Types Of Environmental Samples Research Articles

Conjugated microporous polymer for solid-phase extraction of neonicotinoid insecticides from environmental water samples

Conjugated microporous polymers (CMPs) have unique characteristics and have been used in a range of fascinating applications in separation sciences. In this study, a CMP, designated as CMP-1, was synthesized via the Sonogashira-Hagihara coupling reaction using 1,3,5-triphenylbenzene and 1,4-dibromobenzene as building blocks. CMP-1 features a large surface area, abundant micropore structures, and excellent stability, making it a promising solid-phase extraction adsorbent for the efficient enrichment of neonicotinoid insecticides (NEOs). Under the optimized conditions, CMP-1 was combined with high-performance liquid chromatography and diode array detection to enable the detection of NEOs with a wide linear range (0.5–200 μg·L–1), a low detection limit (0.26–0.58 μg·L–1), and acceptable precision. The developed method was applied to determine spiked NEOs in three types of environmental water samples, with recoveries of 73.7%–112.0% and relative standard deviations of 0.6%–9.4%.

Oil-based extraction as an efficient method for the quantification of microplastics in environmental samples

BackgroundWastewater treatment plant outlets are a major source of microplastics, with more than 90% retained in sewage sludge. No standardised method for the extraction, quantification, and characterisation of microplastics in sewage sludge or soil exists, and direct comparison of studies is often impossible. Our aim was to validate oil extraction efficiency with and without pre-treatment with Fenton’s reagent of selected microplastics in various types of environmental samples (sewage sludge and organic-rich substrates).ResultsOxidation with Fenton’s reagent removed up to 90% of organic material, which improves the recovery rate and made quantification and characterisation easier and more reliable, regardless of type, shape, size, or density of the selected microplastic particles used in this study. Pre-treatment, as a pre-step of the oil extraction method, was shown to be important in reducing organic matter in all environmental samples, including sewage sludge and organic-rich substrates. It also improved the reliability of the selected method, shortened its duration, and, by reducing organic matter, made extracted microplastics more visible. The recovery rate was better for particles 1–5 mm and lower for particles 0.1 < 1 mm.ConclusionsBy achieving up to a 100% recovery rate for certain types of microplastics (polypropylene and polystyrene), the selected method proved to be a promising extraction method. It was also shown to be efficient in the organic-rich substrates, for which the characterisation of microplastic particles was done by Fourier transform infrared spectroscopy. The most commonly detected types of microplastics in organic-rich substrates were polyethylene, polypropylene, polystyrene and polyester.

EDNA for monitoring and conserving terrestrial arthropods: Insights from a systematic map and barcode repositories assessments

Abstract In the past decade, environmental DNA (eDNA) assays have become an essential tool to investigate species presence with samples from the environment instead of collected specimens. eDNA sampling techniques have proved their worth in freshwater and marine studies; now, some trends emerge for their use in terrestrial habitats and particularly to study arthropods. After a systematic review of the literature, we illustrate and analyse the diversity of such studies and discuss their benefits and drawbacks. We identified the most relevant research themes and focused on (i) the taxa and environmental sample types targeted and (ii) the details of the survey scheme. In parallel, we also assessed the available number of sequences from cytochrome c oxidase subunit I (COI), 16S and 18S barcode regions for four major taxa (spiders, centipedes, springtails and insects) in relation to their diversity. We found strong taxonomic and geographic biases regarding coverage per barcode. eDNA research on terrestrial arthropods mainly focuses on insect species that affect humanity in a positive or negative way, and the availability of sequences is much higher for species from temperate‐developed countries than from tropical ones. Moreover, although a high variety of environmental samples are being used, most studies do not assess the barcode completeness of the target taxa nor compare the efficacy of eDNA monitoring technique to other well established and known traditional techniques. Careful workflow designs and comparisons are needed before giving any management or conservation advice as eDNA monitoring does not come without error. Strengths and weaknesses of eDNA assays for conservation are discussed.

