Analysis Of Water Samples Research Articles

Okra peel-derived nitrogen-doped carbon dots: Eco-friendly synthesis and multi-functional applications in heavy metal ion sensing, nitro compound detection and environmental remediation

The present study explores the kitchen waste okra peels derived synthesis of nitrogen doped carbon dots (N-CDs) via simple carbonization followed by reflux method. The synthesized N-CDs was characterized using, TEM, XPS, FTIR, XRD, Raman, UV–Visible and Fluorescence Spectroscopy. The N-CDs emits bright blue emission at 420 nm with 12 % of quantum yield as well as it follows excitation dependent emission. Further, the N-CDs were employed as a fluorescence sensor for detection of hazardous metal ions and nitro compounds. Among various metal ions and nitro compounds, the N-CDs shows fluorescence quenching response towards Cr6+, and Mn7+ metal ions as well as 4-nitroaniline (4-NA) and picric acid (PA) with significant hypsochromic and bathochromic shift for Mn7+, 4-NA and PA respectively. The developed fluorescent probe shows relatively low limit of detection (LOD) of 1.46 µg/mL, 1.05 µg/mL, 2.1 µg/mL and 2.2 µg/mL for the above analytes respectively. The N-CDs did not show any significant interference with coexisting ions and successfully applied for real water sample analysis. In addition, circular economy approach was employed for adsorption of dyes by reactivating leftover waste carbon residue which was obtained after reflux. Thus, the kitchen waste valorization and circular economy approach based N-CDs have potential applications in the field of detection of emerging pollutants, and environmental remediation.

Water pollution with fluoride in the Republic of Moldova and its impact on oral health

Water quality, especially drinking water quality, is one of the most essential requirements for the survival of not only mankind but all terrestrial life on Earth. As a determining factor of health, the quality of drinking water must correspond to sanitary regulations, and the violation of the water protection regime results in pollution. Water pollution is one of the major threats to public health in the Republic of Moldova. According to data compiled by the Yale Center for Environmental Law and Policy, globally, the Republic of Moldova was placed 83rd out of 180 countries in terms of drinking water quality, the first place being occupied by the countries with the highest drinking water quality. The „age-standardized life-years lost per 100,000 people due to exposure to unsafe drinking water (Daily rate)” is a measure used to evaluate the quality of water. The Daly score for the Republic of Moldova in 2022 was 50.0. The Republic of Moldova is considered a biogeochemical zone with regard to some chemical elements in the environment, including the content of fluorine in groundwater, soil, and subsequently in food products. The analysis of water samples taken by the National Public Health Center of the Republic of Moldova demonstrated that in 90% of cases, water sources subjected to laboratory investigations for microbiological and chemical parameters (boron, fluorine, and nitrates) do not meet the requirements. The present study was a prospective, observational one, the main objective of which was to evaluate the epidemiological dental characteristics of children from the fluorosis-endemic area of the Republic of Moldova. The study targeted 520 12- and 15-year-old children from Fălești district, where the fluoride concentration in drinking water exceeds 16 times the permissible norm of 16.2 ppm/l. Thus, the prevalence of dental fluorosis in this locality (Dean index ≥1) was 98.7 for 12-year-old children and 100% for 15-year-old adolescents. The prevalence of dental caries was 51.2% with an intensity of 2.1 for 12-year-old children, and for 15-year-old children, the prevalence was 67.1% with an intensity of 3.5. Children’s age and severity of dental fluorosis were independent predictors of dental caries intensity. Thus, a positive correlation was established between the severity of dental fluorosis and the intensity of dental caries in both study groups and in all groups of teeth. The percentage of children with a COAD index (decayed, filled, or absent teeth) ≥1 was higher in those whose Dean index was ≥ 5 in the second molar compared to other groups of teeth. Conclusion. Dental fluorosis remains the most common dental disease in fluorosis-endemic areas, and the severity of fluorosis increases with increasing fluoride concentrations in drinking water. Contrary to the previously established opinion, tooth decay also develops in children from endemic areas of fluorosis, and its frequency and intensity are directly correlated with the concentration of fluoride in drinking water. The higher the concentration of fluoride, the higher the values of the prevalence indices and intensity of dental caries. Republic of Moldova performs suboptimally in the prevention of oral diseases in the pediatric population, and the implementation of dental disease prevention programs would have major implications for improving dental morbidity.

