Safety Of Water Resources Research Articles

Heavy Metals and Refractory Organic Compounds in Khartoum State’s Groundwater Resources

Groundwater has many characteristics that make it preferable as water supply. But once becomes contaminated, its location and low rate of replacement with fresh water makes it difficult to return it to its pristine state. Toxic and organic chemical pollutants pose threat to the safety of water resources in Khartoum. Contamination of the river Nile system leads to contamination of groundwater resources.Present study aimed to evaluate the current chemical quality of Khartoum state groundwater resources in terms of its heavy metals and refractory organic content. A comparison of the obtained result with national and international standards was also carried out.To realize the objective of this study, a quantitative analysis of nine samples collected from three boreholes named A (Dar Alsalam block (21) ), B (Alkaadarow Almadaris) and C (Alazhari block (15)) during three seasons; autumn, winter and summer were investigated. Heavy metals concentrations (Pb, Cr, Cd and Fe) were determined using Inductively Coupled Plasma- Atomic Emission Spectrometer (ICP- AES). For refractory organic compounds, TOC and BOD5 tests were carried out, the ultimate value (BODu) was calculated as 1.7 BOD5 and then the difference between TOC and BODu was estimated as the concentration of refractory organic compounds.The result showed that groundwater boreholes were safe with respect to cadmium, iron and chromium pollutants, but they contain high levels of lead and refractory organic compounds. The concentrations of lead exceeded both national and international permissible levels which are expected to be due to infiltration of poorly treated sewage and some industrial effluents or from the process of recharging groundwater by contaminated surface water. Since there are no treatment processes in water supply treatment plants targeting the removal of these pollutants, populations consuming this water are expected to be exposed to many health hazards.

Heavy Metals and Refractory Organic Compounds in Khartoum State’s Groundwater Resources

Groundwater has many characteristics that make it preferable as water supply. But once becomes contaminated, its location and low rate of replacement with fresh water makes it difficult to return it to its pristine state. Toxic and organic chemical pollutants pose threat to the safety of water resources in Khartoum. Contamination of the river Nile system leads to contamination of groundwater resources.Present study aimed to evaluate the current chemical quality of Khartoum state groundwater resources in terms of its heavy metals and refractory organic content. A comparison of the obtained result with national and international standards was also carried out.To realize the objective of this study, a quantitative analysis of nine samples collected from three boreholes named A (Dar Alsalam block (21) ), B (Alkaadarow Almadaris) and C (Alazhari block (15)) during three seasons; autumn, winter and summer were investigated. Heavy metals concentrations (Pb, Cr, Cd and Fe) were determined using Inductively Coupled Plasma- Atomic Emission Spectrometer (ICP- AES). For refractory organic compounds, TOC and BOD5 tests were carried out, the ultimate value (BODu) was calculated as 1.7 BOD5 and then the difference between TOC and BODu was estimated as the concentration of refractory organic compounds.The result showed that groundwater boreholes were safe with respect to cadmium, iron and chromium pollutants, but they contain high levels of lead and refractory organic compounds. The concentrations of lead exceeded both national and international permissible levels which are expected to be due to infiltration of poorly treated sewage and some industrial effluents or from the process of recharging groundwater by contaminated surface water. Since there are no treatment processes in water supply treatment plants targeting the removal of these pollutants, populations consuming this water are expected to be exposed to many health hazards.

Ammonia nitrogen removal and recovery from acetylene purification wastewater by air stripping.

Ammonia nitrogen (NH4-N) contaminated wastewater has posed a great threat to the safety of water resources. In this study, air stripping was employed to remove and recover NH4-N from acetylene purification wastewater (APW) in a polyvinylchloride manufacturing plant. Investigated parameters were initial APW pH, air flow rate, APW temperature and stripping time. The NH4-N removal by air stripping has been modeled and the overall volumetric mass transfer coefficient (KLa) of the stripping process has been calculated from the model equation obtained. In addition, the ability of H2SO4 solution to absorb the NH3 stripped was also investigated. The results indicated that under the experimental conditions, the APW temperature and its initial pH had significant effects on the NH4-N removal efficiency and the KLa, while the effects of other factors were relatively minor. The removal efficiency and residual concentration of NH4-N were about 91% and 12 mg/L, respectively, at the optimal operating conditions of initial APW pH of 12.0, air flow rate of 0.500 m3/(h·L), APW temperature of 60 °C and stripping time of 120 min. One volume of H2SO4 solution (0.2 mol/L) could absorb about 93% of the NH3 stripped from 54 volumes of the APW.