Analysis of total thiol concentrations in environmental samples using ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS)

In this study, we developed an ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) approach to measure the concentration of total reactive thiol binding sites in a range of types of environmental samples by monitoring the decrease of monobromo-(trimethylammonio)-bimane (qBBr) caused by thiol-qBBr binding reactions. We first examined the stability of qBBr and potential side reactions that could reduce the accuracy of the UHPLC-MS approach. We found that significant loss of qBBr occurs in the absence of thiols in aqueous solutions after 2–4 h due to qBBr degradation and other side reactions, such as a chloride-for-bromide substitution reaction. To address these issues, in our approach we conduct the thiol-qBBr binding reaction in the presence of excessive qBBr for only 1 h, and we compare the MS signal of unbound qBBr in a thiol-free qBBr standard with that in a thiol-bearing qBBr standard in order to calculate the decrease in the concentration of free qBBr in solution that is caused by thiol-qBBr binding. Using 100–600 nM of N-Acetyl-L-cysteine (ACYS) as a model thiol in a 2 μM qBBr standard, we found that the measured decrease in the MS signal of unbound qBBr linearly correlates to the concentration of added ACYS, with a R2 of 0.988, demonstrating that monitoring the decrease in unbound qBBr can be used to calculate the concentration of total thiol sites in a sample. We demonstrate that the new UHPLC-MS approach yields accurate results when measuring a series of single and mixed thiol standards in the 200–500 nM range, with measured values ranging from 86% to 109% of the known concentration of thiols. In addition to the above control tests, we also used the UHPLC-MS approach to measure dissolved thiol concentrations in several lake water samples. These measurements revealed that each lake contained low μM levels of total thiols, not only demonstrating the ability of the analytical approach to determine thiol site concentrations in natural waters, but also suggesting the widespread importance of these sites in controlling chalcophile element behavior in these systems. The UHPLC-MS approach not only can be used to determine the concentration of dissolved thiol sites at nM levels, but can also be adapted to measure the concentration of thiol binding sites on other environmental samples such as soil, sediment, and solid-phase organic matter surfaces.

The newest Oxford Nanopore R10.4.1 full-length 16S rRNA sequencing enables the accurate resolution of species-level microbial community profiling.

The long-read amplicon provides a species-level solution for the community. With the improvement of nanopore flowcells, the accuracy of Oxford Nanopore Technologies (ONT) R10.4.1 has been substantially enhanced, with an average of approximately 99%. To evaluate its effectiveness on amplicons, three types of microbiomes were analyzed by 16S ribosomal RNA (hereinafter referred to as "16S") amplicon sequencing using Novaseq, Pacbio sequel II, and Nanopore PromethION platforms (R9.4.1 and R10.4.1) in the current study. We showed the error rate, recall, precision, and bias index in the mock sample. The error rate of ONT R10.4.1 was greatly reduced, with a better recall in the case of the synthetic community. Meanwhile, in different types of environmental samples, ONT R10.4.1 analysis resulted in a composition similar to Pacbio data. We found that classification tools and databases influence ONT data. Based on these results, we conclude that the ONT R10.4.1 16S amplicon can also be used for application in environmental samples. IMPORTANCE The long-read amplicon supplies the community with a species-level solution. Due to the high error rate of nanopore sequencing early on, it has not been frequently used in 16S studies. Oxford Nanopore Technologies (ONT) introduced the R10.4.1 flowcell with Q20+ reagent to achieve more than 99% accuracy as sequencing technology advanced. However, there has been no published study on the performance of commercial PromethION sequencers with R10.4.1 flowcells on 16S sequencing or on the impact of accuracy improvement on taxonomy (R9.4.1 to R10.4.1) using 16S ONT data. In this study, three types of microbiomes were investigated by 16S ribosomal RNA (rRNA) amplicon sequencing using Novaseq, Pacbio sequel II, and Nanopore PromethION platforms (R9.4.1 and R10.4.1). In the mock sample, we displayed the error rate, recall, precision, and bias index. We observed that the error rate in ONT R10.4.1 is significantly lower, especially when deletions are involved. First and foremost, R10.4.1 and Pacific Bioscience platforms reveal a similar microbiome in environmental samples. This study shows that the R10.4.1 full-length 16S rRNA sequences allow for species identification of environmental microbiota.

Which environmental sample type and statistical approach provides most information about metal exposure in young children from an urban setting?

