River Water Samples Research Articles

Bacteriological quality and physicochemical analysis of the Kalte River at Wolaita Sodo Town, southern Ethiopia

ObjectiveThe current research aimed to investigate the physicochemical and bacteriological quality status of the Kalte River in Wolaita Sodo Town, southern Ethiopia.MethodsA total of 42 water samples were collected using sterile glass bottles from three different river sites: Damota (upstream), Kera (midstream), and Gututo (downstream). All the water samples were examined for the presence of heterotrophic bacteria, total coliform and fecal coliform using direct plate count method and membrane filtration method. Standard methods suggested by American water works association were used to analysis the physicochemical parameters of the water samples.ResultsThe results revealed that the total heterotrophic bacteria, total coliform, and fecal coliform count ranged from 8.9 to 12.6 × 104 cfu/ml, 7.5–11.3 × 102 cfu/ml and 5.7–9.7 × 104 cfu/ml, respectively. The bacterial count results indicated that the river water crossed the WHO-recommended limit of potable water. Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella, and Shigella species were the common bacterial pathogens isolated from river water samples. The results of the physicochemical analysis revealed that some of the parameters Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and turbidity exceeded the maximum permissible limits of WHO and other parameters were below the WHO permissible limits.ConclusionTherefore, the presence of bacterial pathogens, fecal coliform indicators, and some physicochemical parameters of the Kalte River exceeding the recommended limits may expose users of the river water to the risk of infection.

Multimedia Nitrogen and Phosphorus Migration and Source Control Using Multivariate Analysis and XGBoost: The Case Study in a Typical Agricultural Basin, Danjiangkou Reservoir

Preventing eutrophication requires a deep understanding of nutrient sources and migration processes. The Guanshan River in the Danjiangkou Reservoir was selected as a typical agricultural basin. River water, sediment, and soil samples were collected to determine nitrogen (N) and phosphorus (P) contents and forms. Multivariate statistical analysis, buffer analysis, and extreme gradient boosting regression (XGBoost) were used to investigate the nutrient sources, the sources’ scale effects, and migration. The results showed that the exogenous sources of river nutrients were fertilizer (provided phosphate (PO4-P) and ammonium (NH4-N)), domestic wastewater (provided nitrate (NO3-N) and organic nitrogen), and natural soil and rock leaching (provided PO4-P and organic phosphorus). Fertilization within 300–1200 m and domestic wastewater discharge within 150 m of the river affected the contents of the river nutrients significantly (with R ranging between 0.40 and 0.73, p ≤ 0.01). The sediment was the N source and P sink of the overlying water. With NH4-N/PO4-P compound fertilization, the NO3-N and calcium-bound phosphorus (Ca-P) exhibited co-enrichment. Appropriately increasing NH4-N application could stimulate P biological uptake, thus inhibiting P emigration from agricultural soil under N-limited states. In conclusion, this study effectively recognized river nutrient sources and their scale impacts and also explored more effective fertilization strategies, which are beneficial for the optimized management of agricultural activities.

Label-free and ultrasensitive detection of environmental lead ions based on spatially localized DNA nanomachines driven by hyperbranched hybridization chain reaction

A label-free fluorescent sensing strategy for the rapid and highly sensitive detection of Pb2+ was developed by integrating Pb2+ DNAzyme-specific cleavage activity and a tetrahedral DNA nanostructure (TDN)-enhanced hyperbranched hybridization chain reaction (hHCR). This strategy provides accelerated reaction rates because of the highly effective collision probability and enriched local concentrations from the spatial confinement of the TDN, thus showing a higher detection sensitivity and a more rapid detection process. Moreover, a hairpin probe based on a G-triplex instead of a G-quadruplex or chemical modification makes hybridization chain reaction more controlled and flexible, greatly improving signal amplification capacities and eliminating labeled DNA probes. The enhanced reaction rates and improved signal amplification efficiency endowed the biosensors with high sensitivity and a rapid response. The label-free detection of Pb2+ based on G-triplex combined with thioflavin T can be achieved with a detection limit as low as 1.8 pM in 25 min. The proposed Pb2+-sensing platform was also demonstrated to be applicable for Pb2+ detection in tap water, river water, shrimp, rice, and soil samples, thus showing great potential for food safety and environmental monitoring.