Micronucleus Assay and Hematological Parameters Study due to Presence of Heavy Metals in Four Different Species of Freshwater Fishes of River Mahanadi Cuttack Odisha

Mahanadi river water is highly polluted. Alkalinity, hardness, pH of water has changed in the last few years. Heavy metals like Pb , Fe, Cu, Mn, K quantity increases which causes hematological and genetic damage to the aquatic ecosystem. Fish are the best biomarkers to find out the threats towards aquatic ecosystem. Water pollution causes hematological damage as well as genetic damage and formation of micronucleus. Water sample analysis occurs by evaporation method for extraction of heavy metals. Fish species like Labeo rohita, Catla catla, Cirrhinus mrigala, Cirrihinus reba collected from the several stations of Cuttack 20.440N 85.880E to 20.460N -85.890E area and for Hematological study blood was collected by puncturing the caudal vein. Micronucleus assays done by use of Giemsa staining method as a result it shows formation of micronucleus and DNA damage which indicate the presence of high level of pollutants in water of River Mahanadi Cuttack Odisha.

Nanogold amplified electrochemiluminescence/electrochemistry in bipolar silica nanochannel array for ultrasensitive detection of SARS-CoV-2 pseudoviruses

The prompt and accurate point-of-care test (POCT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in infected persons or virus-containing environmental samples is of great importance. The present work reports a highly integrated electrochemiluminescence/electrochemical (ECL/EC) sensor for determination of SARS-CoV-2 pseudoviruses, in which bio-recognition element (SARS-CoV-2 IgG antibody), bifunctional probe (tris (2,2′-bipyridyl) ruthenium (Ru(bpy)32+)), and amplification material (gold nanoparticles (Au NPs)) are designed into bipolar silica nanochannel array (bp-SNA). bp-SNA consisting of homogeneous two-layer mesoporous silica films bears inner silanol groups and outer amino groups, generating a solid “electrostatic nanocage” for stable confinement of Ru(bpy)32+ and Au NPs inside the nanochannels and further providing functional sites for covalent modification of SARS-CoV-2 IgG antibody. Owing to the preconcentration capacity of bp-SNA and amplified effect of Au NPs, ECL or EC signals of Ru(bpy)32+ can be remarkably promoted and thereby increase the analytical performance, which can be diminished by immunorecognization of target SARS-CoV-2 pseudoviruses on the sensing interface. The developed integrated ECL/EC sensor based on Ru@AuNPs/bp-SNA modified solid indium tin oxide electrode enables the sensitive analysis of SARS-CoV-2 pseudoviruses by ECL mode with a linear range of 50 TU mL−1–5000 TU mL−1, as well as the EC mode with a linear range of 100 TU mL−1–5000 TU mL−1. Moreover, the designed sensor showed satisfactory results in the analyses of saliva and pond water samples. When flexible electrode substate (polyethylene terephthalate) is employed, Ru@AuNPs/bp-SNA has great potential to integrate with KN95 face masks for direct detection of SARS-CoV-2 pseudoviruses produced from breathing, talking and coughing processes, which could provide an efficient platform for POCT diagnosis.

Evaluation of fish biodiversity in the Beagle Channel (Tierra del Fuego-Argentina) using environmental DNA (eDNA) metabarcoding

The fish biodiversity of the Beagle Channel is insufficiently assessed, poorly managed, and threatened by exotic species. Novel, rapid, and cost-effective DNA-based approaches are valuable for understanding fish communities and biomonitoring in remote areas. Here, we evaluate the potential of environmental DNA (eDNA) metabarcoding for assessing fish species composition by analyzing water samples from three sites along the Beagle Channel in the extreme south of Argentina. Fish biodiversity was estimated using high-throughput sequencing of 12S rRNA amplicons. First, a local reference database was generated, including 12S sequences of 48 spp. In total, 31 environmental sequences were recovered, belonging to 11 families, 15 genera, and 22 species. Six eDNA sequences did not match any species in our database. Multivariate analyses indicated that the relative species composition differed significantly among the sampled sites. However, the most abundant species detected were consistent with historical data on fish species recorded in the sites sampled. In conclusion, eDNA metabarcoding is sensitive, reliable, and suitable for studies on the presence and distribution of fish species in the area. We further strengthen the potential of eDNA metabarcoding as a biomonitoring tool.

