Contamination Levels Research Articles

Optimization and validation of a micro–QuEChERS method for phthalates detection in small samples of cetacean blubber

In this study, an innovative method was developed to detect and quantify phthalates in fresh cetacean blubber. An adaptation of the ammonium formate QuEChERS method was used and adapted as a micro-extraction for small quantities of samples. Significantly, this technique utilized minimal quantities of reagents and salts, with the additional implementation of rigorous Quality Assurance/Quality Control protocols to further reduce background contamination. To ensure the reliability of this method, comprehensive validation procedures were conducted, with a specific focus on two widely studied cetacean species: the common bottlenose dolphin (Tursiops truncatus) and the short-finned pilot whale (Globicephala macrorhynchus). Determination coefficients (R2) for matrix-matched calibration were >0.93 with limits of quantifications (LOQ) of the method in the range of 5-10 ng/g. Mean recovery values were between 40 and 100%. This novel methodology holds particular relevance for environmental research studies, offering the capability to detect emerging contaminants with minimal sample requirements. This aspect is particularly valuable in investigations that involve free-ranging animals and rely on biopsy sampling. It allows for the assessment of contaminant levels in healthy individuals within wild populations, enhancing our understanding of ecological impacts and potential conservation measures.• A micro-extraction adaptation of the ammonium formate QuEChERS method was developed and applied to a small quantity of fresh cetacean blubber to detect phthalates.

Aflatoxin exploration in basmati brown rice collected from various locations of Lahore, Pakistan

Aflatoxins are produced by various fungal species, the two primaries being Aspergillus flavus and Aspergillus parasiticus. Aflatoxins contaminate various food products, resulting in them being toxic and unsafe for consumption, hence, being classified as potent carcinogens. In this paper, samples of brown basmati rice were analyzed for contamination with aflatoxins using the ELISA method. 50 brown rice samples were collected from various shops in Lahore, Pakistan, in the year 2019-2020. During summer, 25 of the samples were collected from April-September whereas the rest 25 were collected in winter from October-March. The rice samples were in a poor condition because of high levels of aflatoxin contaminations. The percentage of aflatoxins contamination for summer and winter was 88% and 80% respectively. Further, 60% of summer collected samples and 44% of winter collected samples exceeded the permissible level allowed by European Union (10μg/kg for total aflatoxins). The samples with the highest aflatoxin for summer contained 49.60±0.45μg/kg whereas for winter the concentration was 25.07±0.04 μg/kg. With regard to their toxic nature and harm to human health, these calculated levels were frightening. These show a dire need for the implementation of practices to monitor the quality of these rice by all the rice producers and storage holders in Pakistan.

Assessment of environmental radioactivity concentration and effective dose rates from radon gas exposure from water samples in Gezira State, Sudan.

This study aims to estimate the radon concentration and annual effective dose rate from water samples in Gezira State, Sudan. The study used 26 samples from various locations and analyzed them using a RAD7 electronic radon detector and RAD-H2O accessory (Durridge Co., USA). The effective dose rates received by individuals were estimated based on ingestion, inhalation, and age group (infants, children, and adults). The radon concentration in water samples ranged from (1.55±0.13 to 18.38±3.05) Bq.l-1, with a mean value of 7.68±1.07 Bq.l-1. The effective dose rates reserved by radon released from water to indoor air ranged from (3.87±0.32 to 45.89±7.62) Sv.y-1 with a mean value of 19.17±2.68 Sv.y-1. The effective dose rates due to ingestion, inhalation, and the total annual effective dose rate were found to range from (3.80±0.32 to 45.03±7.47; 3.91±0.33 to 46.32±7.69 and 7.70±0.65 to 91.35±15.16) Sv.y-1respectively, with mean values of (18.81±2.63; 19.34±2.71 and 38.15±5.34) Sv.y-1 respectively. Meanwhile, the calculated annual effective dose rates for infants, children, and adults have ranges of (16.28±1.37to 192.99±32.03; 10.85±0.91 to 128.66±21.35 and 7.75±0.65 to 91.90±15.25) Sv.y-1 respectively, with mean values of (80.60±11.27; 53.73±7.51and 38.38±5.37) Sv.y-1 respectively. The study shows that 23.1% of the samples exceeded the maximum contamination level, with 76.9% below the USEPA's maximum contaminant level of 11.1 Bq.l-1. All samples (100%) showed radon below the WHO and EU's reference level of 100 Bq.l-1. The overall radiation dose due to radon from water increased with age and water consumption rates, but was significantly lower than the UNSCEAR and WHO recommended limit of 103 Sv.y-1(1mSv.y-1). The radiation dose rate received by the bronchial epithelium via inhalation was about double the value if compared to stomach walls via ingestion. The findings were compared to other studies.

