Salt Content In Groundwater Research Articles

Distribution of Groundwater Hydrochemistry and Quality Assessment in Hutuo River Drinking Water Source Area of Shijiazhuang (North China Plain)

The Hutuo River Drinking Water Source Area is an important water source of Shijiazhuang (North China Plain). Knowing the characteristics of groundwater chemistry/quality is essential for the protection and management of water resources. However, there are few studies focused on the groundwater chemistry evolution over the drinking water area. In this study, total of 160 groundwater samples were collected in November 2021, and the spatial distribution of groundwater chemistry and related controlling factors were analyzed using hydrological and multivariate analysis. The entropy-weighted water quality index (EWQI) was introduced to assess the groundwater quality. The results show that the hydrogeochemical types of groundwater are Ca-HCO3 (78.1%), mixed Ca-Mg-Cl (20%), and Ca-Cl (1.9%) in the area. Graphical and binary diagrams indicate that groundwater hydrochemistry is mainly controlled by water–rock interaction (i.e., rock weathering, mineral dissolution, and ion exchange). Five principal components separated from the principal component analysis represent the rock–water interaction and agricultural return, redox environment, geogenic sources, the utilization of agricultural fertilizer, the weathering of aluminum silicates, and dissolution of carbonates, respectively. More than 70% of the samples are not recommended for irrigation due to the presence of high salt content in groundwater. EWQI assessment demonstrates that the quality of the groundwater is good. The outcomes of this study are significant for understanding the geochemical status of the groundwater in the Hutuo River Drinking Water Source Area, and helping policymakers to protect and manage the groundwater.

Development of Low-Cost IoT System for Monitoring Piezometric Level and Temperature of Groundwater

Rural communities in Mexico and other countries with limited economic resources require a low-cost measurement system for the piezometric level and temperature of groundwater for their sustainable management, since anthropogenic action (pumping extractions), natural recharge and climate change phenomena affect the behavior of piezometric levels in the aquifer and its sustainability is at risk. Decrease in the piezometric level under a balanced level promotes salt intrusion from ocean water to the aquifer, salinizing and deteriorating the water quality for agriculture and other activities; and a decrease in water level under the pumps or well drilling depth could deprive communities of water. Water temperature monitoring is essential to determine electric conductivity and dissolved salt content in groundwater. Using IoT technology, a device was developed that monitors both variables inside the well, and the ambient temperature and atmospheric pressure outside the well. The measurements are made in real time, with sampling every second and sending data to a dedicated server every 15 min so that the visualization can be accessed through a device with Internet access. The time series of the variables measured inside and outside the well were obtained over a period of three months in the rural community of Agua Blanca, Guasave, Sinaloa, Mexico. Through these records, a progressive temporary drawdown of the piezometric level is observed, as well as the frequency of pumping. This low-cost IoT system shows potential use in hydrological processes of interest such as the separation of regional and local flow, drawdown rates and recognition of geohydrological parameters.

Air Quality Monitoring for Preventive Conservation of the Built Heritage Deteriorated by Salt Crystallization

The Santo Domingo Diocesan School (Orihuela, SE Spain) is a singular case study that relates air quality monitoring and stone conservation. The monument suffers severe damage due to salt crystallization by rising damp, which is related to the indoor environment dynamics, high groundwater salt content, and microstructure, the building’s porous stone (biocalcarenite). Results revealed that 222Rn concentration in indoor air is low due to the building’s high ventilation rate, despite the medium-low geogenic radon potential in the area. Wavelets analysis showed that ventilation is caused by outdoor and indoor temperature variations and directly affects the 222Rn and CO2 dynamics inside the church. CO2, as well as relative humidity (RH), presented periodicities with intermediate frequencies (5–8 days) related to visits. These RH and temperature (T) variations intensified the salt damage by increasing the frequency of dissolution-crystallization cycles. The mineralogical characterization and geochemical calculations concluded that chlorides (halite and sylvite), sulfates (thenardite, epsomite, hexahydrite and aphthitalite) and nitrates (niter) present from dissolution forms to whiskers and hopper-type morphologies. This indicates high saturation values and, therefore, higher crystallization pressure values within the porous media of the biocalcarenite. On the contrary, the near-equilibrium crystal shape and incongruent precipitation reaction for humberstonite suggest a lower alteration for this salt on the building stone.

