Showing papers in "Environmental Science & Technology in 2021"

SARS-CoV-2 RNA in Wastewater Settled Solids Is Associated with COVID-19 Cases in a Large Urban Sewershed.

Abstract: Wastewater-based epidemiology may be useful for informing public health response to viral diseases like COVID-19 caused by SARS-CoV-2. We quantified SARS-CoV-2 RNA in wastewater influent and primary settled solids in two wastewater treatment plants to inform the preanalytical and analytical approaches and to assess whether influent or solids harbored more viral targets. The primary settled solids samples resulted in higher SARS-CoV-2 detection frequencies than the corresponding influent samples. Likewise, SARS-CoV-2 RNA was more readily detected in solids using one-step digital droplet (dd)RT-PCR than with two-step RT-QPCR and two-step ddRT-PCR, likely owing to reduced inhibition with the one-step ddRT-PCR assay. We subsequently analyzed a longitudinal time series of 89 settled solids samples from a single plant for SARS-CoV-2 RNA as well as coronavirus recovery (bovine coronavirus) and fecal strength (pepper mild mottle virus) controls. SARS-CoV-2 RNA targets N1 and N2 concentrations correlated positively and significantly with COVID-19 clinically confirmed case counts in the sewershed. Together, the results demonstrate that measuring SARS-CoV-2 RNA concentrations in settled solids may be a more sensitive approach than measuring SARS-CoV-2 in influent.

Lifetime Accumulation of Microplastic in Children and Adults.

Abstract: Human exposure to microplastic is recognized as a global problem, but the uncertainty, variability, and lifetime accumulation are unresolved. We provide a probabilistic lifetime exposure model for children and adults, which accounts for intake via eight food types and inhalation, intestinal absorption, biliary excretion, and plastic-associated chemical exposure via a physiologically based pharmacokinetic submodel. The model probabilistically simulates microplastic concentrations in the gut, body tissue, and stool, the latter allowing validation against empirical data. Rescaling methods were used to ensure comparability between microplastic abundance data. Microplastic (1-5000 μm) median intake rates are 553 particles/capita/day (184 ng/capita/day) and 883 particles/capita/day (583 ng/capita/day) for children and adults, respectively. This intake can irreversibly accumulate to 8.32 × 103 (90% CI, 7.08 × 102-1.91 × 106) particles/capita or 6.4 (90% CI, 0.1-2.31 × 103) ng/capita for children until age 18, and up to 5.01 × 104 (90% CI, 5.25 × 103-9.33 × 106) particles/capita or 40.7 (90% CI, 0.8-9.85 × 103) ng/capita for adults until age 70 in the body tissue for 1-10 μm particles. Simulated microplastic concentrations in stool agree with empirical data. Chemical absorption from food and ingested microplastic of the nine intake media based on biphasic, reversible, and size-specific sorption kinetics, reveals that the contribution of microplastics to total chemical intake is small. The as-yet-unknown contributions of other food types are discussed in light of future research needs.

Single-Atom Fe Catalyst Outperforms Its Homogeneous Counterpart for Activating Peroxymonosulfate to Achieve Effective Degradation of Organic Contaminants

Abstract: Recently, reactive iron species (RFeS) have shown great potential for the selective degradation of emerging organic contaminants (EOCs). However, the rapid generation of RFeS for the selective and efficient degradation of EOCs over a wide pH range is still challenging. Herein, we constructed FeN4 structures on a carbon nanotube (CNT) to obtain single-atom catalysts (FeSA-N-CNT) to generate RFeS in the presence of peroxymonosulfate (PMS). The obtained FeSA-N-CNT/PMS system exhibited outstanding and selective reactivity for oxidizing EOCs over a wide pH range (3.0-9.0). Several lines of evidences suggested that RFeS existing as an FeN4═O intermediate was the predominant oxidant, while SO4·- and HO· were the secondary oxidants. Density functional theory calculation results revealed that a CNT played a key role in optimizing the distribution of bonding and antibonding states in the Fe 3d orbital, resulting in the outstanding ability of FeSA-N-CNT for PMS chemical adsorption and activation. Moreover, CNT could significantly enhance the reactivity of the FeN4═O intermediate by increasing the overlap of electrons of the Fe 3d orbital, O 2p orbital, and bisphenol A near the Fermi level. The results of this study can advance the understanding of RFeS generation in a heterogeneous system over a wide pH range and the application of RFeS in real practice.

Peroxydisulfate Activation and Singlet Oxygen Generation by Oxygen Vacancy for Degradation of Contaminants.

