Low Total Dissolved Solids Research Articles

Hydrochemical assessment of groundwater utilizing statistical analysis, integrated geochemical methods, and EWQI: a case study of Laiwu region, North China.

The investigation of groundwater quality and hydrochemical assessment holds immense significance in safeguarding and ensuring the rational utilization of groundwater resources. This study utilizes groundwater sampling and testing data from the Laiwu region (LWR), encompassing both dry and wet seasons, to delve into the hydrochemical characteristics, ion sources, and overall groundwater quality. The research findings indicate that the groundwater in LWR exhibits weak alkalinity, with the dominant ions being Ca2+ followed by Mg2+, Na+, and K+, and HCO3-, SO42-, NO3-, Cl-, and F-. The average total dissolved solids (TDS) concentrations during the dry and wet seasons are recorded as 683mg/L and 679mg/L, respectively, classifying LWR's groundwater primarily as hard-fresh water. The spatial pattern of TDS concentration in LWR displays consistency throughout both the dry and wet seasons, with relatively low TDS levels observed in the northern and southeastern regions and higher concentrations in the lower reaches of the Dawen River and nearby Gangcheng. Predominantly, Ca2+, Mg2+, and HCO3- ions in groundwater originate from the dissolution of calcite and dolomite, with the hydrogeochemical process of carbonate rock weathering involving the presence of sulfuric acid. It is noteworthy that human activities significantly impact the chemical composition of groundwater in LWR. Notably, during the dry and wet seasons, the average concentration of NO3- in groundwater is 102.81 and 106.61mg/L respectively, and the analysis shows that agricultural practice is the main source. Furthermore, the calculated average values of the entropy water quality index (EWQI) during those seasons are 58.44 and 57.24, respectively. The EWQI shows good to moderate water quality in most areas, except for a few poor-quality spots in the west. It is worth mentioning that LWR's groundwater is deemed suitable for agricultural irrigation. These research findings provide valuable insights and serve as a significant reference for the rational development and sustainable utilization of groundwater resources in the LWR region.

A Localized Evaluation of Surface Water Quality Using GIS-Based Water Quality Index along Satpara Watershed Skardu Baltistan, Pakistan

Surface water quality in Skardu, Gilgit-Baltistan, Pakistan, is of immense importance because of the city’s dependence on these resources for domestic uses, agriculture, and drinking water. The water quality index (WQI) was integrated with the Geographic Information System (GIS) to spatially envision and examine water quality data to facilitate the identification of pollution hotspots, trend analysis, and knowledge-based decision-making for effective water resource management. This study aims to evaluate the physiochemical and bacteriological parameters of the Satpara watershed and to provide the spatial distribution of these parameters. This study endeavors to achieve Sustainable Development Goal 6 (SDG 6) by identifying localities with excellent and unfit water for drinking, sanitation, and hygiene. A total of fifty-one surface water samples were collected from various parts of the Satpara watershed during the fall season of 2023. Well-established laboratory techniques were used to investigate water for parameters like Electrical Conductivity (EC), pH, turbidity, total dissolved solids (TDSs), major cations (K+, Na+, Mg2+, Ca2+), major anions (Cl−, SO42−, NO3−, HCO3−), and bacteriological contaminants (E. coli). Spatial distribution maps of all these parameters were created using the Inverse Distance Weighted (IDW) technique in a GIS environment. A significant variation in the quality of water was observed along the study area. The level of Escherichia coli (E. coli) contamination is above the permissible limit at various locations along the watershed, making water unsafe for direct human consumption in these areas. Some regions showed low TDS values, which could adversely affect human health and agricultural yield. From the WQI valuation, 58.82% of the collected samples were “Poor”, 31.8% were “Very poor” and 9.8% were found to be “Unfit for drinking”. The research findings emphasize the pressing need for consistent monitoring and adoption of water management strategies in Skardu City to warrant sustainable soil and water use. The spatial maps generated for various parameters and the water quality index WQI offer critical insights for targeted intercessions.

