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The occurrence, spatiotemporal changes, and health hazard of antibiotics in source water and finished water in the Wuhan section of the Yangtze River are not well understood. In this study, 43 source water and finished water samples were collected from 11 water plants in Wuhan in August 2021 and May 2022. Fifty-one antibiotics from eight categories were measured. A total of 41 antibiotics were detected in the source water samples, and 24 in the finished water samples. The total antibiotic concentration in source water ranged from 1.68 to 437.18 ng/L, which is significantly higher than that in finished water (2.04–87.25 ng/L). Sulfonamides and lincosamides were predominant, accounting for nearly 80% of the total antibiotic concentration. Lincomycin constituted nearly 30% of the total antibiotic concentration in the source water. In August 2021, the average total antibiotic concentration in source water was 107.12 ng/L, higher than in May 2022 (63.13 ng/L). Spatially, the total antibiotic concentrations in samples collected from the Han River, a tributary of the Yangtze River, were higher than those in the main stream of the Yangtze River. Ecological risk assessment indicated that the hazard posed by most antibiotics were negligible. Lincomycin potentially posed a high health hazard, and clarithromycin and roxithromycin posed a moderate hazard to infants. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have been found in both surface water and groundwater, which are sources of drinking water. Since one of the most important routes for MPs to enter the human body is through drinking water, the enormous buildup of MPs in waterbodies and the resulting effects on human health have caused social concern. However, our knowledge of drinking water treatment plant (DWTP) treatment techniques affects the removal of MPs, and there aren't any standardized or efficient quality assurance and quality control (QA/QC) measures for sampling and analysis. The current state of MPs in drinking water sources is described in this review, which also provides the most recent data on MPs removal by various DWTP units. Lastly, we propose practical QA/QC techniques to ensure the accuracy of MP analysis. This review intends to present the most recent data on MPs in drinking water and the effectiveness of MPs removal by DWTP units. It also advises that further research into the mechanisms of MPs removal be done in the future. [ABSTRACT FROM AUTHOR]

Source water challenges can add complexity to water treatment decisions, but operators must be educated and prepared to meet these challenges. [ABSTRACT FROM AUTHOR]

When a US Marine Corps training facility decided to add a second aquifer to its existing groundwater supply, it designed a treatment plant that would successfully blend the two source waters and meet strict water quality goals. [ABSTRACT FROM AUTHOR]

Increased wildfire activity in the western United States can lead to detrimental cascading effects to water quality. After fires, burned areas may experience significant runoff‐induced erosion and sediment transport into rivers and reservoirs, which could rapidly overwhelm existing drinking water treatment plants. This paper couples an assessment of wildfire risk with an evaluation of water utility preparedness to understand where key fire‐related drinking water vulnerabilities exist. Wildfire risk assessments were constructed and expanded from a commonly used methodology co‐developed between researchers and water managers (Edel et al., 2002), to understand drinking water impacts on water quality after wildfires. A water utility preparedness index was created for this study using publicly available information to contextualize how well utilities may be able to respond to water quality degradation after fires. Results indicate that 22% of utilities studied (10% of the population served) were underprepared for fire and 11% of watersheds used were at greater risk of wildfire (9% of the population served). However, nearly three‐quarters of utilities (76% of the population served) showed a moderate risk of fire and some need for improved fire preparedness. Information developed here could provide a useful framework from which utility managers can better assess their likely wildfire risk and preparation plans. [ABSTRACT FROM AUTHOR]

Safe, good-quality drinking water is a foundation of public health. Its provision relies on multiple barriers, the first being the protection of source water. Source water refers to the bodies of water (aquifers, rivers, lakes, springs, reservoirs) from which communities and individuals take their drinking water. A large waterborne campylobacter outbreak in 2016 spurred the New Zealand government to make a suite of legislative and policy reforms to strengthen the country's drinking water supply system. However, the nitrate contamination of a municipal drinking water source, and its subsequent breach of drinking water standards, should bring renewed attention to the protection of source water. This article presents a case study of the exceedance and a review of legislation and policy governing drinking water sources. It finds that while important steps have been made since 2016, weaknesses in responsibility and accountability remain in Aotearoa's drinking water supply system. [ABSTRACT FROM AUTHOR]

