Hydrochemical Characteristics Research Articles

Origin and Geochemical Characterization of Groundwater from Coal Seam: A Case Study of Balasu Coalfield, Ordos Basin.

The hydrochemical characteristics of groundwater are of great significance for studying the source, development, and utilization of groundwater. This study investigated the characteristics of anions and cations, total dissolved solids (TDS), hydrochemical types, and hydrogen and oxygen isotopes of surface water and groundwater in the Balasu coalfield. By conducting experiments using inductively coupled plasma emission electron spectrometry, ion chromatography, acid-base titration, and gravimetric analysis, the characteristics of ion concentration and TDS in different aquifers were analyzed to determine the possible source of groundwater in C2 (number 2 coal seam in Yan'an Formation). The Piper trilinear diagram was used to determine the hydrochemical types of aquifers, and the source of groundwater was determined based on the stable isotope characteristics of hydrogen and oxygen. The changes in ion, TDS, hydrogen, and oxygen isotopes of surface water and groundwater were analyzed, and the groundwater differences between the two sets of coal seams were compared. The research results indicate that the groundwater in C2 (number 2 coal seam in Yan'an Formation) is caused by the original sedimentary water and the infiltration of Zhiluo Formation and A1 (strata at the top of the Yan'an Formation to number 2 coal seam). However, C4 (number 3 coal seam in Yan'an Formation) is hindered by the well-developed mudstone in A3 (bottom of number 2 coal seam to the top of number 3 coal seam), which hinders the infiltration of groundwater. The study emphasizes that the overlying strata can have a significant impact on the coal seam when the moisture content is high and there is a lack of overlap, thereby promoting changes in the moisture content of the coal seam. This study provides some insights into the safety of coal mines, especially in mining areas with a high coal seam moisture content.

Dynamic characteristics and evolution laws of underground brine in Mahai salt lake of Qaidam Basin during mining process

In the late stage of underground brine mining in salt lakes, the method of injecting fresh water is often used to extract the salt from the brine storage medium. This method of freshwater displacement breaks the original water–rock equilibrium and changes the evolution process of the original underground brine. To explore the mechanism of salt release in saline water-bearing media under conditions of relatively fresh lake water dissolution, this paper analyzes the changes in the chemical parameters of brine from 168 sampling points in the Mahai salt lake in the Qaidam Basin at three stages (before exploitation, during exploitation, and late exploitation) by correlation analysis, ion ratio analysis, and other methods and investigate the variations in porosity and the evolution laws of brine. The results show that the changes in the main ion content and brine mineralization during the exploitation process are small. The changes in Ca2+ content are significant due to the low solubility of calcium minerals, the precipitation of gypsum during the mixing process, and the adsorption of cations by alternating with Ca2+. Primary intergranular pore skeletons are easily corroded to form secondary pores, which increase the geological porosity. Na+ and Cl- are the dominant ions in the brine in the study area, but the concentration of Ca2 + decreased significantly under the influence of mining, by 41.7% in the middle period and 24.5% in the late period. The correlation between Ca2+ and salinity changes significantly in different mining stages, and the reason for the decrease of Ca2+ may be due to the influence of mineral dissolution, mixing, and anion-cation exchange. The porosity of the layer in the study area showed the opposite trend of Ca2+, and the porosity increased first and then decreased. The innovation of this paper lies in analyzing the reasons and mechanisms of the disturbance of artificial dissolution mining on stratum structure by comparing the hydrochemical characteristics and porosity of underground brine storage media in three different mining stages. The research in this paper provides a theoretical basis for the calculation of brine resource reserves and the sustainable development of underground brine in salt lake areas.

Hydrochemical characteristics and sources of groundwater pollution in Soubré and Gagnoa counties, Côte d’Ivoire

