A high concentration of chromium (VI) in groundwater can threaten the health of consumers. In this study, the concentration of chromium (VI) in 18 drinking water wells in Birjand, Iran, s was ...investigated over a period of two yearsNon-carcinogenic risk assessment, sensitivity, and uncertainty analysis as well as the most important variables in determining the non-carcinogenic risk for three age groups including children, teens, and adults, were performed using the Monte Carlo simulations technique. The northern and southern regions of the study area had the highest and lowest chromium concentrations, respectively. The chromium concentrations in 16.66% of the samples in an area of 604.79 km2 were more than World Health Organization (WHO) guideline (0.05 mg/L). The Moran's index analysis showed that the distribution of contamination is a cluster. The Hazard Index (HI) values for the children and teens groups were 1.02 and 2.02, respectively, which was more than 1. A sensitivity analysis indicated that the most important factor in calculating the HQ was the concentration of chromium in the consumed water. HQ values higher than 1 represent a high risk for the children group, which should be controlled by removing the chromium concentration of the drinking water.
The presence of toxic metals such as vanadium in water resources has attracted considerable attention as a new concern in international health. Systematic review and meta-analysis were performed to ...assess the concentration of vanadium in water resources along with the relevant ecological risk assessment. Databases of Scopus, PubMed, and Embase were investigated to retrieve the related articles from January 01, 1974 to December 25, 2019. Twenty-eight articles containing 152 samples from 24 countries were included. Furthermore, the meta-analysis was conducted by the approach of z-score to estimate differences in the effect size. In addition, the mean of concentrations of vanadium was applied to calculate the risk assessment only to the water surface and choose the maximum environmental concentration (MEC) for demonstrate a worst-case scenario. Here, the risk assessment approach was used to show that the MEC of vanadium confirm the risk it for aquatic ecosystems, being fish (e.g., Danio rerio) our model organism due to their sensibility. According to findings, the MEC of vanadium in surface water varied from 0.010 μg L−1 (USA) and 68 μg L−1 (China), with an overall mean of 6.21 ± 13.3 μg L−1 (mean ± standard deviation). The ecological risk assessment demonstrated that people living in some countries such as China and Japan were at an adverse ecological risk of vanadium in the water resources. Hence, essential control plans besides adequate removal techniques must be implemented for significant deracination of heavy metals like vanadium.
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•Twenty eight articles with 152 samples were included in the study.•Maximum environmental concentration (MEC) of Vanadium in water was varied from 0.010 μgL−1 (USA) and 68 μgL−1 (China).•China and Japan are exposed to adverse vanadium ecological risk in the water.•The order of sensitivity to vanadium-based on SSD was as R. subcapitata > D. magna > O. mykiss.
•Groundwater fluoride risk map (> 1.0 mg/L) created with random forest modeling identifies risk areas in Ghana.•Geology and climate are major drivers of geogenic fluoride contamination.•Most affected ...areas are in the northeast of the country.•About 920,000 people, including 240,000 children (0–9 years), live in at-risk areas.
Most people in Ghana have no or only basic access to safely managed water. Especially in rural areas, much of the population relies on groundwater for drinking, which can be contaminated with fluoride and lead to dental fluorosis. Children under the age of two are particularly susceptible to the adverse effects of fluoride and can retain 80–90% of a fluoride dose, compared to 60% in adults. Despite numerous local studies, no spatially continuous picture exists of the fluoride contamination across Ghana, nor is there any estimate of what proportion of the population is potentially exposed to unsafe fluoride levels. Here, we spatially model the probability of fluoride concentrations exceeding 1.0 mg/L in groundwater across Ghana to identify risk areas and estimate the number of children and adults exposed to unsafe fluoride levels in drinking water. We use a set of geospatial predictor variables with random forest modeling and evaluate the model performance through spatial cross-validation. We found that approximately 15% of the area of Ghana, mainly in the northeast, has a high probability of fluoride contamination. The total at-risk population is about 920,000 persons, or 3% of the population, with an estimated 240,000 children (0–9 years) in at-risk areas. In some districts, such as Karaga, Gushiegu, Tamale and Mion, 4 out of 10 children are potentially exposed to fluoride poisoning. Geology and high evapotranspiration are the main drivers of fluoride enrichment in groundwater. Consequently, climate change might put even greater pressure on the area's water resources. Our hazard maps should raise awareness and understanding of geogenic fluoride contamination in Ghana and can advise decision making at local levels to avoid or mitigate fluoride-related risks.
