined features of high fission yield, long half-life, and high environmental mobility. There are only a handful of functional materials that can remove TcO 4 – anion from aqueous solution and identifying for new, stable materials with high anion-exchange capacities, fast kinetics, and good selectivity remains a challenge. We report here an 8-fold interpenetrated three-dimensional cationic metal–organic framework material, SCU-100, which is assembled from a tetradentate neutral nitrogen-donor ligand and two-coordinate Ag + cations as potential open metal sites. The structure also contains a series of 1D channels filled with unbound nitrate anions. SCU-100 maintains its crystallinity in aqueous solution over a wide pH range from 1 to 13 and exhibits excellent β and γ radiation-resistance. Initial anion exchange studies show that SCU-100 is able to both quantitatively and rapidly remove TcO 4 – from water within 30 min. The exchange capacity for the surrogate ReO 4 – reaches up to 541 mg/g and the…

Industrial-use catalysts usually encounter severe deactivation after long-term operation for catalytic oxidation of chlorinate volatile organic compounds (CVOCs), which becomes a “bottleneck” for large-scale application of catalytic combustion technology. In this work, typical acidic solid-supported catalysts of Mn x Ce 1– x O 2 /HZSM-5 were investigated for the catalytic oxidation of chlorobenzene (CB). The activation energy ( E a ), Brønsted and Lewis acidities, CB adsorption and activation behaviors, long-term stabilities, and surficial accumulation compounds (after aging) were studied using a range of analytical techniques, including XPS, H 2 -TPR, pyridine-IR, DRIFT, and O 2 -TP-Ms. Experimental results revealed that the Brønsted/Lewis (B/L) ratio of Mn x Ce 1– x O 2 /HZSM-5 catalysts could be adjusted by ion exchange of H• (in HZSM-5) with Mn n+ (where the exchange with Ce 4+ did not distinctly affect the acidity); the long-term aged catalysts could accumulate ca. 14 organic compounds at surface, including highly toxic tetrachloromethane, trichloroethylene,…

Lead (Pb) pollution in natural water bodies is an environmental concern due to toxic effects on aquatic ecosystems and human health, while adsorption is an effective approach to remove Pb from the water. Surface interactions between adsorbents and adsorbates play a dominant role in the adsorption process, and properly engineering a material’s surface property is critical to the improvement of adsorption performance. In this study, the magnesium oxide (MgO) nanoparticles stabilized on the N-doped biochar (MgO@N-biochar) were synthesized by one-pot fast pyrolysis of an MgCl 2 -loaded N-enriched hydrophyte biomass as a way to increase the exchangeable ions and N-containing functional groups and facilitate the adsorption of Pb 2+ . The as-synthesized MgO@N-biochar has a high performance with Pb in an aqueous solution with a large adsorption capacity (893 mg/g), a very short equilibrium time (<10 min), and a large throughput (∼4450 BV). Results show that this excellent adsorption performance can be maintained with various environmentally relevant interferences including pH, natural…

Manganese oxide has been recognized as one of the most promising gaseous heterogeneous catalysts due to its low cost, environmental friendliness, and high catalytic oxidation performance. Mn-based oxides can be classified into four types: (1) single manganese oxide (MnOx), (2) supported manganese oxide (MnOx/support), (3) composite manganese oxides (MnOx-X), and (4) special crystalline manganese oxides (S-MnOx). These Mn-based oxides have been widely used as catalysts for the elimination of gaseous pollutants. This review aims to describe the environmental applications of these manganese oxides and provide perspectives. It gives detailed descriptions of environmental applications of the selective catalytic reduction of NOx with NH 3, the catalytic combustion of volatile organic compounds, Hg 0 oxidation and adsorption, and soot oxidation, in addition to some other environmental applications. Furthermore, this review mainly focuses on the effects of structure, morphology, and modified elements and on the role of catalyst supports in gaseous heterogeneous catalytic reactions. Finally,…