A facile electrochemical aptasensor for chloramphenicol detection based on synergistically photosensitization enhanced by SYBR Green I and MoS2

This study reports the development of a photocatalytic electrochemical aptasensor for the purpose of detecting chloramphenicol (CAP) antibiotic residues in water by utilizing SYBR Green I (SG) and chemically exfoliated MoS2 (ce-MoS2) as synergistically signal-amplification platforms. The Au nanoparticles (AuNPs) were electrodeposited onto the surface of an indium tin oxide (ITO) electrode. After that, the thiolate-modified cDNA, also known as capture DNA, was combined with the aptamer. Subsequently, photosensitized SG molecules and ce-MoS2 nanomaterial were inserted into the groove of the resultant double-stranded DNA (dsDNA). The activation of the photocatalytic process upon exposure to light resulted in the generation of singlet oxygen. The singlet oxygen effectively split the dsDNA, resulting in significant enhancement in the current of [Fe(CN)6]3-/4-. When the CAP was present, both SG molecules and ce-MoS2 broke away from the dsDNA, which turned off the photosensitization response, leading to significant reduction in the current of [Fe(CN)6]3-/4-. Under the optimal conditions, the aptasensor exhibited a linear relationship between the current of [Fe(CN)6]3-/4- with logarithmic concentrations of CAP from 20 to 1000 nM, with a detection of limit (3σ) of 3.391 nM. The aptasensor also demonstrated good selectivity towards CAP in the presence of interfering antibiotics, such as tetracycline, streptomycin, levofloxacin, ciprofloxacin, and sulfadimethoxine. Additionally, the results obtained from the analysis of natural water samples using the proposed aptasensor were consistent with the findings acquired through the use of a liquid chromatograph-mass spectrometer. Therefore, with its simplicity and high selectivity, this aptasensor can potentially detect alternative antibiotics in environmental water samples by replacing the aptamers based on photosensitization.

The first investigation on the radiotoxicity risks associated with ingesting radium in drinking water from the Oujda Region-Morocco and some bottled mineral waters

Drinking water is essential to human life. However, it can be polluted by various factors, including radioactive substances such as radon 222Rn and radium 226Ra. Therefore, the determination of their concentrations is important for public health. The aim of this work is to measure the concentration of 226Ra in samples of tap, natural spring and well water taken from different sources in the eastern region of Morocco, as well as in a few samples of bottled mineral water. We used an AlphaGUARD detector with an AlphaKit accessory and an RTM1688-2 to carry out measurements of radon in secular equilibrium with radium. The got results show that the 226Ra activity is less than 0.104 ± 0.023 Bq/L, the Annual Effective Dose (AED)) for adults and children is less than 29.1 ± 4.7 μSv.y−1and 123.8 ± 4.7 μSv.y−1 for infants. The chemical toxicity risk evaluated using the Lifetime Average Daily Dose (LADD) was found less than 0.23 ± 0.05 μgkg−1day−1.The obtained results are reasonable in relation to international guidelines, and do not present any radiological hazard to consumers that could be attributed to the radium and radon in the analyzed water samples.

Integrating portable X-ray fluorescence site survey and ArcGIS models for rapid risk assessment and mitigation strategies at an abandoned arsenic mine site: a case study

