High Concentrations Of Total Dissolved Solids Research Articles

Economic assessment of a multistage surface-heated vacuum membrane distillation process for the treatment of hypersaline produced water

The treatment and disposal of hypersaline produced water remains a challenge, particularly for oil and gas producers in the Permian basin where production wells generate significant amounts of wastewater, and the traditional method of injecting wastewater into disposal wells is coming under increasing scrutiny. Here we investigate the viability of using solar energy to power a multi-stage, surface heated, vacuum membrane distillation (SHVMD) with energy recovery to treat hypersaline produced wastewater from Midland, Texas. Membrane distillation is a process that can desalinate waters with high total dissolved solids concentration, and when incorporated into a system with surface heating and energy recovery can achieve high water recovery rates. Model results show that a 6-stage SHVMD system with a 54.4 % water recovery rate and a gained output ratio (GOR) of 3.28 has the potential to be economically viable when used to treat hypersaline produced water in the Permian basin. Assuming energy costs of $0.03/kWhthermal and $0.12kWhelectric, we estimate a project net present value (NPV) of $225,525 and an internal rate of return (IRR) of 13.5 % when an air cooled condensor is used to cool the distillate and a NPV of $570,791 and IRR of 24.52 % when a liquid coooling source is available. SynopsisThis work presents a comprehensive economic assessment of utilizing a surface-heated membrane distillation system with heat recovery to treat hypersaline produced well water.

FROM ABUNDANCE TO ADVERSITY: UNDERSTANDING THE CHANGING DYNAMICS OF LAKE ALAU'S WATER QUALITY

Lake Alau, a critical water resource in the region, was subject to an extensive water quality assessment with the aim of assessing the impact of human activities on the physico-chemical parameters of Lake Alau, with a specific focus on water quality potentials of the Lake. The study spanned over a year, capturing variations in several physicochemical parameters using standard laboratory techniques. The data were computed and analysed using ANOVA. The findings reveal that the lake generally maintains water quality within permissible limits for aquatic ecosystems. The physical parameters of the lake, including Temperature, Total Solids (TS), Total Dissolved Solids (TDS), and Total Suspended Solids (TSS), were within the range of a productive lake, but higher concentrations of TDS (365.68g/L) and TSS (171.95g/L) might have altered the ecological balance of the lake. The chemical parameters, including pH, biochemical oxygen demand (BOD), Chemical Oxygen Demand (COD), Nitrite, Nitrate, and Phosphate, were within the permissible limit for a productive lake, supporting the biological parameters of the lake However, phosphate concentrations exceed 0.1mg/l which is the limit for drinking water. The observed variations underscore the lake's vulnerability to human activities and seasonal changes. Despite some concerns, Lake Alau remains suitable for aquatic life, with certain water quality management practices recommended to maintain its intergrity.

Performance of Copolymerized Organo-Selenium RO Feed Spacers during Fouling

Fouling of reverse osmosis (RO) systems to produce clean drinking water is a major problem. Organo-selenium inhibition is an attractive solution for this application because biofilm prevention has been shown in medical devices, water filtration systems, and plastics. This study examined whether selenium-coated polymers would have positive effects in controlling RO fouling. This study included an analysis of modified feed spacers’ performance on reduction of total biomass concentration, average biofilm thickness on the surface of RO membranes versus real wastewater sources, the impact of selenium catalytic activity on the reduction of RO membrane chemical scaling, and the performance of fouling and biofilm formation. A 1.5% organo-selenium was copolymerized into spacer elements used in an RO system. These systems were then tested with both city and industrial wastewater with different total dissolved solids (TDS) concentrations for effects on (1) flux, (2) biofilm formation, and (3) inorganic binding. The comparison of an organo-selenium spacer with a control spacer yielded the following for RO membranes: (1) lower calcium and magnesium binding; (2) better flux at high TDS concentrations in both city and industrial water; (3) lower biofilm thickness and volume; and (4) a decrease in both dead and viable bacteria. Testing of varying solids concentrations resulted in greater log inhibition of fouling as a result of operating the RO system with selenium copolymerized feed spacer. The impact of selenium catalytic activity versus divalent foulants (magnesium and calcium) is important because of their ability to create bridges between biological cells and membrane surface, leading to increased possibility of biofouling.

