Contamination Of Water Systems Research Articles

Quaternary amine synthesized ionic polymer for efficient removal of Cr(VI) in waste water

A series of imidazolium-based ionic polymer (ImIP2Br, ImIP3Br and ImIP4Br) were successfully prepared by quaternization reaction of 1,4-dimethyl bromide benzene, 1,3,5-tri(bromomethyl), 1,2,4,5-tetramethyl and 1,3,5-tri(1H-imidazol-1-yl)benzene. The as-prepared ImIP2Br, ImIP3Br and ImIP4Br ionic polymers were characterized by SEM, STEM, FTIR, TG and solid-state 13C NMR measurement. In the aqueous solution of [imidazolium] to [Cr] 1:1, the removal rate of Cr(VI) by ImIP4Br was 98.4%, which was much higher than that of ImIP2Br, ImIP3Br. In addition, the ImIP4Br was applied for efficient removal of Cr(VI) for extremely low concentration of Cr(VI) solution and electroplating industry wastewater by anion exchange. Finally, a series of experimentals studies were performed to study the enrichment of hexavalent chromium and evaluate the recycling and reproducibility of ImIP4Br. The result showed the concentration of the residual Cr(VI) is only 0.09 mg L−1, which is lower than the permissible limit of Cr(VI) discharge (0.10 mg L−1) according to the regulations of the US Environmental Protection Agency. For the actual electroplating wastewater, the adsorption efficiency of ImIP4Br for Cr(VI) is over 99.8%, despite the competitive adsorption of other ions in the solution. In a word, ImIP4Br shows outstanding enrichment ability, good regenerative ability and superior recyclability for removal of Cr(VI). The combination of promising removal performances endows ImIP4Br with great promises for capture and separation of Cr(VI) from contaminated water systems.

An autonomous real-time detector system for radionuclide monitoring in drinking water systems

For monitoring radioactive contamination of water systems due to nuclear accidents or terrorist attacks, there is need of an in situ online measurement to assess alpha-, beta- and gamma-emitting radionuclide contaminants quickly and accurately. However, there is no well-established online monitoring system for permanent surveillance of drinking water systems. Therefore, a real-time measurement system was developed based on the readout of plastic scintillator sheets by a photomultiplier. Direct contact between scintillator and streaming water allows for the detection of both long- and short-ranged particles. Using a passive cooling system, detection limits of 141 Bq/L for ^{241}Am, 20 Bq/L for ^{60}Co and 17 Bq/L for ^{137}Cs were achieved with measurements of 60 s counting time. The system has been designed to be operated safely without deep knowledge of radiation measurement technology. The detector can be connected as a bypass to a water system and be operated in a continuous online survey mode, making it applicable as an early warning system.

Photocatalytic degradation of acetaminophen and caffeine using magnetite-hematite combined nanoparticles: kinetics and mechanisms.

The increased use of pharmaceutical and personal care products (PPCPs) has contributed to the contamination of water systems and put pressure on the development of new techniques to deal with this problem. Acetaminophen (paracetamol), a common analgesic and antipyretic drug, and caffeine, a known central nervous system stimulant, are being used frequently by many people and found in large amounts in wastewater systems. In this work, their removal, by photocatalytic degradation, was promoted using magnetic nanoparticles (NPs) based on iron oxides. Besides being obtained from cheap and plentiful source, the magnetic properties of these NPs provide an easy way to separate them from the solution when the reaction is complete. Three types of hematite-based NPs, one pure (1) and two of them composed by a magnetite core partially (2) or completely (3) covered by a hematite shell, were synthesized and characterized. Sample 2 was the best photocatalyst for both pollutants' photo-assisted degradation. Under UV-vis irradiation and using a 0.13g catalyst/L solution, the total acetaminophen and caffeine degradation (20ppm/150mL) was achieved in 45min and 60min, respectively. The identification of some of the intermediate products was carried out by liquid chromatography in combination with electrospray ionization mass spectrometry. A complementary DensityFunctionalTheory (DFT) study revealed the relative stability of several species formed during the acetaminophen and caffeine degradation processes and gave some insight about the most favorable degradation pathways.

Nucleotide Adsorption on Iron(III) Oxide Nanoparticle Surfaces: Insights into Nano-Geo-Bio Interactions Through Vibrational Spectroscopy.