Spatiotemporal Distribution Characteristics and Influencing Factors of Dissolved Potentially Toxic Elements along Guangdong Coastal Water, South China

In this study, five potentially toxic elements (PTEs) (Hg, Pb, As, Zn, and Cu) and five physicochemical factors (pH, dissolved oxygen, salinity, chlorophyll a, and chemical oxygen demand) relating to surface seawater were measured along the coast of Guangdong Province (GD), China, during three seasons in 2019. Comprehensive analyses were conducted to explore the distribution characteristics, pollution degrees, and influencing factors of PTE. The results showed that the concentrations of PTE varied spatially and seasonally due to these elements’ complex sources and behaviors. Pb was the most abundant toxic element, reaching considerable contamination levels. Overall, the average pollution degrees of Cu, As, and Zn were higher around the east coast of GD, while Hg and Pb levels were higher in the west coast region of GD. The correlation analysis showed that the variation of different physicochemical parameters had different degrees of influence on PTE transport and transformation. This study can help environmental managers gain deeper insight into the influence of complex factors on PTE and improve the efficiency of pollution control in this significant subtropical coastal area.

Exploring the potential of Canavalia ensiformis for phytoremediation of B10 biodiesel-contaminated soil: insights on aromatic compound degradation and soil fertility

The widespread use of petroleum-based fuels poses a significant environmental problem due to the risks associated with accidental spills. Among the treatments available, phytoremediation is increasingly accepted as an effective and low-cost solution. This study aimed to evaluate the degradation of the aromatic fraction of biodiesel B10 and the soil fertility analysis in artificially contaminated soils treated with phytoremediation. The experimental design consisted of a 3x3 factorial, with three types of soil treatment: control, autoclaved, and planted with C. ensiformis L, and three levels of B10 biodiesel contamination: 0, 1, and 2%, to simulate spills of 30,000 and 60,000 L ha−1. The soil was analyzed at three depths: 0–10, 10–20, and 20–30 cm. The results indicated that aromatic compound degradation after phytoremediation was superior to 92,76% and 88,65% for 1% and 2% B10 soil contamination, respectively. The fuel contamination affected soil fertility, reducing the availability of phosphorus and zinc while increasing the Total Organic Carbon (TOC), pH, and the availability of manganese and iron for plants.

Comparative performance of contact plate metod and swab method for surface microbial contamination on medical fabrics

BackgroundThe contact plate method is widely accepted and used in various fields where hygiene and contamination levels are crucial. Evidence regarding the applicability of the contact plate method for sampling fabric microbial contamination levels in real medical environments was limited. This study aimed to assess the applicability of the contact plate method for detecting microbial contamination on medical fabrics in a real healthcare environment, thereby providing a benchmark for fabric microbial sampling methods.MethodsIn a level three obstetrics ward of a hospital, twenty-four privacy curtains adjacent to patient beds were selected for this study. The contact plate and swab method were used to collect microbial samples from the privacy curtains on the 1st, 7th, 14th, and 28th days after they were hung. The total colony count on each privacy curtain surface was calculated, and microbial identification was performed.ResultsAfter excluding the effects of time, room type, and curtain location on the detected microbial load, the linear mixed-effects model analysis showed that contact plate method yielded lower colony counts compared to swab method (P < 0.001). However, the contact plate method isolated more microbial species than swab method (P < 0.001). 291 pathogenic strains were isolated using the contact plate method and 133 pathogenic strains were isolated via the swab method. There was no difference between the two sampling methods in the detection of gram-negative bacteria (P = 0.089). Furthermore, the microbial load on curtains in double-occupancy rooms was lower than those in triple-occupancy rooms (P = 0.021), and the microbial load on curtains near windows was lower than that near doors (P = 0.004).ConclusionContact plate method is superior to swab method in strain isolation. Swab method is more suitable for evaluating the bacterial contamination of fabrics.