Contaminated source water for cities contributes to negative human health impacts and rising water treatment costs. Nutrient pollution is the primary source of surface water quality impairment in the United States and agriculture is the largest source of nutrient pollution (specifically nitrogen or nitrate) entering waterways. Solutions to source water contamination have historically centered on nutrient removal at the drinking water plant, which often requires additional investment. Pollution prevention through watershed management may be more cost-effective in some contexts and has greater co-benefits, and some drinking water managers and agricultural stakeholders have collaborated to create successful prevention programs. However, drinking water managers must balance several service requirements and regulatory standards, and may lack the resources or capacity needed to effectively engage in or initiate regional collaborations. This paper serves as an introduction to nutrient contamination of source waters and protection measures in the United States and provides a discussion of watershed-scale collaboration, particularly the engagement of municipal drinking water managers. This article is categorized under: Human Water > Water Governance Water and Life > Conservation, Management, and Awareness Science of Water > Water Quality [ABSTRACT FROM AUTHOR]

• A data processing platform, HDPairFinder, was developed to automatically recognize H/D isotope labeled chemicals in HPLC-HRMS data. • Cross-correlation was proposed to address the RT shift caused by the deuterium isotopic effect. • A suite of bioinformatic algorithms was incorporated to effectively remove false positive features. • AMINES, a library of over 38000 amino-containing chemicals, was constructed to facilitate compound annotation. • Over 1000 highly confident H/D-labeled amino-containing compounds can be identified from the data of environmental water samples. The combination of hydrogen/deuterium (H/D) formaldehyde-based isotopic methyl labeling with solid-phase extraction and high-performance liquid chromatography–high resolution mass spectrometry (HPLC-HRMS) is a powerful analytical solution for nontargeted analysis of trace-level amino-containing chemicals in water samples. Given the huge amount of chemical information generated in HPLC-HRMS analysis, identifying all possible H/D-labeled amino chemicals presents a significant challenge in data processing. To address this, we designed a streamlined data processing pipeline that can automatically extract H/D-labeled amino chemicals from the raw HPLC-HRMS data with high accuracy and efficiency. First, we developed a cross-correlation algorithm to correct the retention time shift resulting from deuterium isotopic effects, which enables reliable pairing of H- and D-labeled peaks. Second, we implemented several bioinformatic solutions to remove false chemical features generated by in-source fragmentation, salt adduction, and natural 13C isotopes. Third, we used a data mining strategy to construct the AMINES library that consists of over 38,000 structure-disjointed primary and secondary amines to facilitate putative compound annotation. Finally, we integrated these modules into a freely available R program, HDPairFinder.R. The rationale of each module was justified and its performance tested using experimental H/D-labeled chemical standards and authentic water samples. We further demonstrated the application of HDPairFinder to effectively extract N-containing contaminants, thus enabling the monitoring of changes of primary and secondary N-compounds in authentic water samples. HDPairFinder is a reliable bioinformatic tool for rapid processing of H/D isotopic methyl labeling-based nontargeted analysis of water samples, and will facilitate a better understanding of N-containing chemical compounds in water. [Display omitted] [ABSTRACT FROM AUTHOR]

BackgroundChina is a big country in the production and use of antibiotics. The abuse of antibiotics enables bacteria in water environment to acquire resistance, and promotes the generation and spread of antibiotics resistance genes (ARGs). The problem of antibiotic-resistant bacteria is increasingly serious and has become a public security issue of global concern. Water environment is a huge reservoir of antibiotics and ARGs. It is of great significance to study the pollution of antibiotics and ARGs in water to protect water sources and optimize the biosecurity of drinking water.ObjectiveTo evaluate the detection of antibiotics and ARGs in typical water sources, and to explore the relationship between antibiotics and ARGs. MethodsWater samples were collected in Heilongjiang, Liaoning, and Hubei provinces during the wet season (from August to October) in 2020. Ten water samples were collected from each of the three places, and a total of 30 water samples were collected in this study. Five kinds of antibiotics, including macrolides, quinolones, sulfonamides, tetracycline, and β-lactam, were detected by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The integron (Intl1), 16S rRNA, and 6 kinds of ARGs were detected by quantitative real-time PCR (qPCR). The ARGs include one macrolide ARGs (ermB), one β-lactam ARGs (blaTEM), two tetracycline ARGs (tetC, tetQ), and two sulfonamide ARGs (sul1, sul2). ResultsThe types of detected antibiotics varied by the three regions, and the concentration ranges of the same antibiotics varied by the three regions (P

Key Takeaways: Source water quality monitoring programs benefit from sampling efforts that address data needs on different spatial and temporal scales. The cost of monitoring programs is more than offset by real savings, avoided costs, and increased support for decision makers. Loveland Water and Power has derived diverse and sometimes unexpected benefits from its monitoring program. [ABSTRACT FROM AUTHOR]