Total Dissolved Solids (TDS) Less than 1000 ppm in Drinking Water Did Not Impact Nursery Pig Performance.

High concentrations of total dissolved solids (TDS) in water have been reported to increase the incidence of diarrhea and reduce nursery pig growth performance. The objective of this study was to investigate the effects of drinking water with high concentrations of TDS from sulfate salts on nursery pigs. Weaned pigs sorted to equalize gender were placed in 44 pens with 26 pigs per pen. One of four water treatments was randomly assigned to each pen: (1) combination of CaSO4, MgSO4, and NaSO4; (2) CaSO4; (3) MgSO4; (4) NaSO4. Access to water and feed (nursery diets fed in four phases) was unrestricted throughout. The weights of pens were measured, feed remaining on weigh days was calculated, and pen water meters were read on d 0, 7, 21, 35, and 42. Water treatment did not affect (p > 0.07) average daily gain, average daily feed intake, or gut integrity of pigs. Water disappearance tended to be greater (p = 0.10) in pens receiving the CaSO4 water compared to the combination treatment from d 21 to 35. The TDS concentrations from sulfate salts used in this experiment did not impact the growth performance or feed or water disappearance of newly weaned nursery pigs.

Hydraulic behaviour and improving of water quality of the Chibayish Marshes

The Central Marshes are a rare and complete ecological system in southern Iraq that is of global and local significance, and Al-Chibayish Marsh makes up the major part of it. The water quality of these marshes suffers from salt accumulation, due to a restricted supply of water from sources, as well as a lack of sufficient outlets. Surface-water Modeling System (SMS) software was used to simulate the hydraulic behavior and the space-time propagation of water quality in the Central Marshes in general, with a focus on Al-Chibayish Marsh. Two types of field measurements were conducted to define the concentration of total dissolved solids (TDS) at nine sites, and water depths at 50 locations within the marsh. Also, samples were taken and examined for the physical properties of water. The defined hydrodynamic properties revealed the necessity of the need for one or more outlets to drain water of marshes, and also to perform a good distribution of TDS along the whole marshes area. Furthermore, results showed that the existence of these outlets will considerably improve water quality and decreasing TDS concentration. The numerical simulation revealed that the best site, taking into account the effect of drainage on neighboring lands, and the effective conditions for the drainage of stored water are case C that will result in a reduction of deterioration areas with high TDS concentration.

Study of soil contamination near R1-Barzina artesian borehole, Vratsa Province

The purpose of the present study is to evaluate the environmental impact of a surface spill of groundwater with high total dissolved solids content by clarifying the extent of contamination in the soil layer near the borehole R1 – Barzina. The overall tendency for limitation of the migration of chloride pollution in the immediate vicinity of the formed surface spill. The fluctuations of the chlorides content in depth indicates the seasonal impact of refreshment by atmospheric waters.

Understanding the activity of Radon-222 in a sand dune aquifer of an arid region through the application of machine learning

Groundwater samples, collected from the sand dune aquifer of Abu Dhabi Emirates, were analyzed for Radon-222 and total dissolved solids (TDS) concentrations. Results indicated that mean Radon-222 concentrations are 7.1 Bq/L in Remah and 7.6 Bq/L in Al Khatim-Al Khaznah areas. These concentrations of Radon-222 were found to be below both WHO and USEPA standard limits; and less than those of Al Ain carbonate aquifer in the vicinity of study area. The TDS concentration was 3184 mg/L and 9878 in Remah and Al Khatim-Al Khaznah groundwater samples, respectively. The correlation between Radon-222 and TDS concentrations was found to be weak, indicating that anthropogenic factors are altering the characteristics of groundwater in the study areas. Higher concentration of TDS in Al Khatim can be attributed to the long-distance rock-water interaction as well as agricultural activities. Radon-222 concentrations in both study areas are due to natural radioactivity of the source aquifer. The effective dose estimation based on these concentrations showed many samples exceeding WHO (2006) limit of 0.04 mSv/a. The carcinogenic risk on the population due to ingestion (stomach and tissue cancer) and inhalation (lungs cancer) was estimated to be in the range of 0.6–23 in a million and 0.15 to 5.7 in a million, respectively. Additional analysis was carried out using unsupervised machine learning algorithms. The k-means algorithm showed two clusters with Radon-222 higher and lower than 11.1 Bq/L. The DBSCAN algorithm showed that there is a presence of possible high concentration of Uranium-238 source near the groundwater at Al Khatim study area.