Identification of sources and pathways is critical in minimizing exposure of young children to toxic materials. We monitored 108 children <5 years old 6-monthly for up to 5 years in a major urban setting. Samples (ñ7000) included interior handwipes (W1) and after exterior playing (W2), interior house dust (PD1) and day care dust (PD2) using petri dishes, exterior dust-fall accumulation, exterior dust sweepings, garden soil, blood and urine. Here we describe multi-element results to determine which sampling method and analysis of the data provide the most reliable indicators of metal exposure to young children. Samples were analysed by ICPMS for Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Ti, V and Zn. Pearson Correlations showed the highest number of significant correlations are for: W1 and W2, dust sweepings and soil. Mixed model analyses (MMA) for the blood levels as the dependent variable and environmental predictor variables showed the most consistent results were for W1, PD1 and sweepings. MMA to investigate the association between each metal (e.g. Ca) and the other 11 metals showed the largest numbers of significant relationships are for W1 and sweepings. Cluster analyses showed that the ‘best’ clusters in W1 and W2 are for Fe–Zn–Mg and Mn–Pb–Ni. For PD1 and PD2 the ‘best’ clusters were Fe–Zn–Mg, Cr–Ni–Ti, and Cu–Mn–Pb. Clusters for dust sweepings and soil are generally similar. Principal component analysis (PCA) loadings for W1 and PD1 accounted for >50% of the variance. Metals comprising loading 1 component for both sample types included Ca, Fe, Mg, and Mn. Overall cluster analyses provided more information than PCA loadings. In summary: The most suitable methods and analyses are MMA of W1 and sweepings, and cluster analyses of W1and PD1. Resuspension from outdoor surfaces and soils and deposition in the residences is a likely pathway for most metals.

Exploring the vertical transport of microplastics in subsurface environments: Lab-scale experiments and field evidence

Microplastics (MPs) defined as smaller 5 mm plastic particles have received increasing attention due to their global occurrence and potential toxicity. This study investigated the effects of environmental factors (rainfall intensity, 13 and 29 mm/h) and MP characteristics (morphology (fiber, flake, and film), polymer type (polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS)) and size (100–300, 300–500, and 500–1000 μm)) on the vertical transport of MP in unsaturated soil conditions using lab-scale column experiments. Additionally, the occurrence and characteristics of MP detected in soil/sediment (total 13 samples) and groundwater samples (total 6 samples) were explored in the field study. Laboratory-scale column experiments revealed that heavy rainfall intensity (29 mm/h) increased the degree of MP vertical transport in unsaturated soil conditions and MP fibers showed the greatest vertical mobility among the various morphologies of MPs assessed. For the polymer type and size, the lighter PP polymer or the larger size of MP (500–1000 μm) showed higher mobility. In the field study, a statistical difference in MP abundance was observed depending on the population density and degree of urban development in both soil and groundwater samples. Comparing to the two different types of environmental media samples obtained from the same site, there was a significant difference in the composition of polymer types present while statistically no difference in MP abundance was observed between the two media samples (i.e., soil or sediment and groundwater). In addition, MP fibers and polyethylene (PE) were predominantly detected in our two study areas. These results suggest that various types of MP can pass through the unsaturated zone by water infiltration, even if it takes a long time to reach groundwater. Overall, we found that the degree of vertical transport of the MPs was highly sensitive to environmental conditions and MP characteristics.

Ion chromatography for analysis of glyphosate and its selected metabolites. A review.

Among all known compounds with herbicide activity glyphosate, has been the most commercially successful one. Currently it is under evaluation because of its possible cancerogenic properties. However, the question is - if it is possible to completely withdraw it from use? Before it can happen, it is important to be sure of all its benefits and limitations, and this requires further detailed research. Due to the extent and prevalence of its use, glyphosate end up in the environment and then in food and our bodies. There are several methods used for their determination. One of them is ion chromatography. Taking into account its advantages and disadvantages, as well as its rapid development, their importance in this field can be expected to increase in the near future. This paper summarizes the literature data from the past 22 years. The applications of ion chromatography in the determination of glyphosate in various types of environmental, food, and other samples is described. Moreover, the methods used so far are compared with the possibilities offered by ion chromatography, which main advantages and benefits are easy availability, low operating costs, green chemistry aspects and suitable validation parameters. This article is protected by copyright. All rights reserved.

WAVES (Web-based tool for Analysis and Visualization of Environmental Samples)-a web application for visualization of wastewater pathogen sequencing results.