Key Takeaways: Regular monitoring of particle concentration in conjunction with turbidity analysis provides supplementary data that can provide important water quality information. Particle analysis using flow imaging microscopy (FIM) can help operators better understand various treatment processes and algae growth in source waters. Specific size ranges can be monitored using FIM for target pathogens such as Cryptosporidium and Giardia. [ABSTRACT FROM AUTHOR]

Key Takeaways: The effectiveness of powdered activated carbon (PAC) at removing cyanotoxins depends on the specific toxin(s), water pH, and PAC source. A study showed that wood–lignite PAC adsorbed more cyanotoxin than bituminous coal–based PAC, and cyanotoxin removal was more effective at a higher pH. In this study, removal costs decreased as toxin concentration increased, and saxitoxin removal was less expensive when it was present with microcystin‐LR. A decision tree that balances treatment costs with toxin removal efficiency was developed to help water utilities. [ABSTRACT FROM AUTHOR]

After seven years in the making, a state‐of‐the‐art microfiltration membrane facility and new source water intake is being celebrated by the City of Sitka, Alaska. [ABSTRACT FROM AUTHOR]

Alert levels can be established using baseline data to trigger action in source water management and/or water treatment. [ABSTRACT FROM AUTHOR]

Water and wastewater laboratories have many similarities, but they also have unique differences that allow them to generate data that protect public health and the environment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Key Takeaways: Des Moines Water Works' (DMWW's) source water faces significant water quality challenges from decades of agricultural nutrient pollution in Iowa. Lackluster results in regulating nutrient pollution, along with population growth and effects of climate change, add urgency to DMWW's drive to improve source water quality. To protect its source water, DMWW has collaborated with groups outside of its typical scope, building relationships with those who have the same values and vision. [ABSTRACT FROM AUTHOR]

Several factors may impact bacterial diversity in drinking water distribution systems (DWDSs) including the origin of the raw water, the water treatment technologies, and the disinfection practices applied. 16S rRNA metabarcoding was used for the in-depth characterization of bacterial communities in the four studied Croatian DWDSs (A, B, C, D) two of which had residual disinfectant (A, B) and two were without (C, D), while only B utilized the conventional water treatment technology. Significantly higher diversity and species richness were evidenced in non-disinfected DWDSs (P <0.05) compared to disinfected DWDSs. The phylum Proteobacteria was the most abundant in all the DWDSs, being proportionately higher in non-disinfected systems (P <0.05). The most abundant genera in DWDS-A Mycobacterium and Sphingomonas both positively correlated, whereas Lactobacillus negatively correlated with the concentration of disinfection by-products (DBPs) as a sum of haloacetic acids (HAAs). Conversely, the genus Ralstonia positively correlated with the individual DBP dichloroacetic acid. These results indicate that genera Sphingomonas, Mycobacterium, Lactobacillus , and Ralstonia could have an effect on promoting the formation of DBPs, in a similar manner to how negatively correlated taxa may influence their degradation. [ABSTRACT FROM AUTHOR]

Key Takeaways: Cyanobacteria can, but do not always, produce toxins that may be found in algal blooms, which can pose a public health threat even at low levels in water. The US Environmental Protection Agency, the World Health Organization, and Health Canada have taken varying approaches to establishing guidances for monitoring and managing algal toxins. Although based on different assumptions and interpretations, with somewhat different outcomes, all of the assessments provide appropriate safeguards for drinking water, with different water system impacts and at different treatment costs. [ABSTRACT FROM AUTHOR]

Understanding different types of drinking water sources is key for operators to provide effective treatment. [ABSTRACT FROM AUTHOR]

Key Takeaways: The concentration and composition of per‐ and polyfluoroalkyl substances (PFAS) in source water and treated water goals are the main drivers affecting PFAS management. Separately or together, granular activated carbon and ion exchange media are effective treatment options when trying to minimize PFAS in finished water. Requirements for ultimate disposal or destruction of PFAS and process residuals significantly affect operating costs, which in turn play a critical role in treatment process selection. [ABSTRACT FROM AUTHOR]