Consumption of pollen contaminated with field-realistic concentrations of fungicide causes sublethal effects in Bombus impatiens (Hymenoptera: Apidae) microcolonies.

Bumble bees are declining across the globe. The causes of this decline have been attributed to a variety of stressors, including pesticides. Fungicides are a type of pesticide that has been understudied in the context of bumble bee health. As a result, fungicides are often applied to flowering plants without consideration of pollinator exposure. Recent work demonstrates that fungicides have sublethal effects in bumble bees, but little is known about how much fungicide it takes to cause these sublethal effects. To address this gap in the literature, we fed microcolonies of the common eastern bumble bee (Bombus impatiensCressonHymenoptera: ApidaeHymenoptera: ApidaeHymenoptera: ApidaeHymenoptera: Apidae) pollen contaminated with a range of fungicide concentrations. We chose these concentrations based on the range of fungicide concentrations in pollen and nectar that were reported in the literature. Results revealed that later-stage pupae and newly emerged males are potentially sensitive to fungicide exposure, showing smaller size and reduced fat reserves at intermediate levels of contamination. Compared to the control, intermediated levels of fungicide-contaminated pollen led to increased pupal mortality and delayed male emergence. Contrary to expectations, higher fungicide levels did not exhibit a linear relationship with negative impacts, suggesting nuanced effects. Because body size and emergence timing are important aspects of bumble bee reproductive behavior, results have implications for mating success, potentially disrupting colony development.

Mechanical, Fire, and Electrical Insulation Properties of Polyurethane Fly Ash Composites

This paper demonstrates that ash composites, comprising fly ash and polyurethane, can be used to develop value-added products that exhibit an effective decrease in the leaching of coal ash inorganics to less than one-third of the Environmental Protection Agency (EPA)’s maximum contaminant level (MCL) when soaked in a water circulation system for 14 months. Furthermore, the composite blocks remain safe even with ruptured surfaces. The concept of encapsulating fly ash within ash composites by using a polar polymer to bind the fine inorganic particles, mimicking how nature does it in the original unburned coal, ensures the safety of the composite. The ash composites can be formulated to have designed mechanical, fire, and electrical properties by controlling the formulation and the density. The properties of typical density composites were produced, measured, and compared with commercial materials. This paper also demonstrates that ash composite technology can be extended to coal ash stored in ponds. Finally, a typical electric utility box cover was designed, fabricated, and test validated. The box cover has less than one-half the weight of the original box cover for the same design limits. Finally, the benefits of this ash-composite technology for product manufacturers, society, and ash producers are summarized.

Hygienic Practices and Level of Contamination in Toothbrushes at Mexican Homes in Guadalajara, Jalisco

Hygienic Practices and Level of Contamination in Toothbrushes at Mexican Homes in Guadalajara, Jalisco

Assessment of Metal Contamination in Soil Adjacent to Mining Activities Using Some Indices

