Prevalence of Antibiotic-Resistant Escherichia coli in Drinking Water Sources in Hangzhou City

This study investigated the distribution of antibiotic resistant Escherichia coli (E. coli) and examined the possible relationship between water quality parameters and antibiotic resistance from two different drinking water sources (the Qiantang River and the Dongtiao Stream) in Hangzhou city of China. E. coli isolates were tested for their susceptibility to 18 antibiotics. Most of the isolates were resistant to tetracycline (TE), followed by ampicillin (AM), piperacillin (PIP), trimethoprim/sulfamethoxazole (SXT), and chloramphenicol (C). The antibiotic resistance rate of E. coli isolates from two water sources was similar; For E. coli isolates from the Qiantang River, their antibiotic resistance rates decreased from up- to downstream. Seasonally, the dry and wet season had little impact on antibiotic resistance. Spearman's rank correlation revealed significant correlation between resistance to TE and phenicols or ciprofloxacin (CIP), as well as quinolones (ciprofloxacin and levofloxacin) and cephalosporins or gentamicin (GM). Pearson's chi-square tests found certain water parameters such as nutrient concentration were strongly associated with resistance to some of the antibiotics. In addition, tet genes were detected from all 82 TE-resistant E. coli isolates, and most of the isolates (81.87%) contained multiple tet genes, which displayed 14 different combinations. Collectively, this study provided baseline data on antibiotic resistance of drinking water sources in Hangzhou city, which indicates drinking water sources could be the reservoir of antibiotic resistance, potentially presenting a public health risk.

Seasonality Affects the Diversity and Composition of Bacterioplankton Communities in Dongjiang River, a Drinking Water Source of Hong Kong

Water quality ranks the most vital criterion for rivers serving as drinking water sources, which periodically changes over seasons. Such fluctuation is believed associated with the state shifts of bacterial community within. To date, seasonality effects on bacterioplankton community patterns in large rivers serving as drinking water sources however, are still poorly understood. Here we investigated the intra-annual bacterial community structure in the Dongjiang River, a drinking water source of Hong Kong, using high-throughput pyrosequencing in concert with geochemical property measurements during dry, and wet seasons. Our results showed that Proteobacteria, Actinobacteria, and Bacteroidetes were the dominant phyla of bacterioplankton communities, which varied in composition, and distribution from dry to wet seasons, and exhibited profound seasonal changes. Actinobacteria, Bacteroidetes, and Cyanobacteria seemed to be more associated with seasonality that the relative abundances of Actinobacteria, and Bacteroidetes were significantly higher in the dry season than those in the wet season (p < 0.01), while the relative abundance of Cyanobacteria was about 10-fold higher in the wet season than in the dry season. Temperature and NO3--N concentration represented key contributing factors to the observed seasonal variations. These findings help understand the roles of various bacterioplankton and their interactions with the biogeochemical processes in the river ecosystem.

The Occurrence and Risks of Selected Emerging Pollutants in Drinking Water Source Areas in Henan, China

The occurrence of organic micropollutants (OMPs) in aqueous environments has potential effects on ecological safety and human health. Three kinds of OMPs (namely, pharmaceuticals, ultraviolet (UV) filters and organophosphate esters (OPEs)) in four drinking water source areas in Henan Province of China were analyzed, and their potential risks were evaluated. Among 48 target chemicals, 37 pollutants with total concentrations ranging from 403.0 to 1751.6 ng/L were detected in water, and 13 contaminants with total concentrations from 326.0 to 1465.4 ng/g (dry weight) were observed in sediment. The aqueous pollution levels in Jiangang Reservoir and Shahe Water Source Area were higher than that in Nanwan Reservoir and Baiguishan Reservoir, while the highest total amount of pollutants in sediment was found in Baiguishan Reservoir. Compared with pharmaceuticals and UV filters, OPEs presented higher concentrations in all investigated drinking water source areas. The highest observed concentration was triphenylphosphine oxide (TPPO, 865.2 ng/L) in water and tripentyl phosphate (TPeP, 1289.8 ng/g) in sediment. Moreover, the risk quotient (RQ) analysis implies that the determined aqueous contaminants exhibited high risks to algae and invertebrates, whereas moderate risk to fish was exhibited. The health risk assessment of aqueous OMPs by means of the hazard index (HI) indicates that the risks to adults and children were negligible. These observations are expected to provide useful information for the assessment of water quality in drinking water sources in Henan, China.