Abstract: Oxygen vacancies (OVs) play a crucial role in the catalytic activity of metal-based catalysts; however, their activation mechanism toward peroxydisulfate (PDS) still lacks reasonable explanation. In this study, by taking bismuth bromide (BiOBr) as an example, we report an OV-mediated PDS activation process for degradation of bisphenol A (BPA) employing singlet oxygen (1O2) as the main reactive species under alkaline conditions. The experimental results show that the removal efficiency of BPA is proportional to the number of OVs and is highly related to the dosage of PDS and the catalyst. The surface OVs of BiOBr provide ideal sites for the inclusion of hydroxyl ions (HO-) to form BiIII-OH species, which are regarded as the major active sites for the adsorption and activation of PDS. Unexpectedly, the activation of PDS occurs through a nonradical mechanism mediated by 1O2, which is generated via multistep reactions, involving the formation of an intermediate superoxide radical (O2•-) and the redox cycle of Bi(III)/Bi(IV). This work is dedicated to the in-depth mechanism study into PDS activation over OV-rich BiOBr samples and provides a novel perspective for the activation of peroxides by defective materials in the absence of additional energy supply or aqueous transition metal ions.

Cobalt Single Atoms on Tetrapyridomacrocyclic Support for Efficient Peroxymonosulfate Activation

Abstract: Transition-metal catalysts that can efficiently activate peroxide bonds have been extensively pursued for various applications including environmental remediation, chemical synthesis, and sensing. Here, we present pyridine-coordinated Co single atoms embedded in a polyaromatic macrostructure as a highly efficient peroxide-activation catalyst. The efficient catalytic production of reactive radicals through peroxymonosulfate activation was demonstrated by the rapid removal of model aqueous pollutants of environmental and public health concerns such as bisphenol A, without pH limitation and Co2+ leaching. The turnover frequency of the newly synthesized Co single-atom catalyst bound to tetrapyridomacrocyclic ligands was found to be 2 to 4 orders of magnitude greater than that of benchmark homogeneous (Co2+) and nanoparticulate (Co3O4) catalysts. Experimental results and density functional theory simulation suggest that the abundant π-conjugation in the polyaromatic support and strong metal-support electronic interaction allow the catalysts to effectively adsorb and activate the peroxide precursor. We further loaded the catalysts onto a widely used poly(vinylidene fluoride) microfiltration membrane and demonstrated that the model pollutants were oxidatively removed as they simply passed through the filter, suggesting the promise of utilizing this novel catalyst for realistic applications.

Enhanced Oxidation of Organic Contaminants by Iron(II)-Activated Periodate: The Significance of High-Valent Iron-Oxo Species.

Abstract: Potassium periodate (PI, KIO4) was readily activated by Fe(II) under acidic conditions, resulting in the enhanced abatement of organic contaminants in 2 min, with the decay ratios of the selected pollutants even outnumbered those in the Fe(II)/peroxymonosulfate and Fe(II)/peroxydisulfate processes under identical conditions. Both 18O isotope labeling techniques using methyl phenyl sulfoxide (PMSO) as the substrate and X-ray absorption near-edge structure spectroscopy provided conclusive evidences for the generation of high-valent iron-oxo species (Fe(IV)) in the Fe(II)/PI process. Density functional theory calculations determined that the reaction of Fe(II) with PI followed the formation of a hydrogen bonding complex between Fe(H2O)62+ and IO4(H2O)-, ligand exchange, and oxygen atom transfer, consequently generating Fe(IV) species. More interestingly, the unexpected detection of 18O-labeled hydroxylated PMSO not only favored the simultaneous generation of ·OH but also demonstrated that ·OH was indirectly produced through the self-decay of Fe(IV) to form H2O2 and the subsequent Fenton reaction. In addition, IO4- was not transformed into the undesired iodine species (i.e., HOI, I2, and I3-) but was converted to nontoxic iodate (IO3-). This study proposed an efficient and environmental friendly process for the rapid removal of emerging contaminants and enriched the understandings on the evolution mechanism of ·OH in Fe(IV)-mediated processes.

Deep Dive into Plastic Monomers, Additives, and Processing Aids.

Abstract: A variety of chemical substances used in plastic production may be released throughout the entire life cycle of the plastic, posing risks to human health, the environment, and recycling systems. Only a limited number of these substances have been widely studied. We systematically investigate plastic monomers, additives, and processing aids on the global market based on a review of 63 industrial, scientific, and regulatory data sources. In total, we identify more than 10'000 relevant substances and categorize them based on substance types, use patterns, and hazard classifications wherever possible. Over 2'400 substances are identified as substances of potential concern as they meet one or more of the persistence, bioaccumulation, and toxicity criteria in the European Union. Many of these substances are hardly studied according to SciFinder (266 substances), are not adequately regulated in many parts of the world (1'327 substances), or are even approved for use in food-contact plastics in some jurisdictions (901 substances). Substantial information gaps exist in the public domain, particularly on substance properties and use patterns. To transition to a sustainable circular plastic economy that avoids the use of hazardous chemicals, concerted efforts by all stakeholders are needed, starting by increasing information accessibility.