To explore the occurrence, source, and risk of 16 priority polycyclic aromatic hydrocarbons (PAHs) in urban source water at the tidal reach of the Yangtze River, eighty-nine surface water samples were collected in 8 field campaigns from July 2018 to November 2019. Fifteen of 16 PAHs except for dibenz(a,h)anthracene (DBA) were found in the water. Detection frequencies were observed between 53 and 72% for PAHs with 4 rings, while most of other PAHs were less detected, e.g., benzo(a)pyrene (BaP) in 31% of samples. The total concentrations of 16 priority PAHs reached up to 2.8 µg·L−1 and increased during the tidal transitions from flood to ebb. The average concentrations of PAHs in ebb tides were higher than those in flood tides. PAH concentrations and compositions showed great variation with different sampling campaigns, and higher levels and more components were observed in the rainy months and cold months. Those priority PAHs in the tidal water source are mainly from combustion activities (especially fossil fuel combustion), but the contribution from oil spills/leakage is also important in rainy months. High-molecular-weight PAHs in this tidal water source may pose risks to aquatic life, while they pose no carcinogenic risk to human health via ingestion of drinking water. [ABSTRACT FROM AUTHOR]

A novel underground reservoir was constructed in an abandoned tunnel for preserving the water in a remote island. The microbial community, potential opportunistic pathogens (OPs) and antibiotic resistance genes (ARGs) of water were analyzed over a year. Results demonstrated that the culturability of the total bacteria and coliforms were both sensitive to the temperature, and the total bacteria culturability had significantly positive relationship with temperature over a year. The ∑ARGs abundance sharply decreased from September to January, but bounced back in July, which was strongly related with phylum Proteobacteria, genera Methylophilus and Methylotenera. The potential OPs almost carried a variety of ARGs, especially in genera Pseudomonas, Enterobacter, Klebsiella, Escherichia with more than 40 ARGs types, which resulted in ARGs enrichment and transfer in the water system. The ∑ARGs of potential OPs variation was extremely significantly related with ARGs subtypes of MacB (r = 0.980, p < 0.05), AcrB (r = 0.997, p < 0.01), AcrA (r = 0.986, p < 0.05) and genus Klebsiella (r = 0.962, p < 0.05).Article Highlights: Significantly positive relationship between total bacteria number and temperature. ∑ARGs strongly related with phylum Proteobacteria, genera Methylophilus/Methylotenera. OPs of Pseudomonas, Enterobacter, Klebsiella, Escherichia with > 40 ARGs subtypes. ∑ARGs of potential OPs extremely significantly related with genus Klebsiella. [ABSTRACT FROM AUTHOR]

Extended drought in the twenty-first century has led to loss of volume for lakes and reservoirs across the globe. In the Colorado River Basin, USA, Lakes Powell and Mead have experienced a 68 and 71% decline in volume, respectively, since 2000. Lake Mead is important to the Las Vegas Valley as it accounts for 90–100% of the source water used to serve the 2.2 million residents and 43 million annual tourists. Lake Powell is also vital to maintaining water quality in Lake Mead as it is located upstream and provides 97% of the water entering Mead. As Lakes Powell and Mead are projected to continue decreasing in volume over the next 5 years, it is important to understand the effects of loss of lake volume on water quality in this highly-managed system. Here, the effects of lake drawdown on water quality parameters that affect disinfection byproduct (DBP) formation in the source water for the Las Vegas Valley are projected over the next 5 years using Federal flow projections, regression modeling to project influent temperature from Lake Powell into Lake Mead, and a three-dimensional hydrodynamic and water quality model for Lake Mead. Results from these modeling efforts include projections for changes in values of water temperature, bromide, and total organic carbon (TOC) at the modeled cell that contains the Las Vegas Valley's urban drinking water intake. Raw water bromide was found to have little change across modeled scenarios; however, raw water temperature is projected to increase because of falling lake surface elevations. Raw water TOC is projected to increase three-fold in the simulated scenario that includes the most loss of volume but remains close to historic values in the remaining simulated scenarios. With these raw water quality projections, water managers can better plan for alterations to the water treatment processes, including mitigation of DBP formation.

Source-water switching can lead to instability in drinking water distribution systems. In estuarine cities using surface water as source water where salt tide occasionally happens, the influence can be particularly complex due to changes of Larson Index (LI). The objective of this study was to investigate the effects of different switching patterns on the stability of water in an estuarine city. Fluctuated LI was found in the current distribution system. LI of the new source water was lower and more stable. Susceptible areas with a high frequency of over standard water quality were identified and pipe scales there were mainly composed of relatively stable iron oxides with dense crystal structures (Fe3O4 and α-FeOOH). Two old pipe sections were used to simulate different switching patterns. The microbial risk did not increase significantly when the original and new water sources were combined in different ratios (2∶8, 5∶5), when multiple water sources were used (3∶3∶4) or when salinity increased. The better water quality, lower LI of the new source water, and stability of the current distribution system together contributed to the biostability. Total iron increased after switching, then declined and stabilized for most switching patterns. Salt tide can lead to sharp iron release. The results provided insightful information for distribution systems that have cast iron pipes and that might encounter source-water switching patterns. [ABSTRACT FROM AUTHOR]

