Ensemble machine learning using hydrometeorological information to improve modeling of quality parameter of raw water supplying treatment plants.

Source and raw water quality may deteriorate due to rainfall and river flow events that occur in watersheds. The effects on raw water quality are normally detected in drinking water treatment plants (DWTPs) with a time-lag after these events in the watersheds. Early warning systems (EWSs) in DWTPs require models with high accuracy in order to anticipate changes in raw water quality parameters. Ensemble machine learning (EML) techniques have recently been used for water quality modeling to improve accuracy and decrease variance in the outcomes. We used three decision-tree-based EML models (random forest [RF], gradient boosting [GB], and eXtreme Gradient Boosting [XGB]) to predict two critical parameters for DWTPs, raw water Turbidity and UV absorbance (UV254), using rainfall and river flow time series as predictors. When modeling raw water turbidity, the three EML models (rRF-Tu2=0.87, rGB-Tu2=0.80 and rXGB-Tu2=0.81) showed very good performance metrics. For raw water UV254, the three models (rRF-UV2=0.89, rGB-UV2=0.85 and rXGB-UV2=0.88) again showed very good performance metrics. Results from this study suggest that EML approaches could be used in EWSs to anticipate changes in the quality parameters of raw water and enhance decision-making in DWTPs.

[Identification method of 2-methylisoborneol and geosmin in water by purge and trap-gas chromatography-mass spectrometry].

OBJECTIVE: To establishe an analysis and identification method for 2-methylisoborneol(2-MIB) and geosmin(GSM) in water using purge and trap-gas chromatography-mass spectrometry. METHODS: The samples were enriched and analyzed using a purge and trap system, followed by the separation on a DB-624(30 m×0.25 mm, 1.4 µm) chromatographic column. Quantification was performed using gas chromatography-mass spectrometry with the selected ion monitoring and internal standard calibration. RESULTS: The calibration curves for 2-MIB and GSM showed an excellent linearity in the range of 1 to 100 ng/L with R~2 values greater than 0.999. The detection limit and quantification limit for both 2-MIB and GSM were 0.33 ng/L and 1.0 ng/L, respectively. Spike recovery experiments were further carried on the source water and drinking water at three concentration levels. It showed that the average recoveries were from 82.0% to 111.0% for 2-MIB while 84.0% to 110% for GSM. Additionally, the test precision of 2-MIB and GSM ranged from 1.9% to 7.3% and 1.9% to 5.0%(n=6), respectively. The analysis of multiple samples including the local source water, treated water and distribution network water confirmed the existence of 2-MIB and GSM. CONCLUSION: Compared to the national standard(GB/T 5750.8-2023), the proposed method enables fully automated sample introduction and analysis without the extra pre-treatment. It provides the advantages of simplicity, good repeatability and high accuracy.

Tracing the sources and evaporation fate of surface water and groundwater using stable isotopes of hydrogen and oxygen.

Recognizing the origins and movement processes of surface water and groundwater is crucial for understanding hydrochemical genesis, conserving water supplies, and managing water resources. Estimating the source water typically involves identifying the intersection of evaporation line (EL) and meteoric water line. However, there is currently confusion in determining the regional EL and selecting strategies for estimating the source water. This study aimed to explore the source of surface water and groundwater, as well as evaporation effect utilizing stable isotope tracing (δ2H and δ18O). The line-conditioned excess was adopted to differentiate evaporated water and non-evaporated water, then Craig-Gordon model and an analytical framework with Bayesian theory were used to investigate the source of surface water and groundwater and the evaporation influence. The findings revealed that surface water and groundwater in the northern region of the Weihe River suffered more sever evaporation impacts that the south, and the evaporated surface water (7.54 % to 27.34 %) with a wider range of mean evaporation ratio than evaporated groundwater (5.38 % to 8.52 %). Monsoon precipitation is the main contributor to both surface water (contribution ratio: 0.46) and groundwater (0.49) sources. This research provides specific information on evaporation and detailed insights into the source water of surface water and groundwater, aiding in understanding the evaporation effect during the hydrological cycle and facilitating the management of regional water resources.