Strategic Importance and Safety of Water Resources

Strategic Importance and Safety of Water Resources

Water Security and Climate Change: The Need for Adaptive Governance

Climate change will bring about unprecedented economic, social and environmental effects, which require both the mitigation of greenhouse gas emissions and adaptation to its adverse effects. Water is the main element through which the impacts of climate change will be felt. Climate change results in increased uncertainties, complexities, stress and potential for conflicts within water management, both among and within states. New forms of governance are needed if the world is to respond to the need to adapt to changes in freshwater supply and to manage water security risks.
 This paper suggests that adaptive governance should to be main-streamed into all water regulation to ensure the availability of and access to safe water resources and to prevent water-related conflicts. The paper discusses the concept of water security in the context of climate change, the threats that climate change poses to water security, and the concept and implications of adaptive governance as a possible solution.
 The application of adaptive governance requires a certain degree of institutional and normative flexibility, instruments and institutions that can respond and adapt to changes and manage the level of uncertainty associated with the impacts of climate change. The governance institutions, methods and instruments should be responsive to new information and different kinds of uncertainties, while reflecting the vulnerabilities, capacities, needs and priorities of both societies and ecosystems in the face of climate change. Water security risks could be reduced by increased hydrosolidarity among states, which would present the challenges posed by climate change on water governance and security as primarily an opportunity for new forms of cooperation.

Analysis of the spatial mismatch of grain production and farmland resources in China based on the potential crop rotation system

At present, China’s grain production pattern runs counter to the distribution patterns of farmland resources and water-heat conditions. It is urgently important to conduct research on the spatial matching of grain production and farmland resources. Based on the Potential Crop Rotation data, with regards to the situations of irrigation and rain feeding, this paper builds a measuring model of potential farmland, and separately measures the spatial matching index of grain yield with actual and potential farmland resources, thus revealing China’s grain production pattern. The results indicate that serious spatial mismatch exists between grain production and farmland resources in China. Take the potential crop rotation system into consideration, the spatial mismatch of grain yield and potential farmland resources has been aggravated by the grain production barycenter’s shift to the north China, with low Crop Rotation Index. The function-promoting regions of grain production in China are going through two evolution patterns of “northward and southward expansion” and “westward movement and northward expansion,” respectively. Inefficient use of farmland mainly occurs in the fragile ecological environments, such as the farming-pastoral ecotone of Northern China, the northwest area of Xinjiang and the southwest karst landform areas. The inefficient use of and the decreasing amount of available farmland have become the main causes of the decline in grain production. The problems facing Chinese agriculture caused by the spatial mismatch include the imbalance in regional structures, ecological risks, agricultural production risks, and the risk of food price. In order to cope with these problems, this paper provides some advices on protecting farmland acreage, expanding farmland potential, ensuring the safety of water resources, and extending the industrial grain chain. Our paper additionally proposes policy reforms and innovations designed to ensure the implementation of the above measures, so as to commonly defuse China’s food security crisis.