On The Evaluation of Water Quality Index: Case Study of Euphrates River, Iraq

This study is used the water quality index (WQI), which is generated by combining several water quality parameters. This index gives a helpful representation of overall water quality for the public and all intended applications, and it demonstrates that pollution is beneficial in water quality management and decision-making. The Euphrates River was assessed in order to determine the quality of drinking water. The Euphrates River was assessed for drinking water quality using the WQI, which includes ten physicochemical water quality criteria. This was achieved by submitting comprehensive physicochemical analysis of water samples collected from 5 stations in the city of Hit-Iraq during 2020-2021. The ten physicochemical parameters included: pH value, Nitrate (NO3), Sulphate (SO4­), Turbidity, temperature, Calcium (Ca), Magnesium (Mg), sodium (Na), electric conductivity (EC) and Total Dissolved Solids (TDS). This was accomplished by submitting a full physicochemical analysis of water samples obtained from 5 sites in Hit, Iraq, between 2020 and 2021. The results of the present study show, the total average WQI was 110,156. The high WQI achieved is caused by the high TDS and magnesium concentration due to the different human activities along the river reach. The Euphrates River quality is classified as 'very poor quality' with a minimum WQI of 97.85 in June and 121.75 in November.

Techno-commercial Assessment of Concurrent Municipal Brown Field Reclamation Procedures: A Pivotal Case study of Jawahar Nagar Dump Site

Techno-commercial Assessment of Concurrent Municipal Brown Field Reclamation Procedures: A Pivotal Case study of Jawahar Nagar Dump Site

Identification of Microbiological Activities in Wet Flue Gas Desulfurization Systems

Thermoelectric power generation from coal requires large amounts of water, much of which is used for wet flue gas desulfurization (wFGD) systems that minimize sulfur emissions, and consequently, acid rain. The microbial communities in wFGDs and throughout thermoelectric power plants can influence system performance, waste processing, and the long term stewardship of residual wastes. Any microorganisms that survive in wFGD slurries must tolerate high total dissolved solids concentrations (TDS) and temperatures (50–60°C), but the inocula for wFGDs are typically from fresh surface waters (e.g., lakes or rivers) of low TDS and temperatures, and whose activity might be limited under the physicochemically extreme conditions of the wFGD. To determine the extents of microbiological activities in wFGDs, we examined the microbial activities and communities associated with three wFGDs. O2 consumption rates of three wFGD slurries were optimal at 55°C, and living cells could be detected microscopically, indicating that living and active communities of organisms were present in the wFGD and could metabolize at the high temperature of the wFGD. A 16S rRNA gene-based survey revealed that the wFGD-associated microbial communities included taxa attributable to both thermophilic and mesophilic lineages. Metatranscriptomic analysis of one of the wFGDs indicated an abundance of active Burholderiaceae and several Gammaproteobacteria, and production of transcripts associated with carbohydrate metabolism, osmotic stress response, as well as phage, prophages, and transposable elements. These results illustrate that microbial activities can be sustained in physicochemically extreme wFGDs, and these activities may influence the performance and environmental impacts of thermoelectric power plants.

Evolution of a Deep Fluid in a Surficial Environment Using Stable Carbon and Sulfur Isotopes: Case of the Transitional Zone of the Edwards Aquifer in South Central Texas