Subsurface complexity controls the aquifer heterogeneity: A case study from the Al-Hassa oasis, Eastern Saudi Arabia

Al-Hassa region in the eastern part of Saudi Arabia is well-known for its geological and hydrogeological importance since it has historically hosted over 280 natural springs, which were used to irrigate the largest oasis in the world. Al-Hassa is located near the renowned Ghawar oil field, the largest conventional oil field globally, which represents a potential pollution source. This study utilizes and integrate hydrochemical investigations and geophysical gravity surveys to understand and reconstruct the subsurface heterogeneity in the Al-Hassa area. The dataset encompasses 113 groundwater wells distributed across the Al-Hassa Oasis which have been analyzed for salinity major ions, and isotopic (oxygen and hydrogen) compositions. A total of 571 gravity stations covering the broader oasis area (approximately 350 km2) are collected, processed, and modeled. The combined hydrochemical and geophysical results show a good agreement between groundwater quality and density (gravity anomalies) distribution within the study area. The southeastern part of the study area exhibits distinctive positive gravity anomalies, indicating denser rock formations alongside high total dissolved solids (TDS) in groundwater, reflecting poor water quality. Conversely, the southwest displays significant negative gravity anomalies, suggesting basins filled with loose sediments and low TDS values, signifying good water quality. Furthermore, the study reveals a certain pattern in groundwater temperature distribution, with cooler waters in the areas characterized by negative gravity anomalies (basins), and hotter waters emerging from areas with positive gravity anomalies. These findings suggest that groundwater quality differences may stem from varying sub-basins and interactions with distinct geological substrates. Temperature variations may also be attributed to differing subsurface flow pathways. This study attempts to explain the controlling factors for groundwater heterogeneity in the Al-Hassa Oasis area, emphasizing the role of geological, tectonic, and hydrogeological elements in shaping the Oasis's hydrological and hydrochemical pattern.

Spatial Variability of Selected Soil Chemical Parameters in Low-yielding Paddy Production Block in Mahaweli System H, Sri Lanka

Although water availability for paddy production in Mahaweli System H is abundant, paddy yield is lower in Nochchiyagama (278 km2), chosen for soil assessment. Paddy yield data were used to identify the low-yielding division using the area-weighted average. Twenty-five random locations were generated, and soil samples were collected for pH, soil conductivity (EC), salinity, and total dissolved solids (TDS) analysis. ArcGIS software was used to create spatial distribution maps and related geostatistical analyses for each parameter. Vector files were created with their associated properties, and thematic maps were generated using spatial interpolation techniques, such as universal kriging (UK), ordinary kriging (OK), and inverse distance weighted (IDW) methods of interpolation techniques to identify the best interpolation method for soil chemical parameters mapping. The entire Nochchiyagama land was observed to have a slightly acidic pH (5.6-5.9) range that may have affected rice crop growth due to nutrient mobility and uptake issues. The spatial interpolation evaluation suggests that at least two-thirds of the area observed for lower TDS levels (591-654 mg/L) is potentially unsafe paddy production. Elevated levels of EC (3.1-7.24 dS/m) along with TDS may lead to physiological drought due to interferences in ion uptake. In overall, spatial interpolation evaluation indicators suggest that the UK method was observed with a lower mean relative error (MRE) than the other two interpolations. However, EC distribution showed low MRE in both IDW and OK interpolation techniques. The IDW method was observed to have a lower RMSE (Root mean square error). The UK spatial interpolation performed better for TDS and salinity predictions than other methods. This study found consistent regional differences in low paddy yields in Mahaweli system H using the UK method for analyzing soil chemical parameters. 
 Keywords: Electrical conductivity, Interpolation errors, Salinity, Spatial interpolation