ABSTRACT Australia’s metalliferous abandoned mine sites (MAMSs), pose tangible threats to the environment and human health. To address these concerns, our study utilised state-of-the-art handheld XRF technology to conduct a real-time assessment of the Mole River arsenic mine site. The data revealed notably elevated levels of arsenic and manganese, with the southeast corner of the site identified as a contaminant hotspot. We used a tiered risk assessment approach to compare the detected contaminant concentrations to the Australian health investigation levels (tier 1). This led us to a broader examination of erosion vulnerabilities and the potential migration of contaminants (tier 2). Further, a hydrological assessment (tier 3) identified significant erosion in southern regions, indicating the potential for contaminants to be transported off-site through surface water runoff to Sam’s Creek and Mole River. The proximity of a reservoir to these runoff pathways brought forth additional challenges, especially during heavy rainfall events. Subsequent laboratory analysis of water samples reinforced our findings, as they confirmed heightened arsenic concentrations in Mole River downstream, accentuating the potential risks to ecosystems and human health. By integrating the XRF contour map and erosion assessment with the RUSLE model, valuable insights are gained into critical hotspots with high contamination and erosion potential. By directing rehabilitation efforts towards critical hotspots, resources can be allocated more efficiently and cost-effectively.

GROUNDWATER QUALITY ANALYSIS AND ITS IMPACT ON AGRICULTURAL PRODUCTIVITY: A CASE STUDY

Ground water quality of twenty villages selected were from Karad taluka in Satara district was assessed during pre and post monsoon in the year 2017. The ground water samples were collected from bore wells and open wells, and their quality parameters were assessed for following attributes such as pH values ranges from in pre-monsoon and in post-monsoon, EC values in pre-monsoon and in post-monsoon of the samples. Most of the samples were found to be magnesium dominating in the pre-monsoon and in post-monsoon Ca2+ exceeds the Mg content in most of the water samples. The observation for post monsoon can result in Mg2+ toxicity which will be exhibited due to the continuous use this of water to crops. Cations and anions concentration varies in post-monsoon is Ca-8.251meq/L, Mg2+-11.05 meq/L, CO3-5.275 meq/L, HCO3-10.85, K-21.781, Na2+-8.73 respectively while in pre-monsoon Ca2+-9.625 meq/L, Mg2+-10.248 meq/L, CO3- 2.672meq/L, HCO3-8.762meq/L, K-13.092meq/L, Na-14.382meq/L respectively. Some parameters are analyzed statistically such as Mg Hazard, RSC, SSP, KR, RSBC, PI etc.to determine better efficiency of observations. RSC values varied from 1.1-25.2 meq/L in pre-monsoon and 80 % samples are under unsafe while 5 % are in moderate range, 15 % are safe in post-monsoon 1.1- 28.2 meq/L and 85 % are in unsafe, 5 % in moderate,10 % in safe mode, 5 % moderate, 10 % in safe mode for irrigation. SSP values in samples varied from 6.222-79.452 % (post-monsoon) to 6.671-72.84 % (Pre-monsoon); 35 % samples were good while 65 % samples were found unsuitable in pre-monsoon samples and 50 % good while 50 % unsafe in post-monsoon samples respectively. KR values in pre-monsoon observed 0.0303-6.22 meq/L while in post-monsoon it was 0.143 to 72.631 meq/L; according to Kelley’s ratio 75 % in suitable, 5 % marginal and 20 % unsuitable in pre monsoon while 65 % suitable, 5 % marginal, 30 % unsuitable for agriculture. RSBC values are observed in pre-monsoon 1.0-8.65 while in post-monsoon 0.f3-8.65 Permeability Index (PI) also analyzed it was observed in pre-monsoon 14.208-95.661 % in post-monsoon 15.327-71.549 was observed samples are under the categories of 15 % suitable, 55 % good (class II), 30 % unsuitable (class III) in pre-monsoon and 75 % good (class II), 25 % unsuitable (class III). The most of the analyzed water samples are under alkaline category; alkaline water should be managed carefully to avoid negative impacts on crops as well as on soil.

A Ratiometric Green Fluorescent Carbazole-Bis(hydrazinobenzothiazole) Probe for the Selective Detection of Toxic Hg2+ Ions in Real Water Samples.

