Main Source Of Drinking Water Research Articles

Occurrence and Risk Assessment of N-nitrosamines and Their Precursors in Qingjiang River Basin

N-nitrosamines are a type of nitrogen-containing organic pollutant with high carcinogenicity and mutagenicity. In the main drinking water sources of small and medium-sized towns in China, the contamination levels of N-nitrosamines remain unclear. In addition, there is still lack of research on the concentration of N-nitrosamines and their precursors in tributary rivers. In this study, eight N-nitrosamines and their formation potentials （FPs） were investigated in the Qingjiang River, which is a primary tributary of the Yangtze River. The sewage discharge sites were also monitored, and the environmental influencing factors, carcinogenic and ecological risks caused by N-nitrosamines, and their precursors were evaluated. The results showed that six N-nitrosamines were detected in water samples of the Qingjiang River, among which NDMA [（10 ±15） ng·L-1], NDEA [（9.3 ±9.3） ng·L-1], and NDBA [（14 ±7.8） ng·L-1] were the dominant N-nitrosamines, whereas seven N-nitrosamines were detected in chloraminated water samples, among which NDMA-FP [（46 ±21） ng·L-1], NDEA-FP [（26 ±8.3） ng·L-1], and NDBA-FP [（22 ±13） ng·L-1] were the dominant N-nitrosamine FPs. The concentrations of N-nitrosamines in the middle reaches of the Qingjiang River were higher than those in the upper and lower reaches. Furthermore, the concentrations of N-nitrosamines in the sample sites of sewage discharge and tributaries were significantly higher than those in other sampling sites. The monitoring results at the direct sewage discharge points indicated that the main source of N-nitrosamines in river water was the sewage carrying N-nitrosamines and their precursors. In addition, the concentrations of the three dominant N-nitrosamines including NDMA, NDBA, and NDEA were positively correlated with each other, mainly because of their similar sewage sources. The average carcinogenic risk to residents due to N-nitrosamine in drinking water sources was 2.4×10-5, indicating a potential carcinogenic risk. Moreover, due to the high concentrations of N-nitrosamine formation potentials in the Qingjiang River, the carcinogenic risk of drinking water may be even higher. The ecological risk assessment showed that the ecological risk quotient values of N-nitrosamines in the Qingjiang River watershed were lower than 0.002, which was negligible.

The Dynamics of the Concentration and Speciation of Arsenic in Private Drinking Water Wells in Eastern Wisconsin, USA

About 2.5 billion people rely on groundwater as their main drinking water source, and arsenic pollution within the groundwater system can cause serious short- and long-term health issues. Within the natural environment, arsenic generally exists as oxyanions which have two oxidation states, As(III) and As(V). Under ambient pH conditions, As(V) is primarily present as an anion (i.e., H2AsO4−) while As(III) tends to be uncharged (i.e., H3AsO3), making it much more difficult to remove As(III) through existing treatment techniques such as adsorption and reverse osmosis (RO). In Eastern Wisconsin, the dolomite and dolomite/sandstone aquifers represent a major drinking water source and high arsenic concentrations have been observed. Previous studies showed that arsenic can be released into private drinking water wells due to the oxidation of sulfide-bearing minerals with arsenic impurities that are usually dispersed within the dolomite and sandstone bedrock. However, there is a lack of information on the concentrations of each arsenic species as well as arsenic dynamics during water pumping/usage. The primary goals of this research were (1) to quantify the baseline concentrations of each arsenic species within selected Eastern Wisconsin private drinking water wells, and (2) to determine how the arsenic concentrations and species could be affected by continuous water usage. Our results showed that As(III) was the dominant species of arsenic, and during continuous water usage, there could be an upward trend in arsenic concentration (there was minimal change in arsenic speciation). Upon the completion of water pumping, arsenic concentrations decreased over time and returned to pre-pumping levels. Our findings highlighted the importance of quantifying the speciation and dynamics of arsenic during water use to the assessment of public health risks and the design of appropriate water treatment techniques.