Ground Improvement Using Dynamic Compaction in Sabkha Deposit

The sabkha soil spreads extensively in the Arabian Gulf Coast region. Sabkha is known as a geotechnically problematic soil because of its loose density, soft consistency, high salinity and water content, and occurrence of fine sands and clays. It is generally highly compressible and requires ground improvement for highway and railway construction. The purpose of this study is to provide a guideline for dynamic compaction to improve the bearing capacity of the coastal sabkha deposit. The ground behavior during dynamic compaction was evaluated for various compaction energy conditions using numerical analysis, and field dynamic compaction tests were also performed and compared with the numerical analysis results. It was found that the bearing capacity of sabkha deposit can be effectively improved by dynamic compaction. However, care must be taken to ensure that excessive porewater pressure is sufficiently dissipated during the application of dynamic compaction because the permeability is pretty low due to the high salt content in groundwater in the sabkha area.

Groundwater quality assessment of the Takelsa phreatic aquifer (Northeastern Tunisia) using geochemical and statistical methods: implications for aquifer management and end-users.

The Takelsa phreatic aquifer (Northeastern Tunisia) is an important source of fresh water for different economic sectors in the region that are strongly dependent on groundwater resources but, the aquifer is showing increasing signs of groundwater quality degradation like many other regions in the Mediterranean Basin. By integrating geochemical and multivariate statistical investigation methods, this research aims to identify the main geochemical processes and anthropogenic activities that are responsible for regional groundwater quality evolution, identifying the origins of salinity and nutrients, and their implications for groundwater use forcropirrigation and drinking water supply in order to improve aquifer management practices. The results show that groundwater facies vary from Ca-Mg-SO4 to Na-Cl water type and that mineralization is strongly controlled by mineral dissolution and cation exchange. The isotopic analyses indicate that groundwater is recharged by rainwater infiltration at higher altitudes and that a cumulative evaporative effect may contribute to local increase of salt content in groundwater. The Water Quality Index (WQI) used to determine the suitability of the Takelsa groundwater for drinking purposes reveals that just half of the groundwater points sampled show good to excellent quality for human consumption. The groundwater quality is also limited for irrigation purposes due to anthropogenic activities existing throughout the region. As groundwater in the studied region is crucial for irrigation and human supply, the identified groundwater quality problems and the identification of the main processes responsible for them should contribute to improve the infrastructure and managementpractices to allow the region to sustainable exploit the available groundwater resources.

Soil water-salt dynamics state and associated sensitivity factors in an irrigation district of the loess area: a case study in the Luohui Canal Irrigation District, China

Soil salinisation determines the distribution pattern of crop processes in irrigation districts. The research presented here was conducted in the Luohui Canal Irrigation District, which is located in the loess area of Shaanxi Province, China. A back-propagation artificial neural network (BPANN) for the soil water-salt state was established to predict soil salinity and alkalinity. The degree of influence of numerous factors on the dynamics was quantitatively determined using the default factor testing method and verified with grey relational analysis. The results show that the BPANN prediction accuracy is very high, and it can efficiently depict the comprehensive relationships between the influential factors and dynamic states. The influence of soil moisture, evaporation, groundwater salt and groundwater depth on the dynamics is significant in the region. The current irrigation method, used for many years, cannot meet the water necessities for the vegetation, causing the groundwater levels to decline and a lowering of the soil moisture zone, leading to the occurrence of serious soil salinisation. Under the action of evaporation, more salt accumulates in the upper part of the soil, resulting in extensive soil salinisation. The higher the groundwater salt content, the more salt is carried by rising capillary water, and the more the soil is salinised. If groundwater depth was to exceed the critical water table, then groundwater and salt would move to the soil surface by moisture evaporation, and salt would build up on the soil surface in this irrigation district. The interactions between each factor forms a complex coupling relationship state.

