Drinking Water Reservoir Research Articles

Considerable declines in odor in a drinking water reservoir: variations of odorous community, precursor enzymes abundance, distribution, and environmental dominant factors

Considerable declines in odor in a drinking water reservoir: variations of odorous community, precursor enzymes abundance, distribution, and environmental dominant factors

ERMƏNİSTANIN AZƏRBAYCANA QARŞI EKOLOJİ TERRORU

Since 1988, 20% of Azerbaijan's lands have been occupied as a result of the war waged by Armenia to pursue its territorial claims against Azerbaijan. After a long occupation, during the 44-day Patriotic War and 24-hour local anti-terrorist operations, our lands, which had been in the hands of the enemy for almost 30 years, were liberated by our brave Army. However, in the territories we liberated from occupation, the enemy left behind ruins and an environmental disaster. For almost 30 years, Armenia deliberately tried to destroy our nature, carried out environmental terrorism against Azerbaijan, spontaneously exploited natural resources, including our occupied territories, polluted drinking water reservoirs with industrial waste, and disrupted the ecological balance of the environment. During the occupation, the enemy committed the great¬est acts of vandalism on our lands; the occupying forces destroyed forests, national parks, nature reserves, valuable trees and other rare examples of biodiversity. The rivers that are the source of Azerbaijan's drinking water are contaminated with chemical, biologi¬cal and other radioactive waste flowing from the territory of Armenia. Over the past years, contamination of water sources flowing from the occupied territories has led to the death of valuable fish species and the depletion of fish stocks. 7 ecologically important relic lakes and 10 reservoirs in the liberated territories of Azerbaijan were subject to serious anthropogenic impact from the occupying Armenia.

Seasonal Rise in the Contents of Microcystin-LR and Odorous Substances Due to Cyanobacterial Blooms in a Drinking Water Reservoir Supplying Xinyang City, China.

Cyanobacterial blooms have become a serious water pollution problem in many parts of the world, and the monitoring and study of the impacts of biotoxins on human health are of vital importance. In this study, the contents of microcystin-LR, 2-methylisoborneol, and geosmin were measured in water and sediment samples from Nanwan Reservoir, China, by means of bimonthly sampling between February and December 2023. The physicochemical and hydrochemical factors and phytoplankton dynamics in the reservoir were also investigated. The results showed that the overall mean concentration of microcystin-LR (0.729 μg/L) in summer approached the guiding standard (1 μg/L) set by the WHO for drinking water. Furthermore, the content of 2-methylisoborneol (143.5 ng/L) was 14 times higher than the national standard (10 ng/L). The results of laboratory cultures showed that lower light levels and medium temperatures were suitable for the growth of Microcystis and Planktothricoides but higher temperatures promoted the synthesis and release of microcystin-LR and 2-methylisoborneol. In addition, the results of co-cultures showed that the growth of Planktothricoides was inhibited by Microcystis. Our results suggest that cyanobacterial bloom and the presence of the metabolites 2-methylisoborneol and microcystin-LR can decrease the drinking water quality of Nanwan Reservoir.

Saxitoxin potentiates human neuronal cell death induced by Zika virus while sparing neural progenitors and astrocytes

The Zika virus (ZIKV) epidemic declared in Brazil between 2015 and 2016 was associated with an increased prevalence of severe congenital malformations, including microcephaly. The distribution of microcephaly cases was not uniform across the country, with a disproportionately higher incidence in the Northeast region (NE). Our previous work demonstrated that saxitoxin (STX), a toxin present in the drinking water reservoirs of the NE, exacerbated the damaging effects of ZIKV on the developing brain. We hypothesized that the impact of STX might vary among different neural cell types. While ZIKV infection caused severe damages on astrocytes and neural stem cells (NSCs), the addition of STX did not exacerbate these effects. We observed that neurons subjected to STX exposure were more prone to apoptosis and displayed higher ZIKV infection rate. These findings suggest that STX exacerbates the harmful effects of ZIKV on neurons, thereby providing a plausible explanation for the heightened severity of ZIKV-induced congenital malformations observed in Brazil’s NE. This study highlights the importance of understanding the interactive effects of environmental toxins and infectious pathogens on neural development, with potential implications for public health policies.