Socio-Economic Factors Related to Drinking Water Source and Sanitation in Malaysia

Access to improved water and sanitation is essential. We describe these practices in Malaysia using data from a nationwide community survey and used logistic regression to assess the determinants. Of the 7978 living quarters (LQs), 58.3% were in urban areas. About 2.4%, 0.5% and 27.4% of LQs had non-improved water sources, non-improved toilet types and improper domestic waste disposal, respectively. Open burning was practiced by 26.1%. Water source was a problem for long houses (10.5%), squatters (8.5%) and shared houses (4.0%). Non-improved toilet types were 11.9% for squatters and 4.8% for shared houses. Improper domestic waste disposal practices were higher for occupants of village houses (64.2%), long houses (54.4%), single houses (45.8%) and squatters (35.6%). An increase in education or income level was associated with a decrease in improper domestic waste disposal methods. House type significantly affected water and sanitation after adjusting for the effects of other variables. Lower household income was associated with non-improved toilet types and improper domestic waste disposal. Lower education and rural location influenced domestic waste disposal. The water and toilet facilities in Malaysia were generally good, while domestic waste management practices could be improved. There remain pockets of communities with environmental challenges for the nation.

H2Oh No! The importance of reporting your water source in your in vivo microbiome studies

Water is a fundamental part of any in vivo microbiome experiment however, it is also one of the most overlooked and underreported variables within the literature. Currently there is no established standard for drinking water quality set by the Canadian Council on Animal Care. Most water treatment methods focus on inhibiting bacterial growth within the water while prolonging the shelf-life of bottles once poured. When reviewing the literature, it is clear that some water treatment methods, such as water acidification, alter the gut microbiome of experimental animals resulting in dramatic differences in disease phenotype progression. Furthermore, The Jackson Lab, one of the world's leading animal vendors, provides acidified water to their in-house animals and is often cited in the literature as having a dramatically different gut microbiome than animals acquired from either Charles River or Taconic. While we recognize that it is impossible to standardize water across all animal facilities currently conducting microbiome research, we hope that by drawing attention to the issue in this commentary, researchers will consider water source as an experimental variable and report their own water sources to facilitate experimental reproducibility. Moreover, researchers should be cognisant of potential phenotypic differences observed between commercial animal vendors due to changes in the gut microbiome as a result of various sources of water used.

[Pollution Characteristics and Risk Assessment of Antibiotics in Lianhua Reservoir]

Thirteen typical antibiotics in surface water of the Lianhua Reservoir were analyzed using HPLC/MS/MS to assess the pollution characteristics and risk levels. Ten antibiotics except for erythromycin, sulfadiazine, and sulfamethoxazole were detected in surface water and the total concentration of antibiotics varied between non-detectable (n.d.) and 925.26 ng ·L^-1. Azithromycin had the highest concentration (n.d.-232.61 ng ·L^-1) with the detection frequency of 75%, followed by enrofloxacin (n.d.-187.69 ng ·L^-1), tetracycline (n.d.-155.05 ng ·L^-1), and ciprofloxacin (n.d.-83.66 ng ·L^-1) with the detection frequencies over 60%. The spatial distribution of antibiotics was as follows: total concentration of upstream (sampling point 1) > Aoxi River stream tributary (sampling point 2) > reservoir downstream (sampling point 3) > reservoir entrance (sampling point 4) > reservoir area (sampling point 5). The seasonal variations in the concentrations of antibiotics were evident; total concentrations in the dry season were significantly higher than those in the wet and normal seasons. The results of the environmental risk assessment indicated that ofloxacin, enrofloxacin, and ciprofloxacin pose significant risks to the environment. In the Lianhua Reservoir, ciprofloxacin showed high potential risk to the ecological environment, while the environmental risks of other antibiotics in the reservoir were below the medium level. The combined risk value of the antibiotics in the dry season was higher than that in the wet and normal seasons.