Disinfection byproducts and their cytotoxicity contribution from dissolved black carbon in source water during chlor(am)ination.

Dissolved black carbon (DBC), the soluble component of black carbon, which mainly comes from the incomplete combustion of fossil fuels or biomass, is widely spread in source water and significantly contributes to the formation of dissolved organic matter (DOM). However, the origin of DBC in different types of source water in China has not been well studied, as well as its subsequent transformation and toxicity contribution during disinfection of source water DOM by chlor(am)ine. In this study, DBC from 17 different source water in East China at different seasons was collected. The δ13C compositions indicated that straw burning was the main origin of DBC in source water. After simulated chlor(am)ination of DBC, 5 categories of aliphatic disinfection byproducts (DBPs) including trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, halonitromethanes and 6 categories of aromatic DBPs including halophenols, halonitrophenols, halohydroxybenzaldehyde, halohydroxybenzoic acid, halobenzoquinones and haloaniline were detected. Compared with chlorination of DBC, higher levels of nitrogenous DBPs and aromatic DBPs were generated during chloramination. Detected DBPs accounted for 42 % of total organic halogen. What's more, Chinese hamster ovary cells cytotoxicity tests showed that the cytotoxicity of DBPs formed by chlor(am)ination of DBC was 4 times higher than that by chlor(am)ination of DOM. Haloacetonitriles contributed to the highest cytotoxicity in the chloramination of DBC, and haloacetic acids contributed to the highest cytotoxicity in chlorination. 67 % of the total cytotoxicity attributed to the undetected DBPs. As a result, DBPs generated from DBC contributed to 11.7 % of the total cytotoxicity in the chlor(am)ination of the source water DOM although DBC only took up 2 % of DOC in the source water. Results obtained from this study systematically revealed the DBPs formation from DBC and their potential cytotoxicity contribution in the chlor(am)ination of source water DOM, which should not be ignored in drinking water treatment.

Integration of nontarget analysis with machine learning modeling for prioritization of odorous volatile organic compounds in surface water.

Assessing the odor risk caused by volatile organic compounds (VOCs) in water has been a big challenge for water quality evaluation due to the abundance of odorants in water and the inherent difficulty in obtaining the corresponding odor sensory attributes. Here, a novel odor risk assessment approach has been established, incorporating nontarget screening for odorous VOC identification and machine learning (ML) modeling for odor threshold prediction. Twenty-nine odorous VOCs were identified using two-dimensional gas chromatography-time of flight mass spectrometry from four surface water sampling sites. These identified odorants primarily fell into the categories of ketones and ethers, and originated mainly from biological production. To obtain the odor threshold of these odorants, we trained an ML model for odor threshold prediction, which displayed good performance with accuracy of 79%. Further, an odor threshold-based prioritization approach was developed to rank the identified odorants. 2-Methylisoborneol and nonanal were identified as the main odorants contributing to water odor issues at the four sampling sites. This study provides an accessible method for accurate and quick determination of key odorants in source water, aiding in odor control and improved water quality management. ENVIRONMENTAL IMPLICATION: Water odor episodes have been persistent and significant issues worldwide, posing severe challenges to water treatment plants. Unpleasant odors in aquatic environments are predominantly caused by the occurrence of a wide range of volatile organic chemicals (VOCs). Given the vast number of newly-detected VOCs, experimental identification of the key odorants becomes difficult, making water odor issues complex to control. Herein, we propose a novel approach integrating nontarget analysis with machine learning models to accurate and quick determine the key odorants in waterbodies. We use the approach to analyze four samples with odor issues in Changsha, and prioritized the potential odorants.