Temporal Analysis of Pharmaceuticals as Emerging Contaminants in Surface Water and Wastewater Samples: A Case Study.

Pharmaceuticals in the environment are a global concern, with studies in all continents highlighting their widespread occurrence and potential ecological impacts, revealing their presence, fate, and associated risks in aquatic ecosystems. Despite typically occurring at low concentrations (ranging from ng/L to µg/L), advancements in analytical methods and more sensitive equipment have enabled the detection of a higher number of pharmaceuticals. In this study, surface and wastewater samples were extracted using solid phase extraction and analyzed using ultra-high-performance liquid chromatography with tandem mass spectrometry. Among the therapeutic classes investigated, nonsteroidal anti-inflammatory drugs/analgesics, antibiotics, and psychiatric drugs showed a higher number of detected pharmaceuticals. Concentrations ranged from below method detection limit (<MDL) to 3.20 µg/L (caffeine) and <MDL to 639 µg/L (hydroxyibuprofen) in 2018, and from <MDL to 0.848 µg/L (diclofenac) and <MDL to 53.0 µg/L (caffeine) in 2019 for river water and wastewater samples. Temporal analysis showed an increase in the sum of pharmaceutical concentrations over the study years, highlighting the importance of monitoring pharmaceuticals in the environment and their potential accumulation over time.

Pathogenic bacteria and their antibiotic resistance profile in irrigation water in farms from Mexico

ABSTRACT The presence of antibiotic-resistant bacteria in the agro-environment is a growing international concern. In Mexico, few studies thus far have assessed the quality of water irrigation through the isolation of bacteria pathogens and the identification of antibiotic-resistant genes. Irrigation water samples obtained from rivers, wells, and ponds in different regions of Mexico were analyzed for the presence and antibiotic resistance of pathotypes of Escherichia coli, Salmonella spp., and Enterococcus spp. using selective agars and polymerase chain reaction. Two Enterococcus faecalis, one typical enteropathogenic (EPEC), and one atypical EPEC pathotypes were isolated from river water samples; two atypical EPEC and one enterotoxigenic pathotypes were isolated from pond water samples. There were no targeted pathogens detected in well water samples. All isolates were resistant to at least three antibiotics, with vancomycin being the most common; however, all isolates were sensitive to trimethoprim and ciprofloxacin. The presence of pathotypes of EPEC and ETEC and E. faecalis in water samples used for crop irrigation are a potential risk to public health because of their pathogenicity and antibiotic resistance.

Insights into the adsorption performance and mechanism of novel 3D bimetallic MOF nanosheets for the high-efficient removal of 6PPD and 6PPD-quinone

N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) is commonly used as the tire rubber antioxidant, causing widespread contamination in water environments. Moreover, its derivative 6PPD-quinone (6PPD-Q) has been identified as highly toxic to aquatic organisms. Therefore, the urgent environmental concern revolves around the elimination of 6PPD and 6PPD-Q from aquatic settings. In this study, a highly effective 3D bimetallic nanosheet material was initially synthesized for the adsorptive removal of 6PPD and 6PPD-Q. The 3D bimetallic nanosheet materials, Al-TCPP-M (M = Co, Cu, Zn), were prepared by the two-step sequential process, displaying excellent adsorption performance with rates exceeding 97% and 98% for 6PPD and 6PPD-Q, respectively. The bimetallic and lamellar structure significantly enhanced the maximum adsorption capacities of Al-TCPP-M (M = Co, Cu, Zn) for 6PPD and 6PPD-Q reaching 331.9–355.9 mg/g and 260.6–335.0 mg/g, respectively. Findings from kinetics and thermodynamics suggested that monolayer adsorption was predominant, primarily driven by chemical adsorption. Additionally, the Al-TCPP-M nanosheets exhibited remarkable reusability and anti-interference ability, and achieved significant removal efficiencies for 6PPD and 6PPD-Q in real river water samples. Furthermore, probable adsorption mechanisms mainly involved hydrogen bonding, electrostatic interactions and π-π stacking. Density functional theory (DFT) calculations proved that the introduction of the second metal increased adsorption active sites of Al-TCPP-M through the formation of π-complexation between transition metals and 6PPD and 6PPD-Q. This research highlights the promising applications of 3D bimetallic MOF nanosheets in environmental remediation.