ASSESSMENT OF CLIMATE CHANGE IMPACT ON SURFACE WATER QUALITY IN SHARE-TSARAGI AND IT’S ENVIRON IN KWARA STATE, NIGERIA

Climate change affects surface water resources through changes in evaporation, surface water recharge, temperature, runoff, and rainfall. Such changes affect the mobilization of nutrients and the distribution and mobility of pollutants in surface water systems. The present study attempts the physiochemical and hydrochemical characterization of surface-quality water in the Share-Tsaragi and its environs in Kwara State, Nigeria. A total of ten (10) water samples were collected from the study area. The physiochemical characteristics such as pH and total dissolved solids (TDS) were determined to understand the surface water characteristics, and the results showed that pH (6.39 to 7.67) and total dissolved solids (35 to 230 mg/l) were significantly moderate across the different stations. This indicated that all the water samples are good for drinking and irrigation. The hydrochemical data were utilized to generate graphical representations and scientific computations that determined the relationship between chemical components and water quality. The main elements found in the samples were Ca‐HCO3 - . Piper diagram indicates that the water samples are made of mixed Ca‐Na‐HCO3 - and mixed Ca‐Mg, indicating transient hardness. Gibbs plots show that water chemistry is primarily influenced by rock-water interactions and precipitation processes. The Gibbs plots show a change with increased bicarbonate and lower TDS, indicating salt intake through precipitation.

Hydrogeochemical characterization of ground and surface water in the eastern part of the Adamawa-Yade domain, Bertoua-Cameroon

Groundwater and surface water are major sources of water supply to the inhabitants of Bertoua. Hydrogeochemical study conducted in the study area aimed at identifying the processes that control the chemistry of groundwater sources and to examine the quality of the water sources for domestic and agricultural purposes. Fifty water samples were collected from boreholes, open wells, springs, and rivers within the study area in January 2022 (the dry season). The samples were analyzed for physicochemical characteristics including pH, electrical conductivity (EC), total dissolved solids (TDS) and major ions. The water samples were acidic with 94% of pH values less than 6.5. The EC varied from 21 to 776 µS/cm and TDS (8.5–388 mg/l). The low EC and TDS indicate low mineralization and fresh water. The relative abundance of major ions (meg/l) was Ca2+> Mg2+> K+>Na+ for cations and {text{H}text{C}text{O}}_{3}^{-}>Cl−>NO3−>SO42− for anions. These major ions concentrations were low and within the WHO guideline values for drinking water. From Piper diagram three water facies were observed; Ca-SO4, Ca-HCO3 and mixed Ca-Mg-Cl. Rock-water interaction, ion exchange, silicate weathering and anthropogenic activities were the processes responsible for the groundwater chemistry with some minor evaporative effects. Based on Sodium Adsorption Ratio and Residual Sodium Bicarbonate all samples fall in the excellent category for agriculture.

Deciphering Hydrochemistry and Fluid-Mineral Equilibria from Characteristic Low-Enthalpy Geothermal Waters of Himalaya and Eastern India

Geothermal energy, with associated low-carbon emissions compared to conventional fossil fuels, is presently one of the potential renewable energy sources. The decryption of the chemistry of thermal manifestations of geothermal systems, in terms of relative abundances of various chemical facies, is mandatory before launching systematic geothermal exploration in a given area as it provides valuable information on the basic characteristics of the geothermal reservoir. For the present study, three clusters of hot springs have been selected -1) Shyok-Nubra valleys geothermal prospect in NW Himalaya, 2) Subansiri valley geothermal areas in NE Himalaya and 3) the hot spring system occurring along Munger-Saharsa Ridge Fault Zone (MSRF) in the Eastern part of India. The study of these geothermal systems with low to moderately high temperatures of 35−75°C, has been carried out with two main objectives. The first objective is to estimate reservoir temperature and other characteristics in the three above-mentioned hot spring groups using conventional chemical geothermometry techniques for the first-hand assessment of the quality of the geothermal resource and postulating its possible application. The second objective of the study is to understand the distribution of stable isotopes (δ2H and δ18O) in the studied geothermal systems to reveal reservoir-related hydrological aspects of the geothermal system. The three groups of hot springs show large variations in total dissolved solids (TDS) from <150 to about 1800 mg/L. Enigmatic and inexplicably low TDS values of 126 to 150 mg/Lare reported from the three Bhimband hot springs along MSRF Zone. These springs discharge Ca−Mg−HCO3 type water. The dearth of dissolved ionic species in these springs indicates lack of water-rock interaction in Bhimband area. Silica is the most abundant solute species and corresponds to a reservoir temperature of about 75°C. It may be inferred that relatively inert lithology in the reservoir and very high water-to-rock ratio might have rendered the observed chemical signatures to Bhimband hot springs. Shyok-Nubra springs at Changlung and Panamik are predominantly Na-HCO3 type with TDS values of about 1700 and 550 mg/L, respectively. These hot springs give an indication of water-rock interaction in different types of lithology at temperatures of 120 to >150°C resulting in the observed chemical differences between the two. Thermal water at Taksing in NE Himalaya is also Na−HCO3 type. Chetu hot spring with TDS of >1100 mg/Lis anomalous in two ways. First, it has a very high SO4 content of 358 mg/Land second, it has the lowest silica value. There is a possibility that the Chetu hot spring has its chemistry influenced by the dissolution of sulfates of Ca and Na. Preliminary stable isotope study indicates that the geothermal fluid is derived from meteoric sources. The lack of any indication for positive δ18O-shift suggests that reservoir temperatures of the springs are generally low. Keywords: Thermal Waters, Hydrogeochemistry, Reservoir Temperature, Stable Isotopes, Himalayas, Bihar