Assessment of Groundwater Quality of Taluka Bulri Shah Karim, District Tando Muhammad Khan, Sindh, Pakistan

Groundwater in Pakistan is the main drinking water source, highlighting the significance of regularlymonitoring its quality. There have been several examples of high concentrations of elements like arsenic and nitrate ingroundwater that harm human health and the environment. Our aim with this study was to assess the groundwater qualityof the sub-district Bhulri Shah Karim for drinking and irrigation purposes. We collected groundwater samples from 53shallow bore well hand pumps in October and November 2018. We determined the concentration of four cations, fiveanions and other parameters like pH, turbidity, TDS, total hardness, EC, alkalinity, total iron, and arsenic. Thegroundwater was found to be very hard, and the relative abundance of cations and anions was Na+> Ca2+> Mg2+> K+ andCl‾ > HCO3‾ > SO42‾ > NO3‾ > F‾. The concentrations of arsenic and iron varied from 0 to 0.2 mg/L and 0.02 to 3.6mg/L, respectively. We discussed groundwater quality for drinking and irrigation purposes by calculating the waterquality index, sodium adsorption ratio, percent of sodium, permeability index, and residual sodium carbonate. Inconclusion, the groundwater of the studied area is suitable for drinking on average and irrigation. However, some watersamples were high in arsenic content, and some were highly saline and may need some prior treatment

SettingsAustin Williams. China’s Urban Revolution: Understanding Chinese Eco-Cities

Austin Williams. China’s Urban Revolution: Understanding Chinese Eco-Cities. London and New York: Bloomsbury Academic. 2017. 220 pages. Price US $ 124.95 (Hardback). China is still considered to be a polluter and its city life is deplorable with unbreathable air and contaminated drinking water. These are the thoughts of the past and China is now bidding to emerge as an environmental soft-power at an impressive rate. The main argument of this book revolves around China’s rapid urbanisation and China’s government-led eco-city building programme. It is an attempt to falsify the Manichean Worldview of China, which tries to provide comprehendible classifications of a country that is much advanced for that. With rapid development and wealth creation, China’s fast urbanisation has outpaced that of any other country in the world, adding 458 cities in just last 4 decades—110 cities in a decade. But China is now pausing to think what it had done right and wrong in the last 40 years. William starts the book by explaining what a city is as well as the eco-city, and simplifies the definition of eco-city provided by the Chinese government i.e. a city where main drinking water sources are ‘adequate’ and its air quality is rated ‘good’ on 123 days of a year. Then he moves on how China has turned barren lands into wealth creating giants. But all this wealth and prosperity at that pace resulted in urban challenges like degraded environment. Over the course of the book, William contextualises the Chinese society and its evolution with respect to political events. Wealth creation is still the top priority of the Chinese government. To portray a soft image of the country, China is trying on multiple facets. For example, the Chinese Society for Urban Studies has created a new 28-item eco-city friendly list, which is different from other checklists such as by UNHABITAT and BREEAM. Throughout the book William uses sarcastic notes on how China is learning to experiment with spaces either by inviting rural households to newly developed cities or by reforming the older ones. From the book, it looks like there is a long way ahead for China to become eco- friendly. [Aqeel Anwar Chaudhry]

Pyrite-based denitrification combined with electrochemical disinfection to remove nitrate and microbial contamination from groundwater

Nitrate and microbial contamination of groundwater can occur in countries that face intense urbanization and inadequate sanitation. When groundwater is the main drinking water source, as is often the case in such countries, the need to remove these contaminants becomes acute. The combination of two technologies is proposed here, a biological step to denitrify and an electrochemical step to disinfect the groundwater, thereby aiming to reduce the chemical input and the footprint of groundwater treatment. As such, a pyrite-based fluidized bed reactor (P-FBR) was constructed to autotrophically denitrify polluted groundwater. The P-FBR effluent was disinfected in an electrochemical cell with electrogenerated Cl2. Nitrate was removed with 79% efficiency from an initial 178 mg NO3− L−1 at an average denitrification rate of 171 mg NO3− L−1 d−1, with 18 h hydraulic retention time (HRT). The electrochemical unit achieved a 3.8-log reduction in total coliforms with a 41.7 A h m−3 charge density.