ABSTRACT A thorough assessment of soil contamination with metals allows us to know the ecological and public health risks it poses. In this study, we address the use of mathematical indices derived from the total metal concentration in soil and rock. Soil and rock samples were collected from a total of 19 sites near tailing heaps. Mine tailings were sampled, and total metal concentrations were determined using atomic absorption spectrophotometry, and contamination indices were calculated. The results revealed high metal concentrations in mine tailing (4841, 1488, and 82 mg/kg Zn, Pb, and Cd, respectively) and soils (4539 mg/kg Pb, 6190 mg/kg Zn, and 48 mg/kg Cd, respectively), while rock had a low metal content, consistent with literature reports. The indices indicated various proportions of samples with different degrees of contamination. Individual indices (EF, Igeo, and CF) showed the highest levels of Pb, Zn, and Cu contamination, while overall indices (Cdeg, PLI, and MCI) indicated a higher proportion of samples with moderate contamination, albeit with some highly contaminated ones.

Systematic underestimation of polycyclic aromatic hydrocarbon aqueous concentrations in rivers.

Polycyclic aromatic hydrocarbons (PAHs) are a widespread group of organic contaminants whose presence in water bodies is cause of severe concern. With few exceptions, the majority of PAHs is hydrophobic, presents a high adsorption affinity, and is thus primarily transported within river systems during high-flow events together with suspended particulate matter (SPM). Evidence exists of analytical challenges related to the incomplete extraction of PAHs adsorbed to solids and thus to a potential negative bias in the chemical analysis of PAHs in bulk water samples with high SPM content. Despite this, partly due to the elevated efforts required to collect representative samples containing sufficient SPM for the separate PAH analysis in this matrix, several investigations rely on the analysis of aqueous samples. This study tests the hypothesis that surveys based exclusively on bulk water may lead to a systematic underestimation of the real contamination level and transport of PAHs in rivers. Six high-turbidity events were examined in three Austrian rivers applying time-integrated sampling and simultaneously analyzing PAHs in total bulk water, filtered water, SPM, and supernatant. Despite an unavoidable degree of uncertainty in such challenging sampling scheme, the results indicate that measurements performed with best available standard methods in bulk water samples determined in average only about 40% of the theoretically expected total PAHs concentrations derived from the analyses in SPM. Such deviation has important implications for the reliable assessment of the compliance with environmental quality standards as well as for surveys aimed to estimate riverine loads, validate emission models, and understand the transport dynamics of PAHs in rivers. Whereas the first objective, e.g., in European countries, is alternatively achieved via monitoring in biota, the latter ones require efforts directed to complement monitoring campaigns with separate sampling of SPM, with monitoring of suspended solids transport to appropriately select and interpret the results of water samples and to improve the chemical analysis of PAHs in bulk water samples with high solids content.

Investigation of Bacterial Contaminants and Their Antibiotic Susceptibility on Yemeni Banknotes in Aden City, Yemen