In-Depth Laboratory Proppant Transport Study Using HVFRs for Marcellus High TDS Environments

Summary Excellent proppant transport can be accomplished by introducing high-viscosity friction reducer (HVFR) fracture fluids. However, HVFRs face several challenges that prevent these fluids from providing good proppant transport performance, including the presence of total dissolved solids (TDS) in the produced water. TDS can negatively impact the viscous and elastic properties of HVFR. This study evaluated the rheological and proppant transport performance using HVFRs at extreme salinity conditions using water samples from the Marcellus Basin. The anionic and cationic HVFRs with a concentration of 4 gpt were used. Experimental evaluation work, including the rheology, static proppant settling measurements, and dynamic proppant transport, was conducted using three Marcellus TDS concentrations (68,000; 137,000; and 229,000 ppm). All the experiments were performed at a high-temperature condition that mimics the Marcellus reservoir temperature of 65.5°C (150°F). The results show that the existence of TDS was largely impacted by both types of HVFRs, but the cationic HVFR exhibited better resistance to the Marcellus TDS compared to the anionic HVFR in terms of transporting proppant. The viscosity of the anionic HVFR was reduced more than that of the cationic HVFR, as TDS concentrations increased to 229,000 ppm. However, the elasticity of both HVFRs was weak, as a switch was made from using low TDS to high TDS. This could imply that HVFR viscosity provides the main contribution to proppant transport in high TDS environments. Therefore, it is crucial to evaluate the impact of TDS on the effectiveness of HVFR by investigating HVFR rheology, static proppant settling, and dynamic proppant transport in the TDS environment.

Sistem Kontrol Kualitas Air pada Akuaponik Ikan Nila dan Cabai Rawit Berbasis Embedded System menggunakan Fuzzy Logic


 
 
 Aquaponics is a cultivation method that combines aquaculture and hydroponics which can produce two products, namely plants and fish at a time and on relatively narrow land. The important thing in implementing aquaponics is to maintain water quality so that it remains at the standard of the two products. Automatic water quality control can make it easier for cultivators to maintain water quality more efficiently. Therefore we need an aquaponic water quality control system that focuses on the parameters of dissolved oxygen (DO), total dissolved solids (TDS), and hydrogen power (PH). DO control uses a pump that functions to increase DO levels. TDS control uses a pump that circulates AB mix nutrients to increase TDS and the addition of water volume to lower TDS. PH control uses a pump that circulates PH up and down PH. In its development, the arithmetic method used to process data is fuzzy. The output of this calculation is the duration of time the pump is running. The system is applied to a concrete pond measuring 4 x 1.5 x 1 meter with aquaponic products in the form of 100 fish and 20 cayenne pepper plants.
 
 