Magnetic nanoparticle loading and application of weak magnetic field to reconstruct the cake layer of coagulation-ultrafiltration process to achieve efficient antifouling: Performance and mechanism analysis.

Abandoning the costly development of new membrane materials and instead directly remodeling the naturally occurring cake layer constitutes a dynamic, low-cost, long-lasting, and proactive strategy to "fight fouling with fouling". Several optimization strategies, including coagulation/modified magnetic seed loading and applying a weak magnetic force (0.01T) at the ultrafiltration end, improved the anti-fouling, retention, and sieving performances of conventional ultrafiltration process during the treatment of source water having complex natural organic matter (NOMs) and small molecule micropollutants. Two modified magnetic seeds we prepared were composite nano-seed particles (Fe3O4@SiO2-NH2 (FS) and Fe3O4@SiO2@PAMAM-NH2 (FSP)). Aim of the study was to regulate the formation of cake layer via comprehensive testing of the antifouling properties of optimized processes and related mechanistic studies. It was found to be essential to enhance the interception of xanthate and tryptophan proteins in the cake layer for improving the anti-fouling performance based on the correlation and redundancy analyses, while the use of modified magnetic seeds and magnetic field showed a significant positive impact on water production. Blockage modeling demonstrated the ability to form a mature cake layer during the initial filtration stage swiftly. This mitigated the risk of irreversible fouling caused by pore blockage during the early stage of coagulation-ultrafiltration. Morphologically, the reconstructed cake layer exhibited elevated surface porosity, an internal cavity channel structure, and enhanced roughness that can promote increased water flux and retention of water impurities. These optimized the maturity of the cake layer in both time and space. Density Functional Theory (DFT), Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and Modified Extended Derjaguin-Landau-Verwey-Overbeek (MDLVO) calculations indicated aggregation behavior of matter on the cake layer to be enhanced effectively due to magnetic seed loading. This is mainly due to the strengthening of polar interactions, including hydrogen bonding, π-π* conjugation, etc., which can happen between the cake layer loaded with FSP and the organic matter. Under the influence of a magnetic field, magnetic force energy (VMF) significantly impacts the system by eliminating energy barriers. This research will provide innovative strategies for effectively purifying intricate source water through ultrafiltration while controlling membrane fouling.

The insightful water quality analysis and predictive model establishment via machine learning in dual-source drinking water distribution system.

Dual-source drinking water distribution systems (DWDS) over single-source water supply systems are becoming more practical in providing water for megacities. However, the more complex water supply problems are also generated, especially at the hydraulic junction. Herein, we have sampled for a one-year and analyzed the water quality at the hydraulic junction of a dual-source DWDS. The results show that visible changes in drinking water quality, including turbidity, pH, UV254, DOC, residual chlorine, and trihalomethanes (TMHs), are observed at the sample point between 10 and 12 km to one drinking water plant. The average concentration of residual chlorine decreases from 0.74 ± 0.05 mg/L to 0.31 ± 0.11 mg/L during the water supplied from 0 to 10 km and then increases to 0.75 ± 0.05 mg/L at the end of 22 km. Whereas the THMs shows an opposite trend, the concentration reaches to a peak level at hydraulic junction area (10-12 km). According to parallel factor (PARAFAC) and high-performance size-exclusion chromatography (HPSEC) analysis, organic matters vary significantly during water distribution, and tryptophan-like substances and amino acids are closely related to the level of THMs. The hydraulic junction area is confirmed to be located at 10-12 km based on the water quality variation. Furthermore, data-driven models are established by machine learning (ML) with test R2 higher than 0.8 for THMs prediction. And the SHAP analysis explains the model results and identifies the positive (water temperature and water supply distance) and negative (residual chlorine and pH) key factors influencing the THMs formation. This study conducts a deep understanding of water quality at the hydraulic junction areas and establishes predictive models for THMs formation in dual-sources DWDS.