A Study of Infrastructural Development in District Siddharth Nagar

Abstract: This research paper focuses on the study of infrastructural development in District Siddharth Nagar, examining the current state of basic infrastructure facilities such as electricity, primary schools, drinking water sources, healthcare facilities, and irrigation infrastructure. The methodology includes a combination of primary data collection through interviews and surveys with key stakeholders and secondary data collection from government reports and relevant sources. The findings reveal that all villages in the district are electrified, with approximately 70% of the villages having primary schools. Hand pumps are the main drinking water source in the majority of villages, indicating a need for improved water supply infrastructure. The presence of sub-centers and healthcare professionals in certain villages reflects progress in healthcare infrastructure. Moreover, a significant portion of cultivable land is under irrigation, supporting agricultural activities. The conclusion emphasizes the importance of continued efforts to address gaps in infrastructure, including enhancing water supply infrastructure, expanding educational facilities, and strengthening healthcare services. Policymakers and stakeholders can utilize the study findings to formulate effective strategies for sustainable infrastructural development in District Siddharth Nagar, ultimately improving the socio-economic conditions and well-being of the residents. Further research and monitoring are recommended to assess progress and inform evidence-based decision-making in the future.

HYDROGEOLOGICAL VARIATIONS IN SAHYADRI GROUP AND SATPURA GROUP OF DECCAN TRAPS: COMPARATIVE STUDY OF REPRESENTATIVE WATERSHEDS FROM THE NANDURBAR DISTRICT OF MAHARASHTRA, INDIA

Water is an elixir of the life and groundwater is the main source of drinking, irrigation, and industrial water uses. Occurrence and movement of the groundwater is mainly depending on the hydrogeological characteristics of the rocks. About 80% of the Maharashtra state is occupied by Deccan basalt exhibiting diversity in the groundwater development. In present study, an attempt has been made to do comparative study of Gomai watershed and Amaravati watershed for analyzing the hydrogeological behavior of basalts of Sahyadri Group and Satpura Group of Deccan Traps.

Portable Water Sources in Rural Communities the Experience of Togmaa Community in the Wa West District

Surface waters are the main drinking water source for many rural communities in Ghana including Wa West District and Togmaa in particular. The water crisis in Togmaa is a threat to quality sanitation and health in the community. This necessitated the study. A case study approach enabled the researchers to delve much into the phenomenon under study. The methodology included the use of a mixed-method approach (qualitative and quantitative). The sampling technique used was simple random and purposive sampling. A semi-structured interview guide was used to gather data from 39 households as sampled for the study. Key informant interviews were also used to gather data from chiefs, assemblymen, Magazia (women leader) and the Wa West District Assembly. The study also used observation to observe the water sources in the community. Data gathered from Semi-structured interviews were coded and entered into the SPSS to generate results and presented in Microsoft word using pie charts, bar charts and tables. With the qualitative data using Key Informant Interviews were transcribed and classified under themes with quotes from respondents. The results and conclusions from the study revealed that Togmaa community lack a portable water source compelling resident to drink from polluted pounds; it was also found that community members’ enthusiasm to contribute to a borehole facility is thwarted by the poor household income status. Other findings revealed that the people of Togmaa believe the Government of Ghana has the main responsibility to provide them with a water facility, even though they are also willing to contribute their human resource and meagre incomes towards getting a befitting water facility.

Assessment of the water quality of the Niger River in Bamako, Mali, based on the Water Quality Index

Abstract The Niger River, threatened by human activities, is the main drinking water source for the population of Bamako city. This study assesses the trend of Niger River pollution in Bamako using the Water Quality Index (WQI). Fourteen parameters, namely Turbidity, Potential of Hydrogen (pH), Electrical Conductivity, Dissolved Oxygen, Total Dissolved Solids, Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Nitrate, Nitrite, Ammonium, Phosphate, Sulphate, Chloride and Copper, were employed to characterise the Niger River water quality during the period from 2016 to 2020. Parameters were measured at 15 sampling locations. High values of Turbidity, pH and high concentrations of BOD5, COD, Nitrite, Ammonium and Phosphates were recorded. The results showed that the Niger River water quality was good for 4 months and poor for 5 months during the dry season in a low flow period. Moreover, the water quality was poor during the 3 months of the wet season in the high flow period. The calculated WQI average values ranged from 75 to 100, indicating very poor water quality from upstream to downstream of Bamako city. Therefore, the Niger River water is polluted and cannot be used for drinking or industrial uses without any treatment.