Environmental monitoring of pathogens provides an accurate and timely source of information for public health authorities and policymakers. In the last 2 years, wastewater sequencing proved to be an effective way of detection and quantification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants circulating in population. Wastewater sequencing produces substantial amounts of geographical and genomic data. Proper visualization of spatial and temporal patterns in these data is crucial for the assessment of the epidemiological situation and forecasting. Here, we present a web-based dashboard application for the visualization and analysis of data obtained from sequencing of environmental samples. The dashboard provides multi-layered visualization of geographical and genomic data. It allows to display frequencies of detected pathogen variants as well as individual mutation frequencies. The features of WAVES (Web-based tool for Analysis and Visualization of Environmental Samples) for early tracking and detection of novel variants in the wastewater are demonstrated in an example of BA.1 variant and the signature Spike mutation S: E484A. WAVES dashboard is easily customized through the editable configuration file and can be used for different types of pathogens and environmental samples. WAVES source code is freely available at https://github.com/ptriska/WavesDash under MIT license. A demo version of this application can be accessed at: https://wavesdashboard.azurewebsites.net/.

Identification of the cause of the difference among TOC quantitative methods according to the water sample characteristics

Total organic carbon (TOC) analysis with accurate determination of particulate organic carbon (POC) content in suspended solids (SS) containing water is critical for evaluating the environmental impact of particulate organic pollutants in water and calculating the carbon cycle mass balance. TOC analysis is divided into the non-purgeable organic carbon (NPOC) and differential (known as TC-TIC) methods; although the selection of method is greatly affected by the sample matrix characteristics of SS, no studies have investigated this. This study quantitatively evaluates the effect of SS containing inorganic carbon (IC) and purgeable organic carbon (PuOC), as well as that of sample pretreatment, on the accuracy and precision of TOC measurement in both methods for various environmental water sample types (12 wastewater influents and effluents and 12 types of stream water). For influent and stream water with high SS, the TC-TIC method expressed 110–200 % higher TOC recovery than that for the NPOC method due to POC component losses in SS owing to its conversion into PuOC during sample pretreatment (using ultrasonic) and subsequent loss in the NPOC purging process. Correlation analysis confirmed that particulated organic matter (POM, mg/L) content in SS directly affected this difference (r > 0.74, p < 0.01, n = 24); for POC water samples (those containing >10 mg/L of POM) featuring purgeable dissolved organic matter, TC-TIC was appropriate in securing TOC measurement accuracy. In constrast, in effluent and stream water with low SS (i.e., < ∼5 mg/L) and high IC (> 70 %) contents, the TOC measurement ratios (TC-TIC/NPOC) of both methods were similar, between 0.96 and 1.08, suggesting that NPOC is appropriate for improving precision. Our results provide useful basic data to establish the most reliable TOC analysis method considering SS contents and its properties along with the matrix characteristics of the sample.

Determination of uranium isotopes in marine sediments and seawaters by SF ICP-MS after rapid chemical separation using TK200 resin.

This work provided a novel analytical procedure for rapid and precise uranium isotopic determination in marine sediment and seawater, using a new type of extraction resin, TK200 resin, in combination with microwave digestion (for marine sediments), Fe(OH)3 co-precipitation (for seawater), and single collector sector field-inductively coupled plasma mass spectrometry (SF ICP-MS) measurement. The removal ability of TK200 extraction chromatography for the interfering elements (IEs) Hg, Pb, Th, Pt, Tl, and the matrix rare earth elements (REEs) was carefully investigated. High decontamination factors (DFs) were obtained for IEs and REEs. Accurate quantification of uranium isotope ratios was accomplished based on a "double-cycle" ICP-MS measurement method. The analytical method was optimized and validated with isotopic standards (IRMM-187), matrix-containing certified reference marine sediments (IAEA-384, IAEA-385, and IAEA-412), and seawater reference material (IAEA-443). A stable chemical recovery of ~ 90% was obtained for both types of marine environmental samples, and the method showed great efficiency with a total analytical time of less than 6h. The proposed procedure was validated following ISO/IEC 17025 guidelines. The important factors affecting the isotope ratio results (instrument background, procedural blank, memory effects, peak tailing, mass discrimination, dead time, and hydride interferences) were considered in the estimation of combined uncertainties. This work provides an alternative way for the determination of trace uranium isotope ratios and can be applied in the emergency monitoring of nuclear accidents and marine environmental analysis.