Assessing the Hydrologic Response of a Major Drinking Water Reservoir to Extreme Flood Events and Climate Change Using SWAT and OASIS

Assessing the Hydrologic Response of a Major Drinking Water Reservoir to Extreme Flood Events and Climate Change Using SWAT and OASIS

Geochemical and Hydrological Controls on Manganese in a Weakly-Stratified Drinking Water Reservoir

Geochemical and Hydrological Controls on Manganese in a Weakly-Stratified Drinking Water Reservoir

Cyanoleptonema yuqiaoensis gen. & sp. nov. (Oscillatoriaceae, Oscillatoriales), a novel filamentous cyanobacterium isolated from a eutrophic reservoir in China

ABSTRACT An unknown filamentous cyanobacterium was isolated from the Yuqiao Reservoir, a eutrophic drinking water reservoir in Tianjin city, northern China. The cyanobacterium shares some morphological similarities with most Leptolyngbya-like species, having thin trichomes that can facultatively produce sheaths, with one trichome per sheath, and contain peripheral thylakoids. Based on a combination of morphological, molecular, ultrastructural and ecological evidence, we propose the description of a new cyanobacterial taxon, Cyanoleptonema yuqiaoensis gen. & sp. nov. which expands our understanding of cyanobacterial diversity. Phylogenetic analyses based on 16S rRNA gene sequences placed this freshwater strain into a well-supported clade closely related to the marine or saline genera Sodalinema and Baaleninema. Genetic identity between Cyanoleptonema and other cyanobacteria, including Sodalinema and Baaleninema, was found to be less than 95% in 16S rRNA. The genus was further distinguished by morphological and ecological characteristics, including cell size and the ratio between cell length and width.

Spatial and temporal dynamics of microbes and genes in drinking water reservoirs: Distribution and potential for taste and odor generation

Numerous reservoirs encounter challenges related to taste and odor issues, often attributed to odorous compounds such as geosmin (GSM) and 2-methylisoborneol (2-MIB). In this study, two large reservoirs located in northern and southern China were investigated. The Jinpen (JP) reservoir had 45.99 % Actinomycetes and 14.82 % Cyanobacteria, while the Xikeng (XK) reservoir contained 37.55 % Actinomycetes and 48.27 % Cyanobacteria. Most of the 2-MIB produced in surface layers of the two reservoirs in summer originated from Cyanobacteria, most of the 2-MIB produced in winter and in the bottom water originated from Actinomycetes. Mic gene abundance in the XK reservoir reached 5.42 × 104 copies/L in winter. The abundance of GSM synthase was notably high in the bottom layer and sediment of both reservoirs, while 2-MIB synthase was abundant in the surface layer of the XK reservoir, echoing the patterns observed in mic gene abundance. The abundance of odor-producing enzymes in the two reservoirs was inhibited by total nitrogen, temperature significantly influenced Actinomycetes abundance in the JP reservoir, whereas dissolved oxygen had a greater impact in the XK reservoir. Overall, this study elucidates the molecular mechanisms underlying odor compounding, providing essential guidance for water quality management strategies and the improvement of urban water reservoir quality.

Effects of storm events on nutrient characteristics in a stratified drinking water reservoir: Behavior, transmission pathways and management strategy