The Effect and Sustainable Management of Simply Overdraft in Two Different Groundwater Observation Wells

The term overdraft has been defined as a situation in which groundwater extraction by pumping exceeds the aquifer charge over an extended period of time. Groundwater is the main source of drinking and utility water in rural areas, especially in arid and semi-arid regions. The aquifer is recharged by precipitation, rivers, and lakes. Causes such as the increase in temperatures due to climate change, decrease in precipitation, pollution of aquifers with wastes negatively affect the recharge of groundwater. When unlicensed wells and unconscious use of water in agriculture are added to all these reasons, which increase overdraft, the future of groundwater is endangered. For this reason, the sustainable management of groundwater is of great importance. In this study, changes in water levels were investigated by using the data of some observation wells within the borders of Uluova micro-basin in Elazig Province, one of the sub-basins of the Fırat basin, one of the important basins of Turkey. The study was carried out by comparing the seasonal water level measurements of two different observation wells drilled at the same ground level in Yurtbaşı and Yazıkonak towns within the borders of the Uluova basin in 2011-2018. Seasonal water level measurements for each year in the relevant observation wells were made in September when the water level is the lowest and in April when the water level is the highest. In both observation wells, it was observed thatgroundwater levels dropped significantly in September, the end of the dry period. Except for 2018, it was observed that the water levels in the Yurtbaşı observation well in September and April decreased much more than the water levels in the Yazıkonak observation well. In the September 2018 measurement, the measurement could not be made because the water in the Yazıkonak observation well was completely exhausted. When the seasonal water changes in the wells are examined, it can be said that the seasonal water level change in the Yurtbaşı observation well is more pronounced, except for 2018. As a result, it was observed that the water level in both wells decreased with each passing year compared to the previous year. This shows that overdraft results should be investigated in more detail by examining different observation wells in the region. In addition, it has been understood that it is very important to create a management model for the sustainability of groundwater resources by using the data of other observation wells in the basin.
 Keywords: Groundwater, Overdraft, Well, Sustainable management*This study has been produced from the PhD research titled “Uluova Mikro Havzası Yeraltı Sularının Sürdürülebilir Yönetimi (Sustainable Management of the Uluova Micro Basin)” which is being prepared in the Graduate School of Sciences Fırat University, Department of Civil Engineering, Hydraulic Doctorate Program

Uranium in groundwater in parts of India and world: A comprehensive review of sources, impact to the environment and human health, analytical techniques, and mitigation technologies

Uranium concentration/contamination in groundwater is currently a subject of concern all over the world due to related severe health problems to humans, as groundwater is the main drinking water source in rural and urban India and also in several parts of the world. Uranium concentration in groundwater in shallow aquifers in various states such as Punjab, Rajasthan, Karnataka Telangana, and Madhya Pradesh of India varies from 0 to 1443 ng/ml exceeding the permissible levels by WHO for drinking water (30 ng/ml), at several places. Very high concentrations ranging up to 1400 ng/ml were reported in some areas in other countries such as Canada, the USA, Mongolia, Burundi, Zambia, Nigeria, South Korea, Pakistan, Jordon, Afghanistan, China, and Myanmar. Various natural aspects which influence the uranium concentration in groundwater such as bedrock geology, water chemistry, and redox conditions, and anthropogenic sources such as mining activities (uranium, coal, and phosphate rock), nuclear activities, agricultural practices of using phosphate fertilizers, and prevalence of excessive nitrate in some areas, are described with examples. Some of the important analytical techniques for the precise and accurate determination of elemental and isotopic concentrations of uranium in water samples, such as LED fluorimetry, Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), high-resolution ICP-MS (HR-ICP-MS), and multi-collector ICP-MS (MC-ICP-MS), are described. A number of advancements have taken place in remediation technologies for the removal of uranium in drinking water using different physical, chemical, and biological methods including rainwater harvesting. Various mitigation strategies for the effective removal of uranium from water during treatment, such as bioremediation using biochars from different sources, nanoparticle technology, and adsorption by magnesium (Mg)-iron (Fe)-based hydrotalcite-like compounds (MF-HT), are described in detail.