The Edwards Aquifer in south central Texas (USA) features a distinct fault line defining the freshwater and saline water zones. We aim to elucidate the evolutionary behavior of carbon and sulfur emanating from deep environments and flowing in surficial environment so as to better understand the cycling of these metals in water environments. To characterize the evolution of carbon and sulfur species in surficial environment as the fluid emanates from a deep saline aquifer, we monitored the chemical and isotopic (δ13CDIC and δ34SSO4) parameters over a 700-m stretch on a stream-pond system situated on the saline-freshwater line of the Edwards Aquifer’s artesian zone. A three-tier evolution process associated with the interaction of a deep saline fluid with a fresh-ponded water was observed, namely: A deep fluid control zone characterized by decreasing pH values and relatively high total dissolved solids (TDS) concentrations along the stream path; a mixing zone of the deep fluid and fresh-ponded water where the TDS concentrations showed a sharp decline and a continual decrease in pH values; and a fresh-ponded water-controlled zone with a stable pH value and low TDS concentrations. The decreasing pH values were a result of CO2 outgassing due to the relatively high CO2 partial pressures (10–2.53 atm) relative to atmospheric (10–3.50 atm) in the aqueous system, and the high TDS concentrations were attributed to the deep saline fluid emanating at the well-head. The enrichment in the δ13CDIC and δ34SSO4 for the initial stream path reflects the kinetic isotopic fractionations associated with CO2 outgassing and with the microbial conversion. The zonation of the evolutionary process indicates that (i) solutes play a critical role in the evolution of carbon and sulfur in surficial environment, (ii) kinetic and chemical fractionation are the dominant processes controlling carbon evolution, and (iii) microbial metabolism primarily controls sulfate fractionation and evolution through the conversion of sulfate to thiosulfate.

Evaluation of sequencing batch bioreactor followed by media filtration for organic carbon and nitrogen removal in produced water

Produced water contains high concentrations of total dissolved solids (TDS), metals, and organic matter. In areas of high water stress, beneficial reuse of produced water needs to be considered. This study evaluates the treatment capabilities, efficiency, and limitations of a sequencing batch reactor (SBR) to remove organic material and nutrients from produced water. SBRs have been used to facilitate biological organic and nutrient removal from municipal and industrial waste streams. Although the bacteria responsible for the treatment of municipal and most industrial wastewaters cannot tolerate the high TDS concentrations in produced water, the microorganisms native to produced water have the capacity to treat produced water. In a bench scale bioreactor test using produced water from the Denver-Julesburg Basin, the produced water was determined to be nutrient limited with respect to phosphorus. By adding a phosphorus supplement, soluble chemical oxygen demand (COD) removal was increased by over 20 % and ammonia removal increased by approximately 40 %. Various supplements, including KH2PO4, centrate from an anaerobic digester, and activated sludge from a municipal SBR, were added to the bioreactors to determine which of them was more effective. A pilot scale SBR followed by media filtration was used to evaluate the effects of operating conditions on produced water treatment. The hydraulic residence time ranged from 1.67 to 8.3 days during various phases of operation, with no measured effect on treatment performance. Adding 7.5 mg-P/L of KH2PO4 as a phosphorus supplement had the most significant effect on treatment performance of the system. The majority of COD removal switched locations from the filter columns to the bioreactors. Comparing total organic carbon to COD, the biologically available portion of COD appears to be treated in the SBR while recalcitrant carbon and inorganic material may need to be removed via physical or chemical methods.

Evaluation of the quality of groundwater for its appropriateness for drinking purposes in the watershed of Naâma, SW of Algeria, by using water quality index (WQI)

Naâma watershed is situated in the southwest of Algeria, where the climate is arid. It is highly dependent on groundwater resources, which are the only available resources for irrigation and domestic purposes. The study was carried out to assess groundwater appropriateness in the study area for drinking uses through a water quality index (WQI) and geographic information system (GIS). Fourteen (14) groundwater samples were collected, and several physicochemical parameters such as electrical conductivity (EC), potential for hydrogen (pH), total dissolved solids (TDS), cations (Ca, Mg, Na, K), and anions (SO4, NO2, HCO3, Cl) were analyzed. The results report that the different water quality parameters were within the permissible limit given by the World Health Organization and Algerian Standards guidelines, except for some boreholes near the Sabkha of Naâma. Eleven (11) parameters were chosen to compile the water quality index. The results showed that 50% of groundwater sites sampled in the study area had excellent water quality, while 50% were suitable. By carefully examining the data, it was revealed that boreholes distant from Sabkha present an excellent groundwater quality, where the WQI ranges between 37 and 41.6 mg/L. On the other hand, the boreholes close to Sabkha are characterized by a high concentration of electrical conductivity, TDS, sodium, and sulfates, explained by the contamination of the surrounding area through the infiltration of salt elements from the Sabkha. This salt contamination of groundwater would be accentuated by the discharge of wastewater from Naâma town into the Sabkha, the irrational use of chemical fertilizers, pesticides, and intensive pumping. The spatial distribution of the physicochemical parameters and water quality index was generated using the inverse distance weighted interpolation method (IDW). This study demonstrates that the combination of WQI and GIS methods could be a helpful tool for water resources management and decision making.