Simultaneous detection of pesticides, carbendazim, and isoproturon using a novel nanocomposite based on graphene oxide/multi-wall carbon nanotube as an electrochemical sensor

This study demonstrates the fabrication of an electrochemical probe and superior performance in the simultaneous determination of two pesticides, carbendazim (CBZ) and isoproturon (ISO), using a modified glassy carbon (GC) electrode with a novel graphene oxide/multi-walled carbon nanotube (GO-MWCNT) nanocomposite for the first time. The existing hydrophilic properties of GO can facilitate the development of a stable dispersion of GO-CNT nanocomposite material through π-π stacking interactions for their intriguing electrochemical detection. This novel nanocomposite was completely characterized by XRD, FT-IR, SEM, and TEM techniques. The MWCNT were dispersed/spread over the crumpled GO nano-sheets, as confirmed by the TEM images. Their oxidation potentials and current are significantly varied with various modified electrodes, such as bare GCE, MWCNT, GO, and GO-MWCNT in 0.1 M PBS (pH 2) at 50 mVs−1. The oxidation of ISO and CBZ on the GO-MWCNT-modified electrode has shown 3 and 5.2 times of current enhancement respectively, compared to the bare GCE. The feasibility of the proposed nanocomposite for the analysis has been shown by the observed maximum oxidation peak current recorded at pH 2. The cyclic voltammogram containing 0.1 mM of ISO and CBZ on the modified GO-MWCNT/GCE have yielded linear plots with the logarithm of scan rate vs peak potential with R2 values of 0.99 and 0.987 respectively, implying the occurred surface adsorption-controlled reaction process. Its reproducibility with 100 μM of ISO and 10 μM of CBZ has shown the related standard deviation for five experiments as 2.8 % and 1.58 % respectively. Moreover, the real sample analysis was optimized with GO-MWCNT/GCE by differential pulse voltammetry technique towards CBZ and ISO in the river and paddy water samples, and the recovery percentages were found to be 99–103 and 99.7–101.3 % respectively.

Pengaruh Cangkang Pomacea canaliculata L Terhadap Sifat Fisika dan Kimia Air Sungai Cisadane

The Cisadane River is a very important ecosystem for the people of the city of Tangerang. Its utilization has the potential to produce waste that can damage aquatic life so that it becomes one of the sources of the problem of decreasing water quality both physically and chemically. One of the efforts made to overcome the problem of Cisadane river water is to use water purifiers derived from natural materials so that they do not endanger health and can bind heavy metals. The purpose of this study was to determine the effect of adding snail shells to the water quality of the Cisadane river in industrial areas, urban areas and slums in terms pH value, TDS value and Pb heavy metal. The experimental procedures in this study were snail shell preparation, Cisadane river water sampling, sample analysis before application, snail shell powder application, and sample analysis after application. The results of analys show that the clarity level of Cisadane river water ranges from 19 NTU to 59 NTU, the pH value ranges from 7.2 to 7.9, the TDS value ranges from 60 mg/l to 170 mg/l and the heavy metal content is 0.0047 mg /l. The conclusion of this research is that there is an increase in the level of clarity with the addition of snail shells by 45%, there is not visible effect of the snail shells addition’s on the pH value and content of Pb heavy metal. And there is an increase in the TDS value after adding snail shells.

Hybrid constructed wetlands and filamentous fungi for treatment of mixed sewage and industrial effluents.

Developing countries face multifaceted problems of water pollution and futile measures to combat water pollution. This study was conducted to explore the potential application of sustainable nature-based solutions, hybrid constructed wetlands, and the application of filamentous fungi to treat polluted river water that receives sewage and industrial wastewater. A pilot-scale hybrid constructed wetland design comprising two types of floating plants in distinct tanks along with a floating wetland and a free-water surface wetland connected in series was commissioned and tested. The system successfully removed organic pollution (BOD 94% and COD 90%), nutrients (NH4-N and NO3-N 67% and PO4-P 81%), and heavy metals (Cr 75%, Ni 56%, and Fe 79%) in 40h and showed a high buffering capacity to cope with the varying pollutant loads. Metagenomics analysis of treated and untreated samples of river water revealed a diversified spatial bacterial community with ~ 25% sequences related to sulfur-metabolizing bacteria, genus Sulfuricurvum. The application of an immobilized strain of A. niger as a mycoremediation technique was also tested. It successfully removed pollutants in the combined sewage and industrial wastewater present in river water: COD (96%), TSS (97%), NH4-N (65%), NO3-N (67%), and PO4-P (78%). This study demonstrated that hybrid constructed wetlands and mycoremediation can be used as sustainable wastewater treatment options in the local context and also in developing countries where most of the conventional wastewater treatment plants do not operate.