Key Takeaways: In 1972, Congress overrode a presidential veto to pass the Clean Water Act in the interest of restoring the environmental integrity of US waters. History reveals prevailing attitudes and concepts that did not consider a need for source water protection and human accountability. One component of the Clean Water Act's continued progress in addressing current and emerging threats to source water quality is a strong relationship with the Safe Drinking Water Act. [ABSTRACT FROM AUTHOR]

Various measures are available to help utilities mitigate drought as well as support water supply, quality, and reliability. [ABSTRACT FROM AUTHOR]

Key Takeaways: For years, geosmin was causing taste and odor (T&O) issues for the residents of Tulsa, Okla. With the application of algaecide at the pipe's intake, the median geosmin concentration was reduced by 83%. While utilities should focus on source water quality, the application of algaecide can help provide immediate relief for T&O issues related to geosmin. [ABSTRACT FROM AUTHOR]

We estimate a cost function for a water treatment plant in Ohio to assess the avoided‐treatment costs resulting from improved source water quality. Regulations and source water concerns motivated the treatment plant to upgrade its treatment process by adding a granular activated carbon building in 2012. The cost function uses daily observations from 2013 to 2016; this allows us to compare the results to a cost function estimated for 2007–2011 for the same plant. Both models focus on understanding the relationship between treatment costs per 1,000 gallons (per 3.79 m3) of produced drinking water and predictor variables such as turbidity, pH, total organic carbon, deviations from target pool elevation, final production, and seasonal variables. Different from the 2007–2011 model, the 2013–2016 model includes a harmful algal bloom toxin variable. We find that the new treatment process leads to a different cost model than the one that covers 2007–2011. Both total organic carbon and algal toxin are important drivers for the 2013–2016 treatment costs. This reflects a significant increase in cyanobacteria cell densities capable of producing toxins in the source water between time periods. The 2013–2016 model also reveals that positive and negative shocks to treatment costs affect volatility, the changes in the variance of costs through time, differently. Positive shocks, or increased costs, lead to higher volatility compared to negative shocks, or decreased costs, of similar magnitude. After quantifying the changes in treatment costs due to changes in source water quality, we discuss how the study results inform policy‐relevant decisions. Key Points: Estimate how drinking water treatment costs change due to changes in source water quality following a plant upgradeUse time series analysis to understand short‐ and long‐run effects on treatment costsRaw water total organic carbon and harmful algal bloom toxin detections are important drivers in drinking water treatment costs [ABSTRACT FROM AUTHOR]

Iopamidol (an iodinated X-ray contrast medium) and bromide are precursors in the formation of halogenated disinfection byproducts (DBPs). The interactions of these precursors are vital to elucidate the formation of halogenated DBPs during chloramination. This work investigated the formation of total organic halogen and select individual DBPs in two laboratory-chloraminated source waters containing iopamidol and bromide. Experiments were carried out in batch reactors containing Barberton source water (BSW) and Cleveland BSW (CSW), spiked with iopamidol (5 μM), bromide (15 μM), and 100 μM monochloramine. Total organic iodine concentrations were approximately equal regardless of source water since they are mostly unreacted iopamidol and iopamidol DBPs. Almost equal amounts of total organic chlorine (3–4 nM) were produced in the source waters, but higher quantities of total organic bromine were formed in BSW than CSW. Substantial quantities of regulated trihalomethanes (THMs) and haloacetic acids (HAAs) were formed in the source waters, along with appreciable concentrations of iodinated trihalomethanes (CHBrClI, CHCl2I, and CHBr2I). Low concentrations of iodo-HAAs were detected, especially at low pH. Overall, bromide concentrations appeared to suppress iodo-DBP formation during chloramination of iopamidol in the presence of natural organic matter. A good correlation (R2 = 0.801) between the yields of regulated DBPs and iodo-DBPs was observed. HIGHLIGHTS Bromide suppressed the formation of iodo-THMs without bromine atoms.; Approximately equal quantities of total organic chlorine were formed regardless of NOM characteristics.; Iodoacetic acids showed substantial formation at low pH irrespective of NOM.;