Large earthquakes create vertical permeability by breaching aquitards

AbstractHydrologic responses to earthquakes and their mechanisms have been widely studied. Some responses have been attributed to increases in the vertical permeability. However, basic questions remain: How do increases in the vertical permeability occur? How frequently do they occur? Is there a quantitative measure for detecting the occurrence of aquitard breaching? We try to answer these questions by examining data from a dense network of ∼50 monitoring stations of clustered wells in a sedimentary basin near the epicenter of the 1999 M7.6 Chi‐Chi earthquake in western Taiwan. While most stations show evidence that confined aquifers remained confined after the earthquake, about 10% of the stations show evidence of coseismic breaching of aquitards, creating vertical permeability as high as that of aquifers. The water levels in wells without evidence of coseismic breaching of aquitards show tidal responses similar to that of a confined aquifer before and after the earthquake. Those wells with evidence of coseismic breaching of aquitards, on the other hand, show distinctly different postseismic tidal response. Furthermore, the postseismic tidal response of different aquifers became strikingly similar, suggesting that the aquifers became hydraulically connected and the connection was maintained many months thereafter. Breaching of aquitards by large earthquakes has significant implications for a number of societal issues such as the safety of water resources, the security of underground waste repositories, and the production of oil and gas. The method demonstrated here may be used for detecting the occurrence of aquitard breaching by large earthquakes in other seismically active areas.

Manganese recovery and ammonia nitrogen removal from simulation wastewater by pulse electrolysis

Abstract Ammonia nitrogen- and manganese-contaminated water poses a considerable threat on the safety of water resources. In this work, pulse current (PC) electrolysis, a novel process, was developed to recover manganese and remove ammonia nitrogen from simulation wastewater simultaneously. Accordingly, the parameters of pulse electrolysis, and technological conditions, including temperature, initial pH, and concentration of addition NaCl, were investigated. The results showed that the concentration of manganese in simulation wastewater could be reduced from 160 mg L−1 to 0.2 mg L−1, meanwhile, ammonia nitrogen could be removed from 80 mg L−1 to 0.1 mg L−1 for 2.5 h PC electrolysis at 30 mA cm−2, 1000 Hz, and duty cycle 50% where settled with Ti/SnO2 IrO2 RuO2 electrodes, when the initial pH was 10.0 and NaCl addition was 0.008 mol L−1 at room temperature. Moreover, XRD and SEM analysis showed that manganese dioxide was deposited on the anode, and manganese in simulation wastewater was mainly recovered in the form of manganese dioxide.

Hydrogeophysical Characterization of Shallow Unconsolidated Alluvial Aquifer in Yenagoa and Environs, Southern Nigeria

Groundwater of the Quaternary shallow alluvial aquifer is the only safe and reliable water resource in Yenagoa and environs, Southern Nigeria. The determination of the aquifer hydrogeophysical parameters is thus critical and constitutes the basic foundation for optimizing the short- and long-term groundwater utilization strategies. In this study, 29 Schlumberger vertical electrical soundings, borehole data, pump test, hydrochemical analysis, and measured and/or calculated hydrogeophysical parameters were integrated to reconnaissance the local aquifer conditions. Aquifer qualitative and quantitative properties in terms of electric and hydraulic conditions were also investigated. The freshwater aquifer was delineated with true resistivity and thickness ranges of 134–664 Ωm and 6.7–41.4 m respectively. Transmissivity and hydraulic conductivity values vary between 189–2609 m2/day and 28–118 m/day, respectively. Porosity ranges between 0.40 and 0.45 and tortuosity ranges between 1.28 and 1.31. Correlation of the results of the geochemical analysis of the groundwater samples with the layer resistivities shows that in the locations where the aquifer is overlain by clay layer (ρ ∼ 10 Ωm) have higher concentrations of dissolved iron (Fe > 0.1 mg/L), whereas the iron concentrations are remarkably low (Fe < 0.1 mg/l) in areas the aquifer is underneath relatively thin silty sand layer (ρ ∼ 349 Ωm). The near-surface lithology acts as a controlling factor for spatial distribution of groundwater iron within the very shallow depths (<20 m). The geochemistry of the groundwater was observed to be controlled mainly by weathering of silicate group of minerals.

Ensure availability and sustainable management of water and sanitation for all

Access to clean, safe and secure water resources is an essential prerequisite for communities to prosper. While access to water and sanitation is often taken for granted in developed countries, this basic right is denied to many across the globe every day.