Evaluation of groundwater quality and suitability for irrigation and drinking purposes in southwest Punjab, India using hydrochemical approach

Groundwater samples from alluvial aquifers of Bathinda district, southwest Punjab were measured for physicochemical parameters as well as major ion chemistry to evaluate the groundwater suitability for drinking and irrigation purposes and to present the current hydrochemical status of groundwater of this district. Temporal variations were analyzed by comparing the pre- and post-monsoon groundwater chemistry. Most of the samples showed contamination: F− (72 %), Mg2+ (22 %), SO42− (28 %), TH (25 %), NO3− (22 %), HCO3− (22 %) and TDS (11 %) during pre-monsoon and F− (50 %), Mg2+ (39 %), SO42− (22 %), TH (28 %), NO3− (22 %) and TDS (28 %) during post-monsoon above permissible limits for drinking, while rest of the parameters fall within the limits. Irrigation suitability was checked using sodium absorption ratio (SAR), residual sodium carbonate (RSC), percent sodium (Na%) and permeability index (PI). Most of the samples fall under good to suitable category during pre-monsoon period, but fall under doubtful to unsuitable category during post-monsoon period. Presence of high salt content in groundwater during post-monsoon season reflects leaching of salts present in the unsaturated zone by infiltrating precipitation. Hydrochemical data was interpreted using Piper’s trilinear plot and Chadha’s plot to understand the various geochemical processes affecting the groundwater quality. The results indicate that the order of cation dominance is Na+ > Mg2+ > Ca2+, while anion dominance is in the order Cl− > HCO3− > SO42−. The geochemistry of groundwater of this district is mainly controlled by the carbonate and silicate mineral dissolution and ion exchange during pre-monsoon and leaching from the salts deposited in vadose zone during post-monsoon. The main sources of contamination are soluble fertilizers and livestock wastes. This study is significant as the surface water resources are limited and the quality and quantity of groundwater are deteriorating with time due to anthropogenic inputs.

The effects of oasis ecosystem hydrological processes on soil salinization in the lower reaches of the Tarim River, China

ABSTRACTOn the basis of the characteristics of the oasis hydrological recycling processes in the lower reaches of the Tarim River, the impacts of surface water and groundwater on soil salt content were analyzed to determine how these processes affect soil salinization. The results showed that the relationship between surface water quality and soil salt content in the 0–50 cm layer of soil was significantly positive, with soil salt content declining as groundwater depths increased. However, there was no clear correlation between surface water and salt content in the 50–100 cm layer of soil. When the groundwater depth was <6 m, the soil salt content showed a high‐surface concentration, exhibiting a ‘T’ distribution and decreased with increasing soil depth in the order of 0–20 cm > 20–50 cm > 50–100 cm. However, with increasing groundwater depth (>6 m), soil salt loads were reduced and showed a ‘rhombus’ distribution, mainly accumulating in the middle layer in the order of 20–50 cm > 0–20 cm > 50–100 cm. When groundwater depth was greater than 6 m, the hardness, total dissolved solids (TDS), and conductance of the groundwater underwent a radical change. Thus, the critical threshold groundwater depth for condensing salt content in groundwater and changing soil salt load distributions was deemed to be 6 m. Salt accumulation in the 0–50 cm layer of soil was determined by the TDS volume in the groundwater when groundwater depth was shallow, which accounted for more than 90% of salt accumulation. However, salt accumulation was determined by the volume of TDS in irrigation water when groundwater depth increased. Copyright © 2013 John Wiley & Sons, Ltd.

The BP Neural Network Model of Soil Water-Salt Dynamic State Analysis

With the survey data of Luohui Canal Irrigation District, Shaanxi, China as the example, we employed the three-layer feed forward BP network modeling method to study the soil water-salt dynamic state under the comprehensive conditions of the irrigation district, and adopted the Additional Momentum Method and Self-adaptive Learning-rate Adjustment Strategy to modify the back propagation algorithm; on this basis, we employed the default-factor testing method to analyze the sensitivity degrees of soil salt content and soil alkalinity to every factor in the input layer. The results show this model has a high accuracy and can characterize effectively the internal relationships between the change of farmland soil water-salt dynamic state at a shallow water table during crop growth period and its influential factors. Soil moisture content, groundwater salt content and groundwater evaporating capacity are main sensitive factors of soil water-salt dynamic state; the factors interact and affect each other, giving rise to a coupling relationship under complex conditions. Combining the above methods can provide a feasible and effective approach to study the law of soil water-salt dynamic state under a shallow water table during crop growth period, which is a supplement to and improvement in conventional research methods for soil water-salt dynamic state.