• The pollution of Taihu Lake source water shaped the DBP distribution. • Taihu Lake source water is polluted with phenolic compounds. • Formulas of ninety-one unknown DBPs were identified. • The occurrence of 5 aromatic and heterocyclic brominated DBPs was confirmed. • Nineteen possible precursors of the discovered DBPs were detected. Although disinfection byproducts (DBPs) in drinking water have been suggested as a cancer causing factor, the causative compounds have not yet been clarified. In this study, we used liquid chromatography quadrupole-time-of-flight spectrometry (LC-QTOF MS) to identify the unknown disinfection byproducts (DBPs) in drinking water produced from Taihu Lake source water, which is known as a convergence point for the anthropogenic pollutants discharged from intensive industrial activities in the surrounding regions. In total, 91 formulas of DBPs were discovered through LC-QTOF MS nontarget screen, 81 of which have not yet been reported. Among the 91 molecules, 56 only contain bromine, 15 only contain chlorine and 20 DBPs have both bromine and chlorine atoms. Finally, five DBPs including 2,4,6-tribromophenol, 2,6-dibromo-4-chlorophenol, 2,6-dichloro-4-bromophenol, 4-bromo-2,6-di-tert-butylphenol and 3,6-dibromocarbazole were confirmed using standards. The former three compounds mainly formed in the predisinfection step (maximum concentration, 0.2-2.6 µg/L), while the latter two formed in the disinfection step (maximum concentration, 18.2-33.6 ng/L). In addition, 19 possible precursors of the discovered DBPs were detected, with the aromatic compounds being a major group. 2,6-di-tert-butylphenol as the precursor of 4-bromo-2,6-di-tert-butylphenol was confirmed with standard, with a concentration of 20.3 µg/L in raw water. The results of this study show that brominated DBPs which are possibly formed from industrial pollutants are relevant DBP species in drinking water produced form Taihu source water, suggesting protection of Taihu Lake source water is important to control the DBP risks. [Display omitted] [ABSTRACT FROM AUTHOR]

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In this study, we examined the inter- and intra-specific variation of hydraulic traits of three conifers of the Northern Rockies: Pinus ponderosa, Picea engelmannii, and Pseudotsuga menziesii to understand the mechanisms that allow different plant species to co-exist across a watershed. We quantified differences in plant xylem water potential (ψx), xylem tissue vulnerability to cavitation (P50, or ψ causing 50% loss of hydraulic conductivity), and safety margins for co-occurring trees from low and high elevations. We then investigated xylem vulnerability to cavitation with rooting depth. We found that xylem vulnerability to cavitation did not correspond to where tree species were found in the landscape. For example, P. ponderosa grew in more xeric locations, while P. engelmannii were largely confined to more mesic locations, yet P. engelmannii had more negative P50 values. P. menziesii had the lowest P50 value, but displayed little variation in vulnerability to cavitation across the hydroclimatic gradient. These patterns were also reflected in the safety margins; P. menziesii had the widest safety margin, P. engelmannii was intermediate, and P. ponderosa displayed the narrowest safety margin. All three species were also using water sources deeper than 30 cm in depth, allowing them to persist throughout the mid-summer drought. Overall, species-specific hydraulic traits did not necessarily follow a predictable response to the environment; instead, a combination of physiological and morphological traits likely allow trees to persist across a broader hydroclimatic gradient than would be otherwise expected from hydraulic trait measurements alone. [ABSTRACT FROM AUTHOR]

Acetochlor is a widely used herbicide in agricultural production. Studies have shown that acetochlor has obvious environmental hormone effects, and long-term exposure may pose a threat to human health. To quantify the hazards of acetochlor in drinking water, a health risk assessment of acetochlor was conducted in major cities of China based on the data of acetochlor residue concentrations in drinking water. The approach of the Species Sensitivity Distributions (SSD) method is used to extrapolate from animal testing data to reflect worst case human toxicity. Results show that hazard quotients related to acetochlor residues in drinking water for different age groups range from 1.94 × 10−4 to 6.13 × 10−4, so, there are no indication of human risk. Compared to the total estimated hazard quotient from oral intake of acetochlor, the chronic exposure imputed to acetochlor residues in drinking water in China accounts for 0.4%. This paper recommends 0.02 mg/L to be the maximum acetochlor residue concentration level in drinking water and source water criteria. [Display omitted] [ABSTRACT FROM AUTHOR]