In-situ growth of ZIF-8 nanocrystals on biochar for boron adsorption

Removing boron (B) from aqueous solution is economically and environmentally important in the treatment of many industrial and agricultural wastewater streams. Here, we produced canola straw-derived biochar (BC), a low-cost and green adsorbent, as a template to prepare a BC/ZIF-8 (zeolite-like imidazolate framework) composite material. We then performed a series of batch experiments and material characterization to evaluate the adsorption processes and practical applications of the material. The results showed that the maximum adsorption capacity of BC/ZIF-8 for B from a low total dissolved solids (TDS) aqueous solution was 44 mg g-1 (adsorbent dosage is 0.5 g L−1, pH=6, C0 =300 mg L-1). Compared to ZIF-8 alone, the adsorption capacity of B to BC/ZIF-8 increased by 76%. In the adsorption tests conducted in the low TDS solution, the adsorption process was well-represented using a pseudo-first-order kinetics model and the Langmuir adsorption isotherm. Through six regeneration cycles, we demonstrated that BC/ZIF-8 remains a robust sorbent for B. Hydraulic fracturing (HF), a key technology for oil and gas stimulation, produces a large amount of flowback and produced water (FPW). BC/ZIF-8 was used to remove boron from FPW, achieving a maximum adsorption capacity of 15.45 mg g-1 (C0 =42 mg L-1), 5.99% lower than that of pure B solution with similar conditions. Physicochemical characterization of BC/ZIF-8 showed that it has a stable structure and suggested that B adsorption to BC/ZIF-8 was primarily due to hydrogen bonding and electrostatic attraction between B(OH)4- and the positively charged BC/ZIF-8 at pH < PZC. Our study shows that BC-based metal-organic frameworks (MOFs) have the potential for broader industrial applications and water treatment.

Assessing the Suitability of Boosting Machine-Learning Algorithms for Classifying Arsenic-Contaminated Waters: A Novel Model-Explainable Approach Using SHapley Additive exPlanations

There is growing tension between high-performance machine-learning (ML) models and explainability within the scientific community. In arsenic modelling, understanding why ML models make certain predictions, for instance, “high arsenic” instead of “low arsenic”, is as important as the prediction accuracy. In response, this study aims to explain model predictions by assessing the relationship between influencing input variables, i.e., pH, turbidity (Turb), total dissolved solids (TDS), and electrical conductivity (Cond), on arsenic mobility. The two main objectives of this study are to: (i) classify arsenic concentrations in multiple water sources using novel boosting algorithms such as natural gradient boosting (NGB), categorical boosting (CATB), and adaptive boosting (ADAB) and compare them with other existing representative boosting algorithms, and (ii) introduce a novel SHapley Additive exPlanation (SHAP) approach for interpreting the performance of ML models. The outcome of this study indicates that the newly introduced boosting algorithms produced efficient performances, which are comparable to the state-of-the-art boosting algorithms and a benchmark random forest model. Interestingly, the extreme gradient boosting (XGB) proved superior over the remaining models in terms of overall and single-class performance metrics measures. Global and local interpretation (using SHAP with XGB) revealed that high pH water is highly correlated with high arsenic water and vice versa. In general, high pH, high Cond, and high TDS were found to be the potential indicators of high arsenic water sources. Conversely, low pH, low Cond, and low TDS were the main indicators of low arsenic water sources. This study provides new insights into the use of ML and explainable methods for arsenic modelling.

Hydrogeochemical characteristics and processes of thermokarst lake and groundwater during the melting of the active layer in a permafrost region of the Qinghai–Tibet Plateau, China

Permafrost degradation and the development of thermokarst lakes are important factors driving the variability of regional hydrologic processes. Hydrogeochemical and isotopic analyses are important methods for investigating the hydrologic processes of thermokarst lakes. This study focused on comparing the chemical and hydrogeochemical characteristics between lake water and groundwater during the melting of the active layer in a typical thermokarst lake region on the Qinghai–Tibet Plateau (QTP). Ninety-five samples were collected during different periods of active layer melting and analyzed using statistical, isotope, hydrogeochemical, and modeling methods. Statistical results showed that the average concentrations of almost all ions were lower in lake water than in groundwater, with wider spatial variability in groundwater. The lake water is of the ClNa and HCO3-Ca type with low TDS (total dissolved solids), whereas groundwater is of the HCO3-Ca and mixed type (or transition type) with high TDS. The chemical types of the lake water and groundwater are mainly driven by rock weathering. In terms of the saturation index (SI), halite and gypsum are unsaturated dissolved, whereas dolomite and calcite are generally saturated. Evaporation significantly affects the chemical composition of groundwater, while the hydrochemical compositions of lake water are relatively stable under the joint control of evaporation, precipitation, surface runoff, and groundwater. The isotopic analysis results showed that the contribution of permafrost meltwater and precipitation to groundwater and lake water varied during different stages of active layer melting. According to hydrogeochemical modeling, the main chemical reactions in groundwater are the precipitation of calcite and the dissolution of halite, dolomite, and gypsum. The intensity of groundwater flow determines the degree of chemical reactions along the flow path at different stages of active layer melting. The findings can provide deeper insight into hydrogeochemical processes in thermokarst lake regions under the background of permafrost degradation.