Storm events result in nutrient fluctuations and deterioration of reservoir water supply quality. Understanding of nutrient dynamics (e.g., concentration, composition, loads and transport pathways) and adoption of effective management strategies are critical for safeguarding water quality. A comprehensive monitoring was conducted for three storm events during the rainy season in 2023. Results showed nitrogen (N) and phosphorus (P) dynamics demonstrate a significant response to hydrological process. Rainfall resulted in the highest event mean concentrations (EMCs) of total nitrogen (TN), nitrate nitrogen (NO3−-N), ammonia nitrogen (NH4+-N), total phosphorus (TP), and particulate phosphorus (PP) in the runoff being 1.97, 2.15, 2.30, 44.17, and 62.38 times higher than those observed in baseflow. On average, NO3−-N/PP accounted for 82 %/96 % of N/P exports. Hysteresis analyses reveal that NH4+-N and PP were mainly transported by surface runoff from over-land sources, whereas TN and NO3−-N were primarily delivered by subsurface runoff. Additionally, nutrient concentrations were significantly higher in the intrusive layer in reservoir compared to the pre-storm period, which gradually decreased from the tail to the head as particulate sedimentation and water column mixing occurred. Water-lifting-aerators (WLAs) were employed to alter the reservoir thermal stratification regime via artificial mixing to affect the intrusive layer of storm runoff. Comparison of the intrusive layer for three storms reveals that WLAs triggers the storm runoff to form an underflow via increasing the reservoir bottom water temperature above that the runoff, ensuring that water quality at the intake position remains unaffected by inflows. These findings serve as a reference for the response of reservoir eutrophication levels to storm events and present practical engineering experience for enhancing water quality safety during the rainy season.

Ignored microbial-induced taste and odor in drinking water reservoirs: Novel insight into actinobacterial community structure, assembly, and odor-producing potential

The presence of actinobacteria in reservoirs can lead to taste and odor issues, posing potential risks to the safety of drinking water supply. However, the response of actinobacterial communities to environmental factors in drinking water reservoirs remains largely unexplored. To address this gap, this study investigated the community structure and metabolic characteristics of odor-producing actinobacteria in water reservoirs across northern and southern China. The findings revealed differences in the actinobacterial composition across the reservoirs, with Mycobacterium sp. and Candidatus Nanopelagicus being the most prevalent genera. Notably, water temperature, nutrient levels, and metal concentrations were associated with differences in actinobacterial communities, with stochastic processes playing a major role in shaping the community assembly. In addition, three strains of odor-producing actinobacteria were cultured in raw reservoir water, namely Streptomyces antibioticus LJH21, Streptomyces sp. ZEU13, and Streptomyces sp. PQK19, with peak ATP concentrations of 51 nmol/L, 66 nmol/L, and 70 nmol/L, respectively, indicating that odor-producing actinobacteria could remain metabolically active under poor nutrient pressure. Additionally, Streptomyces antibioticus LJH21 produced the highest concentration of geosmin at 24.4 ng/L. These findings enhance our understanding of regional variances and reproductive metabolic mechanisms of actinobacteria in drinking water reservoirs, providing a solid foundation for improving drinking water quality control, especially for taste and odor.

Evaluasi Hasil Pembangunan Penampungan Air Minum Masyarakat Desa Silima Banua Umbunasi Kecamatan Ulu Idanotae Kabupaten Nias Selatan

Access to clean water in Silima Banua Village is a quite complex problem. The government then carried out construction of community drinking water reservoirs. After construction was completed, research was carried out on drinking water reservoirs. This research examines the impact of the construction of drinking water reservoirs on the availability of clean water, public health and the quality of infrastructure in Silimabanua Umbunasi Village, South Nias Regency. Data was collected through surveys, interviews, and field observations to analyze changes in access to clean water before and after development, its impact on public health, and the physical quality of water reservoirs. The research results show a significant increase in the availability of clean water after construction, which positively affects public health. Apart from that, the physical quality of the water reservoir is assessed as meeting established standards. Community participation, local government support, and drinking water quality were also identified as important factors in the success of this project.

Biochemical, toxicological and genomic investigation of a high-biomass producing Limnothrix strain isolated from Italian shallow drinking water reservoir