Identify organic contaminants of high-concern based on non-targeted toxicity testing and non-targeted LC-HRMS analysis in tap water and source water along the Yangtze River.

Many organic pollutants were detected in tap water (TW) and source water (SW) along the Yangtze River. However, the potential toxic effects and the high-concern organics (HCOs) which drive the effect are still unknown. Here, a non-targeted toxicity testing method based on the concentration-dependent transcriptome and non-targeted LC-HRMS analysis combining tiered filtering were used to reveal the overall biological effects and chemical information. Subsequently, we developed a qualitative pathway-structure relationship (QPSR) model to effectively match the biological and chemical information and successfully identified HCOs in TW and SW along the Yangtze River by potential substructures of HCOs. Non-targeted toxicity testing found that the biological potency of both TW and SW was stronger in the downstream of the Yangtze River, and disruption of the endocrine system and cancer were the main drivers of the effect. In addition, non-targeted LC-HRMS analysis combined with retention time prediction results identified 3220 and 631 high-confidence compound structures in positive and negative ion modes, respectively. Then, QPSR model was further implied and identified a total of 103 HCOs, containing 35 industrial chemicals, 30 PPCPs, 26 pesticides, and 12 hormones in TW and SW, respectively. Among them, the neuroactive and hormonal compounds oxoamide, 8-iso-16-cyclohexyl-tetranor prostaglandin E2, E Keppra, and Tocris-0788 showed the highest frequency of detection, which were identified in more than 1/3 of the samples. The strategy of combining non-targeted toxicity testing and non-targeted LC-HRMS analysis will support comprehensive biological effect assessment, identification of HCOs, and risk control of mixtures.

Prevalence and Source Tracing of PFAS in Shallow Groundwater Used for Drinking Water in Wisconsin, USA.

Samples from 450 homes with shallow private wells throughout the state of Wisconsin (USA) were collected and analyzed for 44 individual per- and polyfluoroalkyl substances (PFAS), general water quality parameters, and indicators of human waste as well as agricultural influence. At least one PFAS was detected in 71% of the study samples, and 22 of the 44 PFAS analytes were detected in one or more samples. Levels of PFOA and/or PFOS exceeded the proposed Maximum Contaminant Levels of 4 ng/L, put forward by the U.S. Environmental Protection Agency (EPA) in March 2023, in 17 of the 450 samples, with two additional samples containing PFHxS ≳ 9 ng/L (the EPA-proposed hazard index reference value). Those samples above the referenced PFAS levels tend to be associated with developed land and human waste indicators (artificial sweeteners and pharmaceuticals), which can be released to groundwater via septic systems. For a few samples with levels of PFOA, PFOS, and/or PFHxS > 40 ng/L, application of wastes to agricultural land is a possible source. Overall, the study suggests that human waste sources, septic systems in particular, are important sources of perfluoroalkyl acids, especially ones with ≤8 perfluorinated carbons, in shallow groundwater.

Bifunctional Solar Evaporator with Co/N-Doped Graphene Oxide for Synergistic Steam Generation and Organic Pollutant Degradation.

Solar-driven interfacial steam generation (SISG) is a promising technology for alleviating freshwater shortage. However, when the SISG technology is applied to wastewater treatment, the contaminant would be enriched in residual bulk water. Herein, a dual-functional evaporator was constructed via tactfully decorating Co/N-doped graphene oxide (GO) on melamine foam (MF), which can simultaneously achieve efficient vapor production and source water purification. N-doped carbon nanotubes (NCNTs) endowed evaporators with powerful light absorption and water transport performance, guaranteeing an evaporation rate of 2.02 kg m-2 h-1 under 1 sun irradiation. Meanwhile, the catalytic activity of the carbon layer was adjusted by the N dopant and embedded Co particles, providing abundant active sites to activate peroxymonosulfate (PMS). When treating the solution containing sulfamethoxazole (SMX), no SMX residues were detected in the remaining bulk water (up to 100% SMX degradation efficiency within 60 min), demonstrating that reactive oxygen species (ROS) were generated to attack SMX in the source water. The bifunctional evaporator successfully combined SISG and advanced oxidation processes (AOPs), providing an ingenious strategy for solving the problem of wastewater enrichment during SISG.