[Contamination status and speciation for the sediment nutrients in Panjiakou-Daheiting Reservoir]

As the source of the "Luanhe-Tianjin Diversion Project", water environment status in the Panjiakou-Daheiting Reservoir directly affects drinking water safety in the water receiving area, and therefore plays important role in the development of the Beijing-Tianjin-Hebei region. Field survey was carried out in July 2016 to examine the pollution status of the sediment nitrogen, phospho-rus and organic matter. The results showed that total nitrogen (TN) content of surface sediments in Panjiakou-Daheiting Reservoir ranged from 1175.41 to 2415.67 mg·kg^-1 with a mean of 1648.71 mg·kg^-1. Total phosphorus (TP) ranged from 1773.25 to 3471.70 mg·kg^-1 with a mean of 2790.89 mg·kg^-1. Organic matter (OM) ranged from 6.0% to 25.3% with a mean of 12.5%. Daheiting Reservoir which located downstream of Panjiakou Reservoir had higher value in TP content, while had similar TN content. Results from speciation analysis showed that sediment nitrogen was mainly composed of organic nitrogen and phosphorus mainly consisted of calcium-phosphorus which belonged to inorganic phosphorus. The value of C/N ratio indicated that OM mainly originated from exogenous substances. The pollution assessment results demonstrated that the sediment Panjiakou-Daheiting Reservoir was in a severe pollution status, and might have potential effect to the water environment improvement through the nutrient exchange at the sediment-water interface.

[Distribution Characteristics and Health Risk Assessment of Metals in Drinking Water Sources from the Luhun Reservoir]

In order to investigate the distribution characteristics and the human health risks of 12 metals in drinking water sources from the Luhun Reservoir, Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, and Zn concentrations in 46 water samples collected from the reservoir in 2016 were measured and analyzed. The health risks caused by metals were assessed by using a human health risk assessment model. The results showed that the maximum concentration of Al (200.27 μg·L^-1) and all concentrations of Mo (151.42-170.69 μg·L^-1) in drinking water from the Luhun Reservoir exceeded the Environmental Quality Standards for Surface Water (GB 3838-2002) and Standards for Drinking Water Quality (GB 5749-2006) by 4.35% and 100%, respectively. A distinct spatial heterogeneity was found in the metal distribution, and the region with the highest metals concentrations was located southwest (upstream) and northeast (downstream) of the reservoir. The results of a health risk assessment indicated that children had greater health risks than adults. The health risks for metals through drinking were all higher than the values caused by dermal contact. Carcinogenic risks caused by Cr and As exceeded the maximum allowance levels (5×10^-5 a^-1) by 100% and 3.80%, respectively, and Cr accounted for 85% of the total carcinogenic risks. The non-carcinogenic risks of the metals (10^-12-10^-7 a^-1) decreased in the order of Al > Mo > Cu > Pb > Ni > Hg > Fe > Zn > Mn, which had levels two to seven orders of magnitude lower than the maximum allowance levels.

[Distribution Characteristics and Health Risk Assessment of Thirteen Sulfonamides Antibiotics in a Drinking Water Source in East China]

Trace levels of residual antibiotics in drinking water sources may threaten public health and becomes a serious issue in modern society. Occurrence and distribution of 13 sulfonamides antibiotics in a drinking water source in East China were investigated using solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. The results revealed that all 13 sulfonamides were detected with the total concentrations ranging from 10.5 ng·L^-1 to 238.5 ng·L^-1. Sulfamethoxazole (SMX) and sulfonamide (SAM) presented the 100% detected frequency, and the maximum concentrations reached 107.0 ng·L^-1 and 43.1 ng·L^-1, respectively. Sulfonamides contamination levels in the inlet were relatively higher than those in the outlet. The concentration of SMX was substantially unchanged in different positions of drinking water source. Seasonal variation of sulfonamide concentration showed that the concentrations were higher in winter and spring compared with those in summer and autumn. The range of total sulfonamides concentration detected in winter and spring was from 110.8 ng·L^-1 to 117.9 ng·L^-1, which was 3.6-3.8 times higher than those in summer and autumn. Human health risk characterization of residual sulfonamides in drinking water source was based on the assessment of risk quotients (RQs) for which different life stages were taken into account. The results showed that no sulfonamides had a RQs higher than 1. Trimethoprim (TMP) was the most risky antibiotic to the 0-3 months old infants with RQs reaching 0.001. Although the sulfonamides detected in the drinking water source do not pose any risk to the peoples' health, the implication of long-time exposure and comprehensive risk still deserve attention.