Environmental sampling methods’ influence on detection of pathogens in cage-free aviary housing

The environmental sampling of layer housing systems is essential to identifying potential pathogens that are of concern to human health. To identify the natural occurrence of pathogens (Listeria, Campylobacter, and Salmonella) at various locations in a cage-free aviary housing system, swabs were collected when hens were 22 to 39 wks of age. Duplicate environmental swabs were taken and inoculated with a low dose (101 cfu) Salmonella Enteritidis (SE) and examined for the recovery of SE from environmental samples. Detection of Listeria (P < 0.0001) and Campylobacter (P < 0.0001) varied between the environmental sample types taken: concrete dust, drag swabs, egg belt dust, manure belt scraper swabs, and wall dust. Detection of Listeria (P < 0.0001) was the highest (70.0%) at the beginning of the study (22 wk) and decreased over time. Detection of Campylobacter (P < 0.001) was also the highest at 22 wk, however the decrease over time was more gradual. Interestingly, detection of Campylobacter (P < 0.0001) was the greatest in concrete dust samples (96.25%), which can be attributed to the presence of rodent excreta in the samples. Drag swabs and manure belt scraper swabs were the best sampling types for high detection of Listeria and Campylobacter. It should be noted that Listeria recovered was not of human health concern. No naturally occurring Salmonella was identified in this study. The recovery of the SE inoculum increased over time, reaching the greatest recovery in drag (81.25%; P < 0.0001), egg belt dust (100.00%; P < 0.0001) and wall dust swabs (100.00%; P < 0.0001) by 39 wk. This high rate of SE recovery occurred just before US mandatory SE environmental monitoring at 40 to 45 wks of age. Based on this study, the use of drag and manure belt scraper swabs are effective in detecting Listeria and Campylobacter in cage-free aviary housing. Along with good pest management, the occurrence of pathogens could be monitored and reduced in laying hen flocks.

SARS-CoV-2 RNA Is Readily Detectable at Least 8 Months after Shedding in an Isolation Facility.

Environmental monitoring of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for research and public health purposes has grown exponentially throughout the coronavirus disease 2019 (COVID-19) pandemic. Monitoring wastewater for SARS-CoV-2 provides early warning signals of virus spread and information on trends in infections at a community scale. Indoor environmental monitoring (e.g., swabbing of surfaces and air filters) to identify potential outbreaks is less common, and the evidence for its utility is mixed. A significant challenge with surface and air filter monitoring in this context is the concern of "relic RNA," noninfectious RNA found in the environment that is not from recently deposited virus. Here, we report detection of SARS-CoV-2 RNA on surfaces in an isolation unit (a university dorm room) for up to 8 months after a COVID-19-positive individual vacated the space. Comparison of sequencing results from the same location over two time points indicated the presence of the entire viral genome, and sequence similarity confirmed a single source of the virus. Our findings highlight the need to develop approaches that account for relic RNA in environmental monitoring. IMPORTANCE Environmental monitoring of SARS-CoV-2 is rapidly becoming a key tool in infectious disease research and public health surveillance. Such monitoring offers a complementary and sometimes novel perspective on population-level incidence dynamics relative to that of clinical studies by potentially allowing earlier, broader, more affordable, less biased, and less invasive identification. Environmental monitoring can assist public health officials and others when deploying resources to areas of need and provides information on changes in the pandemic over time. Environmental surveillance of the genetic material of infectious agents (RNA and DNA) in wastewater became widely applied during the COVID-19 pandemic. There has been less research on other types of environmental samples, such as surfaces, which could be used to indicate that someone in a particular space was shedding virus. One challenge with surface surveillance is that the noninfectious genetic material from a pathogen (e.g., RNA from SARS-CoV-2) may be detected in the environment long after an infected individual has left the space. This study aimed to determine how long SARS-CoV-2 RNA could be detected in a room after a COVID-positive person had been housed there.

Assessing the lysis of diverse pollen from bulk environmental samples for DNA metabarcoding