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Over the last decades, nutrients and pesticides have proved to be a major source of the pollution of drinking water resources in Europe. Extensive legislation has been developed by the EU to protect ...drinking water resources from agricultural pollution, but the achievement of water quality objectives is still an ongoing challenge throughout Europe.
The study aims to identify lessons that can be learnt about the coherence and consistency of the application of EU regulations, and their effects at the local level, using qualitative expert data for 13 local to regional governance arrangements in 11 different European countries.
The results show that the complexities and inconsistencies of European legislation drawn up to protect drinking water resources from agricultural pollution come forward most explicitly at local level where cross-sectoral measures have to be taken and effects monitored. At this local level, rather than facilitate, they hamper efforts to achieve water quality objectives. The upcoming revision of the Water Framework Directive (WFD) should strengthen the links between the different directives and how they could be applied at local level.
In addition, a more facilitated cross-sectoral approach should be adopted to improve stakeholder networks, between institutional levels and hydrological scales, to attain policy objectives at local level.
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•Nitrate and pesticides from agriculture present some of the highest risks to the quality of drinking water resources.•EU legislation on the protection of drinking water resources from agriculture complex to apply consistently and coherently.•Implementation would benefit from more advanced cross-referencing at the EU level.•Implementation requires capacity at the regional-local level for cross-sectoral decision-making.
A novel concept for fecal pollution analysis was applied at alluvial water resources to substantially extend the information provided by fecal indicator bacteria (FIB). FIB data were linked to river ...connectivity and genetic microbial source tracking (MST). The concept was demonstrated at the Danube River and its associated backwater area downstream of the city of Vienna, using a comprehensive 3-year data set (10 selected sites, n = 317 samples). Enumeration of Escherichia coli (ISO 16649-2), intestinal enterococci (ISO 7899-2) and Clostridium perfringens (ISO 14189) revealed a patchy distribution for the investigation area. Based on these parameters alone a clear interpretation of the observed fecal contamination patterns was not possible. Comparison of FIB concentrations to river connectivity allowed defining sites with dominating versus rare fecal pollution influence from the River Danube. A strong connectivity gradient at the selected backwater sites became obvious by 2D hydrodynamic surface water modeling, ranging from 278 days (25%) down to 5 days (<1%) of hydraulic connectivity to the River Danube within the 3-year study period. Human sewage pollution could be identified as the dominating fecal source at the highly connected sites by adding information from MST analysis. In contrast, animal fecal pollution proofed to be dominating in areas with low river connectivity. The selection of genetic MST markers was focusing on potentially important pollution sources in the backwater area, using human (BacHum, HF183II), ruminant (BacR) and pig (Pig2Bac) -associated quantitative PCR assays. The presented approach is assumed to be useful to characterize alluvial water resources for water safety management throughout the globe, by allocating fecal pollution to autochthonous, allochthonous, human or animal contamination components. The established river connectivity metric is not limited to bacterial fecal pollution, but can be applied to any type of chemical and microbiological contamination.
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•Joining hydrology and microbiology identified main drivers of fecal pollution.•River connectivity and microbial source tracking explained fecal pollution pattern.•Fecal pollution in backwater areas can be caused by internal and external sources.•Human fecal pollution dominated backwater sites with high river connectivity.•Fecal pollution at low connected backwater sites was associated with wildlife.
The objective of this critical review was to provide a comprehensive summary of paralytic shellfish toxins (PSTs) producing species and knowledge gaps in detecting PSTs in drinking water resources, ...with a focus on recent development of PSTs monitoring methods and tools for drinking water monitoring. PSTs, which are also called Saxitoxins (STXs), are a group of neurotoxins not only produced by marine dinoflagellates but also freshwater cyanobacteria. The presence of PSTs in freshwater has been reported from all continents except Antarctica. PSTs in poisoned sea food such as shellfish, molluscs and crustaceans may attack the nerve system after consumption. The high incidences of PSTs occurring in drinking water sources showed another route of potential human exposure. A development of simple and fast screening tools for drinking water surveillance of PSTs is needed. Neurotoxins produced by freshwater cyanobacteria are understudied relative to microcystin and little study is done around PSTs in drinking water monitoring. Some fast screening methods exist. The critical issues for using them in water surveillance, particularly matrix effect and cross-reactivity are summarized, and future research directions are high-lighted. We conclude that monitoring routines at drinking water resources should start from species level, followed by a profound screening of toxin profile. For practical monitoring routine, fast screening methods should be combined with highly sensitive and accurate analytical methods such as liquid chromatography/liquid chromatography–mass spectrometry (LC/LC-MS). A thorough understanding of toxin profile in source water is necessary for screening tool selection.