The Ajuricaba Basin Creek chemical signature of water resources: Geological sources and anthropogenic contributions

The Ajuricaba Basin Creek is located west of the Parana State, it is part of the Parana 3 Hydrographic Basin and it is located at southwest of the Marechal Candido Rondon county. Its area of around 18 km2 is manly used for agricultural purposes. The basin is part of the Serra Geral Aquifer System (SGAS), which comprises basic volcanic rocks of the Serra Geral Group. The main objectives of this study are the characterization of the hydrogeochemical environments and the understanding of the dissolved elements sources, both geological and human, in order to create a water circulation model of the basin. Two field campaigns, in August and November 2019, were done to collect water samples from surface waters (SW), phreatic aquifer (PA) and fractured aquifer (FA). During the 2019 field campaigns, the temperature, pH, total dissolved solids (TDS) and electrical conductivity (EC) were measured on site. Physicochemical parameters (SiO2, HCO3−, CO3−2, Cl−, F−, PO4−3, SO4−2, NO3−, NO2−, Ca+2, Mg+2, Na+, K+, Fe total, Mn+2, Nb, S, V, Zn, Al, Sr, Ba, P, Ti) of the collected samples were analysed. Preexisting data from December 2010 was also used to observe historical changes in water quality through time. Based on this data, statistical (univariate and correlation) and hydrochemical analysis were conducted in order to characterize the hydrogeochemical environments and surface and groundwater flows in the basin. Historical analysis revealed that SW and PA samples have the most significant impacts on water quality with double the median concentration of NO3− and three to nine times the concentration of Cl−. Hydrochemical analysis showed that SW have higher concentrations of HCO3−, Cl−, NO3−, Ca+2, Mg+2, Al, Sr, Ba and Fe, high TDS and neutral to acid pH. PA has the lowest TDS and acid pH and its main ions are HCO3−, NO3−, Ca+2 and Mg+2. In addition, FA was divided in: FA (Ca+2) with HCO3−, Ca+2 and Mg+2 as main ions, neutral pH and low TDS and FA (Na+) with CO3−2, HCO3−, SO4−2, Na+, V, Nb and P as main ions, basic pH and high TDS. SW has a similar pattern to PA and FA (Ca+2) indicating that the rivers are discharge zones for both aquifers. FA (Ca+2) has a similar hydrochemical signature to SGAS, confirming it origins. In opposition, the FA (Na+) aquifer hydrochemical signature differs from the SGAS and, in fact, is more similar to the one of the confined Guarani Aquifer System (GAS), suggesting a higher residence time. Fa (Na+) waters have higher TDS and basic pH, indicating a higher residence time and depth associated with the ascension of even deeper flows from GAS towards the basin. In addition to the hydrochemical model, this research also highlights the potential of the multielement-hydrochemistry to understand the relations between surface and groundwater resources contributing for the management of water resources in watersheds.

Analysis of seawater intrusion into groundwater in the coastal area of Durung Village, Aceh Besar Regency, Aceh Province, Indonesia

Durung Village is a region consisting mostly of coastal and hilly areas. Utilization of groundwater in the coastal zone has been increased these recent years for all purposes of life, from drinking to sanitation and from industry to agriculture. It results new environmental problem, such as seawater intrusion that caused negative impact on groundwater resources. This research aims to analyze the effect of seawater intrusion into the groundwater in the study area. Total Dissolved Solids (TDS) was used in this research as approximation of groundwater salinity value. The spatial distribution of seawater intrusion had been prepared by using Geographic Information System (GIS) spatial interpolation technique for TDS parameter. The results revealed that seawater intrusion presented more obviously near the coastal line and its northern part was the most affected area by this contamination indicated by the highest TDS value of 2.947 mg l-1, whereas the farther location from the coastline were free of seawater intrusion indicated by low TDS values between 181 – 579 mg l-1.