基于机器学习模型的沙漠腹地地下水含盐量变化过程及模拟研究

为了研究塔克拉玛干沙漠腹地的地下水盐分变化规律,模拟地下水盐分变化过程,评价适合该区域的地下水变化规律的模型。通过对研究区蒸发量、降水量、气温、气压、地下水位、地下水电导率数据的统计分析,揭示了地下水含盐量及其影响因素的特征;使用GP模型、GPLVM模型和BP人工神经网络模型以及综合模型,模拟了气候变化和人类活动双重影响下的地下水含盐量变化过程,并评价了模型的模拟结果。研究结果表明:(1)研究区地下水流动系统主要受气候变化和人类活动的影响,地下水位在局部地区随开采过程呈现波动变化。地下水位变化过程与气压的变化规律相一致;而气温和蒸发量的季节变化规律相一致。地下水盐分含量呈上升趋势。(2)GP模型对于地下水含盐量的预测效果最好;GPLVM模型对于已知地下水含盐量条件下,与其他环境因素进行多元回归分析的拟合效果最好。而GP、GPLVM和BP人工神经网络模型的综合模型,对于包括模型训练和模型预测的全体数据集的拟合和预测效果最好。;The Taklimakan Desert, in the center of the Tarim Basin, Northwest China, is near the arid center of the Eurasian Continent. It is an ideal place for carrying out research on circulation systems of ocean-continent and continent-continent, as well as on the environmental effects of the Tibetan Plateau uplift. Oil and natural gas resources are rich in the desert hinterlands, where weather is extremely dry and the ecological environment is extremely frail. How to achieve sustainable development of oil gas energy exploitation and water resources will become a key issue of rapid and sustained energy development in the exploitation area. Since 2000, with the increase of oil and gas production, as well as construction of ecological engineering in oil field areas, regional water use, i.e., water consumption by oil exploitation, life-service water, and ecological engineering water has been increasing. Under this condition, the response of regional groundwater to water-use behavior, and sustainable use of groundwater under scaled development of future oil gas energy, is a focus of discussion in academic circles. All the water used for oil field production, living, and an ecological shelterbelt program in the Tarim oil field was supplied by 19 local water wells. The main groundwater was from surrounding snow cover and glacier meltwater that leak into the groundwater system at a mountain pass, which then inflows slowly as runoff with terrain change. There is a single chemical type of groundwater in the study area, which is mainly alkali and a strong acid ion. Groundwater is an important resource within desert areas, for both human use and maintenance of the ecological environment. However, little information is available on the long-term change and evolutionary trends of groundwater salt content in the region. The aim of this study is to increase knowledge of such content and its influences there. We simulated this content, studied its change, and evaluated the effects and applicability of machine learning models for the hinterland of Taklimakan Desert. For these purposes, three machine learning models and an appropriate integrated model were designed to simulate the variation of groundwater salt content. Based on statistical analysis of evaporation, precipitation, air temperature, air pressure, groundwater level and conductivity, this paper reports some statistical features of that content and its influences. The temporal change of content was simulated using Gaussian Process (GP), Gaussian Process Latent Variable Model (GPLVM), Back Propagation Artificial Neural Network (BP-ANN), and an integrated machine learning model, under the impacts of climate change and human activities. The modeling was evaluated using root mean square error (RMSE) and uncentered R-squared (uncentered <em>R</em>²).The results show that the groundwater flow system is affected by climate change and human activities, and groundwater level appears steady with small fluctuation in the study area. The change of groundwater level was concordant with air pressure, and the change of air temperature was consistent with evaporation. There was an overall uptrend of groundwater salt content. Accurate prediction can be achieved with GP, whereas GPLVM was the better multiple regression method for a known groundwater salt content among the three models. The integrated model of GP, GPLVM, and BP-ANN gave the best results for all observation datasets, including training and prediction data. The results not only help clarify regional hydrologic cycle processes under extremely dry conditions, but can also provide appropriate theoretical evidence for sustainable utilization of water resources and safe production in desert oilfields.