Molecular processes at geochemical interfaces impact many environmental processes that are critical to the fate and transport of contaminants in water systems. Often these interfaces are coated with natural organic matter, oxyanions, or biological components, yet little is understood about these coatings. Herein, we are interested in better understanding the interaction of biological components with nanoscale iron oxide minerals. In particular, we use attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to investigate the adsorption behavior of deoxyadenosine monophosphate (dAMP) on hematite nanoparticle surfaces as a function of pH and in the presence and absence of adsorbed phosphate. These results show that fewer nucleotides adsorb at higher pH. Additionally, when phosphate anions are preadsorbed, nucleotide adsorption is significantly limited due to site-blocking by adsorbed inorganic phosphate. The pH dependence provides insights into the adsorption process and the importance of electrostatic interactions. Preadsorbed phosphate affects the binding mode of dAMP, suggesting synergistic interactions between the coadsorbates. Two-dimensional correlation spectroscopy was used to further analyze the infrared spectra. Based on this analysis, a dAMP adsorption pathway onto a preadsorbed phosphate-hematite surface was proposed, suggesting the displacement of adsorbed phosphate by dAMP. Overall, this study provides some insights into geochemical-biological interactions on nanoscale iron oxide surfaces using vibrational spectroscopy.

Genetic and Phenotypic Factors Associated with Persistent Shedding of Shiga Toxin-Producing Escherichia coli by Beef Cattle

Shiga toxin-producing Escherichia coli (STEC) is a leading cause of foodborne infections. Cattle are an important STEC reservoir, although little is known about specific pathogen traits that impact persistence in the farm environment. Hence, we sought to evaluate STEC isolates recovered from beef cattle in a single herd in Michigan. To do this, we collected fecal grabs from 26 cattle and resampled 13 of these animals at 3 additional visits over a 3-month period. In all, 66 STEC isolates were recovered for genomics and biofilm quantification using crystal violet assays. The STEC population was diverse, representing seven serotypes, including O157:H7, O26:H11, and O103:H2, which are commonly associated with human infections. Although a core genome analysis of 2,933 genes grouped isolates into clusters based on serogroups, some isolates within each cluster had variable biofilm levels and virulence gene profiles. Most (77.8%; n = 49) isolates harbored stx 2a, while 38 (57.5%) isolates formed strong biofilms. Isolates belonging to the predominant serogroup O6 (n = 36; 54.5%) were more likely to form strong biofilms, persistently colonize multiple cattle, and be acquired over time. A high-quality single nucleotide polymorphism (SNP) analysis of 33 O6 isolates detected between 0 and 13 single nucleotide polymorphism (SNP) differences between strains, indicating that highly similar strain types were persisting in this herd. Similar findings were observed for other persistent serogroups, although key genes were found to differ among strong and weak biofilm producers. Together, these data highlight the diversity and persistent nature of some STEC types in this important food animal reservoir.IMPORTANCE Food animal reservoirs contribute to Shiga toxin-producing Escherichia coli (STEC) evolution via the acquisition of horizontally acquired elements like Shiga toxin bacteriophages that enhance pathogenicity. In cattle, persistent fecal shedding of STEC contributes to contamination of beef and dairy products and to crops being exposed to contaminated water systems. Hence, identifying factors important for STEC persistence is critical. This longitudinal study enhances our understanding of the genetic diversity of STEC types circulating in a cattle herd and identifies genotypic and phenotypic traits associated with persistence. Key findings demonstrate that multiple STEC types readily persist in and are transmitted across cattle in a shared environment. These dynamics also enhance the persistence of virulence genes that can be transferred between bacterial hosts, resulting in the emergence of novel STEC strain types. Understanding how pathogens persist and diversify in reservoirs is important for guiding new preharvest prevention strategies aimed at reducing foodborne transmission to humans.

Efficient Removal of Cr(VI) Ions by a Novel Magnetic 4-Vinyl Pyridine Grafted Ni3Si2O5(OH)4 Multiwalled Nanotube.