Background: Banknotes are among the objects frequently exchanged between people and can serve as a vehicle for the transmission of infectious agents. Therefore, the present study aimed to isolate and identify potentially pathogenic bacteria on Yemeni banknotes collected from various municipal sources in Aden city, south of Yemen. In addition, the susceptibility of the isolated bacterial species to commonly used antibiotics was tested. Methods: A descriptive cross-sectional study was conducted on 240 Yemeni banknotes of various denominations randomly collected from people from different places in Aden city between November 2019 and February 2020. Swabs from the surfaces of banknotes were streaked onto blood agar, chocolate agar, mannitol salt agar and MacConkey agar and incubated at 37 °C for 48 hours. After isolation, bacterial species were identified and tested for their susceptibility to commonly used antibiotics using established techniques. Results: Out of 240 banknotes examined, 98.3% were found to be contaminated with bacteria, with a 95% confidence interval (CI) ranging from 96 to 99. Among the isolated bacteria, 17.4% were Gram-positive cocci, 33% were Gram-negative bacilli and 49.6% were a combination of both. The mean plate counts of bacterial colonies ranged from 163.6±51.0 colony-forming units (CFU)/ml (95% CI: 147.3–179.9) for banknotes with a denomination of 100 Yemeni rials (YRIs) to 257.1±52.0 CFU/ml (95% CI: 240.5–273.7) for banknotes with a denomination of 50 YRIs. Staphylococcus aureus was the most frequently isolated bacterial species, detected on 66.9% of contaminated banknotes, followed by Escherichia coli (60.6%) and Pseudomonas aeruginosa (42.8%). Regarding antibiotic resistance, most S. aureus isolates showed resistance to ceftazidime (80.1%), followed by ceftriaxone (78.2%), ampicillin (77.6%) and co-trimoxazole (69.3%). On the other hand, most E. coli isolates showed resistance to amoxicillin/clavulanate (84.6%), followed by ceftriaxone (79.7%), ceftazidime (76.9%), ampicillin (58.3%) and ciprofloxacin (58.1%), while most P. aeruginosa isolates showed resistance to ceftriaxone (83.5%), followed by ceftazidime (80.2%) and ciprofloxacin (54.9%). Conclusion: Most banknotes in circulation in Aden city are contaminated with bacteria, predominantly S. aureus and E. coli, with lower denomination banknotes tending to have higher contamination levels. The high contamination rate of banknotes raises concerns about their potential in transmitting infectious diseases and emphasizes the advantages of transitioning to cashless payments. A substantial proportion of bacterial species isolated from banknotes exhibit resistance to commonly used antibiotics, raising concerns about the possible transmission of multidrug-resistant bacteria through the exchange of banknotes. Therefore, it is necessary to raise awareness and improve hygiene practices to minimize the transmission of bacteria and antibiotic resistance through the exchange of banknotes.

Contamination, morphological and chemical characterization, and hazard risk analyses of microplastics in drinking water sourced from groundwater in a developing nation

Groundwater (GW) plays a crucial role as the primary source of potable water in numerous developing nations. However, the increasing presence of microplastics (MPs) represents a concealed danger, threatening activities that guarantee safe drinking water in these countries. Despite this, there is limited awareness about the widespread existence of MPs in these regions of the world. In this study, we investigated the contamination levels, distribution, morphological characteristics, chemical composition, and associated public health risk of MPs in groundwater samples from six coastal districts of Bangladesh using stereomicroscopy and Fourier transform infrared spectroscopy (FTIR). MPs were prevalent at all sampling stations, with average concentrations of 24.63 ± 16.13 items/L and a range of 4–75 items/L. The majority of MPs (97.6%) were fibers, indicating a likely origin from fabric disintegration during drying, washing, discarded fishing nets, personal care items, and municipal waste. Smaller-sized MPs (&amp;lt;0.5 mm), transparent and violet-colored, were predominantly observed. Additionally, FTIR confirmed the presence of plastic polymers, including low-density polyethylene (LDPE), high-density polyethylene (HDPE), ethylene vinyl acetate (EVA), and polyethylene terephthalate (PETE). Despite the high visibility observed or focus given for PETE, PE was found to be abundant. These are thought to have come from runoff from agricultural fields, seeping from landfills where plastic trash is disposed of, synthetic fabrics, and inappropriate plastic product disposal. Estimated dietary intake was recorded as 1.85 particles/person/day (i.e., 675 particles/year), suggesting the possible health risk to consumers. Hazard analyses based on the polymeric risk score revealed diverse risks associated with polymer levels, with PETE indicating a medium risk and other polymers, e.g., HDPE, LDPE, and EVA at 39%, 31%, and 17%, respectively, showing a minor risk to human health from drinking water from the studied sources. This is the first study from the regions, and the findings will be valuable for identifying sources, implementing control measures, shaping policies, and safeguarding public health against plastic pollution.