Assessment of karst water quality and analysis of pollution sources with a projection pursuit algorithm in Jinan spring area, China

Abstract Karst water is one of the main drinking water sources in North China. The single factor method and projection pursuit algorithm (PPA) are employed to assess the karst water quality of the Baotu spring area in Jinan. The water quality distribution pattern, its causes, and the main groundwater pollution sources are analyzed. The water quality evaluation results of the PPA model are more reliable than those of the single factor method because the PPA model comprehensively considers the weight and correlation of various factors. The water quality of the study area is generally excellent, but the NO3− index content is high. In recent years, the water quality grades have been mainly class II ∼ class IV. The driving factors of water quality evolution are not only human activities, including artificial recharge, but also natural factors, such as carbonate mineral dissolution. These factors control both the distribution and evolution trend of water quality. Urban nonpoint sources have a significant impact on groundwater quality. Based on the current water quality situation, it is urgent to strengthen protection of the ecological environment in the southern recharge area of the spring region and the water quality control in the western region.

Groundwater Quality of Drinking Water Wells in the West Bank, Palestine

Groundwater, the main drinking water source in the West Bank, is highly vulnerable to pollution given the karstic nature of the aquifer. This study was aimed at screening the quality of groundwater used for water supply, in terms of physicochemical and microbiological properties, and heavy metals concentrations. Attention was given to groundwater chemistry, using piper and Durov diagrams, to assess potent impact of pollution on groundwater. Twenty-nine groundwater samples from selected wells, representing the different groundwater fields in the West Bank, were collected and analyzed. The results revealed that the concentration of the ions and parameters affecting the aesthetic and health related water quality, such as Cl−, Na+, NH4+, TDS, and NO3−, and selected (semi) metals, including Cr, Cu, Fe, Mn, Pb, Cd, and As, are within the limits recommended for drinking water. The dominant cations and anions were in the order of Ca2+ > Na+ > Mg2+ > K+ > NH4+ and HCO3− > Cl− > NO3− > SO42−, respectively. The total average groundwater hardness is approximately 2.1 mmol/L and can be attributed to calcium (approximately 60%) and magnesium. The major ground water types in the West Bank were fresh water (Ca-Mg-HCO3), fresh water mixed with another water type (Ca-Mg-Na-HCO3 or Ca-Mg-HCO3-Cl), and extreme water type (Na-Ca-Mg-HCO3-Cl or Na-Ca-HCO3-Cl) showing high TDS, Cl− and Na+. Signs of pollution, namely elevated levels of nitrate and ammonium, were, however, observed even in some deep wells (>600 m), despite the thick cover of soil, tapping the Lower Ceneomanian confined aquifer.

Predicting factors of public awareness and perception about the quality, safety of drinking water, and pollution incidents.

Public perception of drinking water quality and safety results from the interaction of multiple factors, including the public engagement, which requires sufficient knowledge and awareness. This issue has yet to be addressed in Algeria. This study investigated the residents' perception and awareness about the drinking water quality, safety, and water pollution events. A survey-based cross-sectional study was conducted amongst citizens living in the province of Biskra. Multinomial regression analysis was used to identify the predicted public perception factors about drinking water-related issues. Regardless of the degree of public trust in the drinking water sources, the main drinking water source reported by the participants was tank water (43.3%) followed by tap water (32%). Water quality standards are a measure of the condition of water relative to the contaminants. Water consumption profiles gave priority attention to taste (48.7%), odour (35%), appearance (34.7%), and colour (32%), reflecting a low level of knowledge about the water quality standards. Most of the residents (55.7%) reported a deficient communication about the preventive measures to protect public health. The higher level of education showed a statistically significant impact in discriminating between those who felt very satisfied and dissatisfied participants with the drinking water quality and those who felt between satisfied and dissatisfied (P = 0.023, P = 0.034, respectively). Additionally, education level had a statistically significant role in differentiating trust levels in drinking water quality between two groups, those belonging to either confident or relatively confident and the group of extremely worried respondents, with P = 0.000 and P = 0.000, respectively. Interviewed respondents with certain education levels showed higher trust in the safety of drinking water when compared to those with lower education levels. Gender had a significant role in differentiating the group of respondents who were relatively confident from those who were extremely worried (P = 0.016). The public knowledge about the standards of water quality, safety, and the pollution-related issues remains relatively low. This study is of interest to policy makers and public health authorities who implement actions for water contamination prevention and public health protection. These findings could have national implications and are also applicable, in general context, particularly in low and middle-income countries.