Metatranscriptomic data mining together with microfluidic card uncovered the potential pathogens and seasonal RNA viral ecology in a drinking water source

AIMS

Despite metatranscriptomics becoming an emerging tool for pathogen surveillance, very little is known about the feasibility of this approach for understanding the fate of human-derived pathogens in drinking water sources.

METHODS AND RESULTS

We conducted multiplexed microfluidic cards and metatranscriptomic sequencing of the drinking water source in a border city of North Korea in four seasons. Microfluidic card detected norovirus, hepatitis B virus (HBV), enterovirus, and Vibrio cholerae in the water. Phylogenetic analyses showed that environmental-derived sequences from norovirus GII.17, genotype C of HBV, and coxsackievirus A6 (CA6) were genetically related to the local clinical isolates. Meanwhile, metatranscriptomic assembly suggested that several bacterial pathogens, including Acinetobacter johnsonii and V. cholerae might be prevalent in the studied region. Metatranscriptomic analysis recovered 349 species-level groups with substantial viral diversity without detection of norovirus, HBV, and CA6. Seasonally distinct virus communities were also found. Specifically, 126, 73, 126, and 457 types of viruses were identified in spring, summer, autumn, and winter, respectively. The viromes were dominated by the Pisuviricota phylum, including members from Marnaviridae, Dicistroviridae, Luteoviridae, Potyviridae, Picornaviridae, Astroviridae, and Picobirnaviridae families. Further phylogenetic analyses of RNA (Ribonucleic Acid)-dependent RNA polymerase (RdRp) sequences showed a diverse set of picorna-like viruses associated with shellfish, of which several novel picorna-like viruses were also identified. Additionally, potential animal pathogens, including infectious bronchitis virus, Bat dicibavirus, Bat nodavirus, Bat picornavirus 2, infectious bursal disease virus, and Macrobrachium rosenbergii nodavirus were also identified.

CONCLUSIONS

Our data illustrate the divergence between microfluidic cards and metatranscriptomics, highlighting that the combination of both methods facilitates the source tracking of human viruses in challenging settings without sufficient clinical surveillance.

[Distribution Characteristics of Sulfonamide Antibiotic Resistance Genes in a Drinking Water Source in East China]

Antibiotic resistance genes (ARGs) in drinking water sources have attracted widespread attention due to the threat they pose to water security and human health. This study mainly focused on the distribution of sulfonamide ARGs (sul 1, sul 2) and one integrase gene (intI 1) in water and sediment using qualitative and fluorescent quantitative PCR, based on previous work on the characteristics of 13 kinds of sulfonamides in a drinking water source in East China. Results showed that the three target genes were all detected in water and sediment. The sul 1 gene was the sulfonamide ARG with highest concentration, with 1.5×10⁴-6.4×10⁵ copies·mL^-1 in source water and maximum concentration of 1.6×10⁸ copies·g^-1 in sediment. Concentration of sul 1 was 0.6-2.2, 0.5-1.9 order of magnitudes higher than sul 2 and intI 1 genes, respectively. There was no significant difference between the absolute concentrations of sul 1, sul 2, and intI 1 in inflow and outflow. However, in the case of sediment, absolute abundances of sul 1, sul 2, and intI 1 in outflow were higher than those in inflow. The maximum concentration of sul 1 was detected in outflow in summer (6.4×10⁵ copies·mL^-1). The concentration of intI 1 was higher in winter compared to other seasons. There was a positive correlation between sul 1 and 13 sulfonamides (r=0.69, P<0.05), and the relative concentration of sul 1 and amount of sulfamethoxazole were significantly positively related (r=0.79, P<0.01). There were also positive correlations between the relative concentrations of intI 1 and sul 1, sul 2 (r:0.80 and 0.73, P<0.05), respectively, suggesting that intI 1 played an important role in horizontal gene transfer of sulfonamide ARGs in this drinking water source. This study provides basic data for monitoring pollution of ARGs, as well as a basis for controlling ARG pollution in the drinking water environment and making management decisions.