The contamination of water systems by heavy metals greatly threatens human health and ecological safety. An efficient adsorbent is critical for the removal of these contaminants. In this work, magnetic Ni3Si2O5(OH)4 nanotubes (NTs) have been synthesized via in situ hydrothermal reduction and further functionalized by grafting poly(4-vinyl pyridine) (P4VP) brushes on its surface via atom transfer radical polymerization. Characterizations by Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, and X-ray photoelectron spectroscopy proved that P4VP was successfully grafted on the surface of magnetic Ni3Si2O5(OH)4 NTs. The resultant Ni3Si2O5(OH)4-g-P4VP NTs are efficient nanosorbents for removing Cr(VI) anions from water. The Cr(VI) adsorption capacity of Ni3Si2O5(OH)4-g-P4VP NTs reaches 1.49 mmol/g at a pH of 3. The pseudo-second-order kinetic model and the Freundlich isothermal model are suitable to describe the adsorption process. The analysis using Weber–Morris and Boyd models indicates that both intraparticle diffusion and external film diffusion affect the Cr(VI) adsorption process. The adsorption enthalpy is estimated to be 18.37 kJ/mol. More than 90% of the Cr(VI) adsorption capacity of the Ni3Si2O5(OH)4-g-P4VP NTs remains after eight adsorption and desorption cycles.

Environmental Surveillance as a Tool for Identifying High-risk Settings for Typhoid Transmission.

Enteric fever remains a major cause of morbidity in developing countries with poor sanitation conditions that enable fecal contamination of water distribution systems. Historical evidence has shown that contamination of water systems used for household consumption or agriculture are key transmission routes for Salmonella Typhi and Salmonella Paratyphi A. The World Health Organization now recommends that typhoid conjugate vaccines (TCV) be used in settings with high typhoid incidence; consequently, governments face a challenge regarding how to prioritize typhoid against other emerging diseases. A key issue is the lack of typhoid burden data in many low- and middle-income countries where TCV could be deployed. Here we present an argument for utilizing environmental sampling for the surveillance of enteric fever organisms to provide data on community-level typhoid risk. Such an approach could complement traditional blood culture-based surveillance or even replace it in settings where population-based clinical surveillance is not feasible. We review historical studies characterizing the transmission of enteric fever organisms through sewage and water, discuss recent advances in the molecular detection of typhoidal Salmonella in the environment, and outline challenges and knowledge gaps that need to be addressed to establish environmental sampling as a tool for generating actionable data that can inform public health responses to enteric fever.

Rapid removal of Sr2+, Cs+ and UO22+ from solution with surfactant and amino acid modified zeolite Y

In this study, a new and efficient sorbent material was developed by the surface modification of zeolite Y with surfactant of cetyltrimethyl ammonium bromide (CTAB) and amino acid of l -aspartic acid (Asp) for rapid removal of Sr 2+ , Cs + and UO 2 2+ in solution. The as-synthesized and modified zeolite Y were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption-desorption analysis. The results showed that after first grafting the cations of CTAB on the external surface of zeolite Y crystals, negatively charged Asp was then successfully introduced onto zeolite to form the CTAB + Asp dually modified zeolite Y sorbent. The fraction of CTAB and Asp in dually modified zeolite Y is 9.6 wt % and 16.3 wt %, respectively. The sorption isotherm of UO 2 2+ , Sr 2+ and Cs + by such sorbent was better fitted by Langmuir model. The CTAB + Asp dually modified zeolite Y took 20 min to reach the maximum sorption amount, while the unmodified zeolite Y took 240 min. This encouraging result provides a new concept to design sorbent materials for rapid removal of radionuclides from contaminated water system in an emergency. • Comprehensive investigation on modified zeolite Y for radioactive cation removal. • Zeolite Y is successfully modified with CTAB and aspartic acid on the surface. • Aspartic acid modified zeolite Y has a rapid removal efficiency for nuclide cation.