Hydrodynamic and Geostress Controls on CBM Enrichment in the Anze Block, Southern Qinshui Basin, North China

The coalbed methane (CBM) resource in the southern Qinshui Basin, North China, is abundant. Proper understanding of the geological control factors on CBM enrichment in Anze Block of southern Qinshui Basin is critical to design efficient CBM development plan in this area. Field and laboratory data including well logging, well testing, hydraulic fracturing, and groundwater chemical analysis of were used to evaluate the characteristics of the hydrodynamic and geostress, and then, the combined effect of hydrodynamic and geostress field on CBM enrichment was analyzed. The results show that the total dissolved solids (TDS) of groundwater in the west is generally lower than that in other areas in the block, and the primary formation water is NaHCO3-type. The geostress field shows a σ H &gt; σ v &gt; σ h dominated geostress type in this area, and the western block has a lower value than the eastern block. The strong hydrodynamic field with low TDS also has a lower gas content while the weak hydrodynamic field with high TDS has a higher gas content. Both the TDS value and the horizontal stress differences are positively related to the gas content, indicating that inactive hydrodynamics and large horizontal stress difference of coal reservoir is favorable for CBM preservation.

Genesis of As in the groundwater with extremely high salinity in the Yellow River Delta, China

High arsenic (As) groundwater has been extensively found in river delta worldwide, but understanding of the influence of high salinity on As mobilization remains limited. Therefore, this study took the Yellow River Delta as the study area and tested an alternative method–ionic ratios to explore the hydrogeochemical processes of high As groundwater. Eighty–one groundwater samples and three river water samples were collected for chemical analysis. Based on inflection points of HCO3/Cl, Na/Cl, and SO4/Cl cumulative frequency distribution and hydrogeological conditions, three hydrogeochemical zones have been determined: Weathering–Fresh Water Zone (Zone I), Evaporation–Saline Water Zone (Zone II), and Seawater Mixing–Reduction Zone (Zone III). Concentrations of As and total dissolved solids (TDS) showed an increasing trend in groundwater from Zone I to Zone III. Zone I groundwater with low As and low TDS was mainly controlled by rock weathering and strong flushing. Due to intensive evaporation and seawater mixing, the TDS concentration in the groundwater of Zone II and Zone III increased sharply (up to 145997 mg/L). The high As groundwater in Zone II and Zone III was characterized by high Fe2+ and NH4+ and low NO3− and SO4/Cl, indicating that reductive dissolution of As–bearing iron oxides is the key process for As release. In addition, the significantly positive correlation between As and Cl− (>10000 mg/L) under different pH conditions indicated that intensive salinization may contribute to As mobility. Results of cluster analysis revealed that reductive dissolution is the principal driving force for As release in coastal groundwater systems and salinization is the secondary one.

Geological and geomorphological conditions of Archar-Orsoya lowland as a factor for the formation of groundwater chemical composition and in risk of its contamination

The Archar-Orsoya lowland is situated in the Danube floodplain west of the town of Lom, NW Bulgaria. It is aligned in a west-east direction along the Danube River and to the south it is bounded by a high landslide slope, built of Pliocene clays and sands. Parallel to the shore, sand dunes are formed with lowered sections between them, in which there are conditions for swamping. The lowland is made up of the alluvial sediments of the Danube, represented by a lower gravelly-sandy layer and an upper sandy-clayey layer. In the gravelly-sandy layer unconfined groundwater is accumulated, with shallow water table – from 0.5 to 7 m beneath the surface. Groundwater is recharged by infiltration of precipitation, surface water and groundwater, which laterally flows into the alluvium from adjacent aquifers. At high waters, the Danube River suppresses the formed groundwater flow and temporarily feeds it. Due to the described formation conditions in the lowland, the chemical composition of groundwater is formed under the influence of intense dynamics and has a low TDS (total dissolved solids). The shallow groundwater table and the corresponding thin unsaturated zone are a prerequisite for easy groundwater contamination with components entering from the surface. Therefore, a map of depth to groundwater table is drawn to identify the most vulnerable areas.