Silicate-Enhanced Heterogeneous Flow-Through Electro-Fenton System Using Iron Oxides under Nanoconfinement.

Abstract: Herein, a silicate-enhanced flow-through electro-Fenton system with a nanoconfined catalyst was rationally designed and demonstrated for the highly efficient, rapid, and selective degradation of antibiotic tetracycline. The key active component of this system is the Fe2O3 nanoparticle filled carbon nanotube (Fe2O3-in-CNT) filter. Under an electric field, this composite filter enabled in situ H2O2 generation, which was converted to reactive oxygen species accompanied by the redox cycling of Fe3+/Fe2+. The presence of the silicate electrolyte significantly boosted the H2O2 yield by preventing the O-O bond dissociation of the adsorbed OOH*. Compared with the surface coated Fe2O3 on the CNT (Fe2O3-out-CNT) filter, the Fe2O3-in-CNT filter demonstrated 1.65 times higher kL value toward the degradation of the antibiotic tetracycline. Electron paramagnetic resonance and radical quenching tests synergistically verified that the dominant radical species was the 1O2 or HO· in the confined Fe2O3-in-CNT or unconfined Fe2O3-out-CNT system, respectively. The flow-through configuration offered improved tetracycline degradation kinetics, which was 5.1 times higher (at flow rate of 1.5 mL min-1) than that of a conventional batch reactor. Liquid chromatography-mass spectrometry measurements and theoretical calculations suggested reduced toxicity of fragments of tetracycline formed. This study provides a novel strategy by integrating state-of-the-art material science, Fenton chemistry, and microfiltration technology for environmental remediation.

Recent Progress of Thermocatalytic and Photo/Thermocatalytic Oxidation for VOCs Purification over Manganese-based Oxide Catalysts

Abstract: Volatile organic compounds (VOCs) are one of the main sources of air pollution, which are of wide concern because of their toxicity and serious threat to the environment and human health. Catalytic oxidation has been proven to be a promising and effective technology for VOCs abatement in the presence of heat or light. As environmentally friendly and low-cost materials, manganese-based oxides are the most competitive and promising candidates for the catalytic degradation of VOCs in thermocatalysis or photo/thermocatalysis. This article summarizes the research and development on various manganese-based oxide catalysts, with emphasis on their thermocatalytic and photo/thermocatalytic purification of VOCs in recent years in detail. Single manganese oxides, manganese-based oxide composites, as well as improving strategies such as morphology regulation, heterojunction engineering, and surface decoration by metal doping or universal acid treatment are reviewed. Besides, manganese-based monoliths for practical VOCs abatementare also discussed. Meanwhile, relevant catalytic mechanisms are also summarized. Finally, the existing problems and prospect of manganese-based oxide catalysts for catalyzing combustion of VOCs are proposed.

Unraveling the High-Activity Origin of Single-Atom Iron Catalysts for Organic Pollutant Oxidation via Peroxymonosulfate Activation.

Abstract: Single-atom catalysts (SACs) have emerged as efficient materials in the elimination of aqueous organic contaminants; however, the origin of high activity of SACs still remains elusive. Herein, we identify an 8.1-fold catalytic specific activity (reaction rate constant normalized to catalyst's specific surface area and dosage) enhancement that can be fulfilled with a single-atom iron catalyst (SA-Fe-NC) prepared via a cascade anchoring method compared to the iron nanoparticle-loaded catalyst, resulting in one of the most active currently known catalysts in peroxymonosulfate (PMS) conversion for organic pollutant oxidation. Experimental data and theoretical results unraveled that the high-activity origin of the SA-Fe-NC stems from the Fe-pyridinic N4 moiety, which dramatically increases active sites by not only creating the electron-rich Fe single atom as the catalytic site but also producing electron-poor carbon atoms neighboring pyridinic N as binding sites for PMS activation including synchronous PMS reduction and oxidation together with dissolved oxygen reduction. Moreover, the SA-Fe-NC exhibits excellent stability and applicability to realistic industrial wastewater remediation. This work offers a novel yet reasonable interpretation for why a small amount of iron in the SA-Fe-NC can deliver extremely superior specific activity in PMS activation and develops a promising catalytic oxidation system toward actual environmental cleanup.

Toxic Cyanobacteria: A Growing Threat to Water and Air Quality.