Factors Influencing the Concentration of Fecal Coliforms in Oysters in the River Blackwater Estuary, UK

Contamination of water systems can not only entail high risks to human health but can also result in economic losses due to closure of beaches and shellfish harvesting areas. Understanding the origin of fecal pollution at locations where shellfish are grown is essential in assessing associated health risks—as well as the determining actions necessary to remedy the problem. The aim of this work is to identify the species-specific source(s) of fecal contamination impacting waters overlying the shellfisheries in the Blackwater Estuary, East Anglia, UK. Over a twelve-month period, water samples were taken from above the oysters and from a variety of upstream points considered to be likely sources of fecal microorganism, together with oyster samples, and the number of fecal streptococci and E. coli were determined. Transition from low to high tide significantly decreased the concentration of fecal streptococci in waters overlying the oyster beds, indicative of a freshwater input of fecal pollution in oyster bed waters. In 12 months, the number of E. coli remained constant throughout, while fecal streptococci numbers were generally higher in the winter months. Analyses of upstream samples identified a sewage outfall to be the main source of E. coli to the oyster beds, with additional fecal streptococci from agricultural sources. The findings may assist in developing approaches for assessing the risks to shellfishery industries of various fecal inputs into an estuary, which could then help local governmental authorities address the problem.

Meta-SourceTracker: application of Bayesian source tracking to shotgun metagenomics.

BackgroundMicrobial source tracking methods are used to determine the origin of contaminating bacteria and other microorganisms, particularly in contaminated water systems. The Bayesian SourceTracker approach uses deep-sequencing marker gene libraries (16S ribosomal RNA) to determine the proportional contributions of bacteria from many potential source environments to a given sink environment simultaneously. Since its development, SourceTracker has been applied to an extensive diversity of studies, from beach contamination to human behavior.MethodsHere, we demonstrate a novel application of SourceTracker to work with metagenomic datasets and tested this approach using sink samples from a study of coastal marine environments. Source environment metagenomes were obtained from metagenomics studies of gut, freshwater, marine, sand and soil environments. As part of this effort, we implemented features for determining the stability of source proportion estimates, including precision visualizations for performance optimization, and performed domain-specific source-tracking analyses (i.e., Bacteria, Archaea, Eukaryota and viruses). We also applied SourceTracker to metagenomic libraries generated from samples collected from the International Space Station (ISS).ResultsSourceTracker proved highly effective at predicting the composition of known sources using shotgun metagenomic libraries. In addition, we showed that different taxonomic domains sometimes presented highly divergent pictures of environmental source origins for both the coastal marine and ISS samples. These findings indicated that applying SourceTracker to separate domains may provide a deeper understanding of the microbial origins of complex, mixed-source environments, and further suggested that certain domains may be preferable for tracking specific sources of contamination.

The association between sporadic Legionnaires' disease and weather and environmental factors, Minnesota, 2011-2018.

From 2011 through 2018, there was a notable increase in sporadic Legionnaires' disease in the state of Minnesota. Sporadic cases are those not associated with a documented outbreak. Outbreak-related cases are typically associated with a common identified contaminated water system; sporadic cases typically do not have a common source that has been identified. Because of this, it is hypothesised that weather and environmental factors can be used as predictors of sporadic Legionnaires' disease. An ecological design was used with case report surveillance data from the state of Minnesota during 2011 through 2018. Over this 8-year period, there were 374 confirmed Legionnaires' disease cases included in the analysis. Precipitation, temperature and relative humidity (RH) data were collected from weather stations across the state. A Poisson regression analysis examined the risk of Legionnaires' disease associated with precipitation, temperature, RH, land-use and age. A lagged average 14-day precipitation had the strongest association with Legionnaires' disease (RR 2.5, CI 2.1-2.9), when accounting for temperature, RH, land-use and age. Temperature, RH and land-use also had statistically significant associations to Legionnaires' disease, but with smaller risk ratios. This study adds to the body of evidence that weather and environmental factors play an important role in the risk of sporadic Legionnaires' disease. This is an area that can be used to target additional research and prevention strategies.

The Role of Value Deliberation to Improve Stakeholder Participation in Issues of Water Governance

Stakeholder participation is a requirement for environmental decision-making in the European Union. Despite this, numerous instances can be seen in water governance in which stakeholders feel undervalued and unheard, thereby creating unfavourable procedural outcomes, resistance and conflict. In this article, we propose that a process of early-stage deliberation constructed around the values of the stakeholders involved can reduce, and even prevent such conflicts. We suggest that if values that stakeholders perceive as relevant can be identified and discussed as part of the deliberation process then (1) stakeholder preferences can change, and (2) participants can develop a mutual understanding of each other’s values and perspectives. To explore these propositions, facilitated workshops were conducted at two Dutch water institutes, based around the topics of land subsidence and the pharmaceutical contamination of water systems. Participants deliberated on values that they considered relevant. The results suggest that mutual understanding of stakeholders’ perspectives increases as a result of value-based deliberation.