Pollen is ubiquitous year-round in bulk environmental samples and can provide useful information on previous and current plant communities. Characterization of pollen has traditionally been completed based on morphology, requiring significant time and expertise. DNA metabarcoding is a promising approach for characterizing pollen from bulk environmental samples, but accuracy hinges on successful lysis of pollen grains to free template DNA. In this study, we assessed the lysis of morphologically and taxonomically diverse pollen from one of the most common bulk environmental sample types for DNA metabarcoding, surface soil. To achieve this, a four species artificial pollen mixture was spiked into surface soils collected from Colorado, North Carolina, and Pennsylvania, and subsequently subjected to DNA extraction using both the PowerSoil and PowerSoil Pro Kits (Qiagen) with a heated incubation (either 65 °C or 90 °C). Amplification and Illumina sequencing of the internal transcribed spacer subunit 2 (ITS2) was completed in duplicate for each sample (total n, 76), and the resulting sequencing reads taxonomically identified using GenBank. The PowerSoil Pro Kit statistically outperformed the PowerSoil Kit for total DNA yield. When using either kit, incubation temperature (65 °C or 90 °C) used had no impact on the recovery of DNA, plant amplicon sequence variants (ASVs), or total plant ITS2 reads. This study highlighted that lysis of pollen in bulk environmental samples is feasible using commercially available kits, and downstream DNA metabarcoding can be used to accurately characterize pollen DNA from such sample types.

A comparison of six DNA extraction protocols for 16S, ITSand shotgun metagenomic sequencing of microbial communities.

Microbial communities contain a broad phylogenetic diversity of organisms;however, the majority of methods center on describing bacteria and archaea. Fungi are important symbionts in many ecosystemsand are potentially important members of the human microbiome, beyond those that can cause disease. To expand our analysis of microbial communities to include data from thefungal internal transcribed spacer (ITS) region, five candidate DNA extraction kits were compared against our standardized protocol for describing bacteria and archaea using 16S rRNA gene amplicon- and shotgun metagenomics sequencing. The results are presented considering a diverse panel of host-associated and environmental sample typesand comparing the cost, processing time, well-to-well contamination, DNA yield, limit of detectionand microbial community composition among protocols. Across all criteria, the MagMAX Microbiome kit was foundto perform best. The PowerSoil Pro kit performed comparablybut with increased cost per sample and overall processing time. The Zymo MagBead, NucleoMag Foodand Norgen Stool kits were included.

Chain-Shattering Polymers as Degradable Microdispersive Solid-Phase Extraction Sorbents.

A chain-shattering polymer (CSP) has been proposed as a microdispersive solid-phase extraction (μdSPE) sorbent in a proof-of-concept study of degradable materials for analytical purposes. The responsive CSP was synthesized from 1,3,5-tris(bromomethyl)-2-nitrobenzene acting as the self-immolative trigger responsive unit and 2,6-naphthalenedicarboxylic acid as aromatic linker to enhance noncovalent aromatic interactions with the analytes. The CSP was characterized and applied as a μdSPE sorbent of a group of plasticizers, which were selected as model analytes, from different types of environmental water samples (tap, waste, and spring waters). Gas chromatography coupled to mass spectrometry detection was used for analyte determination. Mean recovery values were in the range of 80%–118% with RSD values below 22%. After the extraction, the polymer could be efficiently degraded by UV irradiation or by chemical reduction, recovering the aromatic linker. This work has proved the potential of CSPs as recyclable sorbents, paving the way to more environmentally benign analytical procedures.

Determination of fipronil and its metabolites in environmental water samples by meltblown nonwoven fabric-based solid-phase extraction combined with gas chromatography-electron capture detection.

In this study, a new method for the determination of fipronil and its three metabolites in environmental water samples was developed based on meltblown nonwoven fabric solid-phase extraction combined with gas chromatography-electron capture detection. As the core material of medical masks, meltblown nonwoven fabric is made of polypropylene superfine fibers which are randomly distributed and bonded together with a relatively large specific surface area and good permeability. Polypropylene as a high molecular hydrocarbon-based polymer has the characteristics of good hydrophobicity and lipophilicity, which can be applied for the separation and enrichment of hydrophobic substances in food, environment, and biological samples. The meltblown nonwoven fabric is soft and can fill the solid-phase extraction cartridge tightly. This aspect also makes it suitable to be used as an ideal solid-phase extraction sorbent. A series of parameters influencing the extraction efficiency were investigated, and under the optimized conditions, fipronil and its three metabolites had a good linear relationship in the range of 0.2-100 μg/L with a correlation coefficient R2 of more than 0.999. The recoveries at three spiked concentrations were in the range of 99.2-107.3% with the relative standard deviations less than 9.8% (intra-day) and 8.1% (inter-day). The limit of detection for the four target analytes was in the range of 0.02-0.06μg/L. Finally, this method was successfully applied in the analysis of fipronil and its three metabolites in various types of environmental water samples.