Evidence-based identification of breast cancer and associated ovarian and uterus cancer risk components in source waters from high incidence area in the Pearl River Basin, China.

Breast cancer, ovarian cancer, and uterus cancer are among the most common female cancers. They are suspected to associate with exposures to specific environmental pollutants, which remain unidentified in source waters. In this work, we focused on the Pearl River Basin region in China, which experienced a high incidence of breast, ovarian, and uterus cancers. Combining cancer patient data, mammalian cell cytotoxicity analyses, and exhaustive historical and current chemical assessments, we for the first time identified source water components that promoted proliferation of mammalian cells, and confirmed their association with these female cancers via the estrogen receptor mediated pathway. Therefore, the components that have previously been found to enhance the proliferation of estrogen receptor-containing cells through endocrine disruption could be the crucial factor. Based on this, components that matched with this toxicological characteristic (i.e., estrogen-like effect) were further identified in source waters, including (1) organic components: phthalates, bisphenol A, nonylphenols, and per-/polyfluoroalkyls; (2) inorganic components: Sb, Co, As, and nitrate. Moreover, these identified water components were present at levels comparable to other regions with high female cancer prevalence, suggesting that the potential risk of these components may not be exclusive to the study region. Together, multiple levels of evidence suggested that long-term co-exposures to source water estrogenic components may be important to the development of breast, ovarian, and uterus cancers.

Seasonality of coastal upwelling trends in the Mauritania-Senegalese region under RCP8.5 climate change scenario.

The Mauritania-Senegalese upwelling region (MSUR), the southernmost region of the Canary current upwelling system, is well-known for its coastal productivity and the key role it plays in enriching the oligotrophic open ocean through the offshore transport of the upwelled coastal waters. The great ecological and socio-economic importance makes it necessary to evaluate the impact of climate change on this region. Hence, our main objective is to examine the climate change signal over the MSUR with a high resolution regional climate system model (RCSM) forced by the Earth system model MPI-ESM-LR under RCP8.5 scenario. This RCSM has a regional atmosphere model (REMO) coupled to a global ocean model (MPIOM) with high-resolution in the MSUR, which allows us to evaluate the wind pattern, the ocean stratification, as well as the upwelling source water depth, while maintaining an ocean global domain. Under RCP8.5 scenario, our results show that the upwelling favourable winds of the northern MSUR are year-round intensified, while the southern MSUR presents a strengthening in winter and a weakening in March-April. Along with changes in the wind pattern, we found increased ocean stratification in the spring months. In those months southern MSUR presents a shallowing of the upwelling source water depth associated to changes in both mechanisms. However, in winter the whole MSUR shows a deepening of the upwelling source water depth due to the intensification of the upwelling favourable winds, with the increased ocean stratification playing a secondary role. Our results demonstrate the need to evaluate the future evolution of coastal upwelling systems taking into account their latitudinal and seasonal variability and the joint contribution of both mechanisms.

Twelve natural estrogens and ten bisphenol analogues in eight drinking water treatment plants: Analytical method, their occurrence and risk evaluation.