The presence of cyanobacteria in water for drinking and recreational purposes is considered problematic due to their bloom-forming and toxigenic potential. While most cyanotoxins are produced by extensively studied cyanobacteria, little is known about other abundant genera not usually assessed for their toxic potential. Here, a new isolate of Limnothrix redekei from an Italian drinking water reservoir was cultured and investigated using biological, chemical, and genomic methods. Compared to other Limnothrix spp., the isolate yielded high biomass productivity and was mainly constituted by proteins. The isolate had genomic features similar to those of the other 10 genomes of Limnothrix spp. published so far, regardless of their geographical origin. Most genes were implicated in primary metabolism (e.g. photosynthesis, nutrients transport, cell division), while <1 % of the genome was dedicated to secondary metabolism. Two regions encoding for a cyanobactin and a polyketide were found, whereas those for known cyanotoxins were absent. Toxicological investigations based on the crustacean Artemia sp. bioassay revealed potential toxicity of Limnothrix aqueous extracts (mortality >90 %). The highest toxicity was observed in a single fraction of the extract, whose UV spectrum presented carotenoid-like characteristics. Although the structure of the putative toxin was not yet elucidated, these findings pose the basis for further investigations on Limnothrix spp. toxicity, for which the observed toxic aqueous extracts could not exclude possible implications for ecosystems and humans through drinking water resources.

Water Management on Drinking Water Reservoirs in the Aspect of Climate Variability: A Case Study of the Dobromierz Dam Reservoir, Poland

Water Management on Drinking Water Reservoirs in the Aspect of Climate Variability: A Case Study of the Dobromierz Dam Reservoir, Poland

Response of the algal-bacterial community to thermal stratification succession in a deep-water reservoir: Community structure, co-assembly patterns, and functional groups

Thermal stratification in lakes and reservoirs may intensify and become more persistent with global warming. Periodic thermal stratification is a naturally occurring phenomenon that indicates a transition in aquatic ecosystem homeostasis, which could lead to the deterioration of water quality and impaired aquatic communities. However, the responses of communities and associated nutrient cycling processes to periodic thermal stratification are still poorly understood. This study delved into the changes in water quality, algal-bacterial communities, and functional diversity influenced by thermal stratification succession, and their relationship with nutrient cycling. The results indicated that the apparent community dynamics were driven by environmental factors, with ammonium (NH4+) and nitrate (NO3−-N) being the most important factors that influenced the algal and bacterial community structure, respectively. Ecological niche widths were narrower during thermal stratification, exacerbating the antagonism of the communities, and stochastic processes dominated community assembly. Then, the complexities of the co-occurrence network decreased with succession. Algal community assembly became more deterministic, while bacterial assembly became more stochastic. Moreover, the roles of algal-bacterial multidiversity in nutrient cycling differed: bacterial diversity enhanced nutrient cycling, whereas algal diversity had the opposite effect. These findings broadened our understanding of microbial ecological mechanisms to environmental change and provided valuable ecological knowledge for securing water supplies in drinking water reservoirs.

Geochemical drivers of manganese removal in drinking water reservoirs under hypolimnetic oxygenation

Manganese (Mn) is a naturally occurring contaminant commonly found in drinking water supplies. In lakes and reservoirs, water authorities increasingly use in situ treatment by hypolimnetic oxygenation (HOx) systems to remove metals such as Mn from the water column. HOx systems introduce dissolved oxygen (DO) to the bottom waters (hypolimnion) to promote oxidation and subsequent removal of metals from the water column. Previous laboratory studies have shown the importance of individual geochemical drivers (pH, alkalinity, mineral surfaces) on Mn oxidation, but few studies have examined the influence of these drivers of Mn removal in concert. In this study, we conducted field monitoring and laboratory experiments to examine how pH, alkalinity and the presence of mineral particles influence Mn removal at two drinking water reservoirs in southwest Virginia, both with HOx systems: Falling Creek Reservoir (FCR) and Carvins Cove Reservoir (CCR). Both reservoirs have had historical issues with elevated (>0.05 mg/L) Mn concentrations during seasonal stratification (May–October). Watershed geology contributes to differences in pH and alkalinity between the reservoirs, with FCR having lower historical medians of hypolimnetic pH and alkalinity (6.6 and 18 mg/L CaCO3, respectively) than CCR (7.2 and 62 mg/L CaCO3, respectively).Results of laboratory experiments examining the influence of pH on Mn removal showed substantial Mn loss within 14 days only under high pH (10) conditions. Mn removal did not occur at pH 6 or 8 over the same 14-day period. In experiments with pH 10 and alkalinity >70 mg/L CaCO3, near-total Mn removal occurred within 2 h. Mn removal occurred concurrently with precipitation of microscopic (<5 μm) particles, followed by formation of macroscopic (>100 μm) particles. Particles of both size classes were identified as Mn oxides (MnOx). These observations suggest that increasing pH and alkalinity promotes Mn oxidation and subsequent removal from solution. Results of experiments with pH 10 and alkalinity >70 mg/L CaCO3 suggest that heterogeneous oxidation by MnOx partially drives rapid Mn removal. Thus, initial formation of MnOx creates a positive feedback loop that can enhance additional Mn loss. In experiments using water collected from FCR and CCR, we observed rapid Mn removal in unfiltered water (0.002–0.05 d−1) but no significant removal of Mn in filtered water. These results, in combination with results of analysis of particles collected from reservoir water, suggest that minerals present in the water column likely catalyze MnOx formation. Together, our experimental results suggest that heterogenous oxidation is an important process of Mn removal, while pH and alkalinity variations of the range expected in natural freshwaters contribute less to differential Mn removal. The formation of MnOx particles during in situ oxygenation, as well as the presence of suspended minerals that occur naturally in water columns, play an important role in promoting Mn oxidation and should be accounted for in Mn removal treatment strategies.