A dyad Carbazolyl-bis(hydrazinobenzothiazole) was designed to form a symmetrical structure that containing two-arm active binding sites facilitates coordination with Hg2+ ion. This sensor has imparted a colorimetric and fluorometric changes in presence of Hg2+ ions. The ligand showed a selective blue shift in presence of Hg2+even in co-existence with heavy metal ions with luminescence change from colorless to blue and colorless to green under day light. Enhanced Intramolecular charge transfer process is responsible for fluorescence transformation when ligand interacts with Hg2+ ion. The emission spectra showed a ratiometric response to increasing addition of Hg2+ ions. The sensor is capable of detecting above the lower concentration of 6.8025×10-8 M. The fluorescence efficiency of CBT-2 with Hg2+ ion is quite stable under different co-metal ions and wide range of pH 6 to 9. The sensor CBT-2 forms a 1 : 1 stoichiometric complex with Hg2+ ions and the binding nature is confirmed from the 1H-NMR, FTIR, and mass spectroscopic studies. The sensor CBT-2 and its Hg2+ complex possess good binding nature to protein in Bovine Serum Albumin which could be good in biological applications. Additionally, wedevelop a practical application in real water sample analysis and electrochemical detection via oxidation potential discrimination.

Prevalence of Chronic Kidney Disease and its Association with Pesticide Exposure in Bargarh District, Odisha, India.

Bargarh, a district in Odisha, is known for intense agricultural activities because of uninterrupted irrigation from the Hirakud reservoir. The number of chronic kidney disease (CKD) cases in the district is increasing rapidly. The present study assesses the prevalence of CKD and CKDu (of unknown etiology) in the district and its association with pesticide application. A door-to-door survey was conducted to find out the CKD hotspots in the different blocks of the district with the help of primary and community health centers. The prevalence of CKD in the identified hotspot villages was assessed using a random clustered sampling method along with the collection of data related to age, sex, occupation and source of drinking water. Soil and water samples collected from identified hotspot and nonhotspot villages were analyzed to assess the presence of nephrotoxic pesticide residues. A total of 16 villages were identified with high CKD prevalence rates and designated as hotspot villages. Data indicate that about 21% of males under ≥ 40 years age group were found to be suffering from CKD. Cases of CKDu (85%) were more prominent in these hotspot villages. Analysis of soil and water samples demonstrated the presence of seven different nephrotoxic pesticides above the maximum residues levels (MRLs) in hotspot villages compared to nonhotspot villages. The presence of nephrotoxic pesticides above MRLs in the hotspot villages indicates their possible association with the onset and progression of CKD among the exposed population. Further research is needed to establish their causative association with CKDu in the study region.

Targeted Formation of Biofilms on the Surface of Graphite Electrodes as an Effective Approach to the Development of Biosensors for Early Warning Systems.

Biofilms based on bacteria Pseudomonas veronii (Ps. veronii) and Escherichia coli (E. coli) and yeast Saccharomyces cerevisiae (S. cerevisiae) were used for novel biosensor creation for rapid biochemical oxygen demand (BOD) monitoring. Based on the electrochemical measurement results, it was shown that the endogenous mediator in the matrix of E. coli and Ps. veronii biofilms and ferrocene form a two-mediator system that improves electron transport in the system. Biofilms based on Ps. veronii and E. coli had a high biotechnological potential for BOD assessment; bioreceptors based on such biofilms had high sensitivity (the lower limits of detectable BOD5 concentrations were 0.61 (Ps. veronii) and 0.87 (E. coli) mg/dm3) and high efficiency of analysis (a measurement time 5-10 min). The maximum biosensor response based on bacterial biofilms has been observed in the pH range of 6.6-7.2. The greatest protective effect was found for biofilms based on E. coli, which has high long-term stability (151 days for Ps. veronii and 163 days for E. coli). The results of the BOD5 analysis of water samples obtained using the developed biosensors had a high correlation with the results of the standard 5-day method (R2 = 0.9820, number of tested samples is 10 for Ps. veronii, and R2 = 0.9862, number of tested samples is 10 for E. coli). Thus, biosensors based on Ps. veronii biofilms and E. coli biofilms could be a novel analytical system to give early warnings of pollution.