Bisphenol analogues (BPs) and natural estrogens (NEs) as two important groups of endocrine-disrupting compounds (EDCs) in drinking water treatment plants (DWTPs) have been hardly investigated except bisphenol A (BPA) and three major NEs including estrone (E1), 17ß-estradiol (E2) and estriol (E3). In this study, a GC-MS analytical method was firstly established and validated for trace simultaneous determination of ten BPs and twelve NEs in drinking water, which included BPA, bisphenol B (BPB), bisphenol C (BPC), bisphenol E (BPE), bsiphenol F (BPF), bsiphenol P (BPP), bisphenol S (BPS), bisphenol Z (BPZ), bisphenol AF (BPAF), bisphenol AP (BPAP), E1, E2, E3, 17α-estradiol (17α-E2), 2-hydroestrone (2OHE1), 16hydroxyestrone (16α-OHE1), 4-hydroestrone (4OHE1), 2-hydroxyesstradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 17-epiestriol (17epiE3), 16-epiestriol (16epiE3) and 16keto-estraiol (16ketoE2). This investigation showed that eighteen out of twenty-two targeted compounds were detected in drinking source waters of eight DWTPs with concentrations ranging from not detected to 142.8 ng/L. Although the conventional treatment process of DWTP could efficiently remove both BPs and NEs with respective removal efficiencies of 74.1%-90.9% and 74.5%-100%, BPA, BPS, BPE, BPZ, E1, 2OHE1, and 2OHE2 were found in the finished drinking waters. Chlorination could remove part of BPs and NEs, but the efficiency varied greatly with DWTP and the reason was unknown. In the finished drinking waters of eight DWTPs, the highest chemically calculated estrogen equivalence (EEQ) derived from BPs and NEs was up to 6.11 ngE2/L, which was over 22 times that could do harm to zebrafish, indicating a potential risk to human health. Given the fact that many chlorination products of BPs and NEs likely have higher estrogenic activities, the estrogenic effect of BPs and NEs in finished drinking water should be accurately examined urgently with the inclusion of BPs, NEs as well as their main chlorinated by-products. This study shed new light on the occurrence, removal, and potential estrogenic effects of BPs and NEs in DWTPs.

Evolutions of dissolved organic matter and disinfection by-products formation in source water during UV-LED (275 nm)/chlorine process.

Ultraviolet light-emitting diode (UV-LED) is a promising option for the traditional low-pressure UV lamp, but the evolutions of DOM composition, the formation of disinfection by-products (DBPs) and their toxicity need further study in raw water during UV-LED/chlorine process. In UV-LED (275 nm)/chlorine process, two-dimensional correlation spectroscopy (2DCOS) analysis on synchronous fluorescence and UV-vis spectra indicated the protein-like fractions responded faster than the humic-like components, the reactive sequence of peaks for DOM followed the order: 340 nm→240 nm→410 nm→205 nm→290 nm. Compared to chlorination for 30 mins, the UV-LED/chlorine process enhanced the degradation efficiency of three fluorescent components (humic-like, tryptophan-like, tyrosine-like) by 5.1%-46.1%, and the formation of carbonaceous DBPs (C-DBPs) significantly reduced by 43.8% while the formation of nitrogenous DBPs (N-DBPs) increased by 27.3%. The concentrations of C-DBPs increased by 17.8% whereas that of N-DBPs reduced by 30.4% in 24 h post-chlorination. The concentrations of brominated DBPs increased by 17.2% during UV-LED/chlorine process, and further increased by 18.5% in 24 h post-chlorination. According to the results of principal component analysis, the non-fluorescent components of DOM might be important precursors in the formation of haloketones, haloacetonitriles and halonitromethanes during UV-LED/chlorine process. Unlike chlorine treatment, the reaction of DOM in UV-LED/chlorine treatment generated fewer unknown DBPs. Compared with chlorination, the cytotoxicity of C-DBPs reduced but the cytotoxicity of both N-DBPs and Br-DBPs increased during UV-LED/chlorine process. Dichloroacetonitrile had the highest cytotoxicity, followed by monobromoacetic acid, bromochloroacetonitrile and trichloroacetic acid during 30 mins of UV-LED/chlorine process. Therefore, besides N-DBPs, the more toxic Br-DBPs formation in bromide-containing water is also not negligible in the practical applications of UV-LED (275 nm)/chlorine process.