[Analysis and Prediction of Health Risk from Heavy Metals in Drinking Water Sources Based on Time Series Model]

Health risk analysis can predict and control the risks posed by heavy metals, especially in drinking water, which is a highly sensitive environmental receptors. In order to evaluate heavy metal pollution in drinking water, the monthly average concentrations of As, Cd, Cu, Hg, Ni, and Zn were used to assess the health risk between January 2015 and December 2018 in a drinking water source. Furthermore, Spearman rank correlation coefficient and the ARIMA model were used to analyze temporal variations. The results showed that the monthly average concentrations of heavy metals exceeded the class Ⅲ values as specified by Chinese environmental quality standard for surface water(GB 3838-2002), especially Hg with a minimum monthly average four times more than that set by the standard limits. Overall, the order of carcinogenic risk of As and Cd was decreased; the non-carcinogenic risk of Zn, Cu, Ni, Pb, and Hg was increased. Further, the comprehensive non-carcinogenic risk for adults was lower than 1 throughout the study period except February 2015, when the comprehensive non-carcinogenic risk for children was lower than or close to 1 after October 2017, and the comprehensive carcinogenic risk for children was more than 10^-4. Meanwhile, the children's health risks are higher than that for adults, with the main health risk characteristic factors of As, Cd, and Hg. The Spearman rank correlation coefficient were -0.714069, -0.773122, and -0.62234, indicating the significant downward trend from 2015 to 2018. However, the children's comprehensive carcinogenic risk, whose average value was 0.000234 much more than 10^-4, had significant upward trend in 2018 with Spearman rank correlation coefficient 0.902098. The ARIMA(3,1,3) model was able to predict the comprehensive carcinogenic risk for children from heavy metals in drinking water, and the result indicated the children comprehensive carcinogenic risk should be monitored to ensure levels between 0.000200 and 0.000302. The study has positive significance for risk warning and environmental management compared to the analysis and prediction of health risk from heavy metals in drinking water sources based on time series models.

Characterization of Disinfection By-Products Originating from Residual Chlorine-Based Disinfectants in Drinking Water Sources

In this study, samples from the Yangtze River, Han River, and Liangzi Lake in Wuhan City were utilized to characterize the formation of disinfection by-products (DBPs) from chlorine-based disinfection residues in drinking water sources. The results indicated that the main DBPs in drinking water sources were trichloromethane (TCM) and trichloroacetic acid (TCAA). The generation of DBPs was significantly positively correlated with oxidative substances, aromatic compounds, pH, and ammonia nitrogen (NH3-N) content in the water. The concentration of TCAA increased from 0 to 2.45 ± 0.31 mg/L when the reaction time increased to 72 h. As the NaClO concentration increased from 5 mg/L to 15 mg/L, the concentrations of TCAA, TBM, and DCAN increased from 2.03 ± 0.04 mg/L, 0 mg/L, and 0 mg/L to 2.49 ± 0.34 mg/L, 0.21 ± 0.07 mg/L, and 0.10 ± 0.04 mg/L before decreasing to 1.75 ± 0.19 mg/L, 0.17 ± 0.07 mg/L, and 0.04 ± 0.05 mg/L, respectively. The orthogonal experimental results showed that Br-, NH3-N, and pH all had significant influences on the TCM generation, whereas temperature affected the formation of TCAA in the Han River. This work reveals the factors influencing the generation of DBPs from chlorine-based disinfection residues, offering a prevention and control method for DBPs in drinking water sources from a theoretical perspective.

Antibiotic-resistant bacteria and resistance-genes in drinking water source in north Shoa zone, Amhara region, Ethiopia

Background

The growing number of antimicrobial-resistant bacteria in a range of environments poses a serious challenge to infectious disease prevention. Good water quality is critical to human health and has a direct impact on a country's socio-economic growth. Therefore, assessing the bacteriological quality of drinking water provides benchmark data and provides insight into the development of further protection and treatment measures.