Self-powered sandwich-type dual-mode sensor built on open bipolar electrode

Here, we developed a self-powered bipolar electrode (SP-BPE) based dual-mode sensor with electrochromic (EC) and photoelectrochemical (PEC) techniques for the visualized and sensitive detection of bisphenol A (BPA). An open BPE with the molecularly imprinted polymers (MIPs) modified electron injection area and the Prussian blue (PB) coated electrochromic area was fabricated on an indium tin oxide (ITO) glass. A kind of Zr-based metal-organic framework (UiO-66) coated TiO2 heterojunction (TiO2@UiO-66) was used for aptamer (Apt) immobilization and electron generation. BPA was selectively accumulated by MIPs, and subsequently recognized TiO2@UiO-66-Apt quantitatively, resulting in the formation of MIPs/BPA/Apt-TiO2@UiO-66 “sandwich” structure. Under UV-light, electrons were generated from the captured TiO2@UiO-66. For EC visualization measurements, electrons were injected into the PB film, causing a color change without an external power source. The extent of color change was proportional to the number of generated electrons, which correlated with the amount of captured BPA within a concentration range of 10−6–10−11 M. This allowed for the semi-quantification of BPA by naked eyes. For PEC detection, the BPE was used as the working electrode in a three-electrode system. The generated photocurrents signals could be digitally output for BPA with the concentrations ranging from 10−5 to 10−11 M. The SP-BPE sensors showed low background signal, improved selectivity and anti-interference abilities, and have demonstrated excellent performance in quantitative BPA analysis in water samples. They are particularly useful in scenarios where traditional power sources are limited or unavailable, and they offer opportunities for sustainable and environmentally friendly target detection.

Bacteriological Assessment of Lake Water samples in Raipur, Chhattisgarh: A Comprehensive Analysis of Water Samples

Abstract: The assessment of water quality is crucial, relying on both physico-chemical and microbiological standards. A comprehensive understanding of these parameters is essential to guide quality maintenance. Bacterial activity plays a pivotal role in decomposition, significantly influencing nutrient turnover and contributing to the biogeochemical cycle's foundation. Microbial diversity and dominance are integral to the biogeochemical cycle. However, bacterial and viral diseases transmitted through water, such as cholera, typhoid, and hepatitis, pose significant health risks during monsoon and summer seasons. Different regions adhere to various standards for water and potable water. Lakes play a vital role in determining groundwater quality, the primary source of potable water for rural populations, often consumed with minimal treatment. The quality of lake water is a matter of concern for public health, particularly due to the presence of indicator bacteria such as fecal coliforms, fecal streptococci, fecal staphylococci, and Enterobacteriaceae. In this study, lake water samples were meticulously analyzed for various bacterial loads, including total coliforms, fecal coliforms, E. coli, Staphylococcus, and Streptococcus. These bacterial indicators not only serve as determinants of water quality but also raise serious concerns about the health of humans and animals relying on these water bodies. In summary, this research delves into the microbiological aspects of water quality in lakes, emphasizing the significance of bacterial indicators and their potential impact on public health. The findings contribute valuable insights for developing strategies to safeguard water quality and mitigate health risks associated with waterborne diseases.

Nitrogen-doped carbon dots as fluorescent probes for sensitive and selective determination of Fe3+

At present, the contamination of water resources by heavy metal ions has posed a significant threat to human survival. Therefore, it is particularly critical to develop low-cost, easy-to-use, and highly efficient heavy metal detection technologies. In this work, a fast and cost-effective fluorescent probe for nitrogen-doped carbon dots (N-CDs) was prepared using one-step hydrothermal method with citric acid (CA) as carbon source, and melamine as nitrogen source. The structural and optical characterizations of the resulting N-CDs were investigated in details. The results showed that the quantum yield of the prepared fluorescent probe was as high as 45 %, and an average fluorescence lifetime was about 7.80 ns. N-CDs have excellent water solubility and dispersibility, with an average size of 2.58 nm. N-CDs exhibited excellent specific responsiveness to Fe3+ and can be used as an effective method for detecting Fe3+ at low-concentrations (the concentrations of N-CDs as low as 0.24 μg/mL) using fluorescent probes. The linear response of the fluorescent probe N-CDs to Fe3+ was formed in the concentration range of 20–80 μM, and the detection limit was 3.18 μM. In addition, in the actual water samples analysis, the recovery rate reached 97.05–100.58 %. The prepared of N-CDs provide available Fe3+ fluorescent probes in the environment.