Amplifying Flutamide Sensing through the Synergetic Combination of Actinidia-Derived Carbon Particles and WS2 Platelets.

The development of electrochemical sensors for flutamide detection is a crucial step in biomedical research and environmental monitoring. In this study, a composite of Actinidia-derived carbon particles (CPs) and tungsten disulfide (WS2) was formed and used as an electrocatalyst for the electrochemical detection of flutamide. The CPs had an average diameter of 500 nm and contained surface hydroxyl and carbonyl groups. These groups may help anchor the CPs onto the WS2 platelets, resulting in the formation of a CPs-WS2 nanocomposite with a high surface area and a conducting network, enabling electron transfer. Using the CPs-WS2 composite supported at a glassy carbon electrode, a linear concentration range extending from 1 nM to 104 μM, a limit of detection of 0.74 nM, and a sensitivity of 26.9 ± 0.7 μA μM-1 cm-2 were obtained in the detection of flutamide in a phosphate buffer. The sensor showed good recovery, ranging from 88.47 to 95.02%, in river water samples, and exhibited very good selectivity in the presence of inorganic ions, including Al3+, Co2+, Cu2+, Fe3+, Zn2+, NO3 -, SO4 2-, CO3 2-, and Cl-.

Silkworm-derived carbon nano rods (swCNR) for detection of bismuth ions (Bi3+) in aquatic medium and their antiradical properties

The extensive utilization of bismuth and its derivatives in many industries, such as chemical, semiconductor, pharmaceutical, and cosmetics, leads to their accumulation in wastewater, posing a risk to both human health and the environment. Carbon nanorods (CNR) are fluorescent nanoparticles with an ability to detect various analytes as sensing probes. This study focuses on the production, structure, and chemical composition characterization of silkworm-derived CNR (swCNR) and their ability to detect bismuth ions (Bi3+) and inhibit radicals. The optimum wavelength for exciting the fluorescence of swCNR was 370 nm, and the resulting emission peak was observed at 436 nm. The prepared swCNR showed static fluorescence quenching mechanism-based sensing of Bi3+ ions with a limit of detection of 175 nM and two linear ranges from 0.5 to 5 μM (R2 = 0.9997) and 10–50 μM (R2 = 0.9995). The swCNR demonstrated high selectivity in detecting Bi3+ ions in the spiked river water samples, thus establishing the swCNR's role as a nano fluorescence probe designed for the selective detection of Bi3+ ions among other metal ions. Favorable results for the antiradical ability of swCNR were obtained against hydroxyl, 2,2 diphenyl-1 picrylhydrazyl, and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radicals with scavenging percentages of 15, 32, and 90, respectively. The possible applications of swCNR in the environmental and antioxidant sectors are proposed in this study.

Molecular Characterization and Phylogenetic analyses of Rotaviruses Circulating in Municipal Sewage and Sewage-Polluted River Waters in Durban Area, South Africa.