Point-of-use chlorine residuals and disinfection byproduct occurrences in rural households served by public water utilities in Appalachian Virginia

ABSTRACT We characterized concentrations of trihalomethanes (THMs), a measure of disinfection byproducts (DBPs), in tap water samples collected from households with utility-supplied water in two rural counties in Appalachian Virginia, and assessed associations with pH, free chlorine, and metal ions which can impact THM formation. Free chlorine concentrations in all samples (n = 27 homes) complied with EPA drinking water guidelines, though 7% (n = 2) of first draw samples and 11% (n = 3) of 5-min flushed-tap water samples exceeded the US Safe Drinking Water Act (SDWA) maximum contaminant level (MCL) for THM (80 ppb). Regression analyses showed that free chlorine and pH were positively associated with the formation of THM levels above SDWA MCLs (OR = 1.04, p = 0.97 and OR = 1.74, p = 0.79, respectively), while temperature was negatively associated (OR = 0.78, p = 0.38). Of the eight utilities serving study households, samples from water served by three different utilities exceeded the EPA MCL for THM. Overall, these findings do not indicate substantial exposures to DBPs for rural households with utility-supplied water in this region of southwest Virginia. However, given the observed variability in THM concentrations between and across utilities, and established adverse health impacts associated with chronic and acute DBP exposure, more research on DBPs in rural Central Appalachia is warranted.

Using hyperspectral imaging to identify and classify large microplastic contamination in industrial composting processes

Compostable plastics are used as alternatives to conventional (non-compostable) plastics due to their ability to decompose through industrial composting comingled with food waste. However conventional (non-compostable) plastics sometimes contaminate this industrial composting process resulting in the formation of microplastics in the end compost. Therefore, it is crucial to effectively identify the types of plastics entering industrial composters to improve composting rates and enhance compost quality. In this study, we applied Hyperspectral Imaging (HSI) with various pre-processing techniques in the short-wave infrared (SWIR) region to develop an efficient model for identifying and classifying plastics and large microplastics during the industrial composting process. The materials used in the experimental analysis included compostable plastics such as PLA and PBAT, and conventional (non-compostable) plastics including PP, PET, and LDPE. Chemometric techniques, namely Partial Least Squares Discriminant Analysis (PLS-DA), was applied to develop a classification model. The Partial Least Squares Discriminant Analysis (PLS-DA) model effectively distinguished between virgin PP, PET, PBAT, PLA, and PHA plastics and soil-contaminated plastics measuring larger than 20 mm × 20 mm, achieving accuracy of 100%. Furthermore, it demonstrated a 90% accuracy rate in discriminating between pristine large microplastics and those contaminated with soil. When we tested our model on plastic samples during industrial composting we found that the accuracy of identification depended on parameters such as darkness, size, color, thickness and contamination level. Nevertheless, we achieved 85% for plastics and large microplastics detected within compost.

ScCDC: a computational method for gene-specific contamination detection and correction in single-cell and single-nucleus RNA-seq data

In droplet-based single-cell and single-nucleus RNA-seq assays, systematic contamination of ambient RNA molecules biases the quantification of gene expression levels. Existing methods correct the contamination for all genes globally. However, there lacks specific evaluation of correction efficacy for varying contamination levels. Here, we show that DecontX and CellBender under-correct highly contaminating genes, while SoupX and scAR over-correct lowly/non-contaminating genes. Here, we develop scCDC as the first method to detect the contamination-causing genes and only correct expression levels of these genes, some of which are cell-type markers. Compared with existing decontamination methods, scCDC excels in decontaminating highly contaminating genes while avoiding over-correction of other genes.

Quantification of contaminants level in Otuoke River: Assessment of physicochemical properties, and Water Quality Index for domestic portability

Quantification of contaminants level in Otuoke River: Assessment of physicochemical properties, and Water Quality Index for domestic portability

Modified outlier diagnostics for the extended exponential regression model with interval and right-censored data

. This research will explore the modified outlier diagnostics for the exponentiated exponential regression (EER) model with interval and right-censored data using adjusted residuals and some influence diagnostic measures. The EER model accommodates a monotonically increasing and decreasing hazard rate and reduces to the exponential as a special case. The proposed diagnostics utilize the adjusted residuals based on the bias-corrected bootstrap harmonic mean with random imputation and the measure of curvature. A simulation study is conducted to assess the performances of different methods at various sample sizes, contamination levels, and censoring proportions. The results indicate that the adjusted Cox-Snell residual, martingale residual, and d ma x work best to detect outliers in a data set. Finally, the proposed methods are applied to a data set from the Diabetic Retinopathy (DRS) study.