Odor problems in source water caused by 2-methylisoborneol (MIB) have been a common issue in China recently, posing a high risk to drinking water safety. The earthy-musty odorant MIB has an extremely low odor threshold (4–16 ng/L) and is hard to remove via conventional processes in drinking water plants (DWP), and therefore could easily provoke complaints from consumers. This compound is produced by a group of filamentous cyanobacteria, mainly belonging to Oscillatoriales. Different from the well-studied surface-blooming Microcystis , filamentous cyanobacteria have specific niche characteristics that allow them to stay at a subsurface or deep layer in the water column. The underwater bloom of these MIB producers is therefore passively determined by the underwater light availability, which is governed by the cell density of surface scum. This suggests that drinking water reservoirs with relatively low nutrient contents are not able to support surface blooms, but are a fairly good fit to the specialized ecological niche of filamentous cyanobacteria; this could explain the widespread odor problems in source water. At present, MIB is mainly treated in DWP using advanced treatment processes and/or activated carbon, but these post-treatment methods have high cost, and not able to deal with water containing high MIB concentrations. Thus, in situ control of MIB producers in source water is an effective complement and is desirable. Lowering the underwater light availability is a possible measure to control MIB producers according to their niche characteristics, which can be obtained by either changing the water level or other measures. [Display omitted] [ABSTRACT FROM AUTHOR]

Arctic precipitation (PG) that occurs as rainfall (Prain) or snowfall (Psnow) depending on the prevailing climatic conditions results in seasonally specific hydrological events. Climate change can affect the PG‐ and permafrost‐originated water (Pice) regimes, resulting in change to ecohydrological processes. However, the relative influences of source waters (i.e., Prain, Psnow, and Pice) on terrestrial hydrological processes have not yet been fully established. Here, we report the development and implementation of a numerical water tracer model designed to quantify changes in the storages and fluxes of the source waters and the hydrogen and oxygen isotopic tracers associated with hydrometeorological events. The presented tracer model was used to illustrate the spatiotemporal variability of the tracers in the surface–subsurface system of a deciduous needleleaf boreal forest and to separate the contribution rates of the tracer waters to evapotranspiration (ET). Although Psnow accounted for 22%–57% of ET and the subcomponents, the contribution rates to soil evaporation and transpiration were significant only during spring. The major source water for soil moisture was Prain, which accounted for 69.2% of ET and showed an increasing trend during 1980–2016. Additionally, Prain also accounted for 77.2% of transpiration. Under the present conditions of warming permafrost, Pice demonstrated negligibly low impact on ET. The tracer model was shown capable of quantifying the contribution rates of tracer waters to ET, highlighting the advantages of the tracer model for a similar quantitative separation regarding future climate change. Plain Language Summary: Although snowfall and rainfall are seasonally different processes, their influence on hydrological processes (i.e., evapotranspiration and river discharge) occurs mainly during the growing season. Quantification of their contributions to hydrological processes is an ongoing scientific problem in the field of Arctic hydrology. Thus, we developed a tracer model, which includes isotopic processes, to separate the contributions of snowfall, rainfall, and permafrost‐originated water to evapotranspiration and applied it to a boreal forest. The model simulation suggested that summer rainfall has the greatest impact on evapotranspiration, while water from snowfall is strongly implicated in springtime evaporation. Permafrost‐originated water is not connected directly to evapotranspiration at the study site. However, future warming climate could potentially increase the role of permafrost‐related water in ecohydrological processes. Thus, the presented water tracer model could potentially provide a quantitative assessment of the changes in the physics of water dynamics caused by climate change. Key Points: Tracer model separates contributions of precipitation‐ and permafrost‐originated waters to evapotranspiration in deciduous boreal forestRainfall is the primary contributor to seasonal and interannual variability of evapotranspirationPermafrost‐originated water has negligibly low impact on evapotranspiration [ABSTRACT FROM AUTHOR]

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 (r RF − Tu 2 = 0.87 , r GB − Tu 2 = 0.80 and r XGB − Tu 2 = 0.81) showed very good performance metrics. For raw water UV254, the three models (r RF − UV 2 = 0.89 , r GB − UV 2 = 0.85 and r XGB − UV 2 = 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. [Display omitted] • Decision-tree-based ensemble machine learning models were tested to predict quality parameters of raw water supplying DWTP. • Random forest and eXtreme Gradient Boosting techniques yielded the highest metrics for predicting raw water quality. • Decision-tree-based ensemble machine learning techniques may be used in the modelling component early warning systems. [ABSTRACT FROM AUTHOR]

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. 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. [Display omitted] • Nontarget analysis and machine learning were integrated for odor risk assessment. • GC×GC-TOFMS was employed to identify the odorous compounds in water. • Machine learning models were developed to accurately predict odor thresholds. • 2-MIB and nonanal were prioritized as the potential key odorants. [ABSTRACT FROM AUTHOR]