Physicochemical Characteristics of the Okomu Wetland, Edo State, Nigeria

Water quality assessment was carried out within the 202 km2 Okomu National Park located within the 1,082km2Okomu Forest Reserve between January 2017 and December 2018. Water sampling was carried in ten compartments of approximately 1.6km2 each, covering Ponds, Stream and River, based on easy accessibility. No such study has been carried out for the Okomu Wetlands in the past three decades. Sampling protocols, laboratory analysis and quality control/quality assurance measures followed standard procedures. All physicochemical parameters showed significant (P < 0.001) spatial variations. The maximum and minimum values obtained for physicochemical parameters of the Okomu Wetland are 23.6 and 38.0°C air temperature; 21.0 – 38°C water temperature; 0.15 – 1.02m water level; 16.7 – 150.7mg/l total dissolved Solids (TDS); 0.5 – 18.8mg/l total suspended Solids (TSS); 0.2 – 14.8mg/l turbidity; 40. 0 – 307.4µS/cm electrical conductivity (EC); 4.4 – 6.7 pH; 0.02 – 0.14mg/l salinity; 0.7 – 5.5mg/l dissolve oxygen (DO); 0.5 – 3.8mg/l biochemical oxygen demand (BOD); 1.5 – 120.2mg/l chemical oxygen demand (COD); 23.8 – 593.6mg/l bicarbonates (HCO3); 69.9 – 245.3mg/l Chlorine (Cl); 0.02 – 0.59mg/l nitrite (NO2); 0.11 – 2.34mg/l nitrate (NO3); 0.04 – 2.11mg/l ammonium-nitrogen (NH4N); 0.05 – 2.96mg/l sulphate (SO4); 0.09 – 9.2mg/l phosphorus (P); 0.20 – 2.72mg/l sodium (Na), 0.03 – 1.32mg/l potassium (K); 0.88 – 5.88mg/l calcium (Ca); 0.13 – 3.1mg/l magnesium (Mg); 5.8 – 18.9mg/l iron (Fe); 0.04 – 1.1mg/l manganese (Mn); 0.02 – 0.09mg/l copper (Cu); 0.93 – 6.0mg/l zinc (Zn); 0.01 – 2.9mg/l lead (Pb); 0.01 – 0.18mg/l cadmium (Cd); 0.06 – 4.0mg/l chromium (Cr); 0.01 – 0.15mg/l nickel (Ni); 0.01 – 11mg/l vanadium (V). Air and water temperatures were mostly influenced by forest canopy cover. pH levels indicate that the water bodies within the forested wetland are slightly acidic. Higher DO values were recorded in the Arhakhuan Stream and Okomu River (Agekpukpu and Iron bridge) than in the temporary ponds. BOD levels of greater than 1mg/l were observed which is indicative of slight levels of organic pollution. Higher concentrations of TDS, TSS, turbidity, EC, Colour, HCO3, NH4N, NO2, NO3, P, Na, K, Ca Mg and heavy metals were recorded in the temporary ponds than in the Stream and River. Research on water bodies within wetlands should be carried out routinely in order to monitor changes in the water conditions that could occur overtime whether natural or anthropogenic. This becomes even more pertinent in the light of glaring impacts of climate change and increasing environmental modifications.