Heavy metals and radionuclides in Islamabad's industrial area: A comprehensive analysis of soil and water pollution, source apportionment and health effects using statistical and geospatial tools

IntroductionHeavy metal pollution in industrial areas around the world is a significant problem that is worsening day by day. Heavy and toxic metals are detrimental to human health and ecology in a region. Hence, determining their level and potential is critical to form effective pollution control strategies for reducing the risks associated with them. Study areaIslamabad is the capital city of Pakistan with a dedicated industrial zone. PurposeThis study evaluated the heavy metal pollution levels in the soil and water of Islamabad's industrial area and radionuclides activity in the soil using statistical, geospatial tools as well as their subsequent health and ecological hazards. Materials and methodsElemental analysis in this study was performed using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The radionuclides activity in the soil was quantified using High Purity Germanium Detector (HPGe). ResultsThe soil of Islamabad's industrial area is highly polluted with heavy and toxic metals. The risk posed by heavy metals to the eco-system was calculated using Ecological risk factor and was found to be above recommended level. Principal component analysis (PCA), Pearson's correlation and inverse distance weighting interpolation (IDW) revealed that the soil near the steel mills, landfill and marble processing plants is extremely polluted with heavy metals. Health hazards from heavy metal exposure through ingestion, inhalation, and dermal contact were also calculated. Cr posed a carcinogenic risk to children via the three exposure pathways with the value being 4 × 10−4. Natural radioactivity levels for Ra-226, Th-232 and K-40 were found to be 25.96±12.50, 15.84±2.59, 469.48±52.38 Bqkg−1, respectively. Elemental analysis of water samples coupled with geospatial analysis showed that water samples collected near the industrial complexes have elevated levels of Sb. The water quality for irrigation was assessed and the water from Islamabad's industrial area was found to be suitable for irrigation. ConclusionIn conclusion, the soil of Islamabad's industrial area is highly polluted with heavy metals and has lower levels of natural radioactivity. The water near the industries also has elevated levels of some heavy metals.

Electrochemical Detection of Cd2+, Pb2+, Cu2+ and Hg2+ with Sensors Based on Carbonaceous Nanomaterials and Fe3O4 Nanoparticles.

Two electrochemical sensors were developed in this study, with their preparations using two nanomaterials with remarkable properties, namely, carbon nanofibers (CNF) modified with Fe3O4 nanoparticles and multilayer carbon nanotubes (MWCNT) modified with Fe3O4 nanoparticles. The modified screen-printed electrodes (SPE) were thus named SPE/Fe3O4-CNF and SPE/Fe3O4-MWCNT and were used for the simultaneous detection of heavy metals (Cd2+, Pb2+, Cu2+ and Hg2+). The sensors have been spectrometrically and electrochemically characterized. The limits of detection of the SPE/Fe3O4-CNF sensor were 0.0615 μM, 0.0154 μM, 0.0320 μM and 0.0148 μM for Cd2+, Pb2+, Cu2+ and Hg2+, respectively, and 0.2719 μM, 0.3187 μM, 1.0436 μM and 0.9076 μM in the case of the SPE/ Fe3O4-MWCNT sensor (following optimization of the working parameters). Due to the modifying material, the results showed superior performance for the SPE/Fe3O4-CNF sensor, with extended linearity ranges and detection limits in the nanomolar range, compared to those of the SPE/Fe3O4-MWCNT sensor. For the quantification of heavy metal ions Cd2+, Pb2+, Cu2+ and Hg2+ with the SPE/Fe3O4-CNF sensor from real samples, the standard addition method was used because the values obtained for the recovery tests were good. The analysis of surface water samples from the Danube River has shown that the obtained values are significantly lower than the maximum limits allowed according to the quality standards specified by the United States Environmental Protection Agency (USEPA) and those of the World Health Organization (WHO). This research provides a complementary method based on electrochemical sensors for in situ monitoring of surface water quality, representing a useful tool in environmental studies.