Long-term care Legionella prevention and control strategies: Experiences of nursing homes in Florida and Georgia

Background: Over the past several years, there have been more than 100 confirmed cases in US healthcare facilities of Legionnaires’ disease, a severe and potentially fatal pneumonia caused by the Legionella bacterium found in contaminated water systems. Older people and those with weakened immune systems are particularly vulnerable to Legionella, putting long-term care patients at greater risk of infection. Past efforts to address this growing environmental health crisis have been limited to local surveillance programs for testing water systems in multi-family housing units. In June 2017, the Centers for Medicare and Medicaid Services (CMS) required Medicare-certified healthcare facilities to establish water management programs to reduce the risk of Legionella. Methods: We conducted a mixed methods study (surveys, interviews) to examine the adoption and implementation of these guidelines as well as existing Legionella prevention and control strategies in nursing homes in Florida and Georgia. Results: Findings reveal that most nursing homes in these states do not test their water systems for Legionella because either they have never experienced an outbreak of Legionnaires’ disease or do not have a large water system for testing. Conclusion: Nursing home administrators know of the new CMS Legionella testing requirements and are currently developing water management plans.

Fabrication of cellulose-mediated chitosan adsorbent beads and their surface chemical characterization

The use of nontoxic, biodegradable and biocompatible biopolymers such as chitosan and cellulose is of considerable importance particularly in uptake of metal ions from the contaminated water systems. Current study was aimed to develop a chitosan-based biosorbent in combination with cellulose to form composite adsorbent beads. The developed composite beads were chemo-physically characterized using advanced analytical techniques of scanning electron microscope, Fourier transform infrared, x-ray diffraction and thermogravimetric analysis. The point of zero charge (PZC) of the developed beads was determined using the methods of salt addition, electrokinetic potential and the mass atitration. The average value of PZC of composite beads was found to be 7.26 using the said methods. On incorporating cellulose into chitosan, the thermal properties of the composite beads were considerably enhanced. The adsorption capacity of chitosan–cellulose beads was found to be 99.8, 79.98 and 99.10 mg/g for Ni(II), Cu(II) and Cr(III), respectively. The adsorption extent showed that the developed composite beads could be employed as adsorbent for wastewater treatment.

Legionellosis in Poland in 2017

The aim of this study is to assess the epidemiological situation of legionellosis in Poland in 2017 in comparison with previous years. The analysis is based on national surveillance data published in the annual bulletin: “Infectious diseases and poisonings in Poland in 2017” and bulletins from previous years along with data from legionellosis case reports collected and sent to the Department of Epidemiology of Infectious Diseases and Surveillance NIPH – NIH by Sanitary and Epidemiological Stations. In Poland, both cases of Legionnaires’ disease (an acute form of infection with pneumonia) and Pontiac fever (a mild, influenza-like form of infection) are routinely reported to the surveillance system. In 2017, a total of 39 cases of legionellosis were registered, including 38 cases of Legionnaires’ disease and 1 case of Pontiac fever; the annual incidence rate 0.102 (per 100,000 population) has increased by almost 50 percent since previous year (0.070) and is almost three times higher than the median incidence (0.036) for 2011-2015. The infections were reported in fourteen voivodeships; only one voivodeship (Świętokrzyskie) did not register any case in last years. The incidence in men (0.129 per 100,000) was higher compared to women (0.076); the highest incidence (0.323) was noted in men aged 50-59. All reported cases were sporadic and were hospitalised. The Sanitary Inspection reported nine fatal cases – 6 women and 3 men. Thirty three cases were autochthonous including four cases linked with contaminated water systems in health-care settings. Six cases were associated with travels abroad (to Egypt, Albania, Italy and Crete). Although in recent years number of reported cases continues to rise, the incidence of legionellosis in Poland remains one of the lowest in the entire EU. Also draws attention variation of incidence between provinces and a high mortality among reported cases. Our data suggest significant under-diagnosis of legionellosis. A priority remains to improve early diagnosis of Legionnaires’ disease in health care settings.

