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Groundwater quality management is pivotal for ensuring public health and ecological resilience. However, the conventional water quality indices often face challenges related to parameter selection, geographic coverage, and scalability. The integration of machine learning and spatial analysis represents a promising methodological shift, allowing for high accuracy and adaptive management strategies. The Safe Groundwater Project in Unsupplied Areas (2017–2020) employed a comprehensive Groundwater Quality Index (GQI) to evaluate potable groundwater quality across South Korea, utilizing a large dataset comprising 28 water quality parameters and 3552 wells. This study revealed that over 50 % of the evaluated wells (Total 8326 wells) were inappropriate as sources of drinking water, indicating a pressing need for policy revision. The averaged neural network model achieved a high predictive accuracy of approximately 95 % for GQI grades, outperforming other classification models. The introduction of 2D spatial analysis in conjunction with machine learning algorithms notably increased the predictive accuracy for unevenly distributed groundwater samples. Moreover, this combined approach enabled the intuitive visualization of groundwater vulnerability across various regions, which can inform targeted interventions for effective resource allocation and management. This research represents a methodologically robust, interdisciplinary approach that holds significant implications for a framework for future groundwater quality management and vulnerability assessment. • The Groundwater Quality Index (GQI) was computed from 28 water quality parameters across 3552 potable groundwater wells. • The averaged neural network exhibited superior classification performance with accuracy of 95 % for predicting GQI grades. • The most influential parameters on the GQI were general bacteria, turbidity, nitrate, and total hardness. • Spatial analysis with machine learning enabled the mapping of areas with concerning groundwater quality for drinking. [ABSTRACT FROM AUTHOR]

Railways are typically considered polluted from years of train operation. However, the pollution level of railway in a rural area, which is less exposed to hazardous material from trains and freights, is rarely assessed. This study evaluated common railway pollutants such as heavy metals, total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) and their chemical properties in the waste soil generated from the renovation of an old railway in rural area of Wonju, South Korea. Furthermore, lab-scale cultivation tests of peas ( Pisum sativum ) were performed to assess reusability of the waste soil as a soil amendment. Carbonaceous materials were found in the upper layer of the railway (0 to −40 cm) and the concentration of common railway pollutants was comparable to those of the agricultural land nearby. Specifically, total aromatic and aliphatic TPHs were below detection limit; and total PAHs < 1.0 mg kg −1 was 1000-times less than railway functional parts. Applying the carbonaceous waste soil improved the water holding capacity of soil by approximately 10% and sprouts formed on the soil with 10% waste soil composition had greater fresh weight, stem length, and root length than the control. Although this investigation was confined to a small length of the railway route, the results confirm environmental safety and the potential value of the waste generated from rural railways for the first time. [ABSTRACT FROM AUTHOR]

Crude oil spills, Hebei Spirit in South Korea, is considered as one of the worst environmental disasters of the region. Our understanding on activation of oil-degrading bacteria and resilience of microbial community in oil contaminated sites are limited due to scarcity of such event. In the present study, tidal flat sediment contaminated by the oil spill were investigated for duration of 13 months to identify temporal change in microbial community and functional genes responsible for PAH-degradation. The results showed predominance of previously known oil-degrading genera, such as Cycloclasticus , Alcanivorax , and Thalassolituus , displaying significant increase within first four months of the accident. The disturbance caused by the oil spill altered the microbial community and its functional structures, but they were almost restored to the original state after 13 months. Present study demonstrated high detoxification capacity of indigenous bacterial populations in the tidal flat sediments and its resilience of microbial community. [ABSTRACT FROM AUTHOR]

Vertical alignment of one-dimensional piezoelectric/ferroelectric materials is highly required to take full advantage of their unique electrical and optical properties for various applications. Here, we report the piezoelectric nanogenerator (NG) and second harmonic generator (SHG) applications of a vertically aligned single-crystalline KNbO 3 (KNO) nanorod (NR) array on a conducting Nb:SrTiO 3 substrate. A simple, cost-effective hydrothermal method at low temperature enables growth of ultra-long orthorhombic KNO NR array with a high piezoelectric coefficient. A corona-poled KNO NR array-based NG generates stable piezoelectric power under the compressive force. The open-circuit voltage and closed-circuit current almost linearly increase. In addition, the KNO NR array emits bright and sharp red, green, and blue visible light under the shining of infrared light. The SHG intensity is strongest along the KNO NR direction and weakest perpendicular to the NR direction. These results imply that the vertically aligned KNO NR array could be useful for an environment-friendly pressure sensor and a full-color display application. [ABSTRACT FROM AUTHOR]