Transport of Ferrihydrite Nanoparticles in Saturated Porous Media: Role of Ionic Strength and Flow Rate

The use of nanoscale ferrihydrite particles, which are known to effectively enhance microbial degradation of a wide range of contaminants, represents a promising technology for in situ remediation of contaminated aquifers. Thanks to their small size, ferrihydrite nanoparticles can be dispersed in water and directly injected into the subsurface to create reactive zones where contaminant biodegradation is promoted. Field applications would require a detailed knowledge of ferrihydrite transport mechanisms in the subsurface, but such studies are lacking in the literature. The present study is intended to fill this gap, focusing in particular on the influence of flow rate and ionic strength on particle mobility. Column tests were performed under constant or transient ionic strength, including injection of ferrihydrite colloidal dispersions, followed by flushing with particle-free electrolyte solutions. Particle mobility was greatly affected by the salt concentration, and particle retention was almost irreversible under typical salt content in groundwater. Experimental results indicate that, for usual ionic strength in European aquifers (2 to 5 mM), under natural flow condition ferrihydrite nanoparticles are likely to be transported for 5 to 30 m. For higher ionic strength, corresponding to contaminated aquifers, (e.g., 10 mM) the travel distance decreases to few meters. A simple relationship is proposed for the estimation of travel distance with changing flow rate and ionic strength. For future applications to aquifer remediation, ionic strength and injection rate can be used as tuning parameters to control ferrihydrite mobility in the subsurface and therefore the radius of influence during field injections.

Effect Of Water Resource On Soil Salinization Of Oasis In The Lower Reaches Of Tarim River, China

The development of oasis in the lower reaches of the Tarim River has been impeded due to serious soil salinization and water resource shortage. To examine the effect of water resource on soil salinization, we analyzed the effects of surface water resource, groundwater depths and quantity on soil salt content based on the field monitoring. The results showed that the relationship between quality of surface water and soil salt content in 0-50 cm was significantly positive, but not to the salt content of the 50-100 cm layers. The soil salt content also closely related to the groundwater depth, of which 0-50 cm layers surface soil salt content declined with the increasing groundwater depth, and the change of 0-20 cm soil salt content was biggest. When the groundwater depth was shallower, the soil salt content was high with high surface concentration, which showed a “T” distribution, and soil salt content decreased with the increasing soil depth, in the order 0-20cm>20-50cm>50-100 cm. With the groundwater depth increasing, soil salt loads reduced and showed a “rhombus” distribution, which mainly accumulated in the middle layer, in the order 20-50 cm > 0-20 cm > 50-100 cm. When the groundwater depth was more than 6m, the hardness, total dissolved solids (TDS) and conductance of the groundwater as well as the soil salt loads distribution appeared sharply changes. So, the critical groundwater depth for condensing salt content in groundwater and changing the soil salt loads distribution was 6 m.

EFFECTIVENESS OF OPEN DRAINS IN RECLAIMING SALTY CLAY LOW PERMEABLE SOIL

A field study was carried out at Khalid Ibn Al Walid village, Hessanya, Sharkia Governorate during the winter season of 2006/07 where barely crop was grown toinvestigate the possibility of restoring the deteriorated soil through open field drains. The field served by open drains at a depth of 90 cm with length of 100 m. and the drain spacing treatments were at 10 and 20 m. The results indicated that drain spacing treatments reduced the watertable level. The recession percentages of watertable level were 60, 47, 29 and 28 % after 5, 10, 15 and 20 days, respectively in the treatment of 10 m drain spacing compared to the one of 20 m. Generally, close drain spacing relatively was more effective on lowering watertable level than the wider spacing. Watertable salinity during the recession of watertable increased with depth to reach the maximum value at deeper layers. Closer drain spacing caused a considerable reduction in soil moisture content with days after irrigation more than the obtained reduction under wider drain spacing. The reduction in the moisture content of soil profile was 11.69, 13.08, 25.88 and 24.74 % after 5, 10, 15 and 20 days from irrigation, respectively in 10 m drain spacing treatment compared to that of 20 m. The reduction in soil salinity for the treatment of narrow drain spacing was more obvious than that in wider one especially in the surface layer and short time after irrigation (5 days). The reduction in the salinity of soil profile was 14.71, 8.00, 9.52 and 7.14% after 5, 10, 15 and 20 days from irrigation, respectively in 10 m drain spacing treatment compared to that of 20 m. It might be concluded that drainage alone is not enough for control of the twin menace of waterlogging and salinity. Therefore, supplementary practices to improve drainage efficiency such as subsoiling can be used periodically. Subsoiling will enhance downward movement of irrigation water carrying off excess salts from surface layers. After wards, regular subsequent irrigations will gradually reduce the salt content in groundwater at least when it comes close to soil surface. The percolating water will constitute a temporary front preventing the saline groundwater in subsurface layers from linking with the upper ones.