Abstract: The global expansion of harmful cyanobacterial blooms (CyanoHABs) poses an increasing threat to public health. CyanoHABs are characterized by the production of toxic metabolites known as cyanotoxins. Human exposure to cyanotoxins is challenging to forecast, and perhaps the least understood exposure route is via inhalation. While the aerosolization of toxins from marine harmful algal blooms (HABs) has been well documented, the aerosolization of cyanotoxins in freshwater systems remains understudied. In recent years, spray aerosol (SA) produced in the airshed of the Laurentian Great Lakes (United States and Canada) has been characterized, suggesting that freshwater systems may impact atmospheric aerosol loading more than previously understood. Therefore, further investigation regarding the impact of CyanoHABs on human respiratory health is warranted. This review examines current research on the incorporation of cyanobacterial cells and cyanotoxins into SA of aquatic ecosystems which experience HABs. We present an overview of cyanotoxin fate in the environment, biological incorporation into SA, existing data on cyanotoxins in SA, relevant collection methods, and adverse health outcomes associated with cyanotoxin inhalation.

Atomically Dispersed Cobalt Sites on Graphene as Efficient Periodate Activators for Selective Organic Pollutant Degradation.

Abstract: Pollutant degradation via periodate (IO4-)-based advanced oxidation processes (AOPs) provides an economical, energy-efficient way for sustainable pollution control. Although single-atomic metal activation (SMA) can be exploited to optimize the pollution degradation process and understand the associated mechanisms governing IO4--based AOPs, studies on this topic are rare. Herein, we demonstrated the first instance of using SMA for IO4- analysis by employing atomically dispersed Co active sites supported by N-doped graphene (N-rGO-CoSA) activators. N-rGO-CoSA efficiently activated IO4- for organic pollutant degradation over a wide pH range without producing radical species. The IO4- species underwent stoichiometric decomposition to generate the iodate (IO3-) species. Whereas Co2+ and Co3O4 could not drive IO4- activation; the Co-N coordination sites exhibited high activation efficiency. The conductive graphene matrix reduced the contaminants/electron transport distance/resistance for these oxidation reactions and boosted the activation capacity by working in conjunction with metal centers. The N-rGO-CoSA/IO4- system exhibited a substrate-dependent reactivity that was not caused by iodyl (IO3·) radicals. Electrochemical experiments demonstrated that the N-rGO-CoSA/IO4- system decomposed organic pollutants via electron-transfer-mediated nonradical processes, where N-rGO-CoSA/periodate* metastable complexes were the predominant oxidants, thereby opening a new avenue for designing efficient IO4- activators for the selective oxidation of organic pollutants.

Persulfate Oxidation of Sulfamethoxazole by Magnetic Iron-Char Composites via Nonradical Pathways: Fe(IV) Versus Surface-Mediated Electron Transfer.

Abstract: Despite the vital roles of reactive radical species in the coupled iron-carbon composite/persulfate (PS) system for eliminating pollutants, nonradical contributions are typically overlooked. Herein, we developed two efficient magnetic iron-char composites via low-temperature (BCFe-400) and high-temperature (BCFe-700) pyrolysis. The two composites activated PS through nonradical pathways for sulfamethoxazole (SMX) degradation. In the BCFe-400/PS system, high-valent iron Fe(IV) was the dominant active species for the oxidation, evidenced by methyl phenyl sulfoxide-based probe tests, Mossbauer spectroscopy, and in situ Raman analyses with kinetic evaluation. In the BCFe-700/PS system, surface-mediated electron transfer dominated the oxidation, and the nonradical regime was probed by the electrochemical test and in situ Raman analysis. Furthermore, the BCFe-400/PS system maintained high efficiency in continuous degradation of SMX due to the feasible Fe2+generation toward Fe(IV) formation. In the BCFe-700/PS system, the stability of the system was limited due to the hindered electron transfer between the surface reactive complex (i.e., BCFe-700-PS*) and SMX, and thermal treatment would help recover the reactivity. Both BCFe-400/PS and BCFe-700/PS systems exhibited high performances for SMX removal in the presence of chloride and humic acid and in real water matrixes (e.g., seawater, piggery wastewater, and landfill leachate), exhibiting the great merits of the nonradical system. Overall, the study would provide new insights into PS activation by iron-loaded catalysts to efficiently degrade pollutants via nonradical pathways.

Tracking Air Pollution in China: Near Real-Time PM2.5 Retrievals from Multisource Data Fusion.