(Invited) Ionomer Adhesives, Coatings, and Membranes for Electrochemical Separations

A growing population striving for higher standards of living are stressing water resources around the globe. Because of the anticipated water scarcity and security challenges, water futures began trading as a commodity, like gold, oil and other precious commodities, on the stock market in late 2020. Ensuring water security necessitates water treatment and remediation technologies that are low cost, scalable, and energy efficient. Furthermore, advances in electrochemical separations technologies have been useful for targeted nutrient recovery, carbon valorization, and pollutant removal from liquids. In this talk, I will present our group’s work on addressing ohmic related resistances in membrane capacitive deionization and electrodeionization with new membrane and porous ion conducting materials. Borrowing from advances in fuel cell electrode binder technology, we show that solution processable ionomers are versatile for arriving at a new class of porous ionic conductors that address spacer channel resistances in the said deionization platforms under low TDS (total dissolved solids) concentrations. The new materials improve the separation efficiency and energy efficiency of deionization processes.

Research on drinking water purification technologies for household use by reducing total dissolved solids (TDS).

This study, based in San Bernardino County, Southern California, collected and examined tap water samples within the area to explore the feasibility of adopting non-industrial equipment and methods to reduce water hardness and total dissolved solids(TDS). We investigated how water quality could be improved by utilizing water boiling, activated carbon and sodium bicarbonate additives, as well as electrolysis methods. The results show that heating is effective at lower temperatures rather than long boils, as none of the boiling tests were lower than the original value. Activated carbon is unable to lower TDS, because it is unable to bind to any impurities present in the water. This resulted in an overall TDS increase of 3.5%. However, adding small amounts of sodium bicarbonate(NaHCO3) will further eliminate water hardness by reacting with magnesium ions and improve taste, while increasing the pH. When added to room temperature tap water, there is a continuous increase in TDS of 24.8% at the 30 mg/L mark. The new findings presented in this study showed that electrolysis was the most successful method in eliminating TDS, showing an inverse proportion where an increasing electrical current and duration of electrical lowers more amounts of solids. This method created a maximum decrease in TDS by a maximum of 22.7%, with 3 tests resulting in 15.3–16.6% decreases. Furthermore, when water is heated to a temperature around 50°C (122°F), a decrease in TDS of around 16% was also shown. The reduction of these solids will help lower water hardness and improve the taste of tap water. These results will help direct residents to drink more tap water rather than bottled water with similar taste and health benefits for a cheaper price as well as a reduction on plastic usage.

Sonolytic destruction of Per- and polyfluoroalkyl substances in groundwater, aqueous Film-Forming Foams, and investigation derived waste

Per- and polyfluoroalkyl substances (PFASs) are anthropogenic amphipathic heat-resistant materials found in some household products and Aqueous Film-Forming Foams (AFFFs) used to extinguish hydrocarbon fires. There is a critical need for developing destructive technologies for the treatment of PFAS-impacted waters because several PFASs are classified as probable carcinogens and endocrine disruptors. We tested the destruction of 7 individual PFASs, a mix of 24 native PFASs (24Mix), and samples of AFFF and concentrated Investigation Derived Waste (IDW) by high-frequency ultrasound (700 kHz – 1040 W) in deionized water, groundwater containing low total dissolved solids (TDS) (388 mg L−1), and high-TDS groundwater (10.2 g L−1). This study demonstrated the degradation of novel PFASs, hexafluoropropylene oxide dimer acid (HFPO-DA) and 6:2 fluorotelomer sulfonamidoalkyl betaine (6:2 FTAB), with near-stoichiometric fluoride release. The salts and surfactants affect the air-water partitioning coefficients of PFASs and their availability at the ultrasonic cavity, thereby affecting the degradation rates. The degradation rates of sulfonates and short-chain PFASs were 30% to 60% higher in low TDS groundwater than those in deionized water, while the rates were lower in high TDS groundwater. The degradation rates of sulfonates in AFFF were 40% to 60% higher as compared to the 24Mix. The treatment of concentrated, high-TDS IDW resulted in significant defluorination of 41 PFASs, consuming 3 kWh g−1 – 76 kWh g−1 whereas dilute AFFF degradation utilized 5900 kWh g−1. The results inform important parameters for designing and operating ultrasonic reactors for the degradation of PFASs and verify that sonolytic treatment of concentrated PFAS mixtures and AFFF IDWs can effectively degrade and defluorinate PFASs without the formation of disinfection by-products.