Detecting spatiotemporal variability in the physicochemical properties of water in the Lower Mearim using remote sensing data

Natural or anthropogenic chemical compounds of different origins often accumulate in estuarine regions. These compounds may alter the water quality. Therefore, It is important to constantly monitor the quality of estuarine regions. A combination of remote sensing and traditional sampling can lead to a better monitoring program for water quality parameters. The objective of this work is to assess the spatiotemporal variability of the physicochemical properties of water in the lower region of the Mearim River and estimate water quality parameters via remote sensing. Samples were collected at 16 points, from Baixo Arari to the mouth of the watershed, using a multiparameter meter and Landsat 8 satellite images. The physicochemical parameters of the water had high salinity levels, between 2.30 and 20.10 parts per trillion; a high total dissolved solids content, between 2.77 and 19.70 g/L; and minimum dissolved oxygen values. Estimating the physicochemical properties of the water via remote sensing proved feasible, particularly in the dry season when there is less cloud cover.

Effect of total dissolved solids-contaminated water on the properties of concrete

Total dissolved solids (TDS) is one of the main impurities in the mixing water that can influence the properties of concrete, and therefore, the codes of practice limit the concentration of TDS in water used for producing concrete. The present study investigates the effect of TDS present in the mixing water on the properties of concrete in fresh and hardened states. Concrete mixtures were prepared using water with different selected concentrations of TDS (500, 1000, 5000, and 15000 ppm) keeping the proportions of the main ingredients invariant. Experimental tests including workability, initial setting time, air content, compressive strength, water absorption, water permeability, chloride permeability, and electrical resistivity were conducted. The results showed that the workability and initial setting time were reduced with increase in the TDS concentration, however, these properties remained within the acceptable limits as specified by ASTM C191-18a. At higher concentrations of the TDS, air content and water absorption of concrete deceased by about 31% and 6%, respectively, and compressive strength increased by about 20%, indicating positive effect of the higher concentration of TDS on the quality of concrete. However, the compressive strength was found to be slightly lower at the TDS content of 15000 ppm. Resistance against water penetration and electrical resistivity of concrete decreased slightly at higher TDS concentrations, however, water permeability class and the likelihood of reinforcement corrosion remained unaffected. The chloride permeability increased from moderate to high level when TDS concentration exceeded 1000 ppm. Based on the finding of this study, it may be concluded that the waters having TDS up to 1000 ppm can be recycled for concrete production that would benefit in cost reduction and conservation of water resources.

An Adaptive Surrogate Assisted CE-QUAL-W2 Model Embedded in Hybrid NSGA-II_ AMOSA Algorithm for Reservoir Water Quality and Quantity Management

The Meimeh dam construction is a project, planned to provide sustainable livelihoods, social, and economic developments in the Meimeh River Basin, Ilam, Iran. However, due to the high concentration of TDS in the Meimeh River and its tributaries, river impoundment and water storage can be harmful to the Meimeh Reservoir. The upstream inflow control and the reservoir operation management in a selective withdrawal scheme (SWS) were used to mitigate the potential environmental degradation of Meimeh Reservoir’s low water quality. CE-QUAL-W2 and WEAP (Water Evaluation and Assessment Programming) models were employed to evaluate the effects of various upstream saline inflow control scenarios. The analysis indicated that the diversion of the Siyoul tributary flow rate in the Meimeh River could result in lower violations of Total Dissolved Solids (TDS) concentrations and better water supply satisfaction. Then, the optimal reservoir operation management strategies in a SWS were derived in the best upstream inflow control scenario. The adaptive surrogate-assisted WQSM (water quality simulation model), coupled to hybrid NSGA-II_AMOSA (Non-dominated Sorting Genetic Algorithm-II_Archived Multi-Objective Simulated Annealing) algorithm, has been applied to derive the suitable reservoir operation strategies in SWS, improve the water supply satisfaction and alleviate the adverse effects of reservoir outflow TDS violations. The performances of the best water quality and supply scenarios have been compared with the scenario based on the standard operation policy (SOP) in the Meimeh Reservoir. The results show that most violations of TDS criteria occur during the peak agricultural seasons and significant water deficit in some dry years happens in the SOP.