Water quality ensemble prediction model for the urban water reservoir based on the hybrid long short-term memory (LSTM) network analysis

ABSTRACT The water quality of drinking water reservoirs directly impacts the water supply safety for urban residents. This study focuses on the Da Jing Shan Reservoir, a crucial drinking water source for Zhuhai City and the Macau Special Administrative Region. The aim is to establish a prediction model for the water quality of drinking water reservoirs, which can serve as a vital reference for water plants when formulating their water supply plans. In this research, after smoothing the data using the Hodrick-Prescott filter, we utilized the long short-term memory (LSTM) network model to create a water quality prediction model for the Da Jing Shan Reservoir. Simulation calculations reveal that the model's fitting degree is consistently above 60%. Specifically, the prediction accuracy for pH, dissolved oxygen (DO), and biochemical oxygen demand (BOD) in the water quality prediction model aligns with actual results by more than 70%, effectively simulating the reservoir's water quality changes. Moreover, for parameters like pH, DO, BOD, and total phosphorus, the relative forecasting error of the LSTM model is less than 10%, confirming the model's validity. The results of this study offer an essential model reference for predicting water quality for the Da Jing Shan Reservoir.

Development of a new primer tool for quantification and identification of geosmin-producing cyanobacteria in drinking water reservoirs

Elevated geosmin concentrations in drinking water reservoirs can lead to customer complaints and increased treatment costs for utilities. Use of molecular approaches, like qPCR and targeted amplicon sequencing, can help with prediction and preventive measures, but many of the primers targeting the geosmin synthase gene suffer from limited coverage of taxa or poor specificity. Here, a set of primers (CGeo1F/R) were developed that had high specificity for geosmin synthase in cyanobacteria without the use of probes. When tested on samples from three drinking water reservoirs with elevated geosmin levels, these primers amplified the geosmin synthase gene in seven cyanobacterial genera, including Dolichospermum, Aphanizomenon, Cylindrospermum, Planktothrix, Nostoc, Coelosphaerium, and Tychonema. These primers exhibited acceptable amplification efficiency (∼ 90 %) and a linear amplification range of 6 × 101–6 × 105 copies per ml in lake water. Within the limited set of samples used to evaluate these primers, a good correlation was observed (r = 0.8) between abundance of geosmin synthase and geosmin concentration. When compared to some existing, well-utilized primers in the literature, these new primers had better specificity and amplification properties, and thus may prove valuable to other researchers.