Forward osmosis as appropriate technology with starch-based draw agent

The appropriate technology (AT) has been gaining attention for securing safe water resources in developing countries. Despite its promising energy-saving operation, forward osmosis (FO) system is a lack of suitable draw agent to be implemented as an AT. In this study, we propose a conceptual small-scale FO system with a starch-based draw agent. This FO system successfully produced about 17.3 L/m2d of drinking water and achieved 95% of the arsenic removal rate using a starch paste combined with amylase as a draw agent. The osmotic pressure, which is necessary for producing permeate water, was generated by small molecules, such as maltose. These molecules were formed from the decomposition of starch by amylase. Because the draw agent used in this study is edible, the permeate water is directly drinkable without any further separation. In addition, diverse starch-containing foods such as flour, raw potatoes, raw sweet potatoes, and bananas were also confirmed as an alternative starch source for draw agent.

Detection of Pesticide Residue in Dams and Well Water in Jazan Area, Saudi Arabia

The application of pesticides indoors and on agricultural lands increased dramatically in recent years in the Jazan area (Saudi Arabia) to control termites and the vectors of diseases, such as Rift Valley Fever (RVF) and malaria. This practice increased the potential risk of pesticide contamination of surface water and groundwater. In this study, samples of 44 wells and 3 dams were collected; the samples were analysed for the presence of 15 pesticides used in the Jazan area. The results showed that the most detected compounds in the surface water samples were diazinon, Dichlorodiphenyltrichloroethane (DDT), fenitrothion and cyfluthrin, with average concentrations of 0.098, 0.104, 0.321 and 0.394 µg L-1, respectively. In the groundwater samples, the most detected insecticides were diazinon, dieldrin and fenthion, with average concentrations of 0.117, 0.005 and 0.472 µg L-1, respectively. In general, detected concentrations of organophosphorus insecticides slightly exceeded the allowed Maximum Residue Limit (MRL) of the European Union, which is 0.1 µg L-1, in some samples. However, the findings of this study about the safety of water resources in the Jazan area were not alarming because the detected concentrations were below the MRL and lower than the limit of the sum of all individual compounds detected in the same sample. More extended investigations are highly recommended.

A hybrid dielectrophoretic system for trapping of microorganisms from water.

Assessment of the microbial safety of water resources is among the most critical issues in global water safety. As the current detection methods have limitations such as high cost and long process time, new detection techniques have transpired among which microfluidics is the most attractive alternative. Here, we show a novel hybrid dielectrophoretic (DEP) system to separate and detect two common waterborne pathogens, Escherichia coli (E. coli), a bacterium, and Cryptosporidium parvum (C. parvum), a protozoan parasite, from water. The hybrid DEP system integrates a chemical surface coating with a microfluidic device containing inter-digitated microelectrodes to impart positive dielectrophoresis for enhanced trapping of the cells. Trimethoxy(3,3,3-trifluoropropyl) silane, (3-aminopropyl)triethoxysilane, and polydiallyl dimethyl ammonium chloride (p-DADMAC) were used as surface coatings. Static cell adhesion tests showed that among these coatings, the p-DADMAC-coated glass surface provided the most effective cell adhesion for both the pathogens. This was attributed to the positively charged p-DADMAC-coated surface interacting electrostatically with the negatively charged cells suspended in water leading to increased cell trapping efficiency. The trapping efficiency of E. coli and C. parvum increased from 29.0% and 61.3% in an uncoated DEP system to 51.9% and 82.2% in the hybrid DEP system, respectively. The hybrid system improved the cell trapping by encouraging the formation of cell pearl-chaining. The increment in trapping efficiency in the hybrid DEP system was achieved at an optimal frequency of 1 MHz and voltage of 2.5 Vpp for C. parvum and 2 Vpp for E. coli, the latter is lower than 2.5 Vpp and 7 Vpp, respectively, utilized for obtaining similar efficiency in an uncoated DEP system.

The effect of cyanobacterial biomass enrichment by centrifugation and GF/C filtration on subsequent microcystin measurement.