Assessment of Physicochemical Parameters of Spring Water Sources in Amediye District, Kurdistan Region of Iraq

: Nowadays, the growing population is demanding freshwater resources, and the availability of water influence the population distribution and its activities. Groundwater sources such as springs and wells are the major source of water for drinking, agricultural, and industrial consumptions. However, water resources are always exposed to industrial, agricultural, and residential pollutions. In the current study, water samples were collected from twenty-two springs sources from February to October 2017 in Amadiya districts, in the Kurdistan region of Iraq. The physicochemical characteristics including temperature, pH, dissolved oxygen (DO), biological oxygen demand (BOD5), electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), calcium hardness (Ca2), magnesium hardness (Mg2), turbidity (NTU), total alkalinity (TA), and nitrate (NO3-) of the samples were analyzed. The findings showed that most of the water samples were within the permissible limits for drinking usage according to WHO (World Health Organization) standards, while few samples were without the permissible level for TDS and EC. Also, higher concentrations of TDS and EC reported for some samples attributed to agricultural and residential contamination, which require water treatment for drinking purposes. The statistical analysis illustrated an acceptable correlation between analysis.

Spatial modelling of groundwater quality across a land use and land cover gradient in Limpopo Province, South Africa

The spatial variability of groundwater quality in rural Mokopane District is investigated. This was achieved by evaluating the variability in groundwater physio-chemical parameters in relation to Land Use and Land Cover (LULC)using Kriging geo-statistical technique and key groundwater physio-chemical parameters namely; ammonia, lead, Total Dissolved Solids (TDS), nitrates and chloride. Firstly, we derived the LULC from 30-m Landsat 8-OLI satellite data, with an overall accuracy of 76.67%. Water quality parameters were modelled in geographic information systems using the kriging interpolation technique. We then compared measured water quality and the drinking standards recommended by the South African Water Quality Standards (SAWS) and the World Health Organization (WHO) guideline standards for drinking water. Results indicated that there were significant differences (p < 0.05) in the levels of physio-chemical contents between borehole water and standard values according to the SAWS and WHO. For example, TDS in Mosesetjane exceeded both SAWS and WHO drinking water levels. Nitrate concentrations were also high on the first and second quarter with concentration levels of 5.56–29 mg/l and 30.9 mg/l in Mosesetjane, respectively. However, lead and ammonia were found to be evenly distributed in all the four quarters, but exhibited some slight deviations from the standard levels (±4.7 mg/l) in selected quarters. Results also indicated significant differences in TDS, chloride and nitrate concentrations across different LULC types. Subsistence farming and built-up areas were the main LULC types that were found to have high concentrations of TDS, ammonia and nitrates, exceeding the recommended standards. However, lead and ammonia, did not differ significantly (p > 0.05) and these parameters were fairly distributed, with less spatial variability . The second quarter, extending between October and December, and the fourth quarter, extending from April to June, exhibited high concentrations of nitrates, chloride and TDS during the wet season. On the other hand, the first and third quarter of the dry period were associated with low concentrations. This study indicated that LULC types and seasonal variability have influence on specific groundwater quality parameters.

Influence of High Total Dissolved Solids Concentration and Ionic Composition on γ Spectroscopy Radium Measurements of Oil and Gas-Produced Water.

Radium measurements in high total dissolved solids (TDS) fluids from oil and gas extraction can have unfavorable precision and accuracy, in part because these high-level impurities incur attenuation. γ spectroscopy is often recommended for determining radium activities in these fluids, but even this method can produce a range of reported activities for the same sample. To reduce measurement duration and to maintain or improve accuracy, we propose a method to rapidly assess both 226Ra and 228Ra and to account for the self-attenuation of γ rays in high-TDS oil and gas fluids when they are monitored by a well detector. In this work, comparisons between a NaCl-only and a multi-cation-chloride synthetic brine spiked with known amounts of 226Ra and 228Ra indicated that both the TDS concentration and the type of TDS (i.e., Na only vs Na-Mg-Ba-Ca-Sr) influenced self-attenuation in well-detector γ spectroscopy, thus highlighting the need to correct for this TDS-influenced self-attenuation. Radium activities can be underestimated if the correction is not applied. For instance, 226Ra activities could be ∼40% lower in a sample when measured directly at the 186 keV energy level if the attenuation of the high TDS of the fluid is not considered. We also showed that using a NaCl-only brine to match the matrix of high-TDS oil and gas brines is inadequate to produce accurate measurements, rather, the full set of cations should be included.