Discovery of Three Organothiophosphate Esters in River Water Using High-Resolution Mass Spectrometry.

Records of the environmental occurrence of organothiophosphate esters (OTPEs), which are used as flame retardants and food and industrial additives, are unavailable. In this study, we discovered three OTPEs, namely O,O,O-tris(2,4-di-tert-butylphenyl) phosphorothioate (AO168═S), O-butyl O-(butyl-methylphenyl) O-(di-butylphenyl) phosphorothioate (BBMDBPt)/O,O-bis(dibutylphenyl) O-methyl phosphorothioate (BDBPMPt), and O-butyl O-ethyl O-hydrogen phosphorothioate (BEHPt), in the surface water of the Yangtze River Basin by applying a characteristic phosphorothioate fragment-directed high-resolution mass spectrometry method. Among the 17 water samples tested, the detection frequencies of AO168═S and BEHPt were 100% and that of BBMDBPt/BDBPMPt was 29%. The mean concentration of AO168═S was 56.9 ng/L (30.5-148 ng/L), and semi-quantitative analysis revealed that the mean concentrations of BEHPt and BBMDBPt/BDBPMPt were 17.2 ng/L (5.5-65.4 ng/L) and 0.8 ng/L (

Electronic nose application for detecting different odorants in source water: Possibility and scenario.

The problem of taste and odor (T&O) in drinking water is a widespread societal concern and highlights substantial challenges related to the detection and evaluation of odor in water. In this study, the portable electronic nose PEN3, which is equipped with ten different heated metal sensors, was applied to analyze its applicability, feasibility and application scenarios for the detection of typical odorants, such as 2-methylisobornel (2-MIB), geosmin (GSM), ß-cyclocitral, ß-ionone, and other T&O compounds in source water, while avoiding uncertainties and instability related to manual inspection. All the T&O compounds could be effectively differentiated by principal component analysis (PCA). Linear discriminant analysis (LDA) showed that the odors varied greatly between different samples and could be effectively distinguished. As the odorant concentration increased, the sensor response intensity of the primary identification sensors R6 and R8 increased with a significant positive correlation. For Microcystis aeruginosa, an algae that produces odorants, PCA could distinguish the odors of algae at a series of densities at different concentrations. The responses of R10 showed a significant increase with increasing algae density, implying the production of more aliphatic hydrocarbons and other odor compounds. The results indicated that the electronic nose could provide a promising alternative to traditional unstable and complex detection methods for the detection of odorous substances in surface water and early warning of odor events. This study aimed to provide technical support for rapid monitoring and early warning of odorants in source water management.

Land cover and community water system characteristics as predictors of Safe Drinking Water Act violations in Central Appalachia, USA.

Upstream anthropogenic land cover can degrade source drinking water quality and thereby inhibit the ability of a community water system to provide safe drinking water. This study aimed to predict differences in Safe Drinking Water Act (SDWA) compliance between water systems based on upstream land cover in Central Appalachia and to examine whether national trends correlating violations with system size and source type were relevant for this region. Multiple generalized linear mixed models assessed relationships between SDWA violations and the distance weighted land cover proportions associated with the water system's contributing source watershed, as well as county economic status, system size, and water source. Results indicate that rates of monitoring and reporting violations were significantly higher for smaller water systems in more economically distressed counties. Interestingly, increases in surface mining landuse and high density development decreased monitoring and reporting violations, which may reflect impacts of associated economic development. Increases in low intensity development increased the likelihood of health-based violations. To protect public health, community managers should consider source water protection and/or upgrading drinking water system treatment capacity prior to developing previously undeveloped areas and further motivate compliance with monitoring and reporting requirements.

Permafrost degradation alters the environmental signals recorded in tree-ring lignin methoxy group δ2H in northeastern China.