Bioaccumulation and translocation of radionuclides heavy metals in Cynodon dactylon: A phytoremediation approach in Al-Dora refinery

Oil extraction methods such as fracking and drilling can disperse radioactive elements into the environment, posing potential hazards. Certain plants like Bermuda grass can combat this through rhizodegradation, a process that breaks down pollutants into harmless substances. The efficiency of this process varies by location and is influenced by factors such as soil compatibility and the presence of beneficial microbes. A study showed that Bermuda grass roots absorbed high levels of radioactive elements, especially Uranium in the soil. The distribution and concentration of these isotopes in Bermuda grass varied across different sites. For instance, Cesium-137 showed higher activity in leaves than in soil. These findings highlight the varied accumulation patterns of elements in Bermuda grass and the influence of natural radionuclide distribution on the environment. Approaches like soil amendments, microbial assistance, and genetically modified Bermuda grass can enhance rhizoremediation efficiency. Strategic planning and species selection are key to overcoming rhizoremediation challenges and enhancing its effectiveness. In addition, soil samples from the AL-Dora Refinery showed a high degree of contamination by heavy metals, with the emission from burning fuel and crude oil being the main sources. This indicates the high contamination of soil by these heavy metals. Overall, the text discusses the potential of Bermuda grass in mitigating the environmental impacts of oil extraction through rhizoremediation, and the challenges and strategies in enhancing its effectiveness. It also highlights the issue of soil contamination by heavy metals due to oil refinery emissions. This research examines the levels of heavy metal contamination in the soil of the Al-Dora refinery area, situated in central Iraq. The contamination factor (Cf) was employed to ascertain the contamination status, revealing a significant to extremely high degree of contamination by various heavy metals. The study further investigates the bioaccumulation and translocation of these heavy metals from the soil to the roots and leaves of Cynodon dactylon plants. Two methodologies were utilized to assess the role of Cynodon dactylon in soil phytoremediation: a comparison of heavy metal concentrations in plant parts with global standards, and the application of the Bioconcentration factor (BCF). The findings suggest a high potential for Cynodon dactylon to be employed in the clean-up and phytoremediation process of the contaminated soil. This presents a promising strategy towards environmental remediation in areas contaminated with heavy metals.

Two-year Monitoring of Microbiological Water Quality in Small Water Supply Systems: Implications for Microbial Risk Management.

Small water supply systems (SWSSs) are often more vulnerable to waterborne disease outbreaks. In Japan, many SWSSs operate without regulation under the Waterworks Law, yet there is limited investigation into microbial contamination and the associated health risks. In this study, the microbiological water quality of four SWSSs that utilize mountain streams as water sources and do not install water treatment facilities were monitored for over 2 years. In investigated SWSSs, the mean heterotrophic plate counts were below 350 CFU/mL, and the total bacterial loads (16S rDNA concentration) ranged from 4.71 to 5.35 log10 copies/mL. The results also showed the consistent presence of fecal indicator bacteria (FIB), i.e., Escherichia coli and Clostridium perfringens, suggesting the potential of fecal pollution. E. coli was then utilized as an indicator to assess the health risk posed by E. coli O157:H7 and Campylobacter jejuni. The results indicated that the estimated mean annual risk of infection and disability-adjusted life years (DALYs) exceeded acceptable levels in all SWSSs for the two reference pathogens. To ensure microbial water safety, implementing appropriate water treatment facilities with an estimated mean required reduction of 5-6 log10 was necessary. This study highlighted the potential microbial contamination and health risk level in SWSSs that utilize mountain streams as water sources, even though the water sources were almost not affected by human activities. Furthermore, this study would also be helpful in supporting risk-based water management to ensure a safe water supply in SWSSs.