Abstract: Air pollution has altered the Earth's radiation balance, disturbed the ecosystem, and increased human morbidity and mortality. Accordingly, a full-coverage high-resolution air pollutant data set with timely updates and historical long-term records is essential to support both research and environmental management. Here, for the first time, we develop a near real-time air pollutant database known as Tracking Air Pollution in China (TAP, http://tapdata.org.cn/) that combines information from multiple data sources, including ground observations, satellite aerosol optical depth (AOD), operational chemical transport model simulations, and other ancillary data such as meteorological fields, land use data, population, and elevation. Daily full-coverage PM2.5 data at a spatial resolution of 10 km is our first near real-time product. The TAP PM2.5 is estimated based on a two-stage machine learning model coupled with the synthetic minority oversampling technique and a tree-based gap-filling method. Our model has an averaged out-of-bag cross-validation R2 of 0.83 for different years, which is comparable to those of other studies, but improves its performance at high pollution levels and fills the gaps in missing AOD on daily scale. The full coverage and near real-time updates of the daily PM2.5 data allow us to track the day-to-day variations in PM2.5 concentrations over China in a timely manner. The long-term records of PM2.5 data since 2000 will also support policy assessments and health impact studies. The TAP PM2.5 data are publicly available through our website for sharing with the research and policy communities.

Accelerated Fe2+ Regeneration in an Effective Electro-Fenton Process by Boosting Internal Electron Transfer to a Nitrogen-Conjugated Fe(III) Complex.

Abstract: The regeneration rate of Fe2+ from Fe3+ dictates the performance of the electro-Fenton (EF) process, represented by the amount of produced hydroxyl radicals (·OH). Current strategies for the acceleration of Fe2+ regeneration normally require additional chemical reagents, to vary the redox potential of Fe2+/Fe3+. Here, we report an attempt at using the intrinsic property of the electrode to our advantage, i.e., nitrogen-doped carbon aerogel (NDCA), as a reducing agent for the regeneration of Fe2+ without using foreign reagents. Moreover, the pyrrolic N in NDCA provides unpaired electrons through the carbon framework to reduce Fe3+, while the graphitic and pyridinic N coordinate with Fe3+ to form a C-O-Fe-N2 bond, facilitating electron transfer from both the external circuit and pyrrolic N to Fe3+. Our Fe2+/NDCA-EF system exhibits a 5.8 ± 0.3 times higher performance, in terms of the amount of generated ·OH, than a traditional Fenton system using the same Fe2+ concentration. In the subsequent reaction, the Fe2+/NDCA-EF system demonstrates 100.0% removal of dimethyl phthalate, 3-chlorophenol, bisphenol A, and sulfamethoxazole with a low specific energy consumption of 0.17-0.36 kW·h·g-1. Furthermore, 90.1 ± 0.6% removal of dissolved organic carbon and 83.3 ± 0.9% removal of NH3-N are achieved in the treatment of domestic sewage. The purpose of this work is to present a novel strategy for the regeneration of Fe2+ in the EF process and also to elucidate the role of different N species of the carbonaceous electrode in contributing to the redox cycle of Fe2+/Fe3+.

Correlation of Active Sites to Generated Reactive Species and Degradation Routes of Organics in Peroxymonosulfate Activation by Co-Loaded Carbon.

Abstract: Peroxymonosulfate (PMS)-based advanced oxidation processes (PMS-AOPs) as an efficient strategy for organic degradation are highly dependent on catalyst design and structured active sites. However, the identification of the active sites and their relationship with reaction mechanisms for organic degradation are not fully understood for a composite catalyst due to the complex structure. Herein, we developed a family of Co encapsulated in N-doped carbons (Co-PCN) with tailored types and contents of active sites via manipulated pyrolysis for PMS activation and ciprofloxacin (CIP) degradation, focusing on the correlation of active sites to generated reactive species and degradation routes of organics. The structure-function relationships between the different active sites in Co-PCN catalysts and reactive oxygen species (ROS), as well as bond breaking position of CIP, were revealed through regression analysis and density functional theory calculation. Co-Nx, O-C═O, C═O, graphitic N, and defects in Co-PCN stimulate the generation of 1O2 for oxidizing the C-C bond in the piperazine ring of CIP into C═O. The substitution of F by OH and hydroxylation of the piperazine ring might be induced by SO4•- and •OH, whose formation was affected by C-O, Co(0), Co-Nx, graphitic N, and defects. The findings provided new insights into reaction mechanisms in PMS-AOP systems and rational design of catalysts for ROS-oriented degradation of pollutants.

Differentiating Solutes with Precise Nanofiltration for Next Generation Environmental Separations: A Review.

Abstract: Selective removal or enrichment of targeted solutes including micropollutants, valuable elements, and mineral scalants from complex aqueous matrices is both challenging and pivotal to the success o...

Monthly Global Estimates of Fine Particulate Matter and Their Uncertainty.