The content of heavy metals in the water of Lake Gusinoe (Western Transbaikalia) and its tributaries

Investigation of the transformation of substances in the basin of the Selenga River, the main tributary of Lake Baikal, due to anthropogenic impact under conditions of global climate change, is especially important for Lake Baikal which is a World Natural Heritage Site and the main source of fresh drinking water not only in the region, but also in the world. One of the key research objects in the Selenga River basin, which is subject to significant anthropogenic impact, is the ecosystem of Lake Gusinoe. This study presents the results of analysis of the physical and chemical parameters of the water mass of Gusinoe Lake basin. for the period from 2017 to 2020. Thus, the results on hydrochemical indicators for a long-term period of research of the lake show changes in the chemical composition of water and the concentration of main ions. In 2020, the content of almost all metals was higher than in 2017-2020, which may be due to the rise in the level of Lake Gusinoe and groundwater that began in 2019 and continued in 2020, as a result of rain floods that caused flooding of the coastal territories and the entry of pollutants into watercourses and the lake.

Geochemical and isotopic evidence of groundwater salinization processes in the Essaouira region, north-west coast, Morocco

The city of Essaouira is located along the north-west coast of Morocco, where groundwater is the main source of drinking, domestic and agricultural water. In recent decades, the salinity of groundwater has increased, which is why geochemical techniques and environmental isotopes have been used to determine the main sources of groundwater recharge and salinization. The hydrochemical study shows that for the years 1995, 2007, 2016 and 2019, the chemical composition of groundwater in the study area consists of HCO3–Ca–Mg, Cl–Ca–Mg, SO4–Ca and Cl–Na chemical facies. The results show that from 1995 to 2019, electrical conductivity increased and that could be explained by a decrease in annual rainfall in relation to climate change and water–rock interaction processes. Geochemical and environmental isotope data show that the main geochemical mechanisms controlling the hydrochemical evolution of groundwater in the Cenomanian–Turonian aquifer are the water–rock interaction and the cation exchange process. The diagram of δ2H = 8 * δ18O + 10 shows that the isotopic contents are close or above to the Global Meteoric Water Line, which suggests that the aquifer is recharged by precipitation of Atlantic origin. In conclusion, groundwater withdrawal should be well controlled to prevent groundwater salinization and further intrusion of seawater due to the lack of annual groundwater recharge in the Essaouira region.

VİLƏŞÇAY SU ANBARININ SUYUNUN KEYFİYYƏTİNİN KİMYƏVİ GÖSTƏRİCİLƏRƏ GÖRƏ QİYMƏTLƏNDİRİLMƏSİ

Abstract: The article is devoted to the assessment of water quality according to chemical indicators in the vileshchay water reservoir, which is the main source of drinking water supply in Masalli region. The study used the results of the analysis of water samples covering the years 1994-2017 of the Shikhlar hydrological station operating on the vileshchay, the main source of nutrition of the reservoir. The basic ions and water hardness were determined. The results of the analysis were compared with the existing Sanitary Norms and Regulations, as well as with the World health Organization's permissible Solidarity limit, and the results obtained were analyzed. unlike other lankaran rivers, vileshchay water belongs to the chlorine class of the sodium and potassium group, as the river is dominated by chlorine from anions and sodium and potassium from cations during the year. Keywords: Vileshchay reservoir, water quality, ionic composition, water hardness, permissible concentration limit.

Turbidity reduction by household scale electrocoagulation device

Pollutant parameter that often exceed the standard is turbidity, then the turbidity parameter was the main concern in this research. The electrocoagulation method is an alternative for treating water without using chemicals. This study aims to reduce the turbidity and develop previous research on electrocoagulation methods into a pilot scale with a flow rate of 0.01 L/sec. The flow rate 0.01 L/sec illustrates the water requirements for one household. In this study the electrocoagulation method was tested by the variation of electrode plates 1, 2 and 3 pairs with 3, 5, 7 and 10 Volts to treat artificial sample water with an initial turbidity of 100 NTU made from sample of raw water from Cikapundung River as one of main drinking water sources in Bandung. The optimal conditions obtained in the preliminary study were retested with turbidity variations of 25, 50, 100, 200, 300 and 400 NTU. The optimal condition of the electrocoagulation process is obtained in the variation of 2 pairs of plates with a voltage of 7 Volts and current density 23.53 A/m2. The variation can treat raw water with an initial turbidity up to 400 NTU until it reaches a quality standard with a final turbidity of 3.40 NTU and the percentage of removal is 99.15%.