Microcystins are cyclic peptides produced by multiple cyanobacterial genera. After accumulation in the liver of animals they inhibit eukaryotic serine/threonine protein phosphatases, causing liver disease or death. Accurate detection/quantification of microcystins is essential to ensure safe water resources and to enable research on this toxin. Previous methodological comparisons have focused on detection and extraction techniques, but have not investigated the commonly used biomass enrichment steps. These enrichment steps could modulate toxin production as recent studies have demonstrated that high cyanobacterial cell densities cause increased microcystin levels. In this study, three microcystin-producing strains were processed using no cell enrichment steps (by direct freezing at three temperatures) and with biomass enrichment (by centrifugation or GF/C filtration). After extraction, microcystins were analyzed using liquid chromatography-tandem mass spectrometry. All processing methods tested, except GF/C filtration, resulted in comparable microcystin quotas for all strains. The low yields observed for the filtration samples were caused by adsorption of arginine-containing microcystins to the GF/C filters. Whilst biomass enrichment did not affect microcystin metabolism over the time-frame of normal sample processing, problems associated with GF/C filtration were identified. The most widely applicable processing method was direct freezing of samples as it could be utilized in both field and laboratory environments.

Microbial Quality of Natural Water Resources in Rural South Africa and Their Potential Influence on the Small-Scale Organic Farming Sector

One of the main obstacles faced by rural, South African(SA) small-scale farmers(ssf) include poor access to reliable and safe land and water resources. The use of environmental resources of questio...

Piped-Water Supplies in Rural Areas of the Mekong Delta, Vietnam: Water Quality and Household Perceptions

In the Mekong Delta (MD) in Vietnam, piped-water supply stations are being intensively built to reach the millennium development goal (MDG) to provide safe and clean drinking water resources to communities. However, studies focusing on the effectiveness of supply stations in reaching these goals are scarce to date. Water samples from 41 water supply stations in the MD were collected between June and October 2012. Water samples were analyzed for general parameters, salinity, nutrients, metal(loid)s and microbial indicator bacteria and compared with World Health Organization (WHO) and Vietnamese drinking water guidelines. In addition, 542 household interviews were conducted to investigate the connection rate to piped-water and people’s perceptions regarding piped-water supplies. The results show that water guidelines were exceeded for pH (min. 6.2), turbidity (max. 10 FTU), Cl (max. 1,576 mg·L−1), NH4 (max. 7.92 mg·L−1), Fe (431.1 µg·L−1), Hg (11.9 µg·L−1), and microbial indicator bacteria (max. total coliform 50,000 CFU 100 mL−1). Moreover, more than half of the interviewed households with access to a piped-water supply did not use this supply as a source of drinking water due to (i) high connection fees; (ii) preference for other water sources; and (iii) perceived poor quality/quantity. Our study shows that the maintenance and distribution of water supply stations should significantly improve in order for piped-water to become a reliable drinking water source. Additionally, alternatives, such as rainwater harvesting and decentralized treatment facilities, should also be considered.

Application of Response Surface Methodology to Enhance Phenol Removal from Refinery Wastewater by Microwave Process

Phenol contaminated petroleum refinery wastewater presents a great threat on water resources safety. This study investigates the effect of microwave irradiation on removal of different concentrations of phenol in an attempt for petroleum refinery wastewater treatment. The obtained results show that the MW output power and irradiation time have a significant positive effect on the removal efficiency of phenol. The kinetic reaction is significantly affected by initial MW output power and initial phenol concentrations. Response surface methodology (RSM) was employed to optimize and study the interaction effects of process parameters: MW output power, irradiation time, salinity, pH, and H2O2 concentration using central composite design (CCD). From the CCD design matrix, a quadratic model was considered as an ultimate model (R2 = 0.75) and its adequacy was justified through analysis of variance (ANOVA). The overall reaction rates were significantly enhanced in the combined MW/H2O2 system as proved by RSM. The optimum values for the design parameters of the MW/H2O2 process were evaluated giving predicted phenol removal percentage of 72.90% through RSM by differential approximation and were confirmed by experimental phenol removal of 75.70% in a batch experiment at optimum conditions of 439 W MW power, irradiation time of 24.22 min, salinity of 574 mg/L, pH 5.10, and initial H2O2 concentration of 10% (v/v).