Abstract: Annual global satellite-based estimates of fine particulate matter (PM2.5) are widely relied upon for air-quality assessment. Here, we develop and apply a methodology for monthly estimates and uncertainties during the period 1998-2019, which combines satellite retrievals of aerosol optical depth, chemical transport modeling, and ground-based measurements to allow for the characterization of seasonal and episodic exposure, as well as aid air-quality management. Many densely populated regions have their highest PM2.5 concentrations in winter, exceeding summertime concentrations by factors of 1.5-3.0 over Eastern Europe, Western Europe, South Asia, and East Asia. In South Asia, in January, regional population-weighted monthly mean PM2.5 concentrations exceed 90 μg/m3, with local concentrations of approximately 200 μg/m3 for parts of the Indo-Gangetic Plain. In East Asia, monthly mean PM2.5 concentrations have decreased over the period 2010-2019 by 1.6-2.6 μg/m3/year, with decreases beginning 2-3 years earlier in summer than in winter. We find evidence that global-monitored locations tend to be in cleaner regions than global mean PM2.5 exposure, with large measurement gaps in the Global South. Uncertainty estimates exhibit regional consistency with observed differences between ground-based and satellite-derived PM2.5. The evaluation of uncertainty for agglomerated values indicates that hybrid PM2.5 estimates provide precise regional-scale representation, with residual uncertainty inversely proportional to the sample size.

Oxygen Vacancy-Induced Nonradical Degradation of Organics: Critical Trigger of Oxygen (O2) in the Fe-Co LDH/Peroxymonosulfate System.

Abstract: Ubiquitous oxygen vacancies (Vo) existing in metallic compounds can activate peroxymonosulfate (PMS) for water treatment. However, under environmental conditions, especially oxygenated surroundings...

Challenges in Measuring the Recovery of SARS-CoV-2 from Wastewater.

Abstract: Wastewater-based epidemiology is an emerging tool for tracking the spread of SARS-CoV-2 through populations. However, many factors influence recovery and quantification of SARS-CoV-2 from wastewater, complicating data interpretation. Specifically, these factors may differentially affect the measured virus concentration, depending on the laboratory methods used to perform the test. Many laboratories add a proxy virus to wastewater samples to determine losses associated with concentration and extraction of viral RNA. While measuring recovery of a proxy virus is an important process control, in this piece, we describe the caveats and limitations to the interpretation of this control, including that it typically does not account for losses during RNA extraction. We recommend reporting the directly measured concentration data alongside the measured recovery efficiency, rather than attempting to correct the concentration for recovery efficiency. Even though the ability to directly compare SARS-CoV-2 concentrations from different sampling locations determined using different methods is limited, concentration data (uncorrected for recovery) can be useful for public health response.

Interaction of Microplastics with Antibiotics in Aquatic Environment: Distribution, Adsorption, and Toxicity.

Abstract: As two major types of pollutants of emerging concerns, microplastics (MPs) and antibiotics (ATs) coexist in aquatic environments, and their interactions are a source of increasing concern. Therefore, this work examines the interaction mechanisms of MPs and ATs, and the effect of MPs on ATs bioavailability and antibiotic resistance genes (ARGs) abundance in aquatic environments. First, the mechanisms for ATs adsorption on MPs are summarized, mainly including hydrophobic, hydrogen-bonding, and electrostatic interactions. But other possible mechanisms, such as halogen bonding, CH/π interaction, cation-π interaction, and negative charge-assisted hydrogen bonds, are newly proposed to explain the observed ATs adsorption. Additionally, environmental factors (such as pH, ionic strength, dissolved organic matters, minerals, and aging conditions) affecting ATs adsorption by MPs are specifically discussed. Moreover, MPs could change the bioaccumulation and toxicity of ATs to aquatic organisms, and the related mechanisms on the joint effect are reviewed and analyzed. Furthermore, MPs can enrich ARGs from the surrounding environment, and the effect of MPs on ARGs abundance is evaluated. Finally, research challenges and perspectives for MPs-ATs interactions and related environmental implications are presented. This review will facilitate a better understanding of the environmental fate and risk of both MPs and ATs.

Are Free Radicals the Primary Reactive Species in Co(II)-Mediated Activation of Peroxymonosulfate? New Evidence for the Role of the Co(II)-Peroxymonosulfate Complex.

Abstract: The catalytic activation of peroxymonosulfate (PMS) is under intensive investigation with potentials as an alternative advanced oxidation process (AOP) in wastewater treatment. Among all catalysts examined, Co(II) exhibits the highest reactivity for the activation of PMS, following the conventional Fenton-like mechanism, in which free radicals (i.e., sulfate radicals and hydroxyl radicals) are reckoned as the reactive species. Herein, we report that the primary reactive species (PRS) is proposed to be a Co(II)-PMS complex (Co(II)-OOSO3-), while free radicals and Co(III) species act as the secondary reactive species (SRS) that play a minor role in the Co(II)/PMS process. This Co(II)-OOSO3- exhibits several intriguing properties including ability to conduct both one-electron-transfer and oxygen-atom-transfer reactions with selected molecules, both nucleophilic and electrophilic in nature, and strongly pH-dependent reactivity. This study provides novel insights into the chemical nature of the Co(II)-catalyzed PMS activation process.