Methods

A cross-sectional study was conducted from February 1, 2022, to September 31, 2023, in the diarrhea hotspot areas of North Shewa Zone (Minjar-Shenkora and Mojana-Wedera districts). Water samples were collected from drinking water sources (hand-pumps, boreholes, wells, spring water and ponds) to assess the quality following WHO guidelines. The collected water samples were processed for bacterial isolation, antimicrobial susceptibility testing, and detection of antimicrobial resistance genes. Data were entered and analyzed using the Statistical Package for the Social Sciences (SPSS) version 25.

Results

A total of (49/138, 35.5%) bacteria were isolated from 138 drinking water samples, with a positive rate of (41/138, 29.7%). Among the isolates, (16/138, 11.6%) were Staphylococcus aureus while (33/138, 23.9%) were members of Enterobacteriaceae. Relatively high resistance rate among all isolates were observed for the most prescribed antibiotics in Ethiopia, including erythromycin, cotrimoxazole, doxycycline, ceftriaxone, gentamicin, and chloramphenicol. However, a low resistance was observed for early introduced antibiotics such as ciprofloxacin and recently introduced antibiotics such as cefotaxime, ceftazidime, imipenem, and meropenem. Among the 49 bacteria isolates, (32/49, 65.3%) were multidrug-resistant (MDR) pathogens while (12/49, 24.5%) were ESβL producers. Different ESβL genes were detected in most bacterial isolates. The predominant ESβL genes were blaCTX-M-gp8/25 (6/33, 18.2%), blaCTX-M-gp9 (5/33, 15.2%), and blaCTX-M-gp1 (5/33, 15.2%).

Conclusion

The result of this study suggests that most water sources in the study area were contaminated by various bacterial species that are resistant to different antibiotics. Various ESβL resistance genes have also been detected. Therefore, regular sanitary inspection and bacteriological analysis should be mandatory to protect drinking water sources from contamination and the persistence of resistant bacteria.

[High-Frequency Dynamics of Water Quality and Phytoplankton Community in Inflowing River Mouth of Xin'anjiang Reservoir, China]

The tail of the reservoir is the unstable zone regarding water quality and phytoplankton community. Therefore, it is the crucial zone in aquatic ecosystem transitions. To understand the transition characteristics and driving mechanisms of water environment dynamics, high-frequency monitoring of the water environment and phytoplankton community in the tail of a deep and large reservoir, the Xin'anjiang Reservoir in southeast of China, was conducted using a water quality monitoring buoy and three-day interval water sampling during 18 months. Results show clear seasonal thermal and oxygen stratification in the river mouth of the reservoir. The nutrient and chlorophyll-a concentrations also show stratifying phenomena during the thermal stratification period. Heavy rain and inflow quickly consume the stratification. Nutrient concentrations were highly dynamic in the river mouth. The total phosphorus ranges from 0.011 mg·L^-1 to 0.188 mg·L^-1, and total nitrogen ranges from 0.75 mg·L^-1 to 2.76 mg·L^-1. Dissolved phosphorus comprised 56% of total phosphorus, and dissolved nitrogen occupied 88% of total nitrogen, respectively. Nutrient concentrations were influenced strongly by rainfall intensity and inflow rate. Total phosphorus and nitrogen concentrations were significantly related to the three-day accumulated rainfall. Nutrient concentrations in the flood season (March to June) were significantly higher than in the non-flood season (P<0.001). Seasonal phytoplankton proliferation also significantly influenced by total phosphorus concentration. The phytoplankton community changes significantly with seasons and flood events. Bacillariophytea was generally dominant throughout the year, with the predominant genus of Fragilaria spp., Cyclotella spp., Synedra spp., and Melosira spp. Cyanophyta biomass peaked in July, August, and September, with the dominant genus of Aphanizomenon spp., Microcystis spp., and Oscillatoria spp. Apart from the high temperature, storm inflow events also triggered Cyanophyta proliferation. The proliferation of Chlorophyta was similar to Cyanophyta, with the predominant genus of Pediastrum spp. and Closterium spp.. While the Cryptophyta biomass peaked during March to May, with the predominant genus of Cryptomonas spp.. Redundancy analysis shows that the influence factors of phytoplankton community dynamics include the inflow rate, temperature, water level, water transparency, total nitrogen, total phosphorus, and nitrogen to phosphorus ratio. The meteorological and hydrological factors were major factors for phytoplankton dynamics during later autumn and winter, while the nutrient will be the co-driving factors of phytoplankton community dynamics during summer and early autumn. The research confirmed the huge influence of the intensity rainfall event on the water environment in reservoirs and described the key environmental conditions for phytoplankton community dynamics. The research is useful for the design of the monitoring and forecasting system for water safety in drinking water source reservoirs.