The effects of air pollution within subway systems on public health has far been overlooked. A few previous studies have warned that particulate matter (PM)-bound metals in subway air pose a serious threat to public health, but these have been limited by insufficient risk measurement and limited regional data. Present study aimed to determine the levels of human health risk associated with PM10 and PM2.5-bound trace metals in twelve city subways across North America, Asia, and Europe using the human exposure method. Human health risks were estimated via ingestion, inhalation, and dermal exposure methods. The Monte Carlo statistical method using 50,000 iterations was adopted to calculate the probable risk levels for children and adults. Significant levels of non-cancer and cancer risks (CR) were found in subway systems at all regions, regardless of age, although CR were relatively higher in adults. Inhalation and dermal absorption, in which the acceptable range of carcinogenic risk for subway systems was exceeded. Exposure through ingestion made the greatest contributions to overall CR. Among the all subways Tehran and Seoul were estimated as higher CR zone (Total CR > 10−3). Therefore, the Asian subway systems is not only polluted with respect to particulate matter but also recognized as a highly CR zone among the other continents. Cr and Pb have been identified as PM-bound carcinogenic elements that significantly influence cancer risk by inhalation/dermal absorption and ingestion, respectively. Although, the subway is a convenient transportation system for millions of city inhabitants globally, but these findings support the view that indoor air pollutant levels in subway systems can have a serious impact on the cancerous and non-cancerous risks to human health. Strengthening the regulation of indoor air quality or the application of active air purification techniques in subway systems are highly suggested to manage the worst situation. • Human health risks were assessed due to exposure of indoor PMs in the subway system, globally. • Cancer risk levels are significant and exceed the acceptable ranges for subways. • The Asian subways recognized as highly cancer risk zone for PMs. • Cr and Pb have been identified as most significant carcinogenic elements. [ABSTRACT FROM AUTHOR]

To assess the aquaculture-induced sediment conditions associated with sulfur cycles, shifts in bacterial communities across farming stages were investigated. The sulfate reduction rate (SRR), and concentrations of acid volatile sulfide (AVS) and H 2 S were significantly higher at the mid- and post-farming stages than at the early stage, indicating that the aquaculture effects persist even after harvest. Incomplete organic carbon–oxidizing sulfate-reducing bacteria (IO-SRB) affiliated with Desulfobulbaceae , and gammaproteobacterial sulfur oxidizing bacteria (SOB) (Thiohalobacter , Thioprofundum , and Thiohalomonas) were dominant during the early stage, whereas fermenting bacteria (Bacteroidetes and Firmicutes) and complete oxidizing SRB (CO-SRB) belonging to Desulfobacteraceae , and epsilonproteobacterial SOB (Sulfurovum) dominated during the mid- and post-stages. The shift in SRB and SOB communities well reflected the anoxic and sulfidic conditions of farm sediment. Especially, the Sulfurovum -like SOB correlated highly and positively with H 2 S, AVS, and SRR, suggesting that they could be relevant microbiological proxies to assess sulfidic conditions in farm sediment. • Intense aquaculture activities resulted in highly sulfidic and anoxic sediment conditions. • Shifts in benthic bacterial communities occur with the farming stages. • Fermenters and Desulfobacteraceae predominated under extremely anoxic conditions. • Sulfurovum significantly increased in highly sulfidic condition. • Sulfurovum could be used as a proxy to assess sulfidic conditions of the farm sediment. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The aim of this study was to investigate the bacterial community profile of intracanal microbiota in primary and persistent endodontic infections associated with asymptomatic chronic apical periodontitis by using GS-FLX Titanium pyrosequencing. The null hypothesis was that there is no difference in diversity of overall bacterial community profiles between primary and persistent infections. Methods: Pyrosequencing analysis from 10 untreated and 8 root-filled samples was conducted. Results: Analysis from 18 samples yielded total of 124,767 16S rRNA gene sequences (with a mean of 6932 reads per sample) that were taxonomically assigned into 803 operational taxonomic units (3% distinction), 148 genera, and 10 phyla including unclassified. Bacteroidetes was the most abundant phylum in both primary and persistent infections. There were no significant differences in bacterial diversity between the 2 infection groups (P > .05). The bacterial community profile that was based on dendrogram showed that bacterial population in both infections was not significantly different in their structure and composition (P > .05). Conclusions: The present pyrosequencing study demonstrates that persistent infections have as diverse bacterial community as primary infections. [Copyright &y& Elsevier]