Impacts of hydrologic management on the eutrophication of shallow lakes in an intensive agricultural landscape (Saskatchewan, Canada)

Abstract Hydrologic management of shallow lakes is often undertaken to prevent fluctuations in lake level, and to ensure sufficient water volume for economic, domestic, and recreational uses, but there is inconsistent evidence of whether lake‐level stabilisation through hydrological management promotes or hinders eutrophication. Here we used multi‐proxy paleolimnological assessments of water quality (sedimentary carbon, nitrogen, total phosphorus, fossil pigments), and zooplankton community ecology (fossil Cladocera assemblages), combined with Landsat‐derived estimates of lake surface area in two shallow eutrophic lakes, in the Prairies of southern Saskatchewan, Canada, to quantify how 8 decades of contrasting hydrological management strategies (continuous or intermittent) affect primary production and phytoplankton composition. Analysis revealed that irregular hydrological management of Pelican Lake led to sharp increases in primary production concomitant with lake‐level decline. In contrast, continuously managed Buffalo Pound Lake, a drinking water reservoir for regional cities, exhibited slow, persistent eutrophication over decades despite active regulation of water levels. In both lakes, strong correlations of δ 15N values with pigments from diazotrophic cyanobacteria (canthaxanthin) showed that N2‐fixation increased during eutrophication irrespective of the timing of change. Finally, variation in fossil cladoceran density and composition reflected changes in pelagic and littoral habitats (e.g., reduced macrophyte cover) due to changes in both lake level and water quality. Basin comparison shows that while hydrologic management can moderate water quality degradation due to lake‐level change, it does not prevent eutrophication when nutrient influx remains high. Given that regional water availability is forecast to decline in coming decades, we anticipate that continued hydrological management will be unavoidable and will be unable to improve water quality unless nutrient influx is also controlled.

Elevated lead mobility in sediments of a eutrophic drinking water reservoir during spring and summer seasons: Insights from isotopic signatures

Lead (Pb) pollution in sediments remains a major concern for ecosystem quality due to the robust interaction at the sediment/water interface, particularly in shallow lakes. However, understanding the mechanism behind seasonal fluctuations in Pb mobility in these sediments is lacking. Here, the seasonal variability of Pb concentration and isotopic ratio were investigated in the uppermost sediments of a shallow eutrophic drinking lake located in southeast China. Results reveal a sharp increase in labile Pb concentration during autumn-winter period, reaching ∼ 3-fold higher levels than during the spring-summer seasons. Despite these fluctuations, there was a notable overlap in the Pb isotopic signatures within the labile fraction across four seasons, suggesting that anthropogenic sources are not responsible for the elevated labile Pb concentration in autumn-winter seasons. Instead, the abnormally elevated labile Pb concentration during autumn-winter was probably related to reduction dissolution of Fe/Mn oxides, while declined labile Pb concentration during spring-summer may be attributed to adsorption/precipitation of Fe/Mn oxides. These large seasonal changes imply the importance of considering seasonal effects when conducting sediment sampling. We further propose a solution that using Pb isotopic signatures within the labile fraction instead of the bulk sediment can better reflect the information of anthropogenic Pb sources.

Automated identification of toxigenic cyanobacterial genera for water quality control purposes

Cyanobacteria are the dominating microorganisms in aquatic environments, posing significant risks to public health due to toxin production in drinking water reservoirs. Traditional water quality assessments for abundance of the toxigenic genera in water samples are both time-consuming and error-prone, highlighting the urgent need for a fast and accurate automated approach. This study addresses this gap by introducing a novel public dataset, TCB-DS (Toxigenic Cyanobacteria Dataset), comprising 2593 microscopic images of 10 toxigenic cyanobacterial genera and subsequently, an automated system to identify these genera which can be divided into two parts. Initially, a feature extractor Convolutional Neural Network (CNN) model was employed, with MobileNet emerging as the optimal choice after comparing it with various other popular architectures such as MobileNetV2, VGG, etc. Secondly, to perform classification algorithms on the extracted features of the first section, multiple approaches were tested and the experimental results indicate that a Fully Connected Neural Network (FCNN) had the optimal performance with weighted accuracy and f1-score of 94.79% and 94.91%, respectively. The highest macro accuracy and f1-score were 90.17% and 87.64% which were acquired using MobileNetV2 as the feature extractor and FCNN as the classifier. These results demonstrate that the proposed approach can be employed as an automated screening tool for identifying toxigenic Cyanobacteria with practical implications for water quality control replacing the traditional estimation given by the lab operator following microscopic observations. The dataset and code of this paper are publicly available at https://github.com/iman2693/CTCB.