[Distribution, Sources, and Health Risk Assessment of PAHs in Water Supply Source Regions of Guangzhou]

Trace polycyclic aromatic hydrocarbons (PAHs) in drinking water sources have significant harmful effects on human health. Water and sediment samples from water source regions of three water treatment plants in Guangzhou were collected and the distributions of 16 kinds of PAHs were analyzed. The human risk of PAHs in the water samples was also evaluated using the Risk Assessment Guidance for Superfund (RAGS) of the United States Environmental Protection Agency (USEPA). The results showed that PAHs in the samples from the three water source regions did not exceed the corresponding standard limit for water quality, and the content of ΣPAHs in suspended solids and sediments was below the medium level. The non-carcinogenic risks (HQ and HI) of PAHs in the water samples were less than 1, and the non-carcinogenic risk was negligible. In addition, Risk_ingest, Risk_dermal, and Risk_T for the waters were all in range of 5.53×10^-7 to 5.34×10^-6, indicating that a carcinogen risk was possible but acceptable. The results of the isomer ratio method indicated that the PAHs in the water sources of the three water plants had a mixed input of pollution, including petroleum discharge, petroleum combustion, and incomplete combustion of wood, coal, and biomass. The total organic carbon (TOC) content of the water and sediment samples was positively correlated with the accumulation and enrichment of low-ring PAHs, and there was a significant positive correlation between PAHs and similar molecules in the sediments. The ΣPAHs in the water and sediment samples were also strongly correlated.

[Long-term Changes and Drivers of Ecological Security in Shahe Reservoir, China]

Monthly datasets of ecological indicators from 2010 to 2020 in Shahe Reservoir, Tianmuhu, China, were examined to reveal the long-term variations in water ecological security and its driving factors. The results of Secchi disk depth(SD) measurements revealed significantly spatial variation(P<0.05) within the reservoir. The highest SD was recorded in the downstream-linked reservoir, and the lowest SD was recorded in the upstream tributaries. In contrast, the values of other water ecological indicators were higher in the upstream tributaries than in the transition region and the downstream-linked reservoir area. In summer and autumn, the SD was low, while the concentrations of total phosphorous(TP), chlorophyll a(Chl-a), the permanganate index, and cyanobacterial biomass(BM_c) were high. During the thermal stratification period from May to September, the concentrations of 2-methylisoborneol(MIB) and Chl-a were highest at a depth of 4 m, while diatom biomass(BM_b) and BM_c reached their maximum at depths of 2 m and 0.5 m, respectively. Therefore, spatial and temporal variations should be fully considered when evaluating aquatic ecological security. Focusing on spring and summer, when the risk of water ecological security was high, Chl-a combined with SD and MIB along with their correlation with other water quality indexes, was used to evaluate and optimize the ecological security of Shahe Reservoir. The evaluation results showed that the aquatic ecological security of the reservoir was excellent over the last 10 years; however, annual fluctuations have been large and the evaluation scores were spatially variable. While seasonal sampling strategies focusing on three layers depths are economical and reliable for lake regions with thermal stratification, our results indicate that tailored monitoring may be required to determine the aquatic ecological security of lakes and reservoirs. In Shahe Reservoir, the decrease in the SD and the increase in MIB caused by high TP and algal blooms were the most important drivers of ecological service function in the reservoir. Furthermore, hydrometeorological factors may also play important roles in the aquatic ecological security of reservoirs.