Globally, rotavirus continues to be the leading etiology of severe pediatric gastroenteritis, and transmission of the disease via environmental reservoirs has become an emerging concern in developing countries. From August to October 2021, a total of 69 samples comprising 48 of raw and treated sewage, and 21 surface waters, were collected from four Durban wastewater treatment plants (DWWTP), and effluent receiving rivers, respectively. Rotaviruses recovered and identified from the samples were subjected to sequencing, genotyping, and phylogenetic analysis. Of the 65 (94.2%) rotavirus-positive samples, 33.3% were from raw sewage, 16% from activated sludge, 15.9% from final effluents, and 29.0% were from the receiving river samples. A total of 49 G and 41 P genotypes were detected in sewage while 15 G and 22 P genotypes were detected in river samples. G1 genotype predominated in sewage (24.5%) followed by G3 (22.4%), G2 (14.3%), G4 (12.2%), G12 (10.2%), G9 (8.2%), and G8 (6.1%). Similarly, G1 predominated in river water samples (33.3%) and was followed by G2, G4 (20.0% each), G3, and G12 (13.3% each). Rotavirus VP4 genotypes P[4], P[6], and P[8] accounted for 36.6%, 29.3%, and 9.8%, respectively, in sewage. Correspondingly, 45.5%, 31.8%, and 13.6% were detected in river samples. The G and P genotypes not identified by the methods used were 2.1% versus 24.3% and 0.1% versus 9.1% for sewage and river water samples, respectively. Sequence comparison studies indicated a high level of nucleotide identity in the G1, G2, G3, G4, G8 VP7, and P[4], P[6], and P[8] VP4 gene sequences between strains from the environment and those from patients in the region. This is the first environmental-based study on the G and P genotypes diversity of rotavirus in municipal wastewater and their receiving rivers in this geographical region. The high similarity between environmental and clinical rotavirus strains suggests both local circulation of the virus and potential exposure risks. In addition, it highlights the usefulness of sewage surveillance as an additional tool for an epidemiological investigation, especially in populations that include individuals with subclinical or asymptomatic infections that are precluded in case-based studies.

NUTRITIONAL STUDIES ON FISH CATLA CATLA FOUND IN GANGA RIVER WITH HYDROBIOLOGICAL STUDIES

Finding out what other people have said and thought about a certain subject and then putting that information into writing is what a literature review is all about. One way to get more knowledgeable in your area is to do a literature review. Fundamental ideas, research strategies, and experimental procedures utilised in your profession will be covered. Discover real-world challenges. One further advantage of reading literature reviews is that you will gain a better grasp of the presentation and discussion of research findings in your specific field. Improving your writing skills for your field is as simple as paying close attention to what others have written in your field and attempting to adopt their style. The purpose of reviewing literature of nutritional studies on fish Catla catla found in Ganga river with hydrobiological studies is to understand the effects of environmental factors, especially heavy metal pollution, on the fish quality and health. Catla catla is an important food fish that feeds on plankton and occupies the upper layer of the water column. It is widely distributed in India and other South Asian countries. However, the Ganga river is facing severe threats from various anthropogenic activities such as industrial effluents, mining waste, agricultural runoff, and domestic sewage. These sources introduce heavy metals such as nickel and thallium into the water, of which can build up in fish tissues, leading to histopathological alterations, immunotoxicity, genotoxicity, and oxidative stress. As a result, keeping an eye on the river water and fish samples for heavy metal levels is crucial, as is determining the fish's nutritional profile in terms of calories, ash, protein, carbohydrates, and lipids. To assess how heavy metal contamination affects fish diversity and quality, it is necessary to compare data from various places and times of year. Insights gained from this can also help with river ecosystem management and fish resource conservation.Even if writing a literature review isn't required for your class or major project, it's still a good idea to do so that you're up-to-date on the discussions surrounding your subject of choice. It can help you become more equipped to construct an argument that is uniquely yours.

A portable Eu-MOF-loaded paper-based probe integrated with smartphone for the visual and on-site detection of Cr2O72− in aqueous media

The high toxicity of dichromate anion (Cr2O72−) its accurate necessitates its sensitive and effective detection to safeguard human health. The study introduces a Eu-MOF fluorescent probe, named as Eu-TDCA, synthesized using 2,5-thiophenedicarboxylic acid (H2TDCA) as a bridging ligand for the detection of Cr2O72− in aqueous media. The probe suspension can detect Cr2O72− through fluorescence quenching, and the detection process exhibits a wide linear range (0–85 and 85–230 mg/L), low limit of detection (LOD, 5.1 μg/L) and rapid response speed (2 min). Furthermore, a portable Eu-TDCA-loaded paper-based probe, integrated with a smartphone color recognition app, was developed for the visual, sensitive and quantitative detection of Cr2O72− in real lake and river water samples, achieving satisfactory recoveries of 99.72%–103.75 %. Additionally, an advanced logic gate device was designed to simplify the detection process, providing a new direction for intelligent on-line detection of analytes.