For many years, groundwater has been widely used to meet a variety of human needs. As a result of increased urbanization, industrial use, and agriculture, groundwater is inextricably affected by various threats, resulting in groundwater pollution. This current study was carried out to determine the hydrochemical characteristics of groundwater in Gagnoa and Soubré counties as well as the main sources of pollution and their impact on groundwater chemistry and quality. A total of thirty (30) groundwater samples were collected from boreholes in September 2020. The following physicochemical and chemical parameters were analyzed: Na, Ca, K, Mg, SO4, NO3–N, HCO3, Cl, pH, EC and TDS. The results showed that groundwater was acidic with a pH range from 5.22 to 6.84, fresh and moderately mineralized with a TDS range from 55.96 to 744.46 mg/l. Hydrogeochemical characterization based on the Piper diagram and Gibbs plot was used to identify the groundwater types and the main mechanism controlling the groundwater mineralization. Five (5) water types were identified with the dominance of hydrogen carbonate facies and showed the presence of silicate weathering and carbonate dissolution in the area. This is consistent with the results inferred from Gibbs plot showing that groundwater chemistry is governed by rock-water interaction. The spatial distribution map of major ions showed the different locations where each ion is dominant.According to WHO standards, the parameters show values within the threshold limit except for some of them of which their values exceed the limit. Principal component analysis and ionic ratio plots showed that the high values of nitrate as nitrogen and sulfate observed are due to the influence of natural sources such as carbonate dissolution and anthropogenic activities such as sewage-manure and chemical fertilizers.Therefore, mitigation measures should be adopted to reduce the impact of human activities contributing to groundwater pollution to protect the groundwater quality and human health.

Appraisal of groundwater suitability and hydrochemical characteristics by using various water quality indices and statistical analyses in the Wadi Righ area, Algeria

ABSTRACT This assessment research focuses on the hydrochemical characteristics and groundwater suitability in the Wadi Righ region, in southern Algeria. The statement of the problem revolves around determining water quality using various indices including Permeability Index (PI), Residual Sodium Carbonate (RSC), Water Quality Index (WQI), Sodium Percentage (Na%), Sodium Adsorption Ratio (SAR), Canadian Council of Ministers of the Environment's Water Quality Index (CCME WQI), Magnesium Hazard (MH), Irrigation Water Quality Index (IWQI), and Kelly Index (KR). Additionally, statistical methods were utilized to establish correlations between these indices and chemical elements. The working method involved investigating hydrochemical parameters in Wadi Righ's groundwater and analyzing 52 samples. The results indicate that water quality, as assessed by the water quality indices, was categorized as very poor and unsuitable overall, with lower quality observed particularly in the central and southern regions. However, groundwater demonstrated excellence and suitability for irrigation purposes. Qualitatively, the findings suggest that there are significant relationships among irrigation suitability indices, as indicated by Pearson correlation analysis. These relationships stem from shared inputs and hydrogeochemical characteristics of groundwater. This analysis reinforces the quantitative findings and provides insights into the underlying factors influencing groundwater quality and suitability for irrigation in the Wadi Righ region.

Distribution and Main Controlling Factors of Gas and Water in Tight Sandstone Gas Fields: A Case Study of Sudong 41-33 Block in Sulige Gas Field, Ordos Basin, China

Distribution and Main Controlling Factors of Gas and Water in Tight Sandstone Gas Fields: A Case Study of Sudong 41-33 Block in Sulige Gas Field, Ordos Basin, China

Hydrochemical characterization and comprehensive water quality assessment of groundwater within the main stream area of Yishu River.

To gain a comprehensive understanding of the hydrochemical characteristics, controlling factors, and water quality of groundwater in the main stream area of Yishu River (MSYR), a study was conducted using water quality data collected during both the dry and wet seasons. Through statistical analysis, hydrochemical methods, fuzzy comprehensive evaluation, and health risk evaluation modeling, the water chemical characteristics of the main stream area of Yishu River were studied, and the water quality of the area was comprehensively evaluated. The findings indicate that HCO3- and Ca2+ are the predominant anions and cations in the MSYR during the dry and wet seasons, respectively. Moreover, anion concentration in groundwater follows HCO3- > SO42- > NO3- > Cl-, while cations are ranked as Ca2+ > Na+ > Mg2+ > K+. Overall, the groundwater manifests as weakly alkaline and is predominantly classified as hard-fresh water. During the wet season, there is greater groundwater leaching and filtration, with rock and soil materials more readily transferred to groundwater, and the concentrations of main chemical components in groundwater are higher than those during the dry season, and the hydrochemical types are primarily characterized as HCO3-Ca·Mg and SO4·Cl-Ca·Mg types. These results also suggest that the chemical composition of the groundwater in the MSYR is influenced mainly by water-rock interaction. The primary ions originate from the dissolution of silicate rock and carbonate rock minerals, while cation exchange plays a critical role in the hydrogeochemical process. Groundwater in the MSYR is classified mostly as class II water, indicating that it is generally of good quality. However, areas with high levels of class IV and V water are present locally, and NO3- concentration is a crucial factor affecting groundwater quality. In the wet season, more groundwater and stronger mobility lead to greater mobility of NO3- and wider diffusion. Therefore, the risk evaluation model shows that nitrate health risk index is higher in the wet season than it is in the dry season, with children being more vulnerable to health risks than adults. To study groundwater in this area, its hydrochemical characteristics, water quality, and health risk assessment are of great practical significance for ensuring water safety for residents and stable development of social economy.