Double-endpoint Genotoxicity Quantification and PAHs Characterization of Drinking Water Source alongside Polluted Yinghe River with High Tumor Mortality

The etiology for the high tumor mortality in heavy polluted Yinghe river basin is still unclear and polycyclic aromatic hydrocarbons (PAHs) belong to the priority pollutants in water based on the former surveillance data. In order to explore the potential genotoxicants contributing to the double-endpoint genotoxicity of polluted drinking water source, 12 groundwater and 3 surface water samples were collected from 3 villages and the nearby rivers alongside Yinghe river basin, respectively and their comprehensive genotoxicity was estimated with a bioassay group of SOS/umu test and micronucleus (MN) test (MNT). Some groundwater samples showed positive genotoxicity and all surface water samples were highly genotoxic. Eight groundwater samples showed DNA genotoxic effect with the average 4-NQO equivalent concentration (TEQ_(4-NQO)) of 0.067 µg/L and 0.089 µg/L in wet and dry season, respectively. The average MN ratios of groundwater samples were 14.19‰ and 17.52‰ in wet and dry season, respectively. Groundwater samples showed different genotoxic effect among 3 villages. The total PAHs concentrations in all water samples ranged from 8.98 to 25.17 ng/L with an average of 14.97±4.85 ng/L. BaA, CHR, BkF, BaP and DBA were the main carcinogenic PAHs contributing to the genotoxicity of water samples. In conclusion, carcinogenic PAHs are possibly related to the high tumor mortality in the target area. Characterization of carcinogenic PAHs to genotoxicity of drinking water source may shed light on the etiology study for high tumor mortality in Yinghe river basin.

Rainfall and Temperature Influences on Childhood Diarrhea and the Effect Modification Role of Water and Sanitation Conditions: A Systematic Review and Meta-Analysis

The latest report from the Intergovernmental Panel on Climate Change (IPCC) highlighted the worsening impacts of climate change. Two climate factors-temperature and rainfall uncertainties-influence the risk of childhood diarrhea, which remains a significant cause of morbidity and mortality in low- and middle-income countries. They create a conducive environment for diarrhea-causing pathogens and overwhelm environmental prevention measures. This study aimed to produce comprehensive evidence on the association of temperature and rainfall variability with the risk of childhood diarrhea and the influence of water and sanitation conditions on those associations. We conducted a systematic review and meta-analysis using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) approach. Records published in English from 2006 to 2023 were searched on 8 January 2024 via PubMed, EMBASE, ScienceDirect, Scopus, the Cochrane Library, and Google/Google Scholar using comprehensive search terms. We assessed studies for any risk of bias using the Navigation Guide and rated the quality of the evidence using the GRADE approach. The heterogeneity among estimates was assessed using I-squared statistics (I2). The findings of the analysis were presented with forest plots using an incidence rate ratio (IRR). A meta-analysis was conducted on effect modifiers (water supply and sanitation conditions) using a random effects model with a 95% confidence interval (CI). The statistical analyses were conducted using R 4.3.2 software and Review Manager 5.3. A total of 2017 records were identified through searches, and only the 36 articles that met the inclusion criteria were included. The analysis suggests a small positive association between increased temperature and the occurrence of under-five diarrhea, with the pooled IRR = 1.04; 95% CI [1.03, 1.05], at I2 = 56% and p-value < 0.01, and increased rainfall and U5 diarrhea, with IRR = 1.14; 95% CI [1.03, 1.27], at I2 = 86% and p-value < 0.01. The meta-analysis indicated a positive association between unimproved latrine facilities and drinking water sources with a rainfall-modified effect on U5 diarrhea, with IRR = 1.21; 95% CI [0.95, 1.53], at I2 = 62% and p-value = 0.03. We found that an increase in mean temperature and rainfall was associated with an increased risk of childhood diarrhea. Where there were unimproved latrine facilities and drinking water sources, the increase in mean rainfall or temperature would increase the incidence of childhood diarrhea. The results of this review help in assessing the effectiveness of current intervention programs, making changes as needed, or creating new initiatives to lower the prevalence of childhood diarrhea.