•The risk of finding PSPs in drinking water resources is elaborated.•Recent developments of PSTs monitoring methods and tools are presented.•A gap between detection level and regulation level in paralytic shellfish poisoning toxins (PSPs) in practice was discovered.•A multistep monitoring system for practical application for PSPs monitoring in drinking water treatment plants was suggested.
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•First regional investigation of EOCs in Dinaric karst aquifers.•65 different EOCs detected, conc. <1 ng/L for almost half.•EOC concentrations are two orders of magnitude lower than ...in other groundwater types.•EOCs are detected more frequently than in other types of groundwater.•EOCs are detected in greater or comparable numbers than in other groundwater types.
Emerging organic contaminants (EOCs) have become of increasing interest due to concerns about their impact on humans and the wider environment. Karst aquifers are globally widespread, providing critical water supplies and sustaining rivers and ecosystems, and are particularly susceptible to pollution. However, EOC distributions in karst remain quite poorly understood. This study looks at the occurrence of EOCs in the Croatian karst, which is an example of the “classical” karst, a highly developed type of karst that occurs throughout the Dinaric region of Europe. Samples were collected from 17 karst springs and one karst lake used for water supply in Croatia during two sampling campaigns. From a screen of 740 compounds, a total of 65 compounds were detected. EOC compounds from the pharmaceutical (n = 26) and agrochemical groups (n = 26) were the most frequently detected, while industrials and artificial sweeteners had the highest concentrations (range 8–440 ng/L). The number of detected compounds and the frequency of detection demonstrate the vulnerability of karst to EOC pollution. Concentrations of 5 compounds (acesulfame, sucralose, perfluorobutane sulfonate, emamectin B1b, and triphenyl phosphate) exceeded EU standards and occurred at concentrations that are likely to be harmful to ecosystems. Overall, most detections were at low concentrations (50 % <1 ng/L). This may be due to high dilution within the exceptionally large springs of the Classical karst, or due to relatively few pollution sources within the catchments. Nevertheless, EOC fluxes are considerable (10 to 106 ng/s) due to the high discharge of the springs. Temporal differences were observed, but without a clear pattern, reflecting the highly variable nature of karst springs that occurs over both seasonal and short-term timescales. This research is one of a handful of regional EOC investigations in karst groundwater, and the first regional study in the Dinaric karst. It demonstrates the need for more frequent and extensive sampling of EOCs in karst to protect human health and the environment.
Arsenic contamination of shallow groundwater is among the biggest health threats in the developing world. Targeting uncontaminated deep aquifers is a popular mitigation option although its long-term ...impact remains unknown. Here we present the alarming results of a large-scale groundwater survey covering the entire Red River Delta and a unique probability model based on three-dimensional Quaternary geology. Our unprecedented dataset reveals that ~7 million delta inhabitants use groundwater contaminated with toxic elements, including manganese, selenium, and barium. Depth-resolved probabilities and arsenic concentrations indicate drawdown of arsenic-enriched waters from Holocene aquifers to naturally uncontaminated Pleistocene aquifers as a result of > 100 years of groundwater abstraction. Vertical arsenic migration induced by large-scale pumping from deep aquifers has been discussed to occur elsewhere, but has never been shown to occur at the scale seen here. The present situation in the Red River Delta is a warning for other As-affected regions where groundwater is extensively pumped from uncontaminated aquifers underlying high arsenic aquifers or zones.
The present study was conducted to investigate the concentration of nitrate in drinking water resources and its carcinogenic risk in the southern provinces of Iran in 2020. Raw data of nitrate ...concentrations were obtained from wastewater and water Company of each province, and Mont Carlo Simulation (MCS) was considered 10
-5
for estimating human carcinogenic risk. Our results demonstrated that in the drinking water resources of Khuzestan and Fars provinces, the nitrate level was 59 and 72 mg/L, respectively, higher than the World Health Organization (WHO) recommendation. The calculated carcinogenic risk of nitrate for Khuzestan and Fars provinces were higher than the range set by WHO and Health Canada, 8.8 × 10
−5
and 1.3 × 10
−5
, respectively. Exposure to an unacceptable nitrate level through drinking water can affect blood carrying oxygen and cause methemoglobinemia and a significant relationship with gastrointestinal cancer spread.
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