Monitoring SARS-CoV-2 in air and on surfaces and estimating infection risk in buildings and buses on a university campus.

BackgroundEvidence is needed on the presence of SARS-CoV-2 in various types of environmental samples and on the estimated transmission risks in non-healthcare settings on campus.ObjectivesThe objective of this research was to collect data on SARS-CoV-2 viral load and to examine potential infection risks of people exposed to the virus in publicly accessible non-healthcare environments on a university campus.MethodsAir and surface samples were collected using wetted wall cyclone bioaerosol samplers and swab kits, respectively, in a longitudinal environmental surveillance program from August 2020 until April 2021 on the University of Michigan Ann Arbor campus. Quantitative rRT-PCR with primers and probes targeting gene N1 were used for SARS-CoV-2 RNA quantification. The RNA concentrations were used to estimate the probability of infection by quantitative microbial risk assessment modeling and Monte-Carlo simulation.ResultsIn total, 256 air samples and 517 surface samples were collected during the study period, among which positive rates were 1.6% and 1.4%, respectively. Point-biserial correlation showed that the total case number on campus was significantly higher in weeks with positive environmental samples than in non-positive weeks (p = 0.001). The estimated probability of infection was about 1 per 100 exposures to SARS-CoV-2-laden aerosols through inhalation and as high as 1 per 100,000 exposures from contacting contaminated surfaces in simulated scenarios.SignificanceViral shedding was demonstrated by the detection of viral RNA in multiple air and surface samples on a university campus. The low overall positivity rate indicated that the risk of exposure to SARS-CoV-2 at monitored locations was low. Risk modeling results suggest that inhalation is the predominant route of exposure compared to surface contact, which emphasizes the importance of protecting individuals from airborne transmission of SARS-CoV-2 and potentially other respiratory infectious diseases.ImpactGiven the reoccurring epidemics caused by highly infectious respiratory viruses in recent years, our manuscript reinforces the importance of monitoring environmental transmission by the simultaneous sampling and integration of multiple environmental surveillance matrices for modeling and risk assessment.

Isolation and multidrug drug resistance profile of Listeria species in selected Dairy Farm's Operational stages in Oromia Regional State, Ethiopia

Listeriosis occurs due to consumption of contaminated food including raw milk. This study was aimed to assess the occurrence of Listeria species along Haramaya University Dairy Farm's operational stages with antibiotic resistance test on the isolates in oromia-Ethiopia. Study involves 30 lactating cows and 170 randomly collected different types of dairy environmental samples. The samples were examined for Listeria species. The isolates were tested against eight antibiotics. Out of 200 samples, 10 (20%) were positive for Listeria species. Listeria was isolated from cow barn, milk supply, silage feed and milk from cow teat, milking operation and milk auditing at 30%, 26.7%, 20%, 18.6% and 10%, respectively. Listeria species including L. monocytogenes (5.5%), L. innocua (5%), L. gray (3%), L. ivanovii (2.5%), L. seeligeri (2%) and L. welshimeri (2%) were also isolated. High resistant L. monocytogene to tetracycline (54.5%), L. ivanovii to amoxicillin (40%), L. innocua to each of penicillin and tetracycline (60%), L. seeligeri to tetracycline (100%), L. welsheri to penicillin (75%) and L. gray to each of penicillin and tetracycline (66.7%) were observed. Of all the 40 Listeria species isolates, 35%, 25%, 17.5% and 5% isolates were resistant to single, two, three and four drugs, respectively. Detection of considerable proportion of, different species of and antibiotic resistant Listeria isolates in the studied dairy sampling location shows there rere risk for raw milk contamination. Thus application of basic hygiene along the studied dairy operational stages could reduce consumer infection.

Application of modern radiochemical techniques to the determination of Sr-89/Sr-90 in environmental samples

Abstract A method for the determination of Sr-89/-90 in different types of environmental samples (German IMIS program) was to be adopted to the 2nd Saxon state laboratory for environmental radioactivity. Resulting from literature studies a combination of variable extraction steps for Y and Sr was chosen to be able for determining Sr-90 or Sr-89/-90 in a common as well as a rapid way. Measurements with a liquid-scintillation counter (LSC) and a low-background proportional counter (LBC) were performed after the same chemical separation steps in each case to find out the detector which is the best suitable one for our requirements. Different steps of the analytical procedure are discussed in detail and its characteristic parameters are given.