How Much of the Total Organic Halogen and Developmental Toxicity of Chlorinated Drinking Water Might Be Attributed to Aromatic Halogenated DBPs

Abstract: Although >700 disinfection byproducts (DBPs) have been identified, >50% of the total organic halogen (TOX) in drinking water chlorination is unknown, and the DBPs responsible for the chlorination-a...

Weathering Plastics as a Planetary Boundary Threat: Exposure, Fate, and Hazards.

Abstract: We described in 2017 how weathering plastic litter in the marine environment fulfils two of three criteria to impose a planetary boundary threat related to "chemical pollution and the release of novel entities": (1) planetary-scale exposure, which (2) is not readily reversible. Whether marine plastics meet the third criterion, (3) eliciting a disruptive impact on vital earth system processes, was uncertain. Since then, several important discoveries have been made to motivate a re-evaluation. A key issue is if weathering macroplastics, microplastics, nanoplastics, and their leachates have an inherently higher potential to elicit adverse effects than natural particles of the same size. We summarize novel findings related to weathering plastic in the context of the planetary boundary threat criteria that demonstrate (1) increasing exposure, (2) fate processes leading to poorly reversible pollution, and (3) (eco)toxicological hazards and their thresholds. We provide evidence that the third criterion could be fulfilled for weathering plastics in sensitive environments and therefore conclude that weathering plastics pose a planetary boundary threat. We suggest future research priorities to better understand (eco)toxicological hazards modulated by increasing exposure and continuous weathering processes, to better parametrize the planetary boundary threshold for plastic pollution.

Duet Fe3C and FeNx Sites for H2O2 Generation and Activation toward Enhanced Electro-Fenton Performance in Wastewater Treatment.

Abstract: Heterogeneous electro-Fenton (HEF) reaction has been considered as a promising process for real effluent treatments. However, the design of effective catalysts for simultaneous H2O2 generation and ...

COVID-19 Outbreak and Hospital Air Quality: A Systematic Review of Evidence on Air Filtration and Recirculation.

Abstract: The outbreak of SARS-CoV-2 has made us all think critically about hospital indoor air quality and the approaches to remove, dilute, and disinfect pathogenic organisms from the hospital environment. While specific aspects of the coronavirus infectivity, spread, and routes of transmission are still under rigorous investigation, it seems that a recollection of knowledge from the literature can provide useful lessons to cope with this new situation. As a result, a systematic literature review was conducted on the safety of air filtration and air recirculation in healthcare premises. This review targeted a wide range of evidence from codes and regulations, to peer-reviewed publications, and best practice standards. The literature search resulted in 394 publications, of which 109 documents were included in the final review. Overall, even though solid evidence to support current practice is very scarce, proper filtration remains one important approach to maintain the cleanliness of indoor air in hospitals. Given the rather large physical footprint of the filtration system, a range of short-term and long-term solutions from the literature are collected. Nonetheless, there is a need for a rigorous and feasible line of research in the area of air filtration and recirculation in healthcare facilities. Such efforts can enhance the performance of healthcare facilities under normal conditions or during a pandemic. Past innovations can be adopted for the new outbreak at low-to-minimal cost.

HCl-Tolerant HxPO4/RuOx–CeO2 Catalysts for Extremely Efficient Catalytic Elimination of Chlorinated VOCs

Abstract: Bulk metal doping and surface phosphate modification were synergically adopted in a rational design to upgrade the CeO2 catalyst, which is highly active but easily deactivated for the catalytic oxidation of chlorinated volatile organic compounds (Cl-VOCs). The metal doping increased the redox ability and defect sites of CeO2, which mostly promoted catalytic activity and inhibited the formation of dechlorinated byproducts but generated polychlorinated byproducts. The subsequent surface modification of the metal-doped CeO2 catalysts with nonmetallic phosphate completely suppressed the formation of polychlorinated byproducts and, more importantly, enhanced the stability of the surface structure by forming a chainmail layer. A highly active, durable, and selective catalyst of phosphate-functionalized RuOx-CeO2 was the most promising among all the metal-doped (Ru, Pd, Pt, Cr, Mn, Fe, Co, and Cu) CeO2 catalysts investigated owing to the prominent chemical stability of RuOx and its superior versatility in the catalytic oxidation of different kinds of Cl-VOCs and other typical pollutants, including dimethyl sulfide, CO, and C3H8. Moreover, the chemical stability of the catalyst, including its bulk and surface structural stability, was investigated by combining intensive treatment with HCl/H2O or HCl with subsequent ex situ ultraviolet-visible light Raman spectroscopy and confirmed the superior resistance to Cl poisoning of the phosphate-functionalized RuOx-CeO2. This work exemplifies a promising strategy for developing ideal catalysts for the removal of Cl-VOCs and provides a catalyst with the superior catalytic performance in Cl-VOC oxidation to date.