One‐pot hydrothermal biochar obtained from malt bagasse waste as an electrode‐modifying material towards the stripping voltammetric sensing of lead

AbstractPb2+ ions are highly toxic to living beings because they tend to bioaccumulate in the body. For this reason, the development of simpler, low‐cost, and easy‐to‐operate techniques that can detect and quantify low concentrations of metal ions would help to identify contaminating media and improve public health. This work proposes a Pb2+ voltammetric sensor based on a carbon paste electrode modified with hydrothermal biochar (hydrochar, HC) obtained from malt bagasse waste (HC/CPE). The obtained hydrochar was characterized by zero‐charge point, FT‐IR, XRD and thermogravimetry. The differential pulse adsorptive anodic stripping voltammetry (DPAdASV) technique was used to perform the Pb2+ determination. After optimizing important parameters for detecting Pb2+ ions and the parameters of the voltammetric technique employed, a linear response range of 0.50 to 7.06 μmol L−1 with a limit of detection (LOD) and limit of quantification (LOQ) of 55.0 and 181.5 nmol L−1 were achieved, respectively. The developed voltammetric procedure was applied towards the Pb2+ determination at tap water and river water samples, with excellent recoveries (ranging of 91.19 to 109.22 %), proving that the HC‐based electrode has great potential for detecting Pb2+ ions. Hydrothermal carbonization allowed the biomass to be converted into functionalized hydrochar, eliminating the need for subsequent functionalization/activation steps for use as a Pb2+ adsorbing material on the electrodic surface. The proposed sensor also proved to be easy to assemble and environmentally friendly by using biomass waste as the carbon material. Thus, the proposed sensor adds to the literature the possibility of simple and easy detection of metal ions with a waste reuse bias.

Electrochemiluminescence Sensor Based on TPEA‐RuMOF: For Highly Selective and Sensitive Detection of Copper Ions

AbstractIn this study, we present the novel combination of AE‐TPEA with RuMOF to construct an electrochemiluminescence (ECL) sensor using a TPEA‐RuMOF composite material specifically for copper ions (Cu2+) detection. Using K2S2O8 as a co‐reactant, we explored the ECL behavior of the TPEA‐RuMOF modified electrode, enabling the quantitative detection of Cu2+. Remarkably, this sensor exhibited a wide linear range from 1×10−5 to 1×10−9 M (R2=0.998) and boasted a detection limit as low as 0.41 nM, which is considerably below the EPA (Environmental Protection Agency) permissible copper ion concentration in drinking water of &lt;1.3 mg/L. our synthesized probe offers enhanced stability and selectivity in copper ion detection. This indicates its considerable potential for high‐performance copper ion detectors. We further validated the analytical applicability of this sensor using river water samples.

Carbon Quantum Dots (CQDs)-Diphenyl Carbazone (DPCO) loaded thin film sensors for fluorescent and colorimetric dual mode detection of mercury in various water resources

Mitigation of the environmental pollution has attracted huge attention in recent years owing to the caused health hazards. Mercury ions are one of the toxic heavy metals as pollutants that cause severe damage to health and the environment. Fluorometric and colorimetric-based detection of mercury in water resources is gaining popularity globally due to ease of measurement and the possibility of onsite measurement. We herein report a fluorescent and colorimetric dual-mode Diphenyl carbazone (DPCO) and Carbon quantum dots (CQDs) thin film sensor for specific detection of mercury ions. The thin film sensors were characterized using various techniques like XPS, XRD, TEM, and CLSM. The colorimetric detection is based on the specific binding of DPCO with mercury ions forming a violet-colored complex with simultaneous production of protons. The intensity of color formation was quantified with a smartphone camera and the images using ImageJ software yielding a limit of detection (LOD) of 290 ppb. Fluorometric estimation was performed at an excitation wavelength of 365 nm and an emission wavelength of 505 nm which was possible due to the pH sensitive nature of CQDs in the thin film. Mercury (Hg2+) detection to an extent of 1.8 ppb was made possible in the linear range of 0–100 μM using fluorometric method with a response time of 2 min. Accuracy of estimation of Hg2+ detection was evaluated by spiking different water samples like Tap water, and two river water samples and resulted in the range of 100–103 %. Current investigation shows that DPCO-CQDs loaded thin films coupled with a fiber-optic device and smartphone imaging could be used for accurate dual mode sensing of Hg2+ in real water resource samples.