Key Takeaways: After finding nitrosamines in its water system, the City of Houston studied how polymer coagulants and different stages of water purification affect nitrosamine formation. Results showed that as polymer dose increased and as water backwash or recycled water was mixed in, nitrosamine levels increased. Utilities should remove nitrosamine precursors from source water and optimize polymer dosage to reduce nitrosamines in the purification plant and drinking water distribution system. [ABSTRACT FROM AUTHOR]

The hydrogen isotope ratio of water cryogenically extracted from plant stem samples (δ²Hstem_CVD) is routinely used to aid isotope applications that span hydrological, ecological, and paleoclimatological research. However, an increasing number of studies have shown that a key assumption of these applications--that δ²Hstem_CVD is equal to the δ²H of plant source water (δ²Hsource)--is not necessarily met in plants from various habitats. To examine this assumption, we purposedly designed an experimental system to allow independent measurements of δ²Hstem_CVD, δ²Hsource, and δ²H of water transported in xylem conduits (δ²Hxylem) under controlled conditions. Our measurements performed on nine woody plant species from diverse habitats revealed a consistent and significant depletion in δ²Hstem_CVD compared with both δ²Hsource and δ²Hxylem. Meanwhile, no significant discrepancy was observed between δ²Hsource and δ²Hxylem in any of the plants investigated. These results cast significant doubt on the long-standing view that deuterium fractionation occurs during root water uptake and, alternatively, suggest that measurement bias inherent in the cryogenic extraction method is the root cause of δ²Hstem_CVD depletion. We used a rehydration experiment to show that the stem water cryogenic extraction error could originate from a dynamic exchange between organically bound deuterium and liquid water during water extraction. In light of our finding, we suggest caution when partitioning plant water sources and reconstructing past climates using hydrogen isotopes, and carefully propose that the paradigm-shifting phenomenon of ecohydrological separation ("two water worlds") is underpinned by an extraction artifact. [ABSTRACT FROM AUTHOR]

Sondes can also be deployed at various water depths near the intake to monitor specific concentrations of temperature, dissolved oxygen, chlorophyll a, and phycocyanin. Keywords: Cyanotoxins; Algae; Cyanobacteria; Source Water; Odor; Water Quality EN Cyanotoxins Algae Cyanobacteria Source Water Odor Water Quality 73 76 4 04/03/21 20210401 NES 210401 GLO:KNS/01apr21:awwa1693-gra-0001.jpg PHOTO (COLOR): . gl I Layout imagery by Alexlky/Shutterstock.com i As the chair of AWWA's Aesthetics and Water Quality and Perception Committee, I know there are many water utility managers who have been kept up at night worrying about the occurrence of taste and odor (T&O) compounds such as methylisoborneol (MIB) or geosmin and cyanotoxins like microcystin or cylindrospermopsin in impounded source waters. Improving Water Quality Water systems, particularly those that rely on surface water sources that experience periodic cyanobacteria blooms, often incorporate proactive or reactive treatment unit processes to address elevated levels of T&O compounds and possibly cyanotoxins. [Extracted from the article]

Key Takeaways: Net‐zero water for long‐term water security and sustainability can be best quantified by comparing consumption with the net freshwater balance, including source water recharge. This approach can support individual decisions when investing in water infrastructure and water conservation projects or for identifying critical locations for aquifer recharge. While the sites studied did not meet US Army's Net Zero water criteria using the traditional calculation, all achieved or have feasible plans to achieve Net Zero under this more holistic approach. [ABSTRACT FROM AUTHOR]

Source water apportionment studies using the dual isotopes of oxygen and hydrogen have revolutionized our understanding of ecohydrology. But despite these developments—mostly over the past decade—many technical problems still exist in terms of linking xylem water to its soil water and groundwater sources. This is mainly due to sampling issues and possible fractionation of xylem water. Here we explore whether or not leaf water alone can be used to quantify the blend of rainfall event inputs from which the leaf water originates. Leaf water has historically been avoided in plant water uptake studies due to the extreme fractionation processes at the leaf surface. In our proof of concept work we embrace those processes and use the well‐known Craig and Gordon model to map leaf water back to its individual precipitation event water sources. We also employ a Bayesian uncertainty estimation approach to quantify source apportionment uncertainties. We show this using a controlled, vegetated lysimeter experiment where we were able to use leaf water to correctly identify the mean seasonal rainfall that was taken up by the plant, with an uncertainty typically within ±1‰ for δ18O. While not appropriate for all source water studies, this work shows that leaf water isotope composition may provide a new, relatively un‐intrusive method for addressing questions about the plant water source. [ABSTRACT FROM AUTHOR]