Aquatic photosynthetic carbon pump driven by periodic temperature variations affects dissolved inorganic carbon and hydrochemical characteristics in a groundwater-fed reservoir

Under the influence of periodic temperature variations, biogeochemical cycling in water bodies is markedly affected by the periodic thermal stratification processes in subtropical reservoirs or lakes. In current studies, there is insufficient research on the influence and mechanism of dissolved inorganic carbon (DIC) distribution in karst carbon-rich groundwater-fed reservoirs under the coupled effects of thermal structure stratification and the biological carbon pump (BCP) effect. To address this issue, the Dalongdong (DLD) reservoir in the subtropical region of southern China was chosen as the site for long-term monitoring and research on relevant physicochemical parameters of water, DIC, and its stable carbon isotope (δ13CDIC), CO2 emission flux, as well as the reservoir's thermal stratification index. The results show that: (1) the DLD reservoir is a typical warm monomictic reservoir, which exhibits regular variations of mixing period-stratification period-mixing period on a yearly scale due to thermal structure changes; (2) DIC was consumed by aquatic photosynthetic organisms in the epilimnion during the stratification period, leading to a decrease in DIC concentration, partial pressure of CO2 (pCO2) and CO2 emission flux, and an increase in stable carbon isotope (δ13CDIC). During the mixing period, the trend was reversed; (3) During the thermal stratification, aquatic photosynthesis and water temperature were the primary factors controlling DIC variations in both the epilimnion and thermocline. Regarding the hypolimnion, calcite dissolution, organic matter decomposition, and water temperature were the dominant controlling factors. These results indicate that although carbon-rich karst groundwater provides a plentiful supply of DIC in the DLD reservoir, its availability is still influenced by variations in the reservoir's thermal structure and the metabolic processes of aquatic photosynthetic organisms. Therefore, to better estimate the regional carbon budget in a reservoir or lake, future studies should especially consider the combined effects of BCP and thermal structure variations on carbon variations.

Hydrogeochemical characteristics of shallow aquifers in Thanh Phu District, Ben Tre Province, Vietnam

Shallow aquifers in the Thanh Phu coastal area in Ben Tre Province are increasingly withdrawn for domestic and irrigation purposes. However, groundwater resources here are declining in quality due to the effects of seawater intrusion and anthropogenic activities. It requires an understanding of the groundwater origin and changes in water quality to protect local groundwater resources. By applying the hydrogeochemical approach, the origin and quality of groundwater here have been clarified. A total of 35 water samples were collected during the 2023 dry season. The laboratory analysis included 16 ions. The results show that the groundwater water types are Ca-Cl, Ca-Mg-Cl and Na-Cl, with the domination of the third pattern. Hydrochemical characteristics have shown evaporation, silicate weathering, cation exchange and marine effects as the vital processes governing the mineralization of regional groundwater. Most of the water samples are of poor quality, not adapting to domestic water standards according to the National Technical Regulation on Domestic Water Quality and WHO 2011. It requires water treatment before being used for domestic purposes. However, the SAR, Na%, PI, KR and EC values displayed that groundwater here was still acceptable for irrigation purposes, demonstrating the prospect of using groundwater for agricultural purposes in the study area.

The source of lithium in Lakkor Co Salt Lake on Qinghai-Tibet Plateau, China: evidence from hydrochemical characteristics and boron isotope

The source of lithium in Lakkor Co Salt Lake on Qinghai-Tibet Plateau, China: evidence from hydrochemical characteristics and boron isotope

Assessment of hydrochemical characteristics and trace metals of Punpun River water – a tributary of the Ganga River