Infection Risk Assessment of COVID-19 through Aerosol Transmission: a Case Study of South China Seafood Market.

Abstract: The Corona Virus Disease 2019 (COVID-19) is rapidly spreading throughout the world. Aerosol is a potential transmission route. We conducted the quantitative microbial risk assessment (QMRA) to evaluate the aerosol transmission risk by using the South China Seafood Market as an example. The key processes were integrated, including viral shedding, dispersion, deposition in air, biologic decay, lung deposition, and the infection risk based on the dose-response model. The available hospital bed for COVID-19 treatment per capita (1.17 × 10-3) in Wuhan was adopted as a reference for manageable risk. The median risk of a customer to acquire SARS-CoV-2 infection via the aerosol route after 1 h of exposure in the market with one infected shopkeeper was about 2.23 × 10-5 (95% confidence interval: 1.90 × 10-6 to 2.34 × 10-4). The upper bound could increase and become close to the manageable risk with multiple infected shopkeepers. More detailed risk assessment should be conducted in poorly ventilated markets with multiple infected cases. The uncertainties were mainly due to the limited information on the dose-response relation and the viral shedding which need further studies. The risk rapidly decreased outside the market due to the dilution by ambient air and became below 10-6 at 5 m away from the exit.

Critical Review: Role of Inorganic Nanoparticle Properties on Their Foliar Uptake and in Planta Translocation.

Abstract: There is increasing pressure on global agricultural systems due to higher food demand, climate change, and environmental concerns. The design of nanostructures is proposed as one of the economically viable technological solutions that can make agrochemical use (fertilizers and pesticides) more efficient through reduced runoff, increased foliar uptake and bioavailability, and decreased environmental impacts. However, gaps in knowledge about the transport of nanoparticles across the leaf surface and their behavior in planta limit the rational design of nanoparticles for foliar delivery with controlled fate and limited risk. Here, the current literature on nano-objects deposited on leaves is reviewed. The different possible foliar routes of uptake (stomata, cuticle, trichomes, hydathodes, necrotic spots) are discussed, along with the paths of translocation, via the phloem, from the leaf to the end sinks (mature and developing tissues, roots, rhizosphere). This review details the interplays between morphological constraints, environmental stimuli, and physical-chemical properties of nanoparticles influencing their fate, transformation, and transport after foliar deposition. A metadata analysis from the existing literature highlighted that plant used for testing nanoparticle fate are most often dicotyledon plants (75%), while monocotyledons (as cereals) are less considered. Correlations on parameters calculated from the literature indicated that nanoparticle dose, size, zeta potential, and affinity to organic phases correlated with leaf-to-sink translocation, demonstrating that targeting nanoparticles to specific plant compartments by design should be achievable. Correlations also showed that time and plant growth seemed to be drivers for in planta mobility, parameters that are largely overlooked in the literature. This review thus highlights the material design opportunities and the knowledge gaps for targeted, stimuli driven deliveries of safe nanomaterials for agriculture.

Novel Pathway for Vanadium(V) Bio-Detoxification by Gram-Positive Lactococcus raffinolactis.

Abstract: Whereas prospects of bioremediation for a vanadium(V) [V(V)]-contaminated environment are widely recognized, reported functional species are extremely limited, with the vast majority of Gram-negative bacteria in Proteobacteria Herein, the effectiveness of V(V) reduction is proved for the first time by Lactococcus raffinolactis, a Gram-positive bacterium in Firmicutes The V(V) removal efficiency was 865 ± 217% during 10-d operation, with an average removal rate of 432 ± 028 mg/L·d in a citrate-fed system correspondingly V(V) was bio-reduced to insoluble vanadium(IV) and distributed both inside and outside the cells Nitrite reductase encoded by gene nirS mainly catalyzed intracellular V(V) reduction, revealing a previously unrecognized pathway Oxidative stress induced by reactive oxygen species from dissimilatory V(V) reduction was alleviated through strengthened superoxide dismutase and catalase activities Extracellular polymeric substances with chemically reactive hydroxyl (-OH) and carboxyl (-COO-) groups also contributed to V(V) binding and reduction as well as ROS scavenging This study can improve the understanding of Gram-positive bacteria for V(V) bio-detoxification and offer microbial resources for bioremediation of a V(V)-polluted environment