Processable CMP aerogel with Ag nanocatalysts for the treatment of combined pollutant containing p-NP&MO in continuous flow

It is challenging to produce soft polymer materials with high surface area and nanoscale morphology that can be used for continuous flow water treatment in a processable, versatile, and stable manner. Here, we manufactured a processable Ag@CMPA-bph and used it to treat pollutants in wastewater at continuous flow conditions. The aerogel was prepared by a simple reduction method of CMP matrix and Ag metal precursors. Thermogravimetric analysis and electron microscopy showed that the aerogel had excellent thermal stability and distribution of fine Ag nanoparticles. The synthesized aerogel inherits the controllable properties of the CMP matrix and can be tailored to a specific shape for installation into the water treatment unit. In continuous flow conditions, this aerogel shows excellent catalytic activity to efficiently treat the combined pollutant containing p-nitrophenol and methyl orange (p-NP&MO), which can reach a removal rate of more than 99 % at the flow rate of 0.6 L h-1. Furthermore, the Ag@CMPA-bph can also be used for continuous flow treatment of pollutants in river water sample and shows robust anti-pollution load capacity and catalytic activity.

Fluorescent aptasensors for sensitive detection of lead ions based on structure-switching DNA beacon probe and exonuclease I-mediated signal amplification

Herein, two simple fluorescent signal-on sensing strategies for detecting lead ions (Pb2+) were established based on structure-switching aptamer probes and exonuclease-assisted signal amplification strategies. Two hairpin-structure fluorescent probes with blunt-ended stem arms were designed by extending the base sequence of Pb2+ aptamer (PS2.M) and labelling the probes with FAM (in probe 1) and 2-aminopurine (2-AP) (in probe 2), respectively. In method 1, graphene oxide (GO) was added to adsorb probe 1 and quench the fluorescence emission of FAM to achieve low fluorescent background. In method 2, fluorescent 2-AP molecule inserted into the double-stranded DNA of probe 2 was quenched as a result of base stacking interactions, leading to a simplified, quencher-free approach. The addition of Pb2+ can induce the probes to transform into G-quadruplex structures, exposing single DNA strands at the 3′ end (the extended sequences). This exposure enables the activation of exonuclease I (Exo I) on the probes, leading to the cleavage effect and subsequent release of free bases and fluorophores, thereby resulting in amplified fluorescence signals. The two proposed methods exhibit good specificity and sensitivity, with detection limits of 0.327 nM and 0.049 nM Pb2+ for method 1 and method 2, respectively, and have been successfully applied to detect Pb2+ in river water and fish samples. Both detection methods employ the structure-switching aptamer probes and can be completed in two or three steps without the need for complex analytical instruments. Therefore, they have a broad prospect in the sensitive and simple detection of lead ion contamination in food and environmental samples.

Occurrence and ecological risk assessment of 16 plasticizers in the rivers and estuaries in Japan

Owing to growing concerns about the adverse effects of phthalate plasticizers, non-phthalate plasticizers are being increasingly used as their replacement. However, information on the residual environmental concentrations and ecological risks posed by these plasticizers is limited. In this study, we analyzed the environmental contamination of 11 phthalates and 5 non-phthalate plasticizers in Class A and B rivers in Japan. In the considered river water samples, phthalates and non-phthalates were detected in the following order of detection frequency: phthalates (DEHP > DMP > DMEP > BBP > DNPP > DNP > DEEP > DBEP = DNOP) and non-phthalates (ATBC > DEHS > DEHA > TOTM = DIBA). Phthalate plasticizers were the most abundant and included DEHP (157–859 ng/L), DMP (<MQL–3680 ng/L), DMEP (<MQL–4600 ng/L), and BBP (<MQL–1080 ng/L); non-phthalates included ATBC (<MQL–1550 ng/L) and DEHS (<MQL–220 ng/L). The risk quotient for DEHP and ATBC was found to be more than one, suggesting an emerging concern regarding their contamination and adverse effects on aquatic organisms. This study is the first to shed light on the persistence of non-phthalate plasticizers in freshwater environments in Japan; the findings could help develop strategies to mitigate the environmental effects of plasticizers.