926. Outbreak of Invasive Nontuberculous Mycobacterium (NTM) Infections Associated With a Pediatric Dental Practice

BackgroundIn 2016, an Orange County, California, pediatric dental clinic’s contaminated water system led to the largest outbreak of odontogenic NTM infections yet described.MethodsMandatory reporting and active case finding directed by County Public Health were conducted in collaboration with community Pediatric Infectious Disease physicians for patients who underwent pulpotomy at Dental Clinic A from January 1 to September 6, 2016. Confirmed cases were those with positive NTM culture. Probable cases were those with multiple pulmonary nodules on computed tomography (CT), necrotic bone or osteomyelitis seen at surgery, or pathology with positive acid-fast bacilli stain, granulomatous inflammation or chronic osteomyelitis. Clinical data was collected from medical records.ResultsOf 1,089 patients at risk, 71 cases (22 (31%) confirmed and 49 (69%) probable) (Figure 1) had been identified as of March 19, 2018 (Figure 2). Median case age was 6 years (range 2–11 years). Symptoms began a median of 85 days (range 1–409 days) after pulpotomy (Figure 3). Pain and/or swelling on admission were reported in 79%; 21% were asymptomatic. CT findings included 49/70 with abnormalities of the mandible or maxilla, 13/70 with lymphadenopathy, and 19/68 with pulmonary nodules. Only 6/60 had erythrocyte sedimentation rate >40 mm/hour. Of 71 cases, 70 were hospitalized and underwent surgical debridement, for an average of 8.5 inpatient days (range 1–60 days); 23 had >1 hospitalization and 26 required >1 inpatient surgery. Permanent teeth were lost in 45/65 (range of 1–6 teeth lost). Intravenous antibiotics were administered to 32 cases for a median length of 137 days (range 113–282 days). Clofazimine was obtained for 29/32 cases as part of the regimen. Medical therapy was complicated by peripherally inserted central catheter malfunction/replacement/infection (18/27), rash (2/27), neutropenia (12/27), and elevated creatinine (7/27). All treated children showed evidence of jaw healing with resolved or improving lung nodules at 1-year follow-up.ConclusionThis is the largest outbreak of invasive NTM infections seen associated with a pediatric dental practice. While infections were indolent, patients suffered medical and surgical consequences of treatment. Enhanced national dental water quality standards are needed to prevent future outbreaks. Disclosures A. Arrieta, Melinta Therapeutics: Investigator, Research support

Compounding and Mixing Methodology for Good Performance of EPDM in Tire Sidewalls

ABSTRACT Ethylene propylene diene terpolymer (EPDM), which is a terpolymer of ethylene, propylene, and a diene, is characterized by having a fully saturated polymer backbone, resulting in excellent ozone and oxidative aging resistance. By contrast, diene elastomers such as natural rubber (NR) and polybutadiene rubber (BR) have high levels of unsaturation along their main polymer backbones, increasing their susceptibility to chemical degradation by main chain scission and therefore their need for a protection system. This is generally provided by adding combinations of primary antioxidants and migrating waxes. Protective systems based on paraphenylenediamines (PPDs) are very effective and are used extensively for the protection of tire sidewalls, but because they function by preferentially reacting with ozone, their activity becomes depleted over the service life of the tire. Other potential drawbacks are that PPDs form a reaction product that discolors the surface of the sidewall, and they are considered to be potentially hazardous to human health and the environment through contamination of water systems. By contrast, it has been shown that the addition of EPDM to a conventional sidewall compound can give a permanent high level of ozone protection that is nonhazardous and non-discoloring. However, differences in polarity, solubility, and levels of unsaturation create significant challenges for achieving successful blends of EPDM in typical NR/BR sidewall compounds, leading to inferior physical and dynamic properties. This study shows that by combining best practices for compound design and mixing methodology with optimum grades of EPDM, it has been possible to produce tire sidewall compounds having full ozone protection as well as physical and dynamic properties closely matching a typical sidewall compound. Additionally, this study shows that the presence of EPDM leads to improved properties after heat aging and vulcanized compounds having reduced energy dissipation behavior, which could lead to tires having reduced rolling resistance.