Climate warming has profoundly altered the status of permafrost and has caused extensive permafrost degradation in the Northern Hemisphere. However, long-term observations investigating the hydrological dynamics of permafrost and its ecological effects on plant growth are lacking. Previous studies have reported tree-ring stable hydrogen isotope ratios of lignin methoxy groups (δ2HLM) as an archive of hydrological signals. This study sampled tree-ring cores from a Larix gmelinii forest in Nanwenghe Forest Park, Northeastern China, and separately measured the tree-ring δ2HLM for earlywood and latewood from 1900 to 2020. Earlywood and latewood δ2HLM values, as well as the difference between them, showed no significant long-term trend from 1900 to 1987; however, they both exhibited significant increasing trends since 1988 at rates of 2.6 ‰ and 4.9 ‰ per decade, respectively. This variance changes the magnitude of the difference between the two chronologies and can be explained by the shift in source water δ2H values during tree growth. Based on a structural equation model analysis, when the influence of permafrost melting weakened due to permafrost degradation, the growing season temperature was better recorded in latewood δ2HLM through the effects of precipitation δ2H from July to September. Based on the environmental response of tree-ring δ2HLM in the permafrost region, permafrost degradation influences the source water δ2H values of trees, thereby affecting the expression of temperature signals in tree-ring δ2HLM. The novel results in this study provide a new perspective on permafrost degradation based on the dynamic responses of tree-ring δ2HLM to source water δ2H during permafrost degradation.

Effect-Based Trigger Values Are Essential for the Uptake of Effect-Based Methods in Water Safety Planning.

Effect-based methods (EBMs) using in vitro bioassays and well plate-based in vivo assays are recommended for water quality monitoring because they can capture the mixture effects of the many chemicals present in water. Many in vitro bioassays are highly sensitive, so an effect in a bioassay does not necessarily indicate poor chemical water quality. Consequently, effect-based trigger values (EBTs) have been introduced to differentiate between acceptable and unacceptable chemical water quality and are required for the wider acceptance of EBMs by the water sector and regulatory bodies. These EBTs have been derived for both drinking water and surface water to protect human and ecological health, respectively, and are available for assays indicative of specific receptor-mediated effects, as well as assays indicative of adaptive stress responses, apical effects, and receptor-mediated effects triggered by many chemicals. An overview of currently available EBTs is provided, and a simple approach is proposed to predict interim EBTs for assays currently without an EBT based on the effect concentration of the assay reference compound. There was good agreement between EBTs predicted using this simplistic approach and EBTs from the literature derived using more robust methods. Finally, an interpretation framework that outlines the steps to take if the effect of a sample exceeds the EBT was developed to help facilitate the uptake of EBMs in routine water quality monitoring and water safety planning for drinking water production. Environ Toxicol Chem 2023;42:714-726. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Analysis of the existence form of landfill leachate water level and its development pattern under the condition of considering internal source water: a case study.

In this paper, we study the existence form and development pattern of leachate level in the pile through a case of high water level landfill. The innovation of this paper is to consider not only the infiltration of rainfall, but also the internal source water of waste as the source of leachate. There is one main water level and multiple layers of stagnant water levels in this study area. The main water level of the pile first appears along the base slope of the landfill, and the trend of development is to connect from the bottom pile upwards layer by layer. The connection point of each layer gradually moves from the upstream side to the downstream side with time, and the main water level is formed by the gradual connection of the stagnant water level in each layer of the pile. Piles filled with slope as the base surface, and the stagnant water level in the pile first develops on the slope. And piles that are filled with a gentle base surface, and stagnant water level in the pile is uniformly developed on the base surface. At least one layer of stagnant water level exists in each layer of the pile, and multiple saturated zones occur in landfills with gentle base surfaces, and the saturation zone of the upper and lower waste pile will be penetrated. Depending on the form of leachate water level present in the pile, the location can be reasonably chosen for engineered precipitation of the landfill, and based on the development trend of each water level in the pile, it can provide a reference for the site selection and design of the landfill.