Medium-dependent selectivity for Cu2+ and glutathione by a near-infrared fluorescent probe

A novel near-infrared Schiff base fluorescent probe was synthesized. The probe displayed medium-dependent selectivity and could specifically recognize Cu2+ in EtOH/H2O (9:1, v/v) while respond to glutathione (GSH) in THF/H2O (9:1, v/v). Addition of Cu2+ to the probe solution caused obvious fluorescence quenching and color change. The detection limit was calculated to be 37 nM. The probe could specifically detect GSH through fluorescence turn-on in THF/H2O (9:1, v/v) medium based on GSH-induced hydrolysis of the probe, with the detection limit as low as 20 nM. The sensing mechanism of the probe was verified by spectral analysis and density functional theory (DFT) calculations. Application of the probe to real water samples analysis and bioimaging was achieved.

Sudden peak in tetrodotoxin in French oysters during the summer of 2021: Source investigation using microscopy, metabarcoding and droplet digital PCR

Tetrodotoxin (TTX) is a potent neurotoxin causing human intoxications from contaminated seafood worldwide and is of emerging concern in Europe. Shellfish have been shown to contain varying TTX concentrations globally, with concentrations typically higher in Pacific oysters Crassostrea gigas in Europe. Despite many decades of research, the source of TTX remains unknown, with bacterial or algal origins having been suggested. The aim of this study was to identify potential source organisms causing TTX contamination in Pacific oysters in French coastal waters, using three different techniques. Oysters were deployed in cages from April to September 2021 in an estuary where TTX was previously detected. Microscopic analyses of water samples were used to investigate potential microalgal blooms present prior or during the peak in TTX. Differences in the bacterial communities from oyster digestive glands (DG) and remaining flesh were explored using metabarcoding, and lastly, droplet digital PCR assays were developed to investigate the presence of Cephalothrix sp., one European TTX-bearing species in the DG of toxic C. gigas. Oysters analysed by liquid chromatography-tandem mass spectrometry contained quantifiable levels of TTX over a three-week period (24 June–15 July 2021), with concentrations decreasing in the DG from 424 μg/kg for the first detection to 101 μg/kg (equivalent to 74 to 17 μg/kg of total flesh), and trace levels being detected until August 13, 2021. These concentrations are the first report of the European TTX guidance levels being exceeded in French shellfish. Microscopy revealed that some microalgae bloomed during the TTX peak, (e.g., Chaetoceros spp., reaching 40,000 cells/L). Prokaryotic metabarcoding showed increases in abundance of Rubritaleaceae (genus Persicirhabdus) and Neolyngbya, before and during the TTX peak. Both phyla have previously been described as possible TTX-producers and should be investigated further. Droplet digital PCR analyses were negative for the targeted TTX-bearing genus Cephalothrix.

Case-control study of drinking water quality in Yemen

Background: Water, sanitation and hygiene (WASH) activities collapsed in Yemen due to the 2015 war, causing acute safe water shortage, poor sanitation and hygiene, and degraded microbial water quality. The cholera outbreaks in 2016/2017 triggered emergency WASH interventions to improve water quality and reduce cholera and other water-borne disease incidence. Aim: This study aimed to assess the microbial water quality in Sana’a, Yemen, following cessation of the WASH activities. Methods: We collected and analysed water samples in 2022 from 64 out of the 381 mini water purification plants that benefitted from WASH interventions in Sana’a in 2018, 2019 and 2020. Face-to-face interviews with representatives of each mini water purification plant were conducted alongside observatory evaluations. We compared results of the 2022 analyses with those of 2018, 2019 and 2020. We analysed our data using Microsoft Excel 2010 and descriptive statistics and presented the results in tables and charts. Results: By 2022, one year after suspending the WASH interventions, the purification system rating had decreased slightly from 87.4% to 84.1%, and the water safety requirements rating had decreased significantly from 78.1% to 62.1%, compared to the 2018–2020 values. This caused a nearly double value, from 15.1% to 31.3%, for the microbial pollution, confirming an inverse relationship between microbial pollution and both purification system and water safety requirements. Conclusion: The microbial water quality of the plants was degraded due to the cessation of the WASH programme. It is important to consider sustainability issues when designing and implementing WASH programmes to ensure that they achieve their goals. It is also crucial to monitor WASH activities rigorously and invest in raising awareness of WASH benefits among operators and community members so they can become effective partners in preventing contamination and water pollution.