The Levels, Sources, and Spatial Distribution of Heavy Metals in Soils from the Drinking Water Sources of Beijing, China

Our study area is the upstream watershed of the Guanting and Miyun Reservoirs; together, these two reservoirs comprise the main drinking water source of Beijing, China. In order to prevent crop contamination and preserve the quality of the water and soil, it is important to investigate the spatial distribution and the sources of the heavy metals in farmland soils on the watershed scale. For this study, we collected 23,851 farmland surface soil samples. Based on our analysis of the concentrations of eight heavy metals in these samples, we found that the overall soil quality in our study area is excellent, but that the Cd, Cu, Zn, and Cr contamination risks are relatively high. Moreover, a percentage of samples exceeded the Cd (1.54%,), Cu (0.28%), Zn (0.25%), Cr (0.13%), Pb (0.09%), As (0.05%), Ni (0.04%), and Hg (0.02%) risk screening values for soil contamination in agricultural land. In addition to determining the spatial distribution characteristics of the heavy metal concentrations of the soil samples, we also conducted a factor analysis and an R cluster analysis (CA) whcih can gathered the similar variables to track the sources of the heavy metals. We found that the Cd, Pb, and Zn are likely sourced from a quartz syenite porphyry body and from coal-fired enterprises, while the Cr, Cu, and Ni contaminations are mainly caused by runoff from iron ore smelting. Additionally, agricultural production contributes to the local accumulation of Cu, and industrial (smelting) discharge is partially responsible for the As contamination. As a result of the atmospheric deposition of pollutants, areas with high Hg concentrations are generally centered on large- and medium-sized cities. Due to these high natural heavy metal background values, the existing and future heavy metal contamination in the watershed poses a serious ecological risk to both the soil and the surface water.

Relationship between household safe drinking water, hygienic toilet and prevalence of stunting for Chinese children aged 0 to 5 years old in 2013

To investigate the relationship between household drinking water, toilet status and the prevalence of stunting for Chinese children aged 0 to 5 years old in 2013. Data was extracted from the Chinese National Nutrition and Health Surveillance in 2013. A total of 32 861 children aged 0 to 5 years old were selected from 165 townships(streets) of 55 counties(cities/districts) in 30 provinces. Caregivers were face to face interviewed to collect data, including demographic characteristics of children, mothers and household, main source of household drinking water and main type of household toilet. Height/Length of children was measured using a standard procedure. Height(Length) for age Z score(HAZ(LAZ)) was calculated using WHO Anthro Survey Analyser software(online version), and stunting was defined as HAZ(LAZ)<-2. SAS 9. 4 was used to analyze. SURVEYFREQ procedure was used to calculate the coverage rate of safe drinking water, hygienic toilet, and the prevalence of stunting. SURVEYLOGISTIC procedure was used to analyze the relationship between household safe drinking water, hygienic toilet and prevalence of stunting for Chinese children aged 0 to 5 years old in 2013. A total of 32 861 children completed the study. The coverage rate of safe drinking water was 86. 9%. The proportion of water piped into household, a public tab and water from a protected spring or well was 49. 4%, 15. 9% and 15. 6%, respectively. The coverage rate of hygienic toilet was 56. 8%. The proportion of pour-flush toilet and pit latrine were 52. 1% and 4. 7%. The prevalence of stunting for 0 to 5 years old children was 8. 1% in China. The prevalence of stunting were 8. 1% for children aged 0-5 years old with safe household drinking water and 7. 8% for those without safe household drinking water. The difference was not significant(P=0. 882). The prevalence of stunting was 6. 6% for children aged 0-5 years old with hygienic household toilet and 10. 0% for those without hygienic household toilet. The difference was not significant(P=0. 069). There was no significant relationship between household sanitary condition and stunting for children aged 0 to 5 years old. Household sanitary conditions, including main source of household drinking water and the main type of household toilet may not be associated with the prevalence of stunting for children aged 0 to 5 years old in this settings.