Developmental toxicity of synthetic phenolic antioxidants to the early life stage of zebrafish

Synthetic phenolic antioxidants (SPAs) have gained high concerns due to their extensive usages and unintended environmental release via various routes. Their contamination in water system could pose potential threat to aquatic organisms, therefore, the studies on the aquatic toxicology of this kind of chemicals are of high importance. In this research, the developmental toxicities of four commonly used SPAs, including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ), and 2,2′-methylenebis (6-tert-butyl-4-methylphenol) (AO2246) were investigated using the zebrafish embryo toxicity test (ZFET). The results showed that these four SPAs exerted different acute toxicities to zebrafish, and the toxic order, based on their 96 h LC50 values, was AO2246 > TBHQ > BHA > BHT, and decreased hatching rates were induced for the embryos in BHA, TBHQ and AO2246 exposure groups. Non-lethal exposures of BHA (≤20 μM), TBHQ (≤20 μM), BHT (≤200 μM) and AO2246 (≤2 μM) decreased the heart rates and body lengths of zebrafish in exposure concentration-dependent manners. Diverse morphological deformities, including uninflated swim bladder, pericardial edema, spinal curvature, severe yolk deformation, or abnormal pigmentation, were induced in zebrafish larvae upon SPA treatments. The transcriptional levels of the related genes, examined by quantitative PCR, indicated that the interferences of SPAs with hypothalamic-pituitary-thyroid axis (HPT axis), GH/PRL synthesis and Hedgehog (hh) pathway contributed to their developmental toxicities in zebrafish. The up-regulation of pluripotency biomarker, Oct4, caused the developmental retardation during the early stages of zebrafish embryos in BHA and TBHQ exposure groups. The results obtained herein provided important information on the developmental toxicity of SPAs, which could be very helpful in guiding the risk assessment on their aquatic toxicology.

Enhanced adsorption at ZnO nanoflakes@zeolite core shell interface: A study of changing adsorption dynamics

The present work describes the effect of surface modification of a high silica zeolite on removal of multiple ions [Pb(II), Fe(III), Cd(II)] and organics (Methylene blue, Aniline and p-nitrophenol) from contaminated water systems. Porous layer of ZnO nanoflakes (NFs) is grown on the surface of the zeolite in the form of a core-shell (CSPs) which alters the interface of the zeolite to convert the adsorption mechanism from slower chemisorption in zeolite to rapid physiochemisorption in CSPs as inferred from the comparative analysis of the adsorption dynamics. An inter-particle synergy encompassing ion exchange by zeolite and adsorption/photodegradation by the ZnO has been established by changed interfacial charge, enhanced surface area and increased porosity of the CSPs. Specificity of the developed CSPs for particular ions/organics and possible mechanism for enhanced adsorption of the CSPs has been discussed in detail. The specificity of adsorption follows the order of Pb (II) > Fe (III) > Cd (II) for heavy metal ions whereas for organics, the order of adsorption is methylene blue > p-nitrophenol > aniline. Results indicate that presence of ZnO nanoflakes as porous shell increases the equilibrium adsorption capacity of the CSPs to 74.661 mg/g in comparison to 45.96 mg/g of zeolite. The results of the specificity studies and significant increase in adsorption capacity prove that the altered interface leads to enhanced and rapid removal of toxic pollutants from water with highest specificity for Pb(II) and MB dye.

Online Serum PFOA Calculator for Adults.

Summary:Perfluorooctanoic acid (PFOA) is a persistent environmental contaminant that has been detected in public water systems in the United States alone. A variety of epidemiological investigations of PFOA have been published, mostly using measured or modeled serum PFOA concentrations as the exposure metric. Comparison of drinking water PFOA concentrations to those study findings or to typical serum concentrations requires pharmacokinetic modeling. This brief communication describes an online Javascript calculator that easily plots the expected serum PFOA concentration over time and at steady state for adults after starting or stopping consumption of PFOA-contaminated water. Two examples of usage are provided, including increasing serum PFOA after ongoing consumption of contaminated water at the federal limit, and decreasing serum PFOA after carbon filtration began in a contaminated water system. https://doi.org/10.1289/EHP2820