Hydrogeochemical zonation and its implication for arsenic mobilization in deep groundwaters near alluvial fans in the Hetao Basin, Inner Mongolia

Summary High As groundwater has been found in shallow aquifers of the flat plain of the Hetao basin, but little is known about As concentration in deep groundwaters around piedmont areas, which are the major drinking water resources. One hundred and three groundwater samples from wells with depths >50 m and seven samples from one multi-level monitoring well (89 m in depth) were analyzed for chemical compositions and 18O and D isotopes to examine the geochemical processes controlling As mobilization. According to hydrogeological setting, chemical and isotopic characteristics of deep groundwater, three distinguished hydrogeochemical zones are delineated, including Recharge-Oxic Zone (Zone I), Groundwater Flow-Moderate Reducing Zone (Zone II), and Groundwater Flow-Reducing Zone (Zone III). Zone I is located in proximal fans in the recharge area with oxic conditions, where low As groundwater generally occurs. In Zone II, located in the intermediate between the fans and the flat plain with Fe-reduction predominated, groundwater As is moderate. Zone III lies in the flat plain with the occurrence of SO 4 2 - reduction, where high As groundwater is mostly found. This indicates that release of As to groundwater is primarily determined by reduction sequences. Arsenic is immobilized in O 2 / NO 3 - reduction stage in Zone I and released in Fe-reducing conditions of Zone II, and displays a significant elevated concentration in SO4-reducing stage in Zone III. Dissolution of carbonate minerals occurs in Zone I, while Ca2+ and Mg2+ are expected to precipitate in Zone II and Zone III. In the multi-level monitoring well, both chemical and isotopic compositions are dependent of sampling depths, with the similar trend to the hydrogeochemical zonation along the flow path. The apparent increases in δD and δ18O values in Zone III reveal the possibility of high As shallow groundwater recharge to deep groundwater. It indicates that deep groundwaters in proximal fans have low As concentrations and are considered as safe drinking water resources in the Hetao basin. However, high As concentration is frequently observed in deep groundwater in the flat plain, which should be routinely monitored in order to avoid chronic As poisoning.

Successive advanced oxidation of pyridine by ultrasonic irradiation: effect of additives and kinetic study

Pyridine has received considerable attention from environmental scientists and engineers, due to its undesirable effect in the water environment. Pyridine contaminated wastewater presents a great threat on water resources safety. In this research, the degradation and advanced oxidation of pyridine in aqueous solution by ultrasonic waves were studied under various process variables including different initial concentration, H2O2, NaCl, and Fenton reagent. The results show that the degradation efficiency of pyridine decreases with the increasing of the initial concentration of pyridine. The removal rates of pyridine decreased from 52 to 15% with increasing the initial concentration from 10 to 100 mg/L. In the concentration range studied, the amount of H2O2 and NaCl added has positive contribution on the degradation of pyridine. The removal effect of ultrasound and Fenton is better than ultrasound or H2O2 alone acting on pyridine. A possible degradation pathway for pyridine was also proposed. In the end, it could be proposed that ultrasonic irradiation was an effective method for the removal of pyridine from wastewater.

Water Resource Security Strategy in Qinhuangdao City, Hebei Province

With the quick development of economy, increase o f population and urbanization, urban water security becomes a limited factor to fulfill the urban sustainable development. Qinhuangdao is a water shortage of resources and pollution-induced water shortage city. Under the major background of global warming, the climate of Qinhuangdao becoming warmer and drier in recent years, the precipitation has decreased correspondingly. The rivers runoff reduces obviously and the level of the groundwater drops. The quantity of usable water resource is reduced significantly. Impacted by the urbanization, social-economic development and rapid population growth, the demand of water resource increases continuously. The security situation of water resource in Qinhuangdao is becoming more severe. Through analyzing the water resource situation, existing issues and reasons in Qinhuangdao city, the author proposed regulating approaches to ensure safety of water resources.