ABSTRACT This manuscript presents the first inventory of dissolved ions (cations and anions) and trace metals (Pb, Mn, Cr, Co, Ni, Cu and Zn) in the Punpun River water to assess its irrigational suitability, pollution sources and hydrogeochemical processes. For this, the physicochemical parameters and trace metals in river water were analysed in the pre- and post-monsoon seasons. The results showed that the concentrations of cations and anions were Ca2+ > Na+ > Mg2+ > K+ and HCO3− > SO42- > Cl− > NO3− > PO43-, respectively, in both the pre- and post-monsoon seasons. However, trace metal concentration in pre- and post-monsoon followed the trend of Pb > Mn > Cr > Ni > Cu > Zn > Co and Pb > Ni > Mn > Cr > Zn > Co > Cu, respectively. The results reveal that combined effects of rock weathering and evaporation-concentration influence hydrochemistry, along with anthropogenic factors like industrial effluents, urban domestic sewage and agricultural runoff. Piper and Durov plots suggest that the river water is dominated by Ca–Mg–HCO3− type, and the processes were governed by simple ion dissolution and mixing. However, the Gibbs plot shows that silicate and carbonate weathering govern the hydrochemical properties. Irrigational indices like sodium adsorption ratio, %Na, residual sodium carbonate, Kelly's ratio, magnesium hazard, and trace metals indicate that most of the water samples are suitable for irrigation. Comprehensive pollution index values suggest that the river water quality ranges from sub-clean to slightly to moderately polluted.

Hydrochemical Characteristics and Reverse Hydrogeochemical Modeling of Taiyuan Formation Limestone Groundwater of Sunan Mining Area in Huaibei Coalfield

Hydrochemical Characteristics and Reverse Hydrogeochemical Modeling of Taiyuan Formation Limestone Groundwater of Sunan Mining Area in Huaibei Coalfield

Groundwater Quality and Suitability Assessment in Tirupur Region, Tamil Nadu, India

The study aims to understand the hydrochemical characteristics and groundwater suitability for agricultural and drinking purposes. For this purpose, 21 groundwater samples were collected, and major physicochemical parameters such as pH, EC, TDS, temp, salinity, Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, and SO42− were analyzed, followed by the standard analytical procedures. Different groundwater quality graphical representations were constructed by using Aqua Chem software. The results indicate groundwater samples were alkaline with fresh to moderate saline in nature, sixty-eight percent of the samples were suitable for drinking in accordance with WHO, and thirty-two percent of the samples were unsuitable due to the excess amount of different ionic concentrations derived from natural and various anthropogenic sources. Irrigation water quality parameters such as SAR, EC, PI, Na %, RSBC, MR, and KR were used to understand the irrigation suitability. The US salinity diagram exemplifies that most groundwater samples fall in the C3S1 category with high salinity hazard and low alkali hazard. The Wilcox plot reveals that 80% of the samples were found under very good to permissible limits, and few samples fall with doubtful to unsuitable quality due to the excess amount of alkali and salinity. Permeability index values show that groundwater is suitable for irrigation. Three major hydrochemical facies were identified with the dominance order of mixed CaMgCl, NaCl, and CaCl. Gibb’s plot suggests that evaporation and rock-water interaction are the dominant natural mechanisms controlling the groundwater chemistry in the present study area.

Analysis on the spatiotemporal evolutions of groundwater hydrochemistry and water quality caused by over-extraction and seawater intrusion in eastern coastal China

The over-extraction of groundwater has resulted in seawater intrusion and the southward migration of the saltwater interface, gradually deteriorating the groundwater quality in the Weibei Plain. In this research, groundwater samples were gathered from 46 monitoring wells for shallow groundwater during the years 2006, 2011, 2016, and 2021. The hydrochemical features of regional groundwater and the factors influencing the issue were subjected to statistical analysis. Additionally, the assessment of spatiotemporal variations in groundwater quality was conducted using the customized entropy-weighted water quality index (EWQI) method. The relationship between groundwater over-extraction and the southward intrusion of the saltwater interface was compared and analyzed. The results of this paper revealed that the Weibei Plain has been in a state of long-term over-extraction of groundwater from 2000 to 2021, with an average annual over-extraction of 118.49 million m3. The groundwater depression cone areas in the northern part of the study area increased from 3,247.37 to 4,581.34 km2 from 2006 to 2021, with the center of the cone experiencing a drop in groundwater level from −22 to −85 m. The saltwater interface shifted southward by 711.71 km2 from 2006 to 2021. In groundwater, the high concentrations of TH, TDS, and Cl− were primarily related to the seawater intrusion, while higher concentrations of NO3− were mainly determined by frequent agricultural production, industrial wastewater, and domestic sewage discharges. The groundwater hydrochemical types in the study area transitioned from predominantly HCO3·Ca-Mg type in 2006 to HCO3-Na type and SO4·Cl-Ca·Mg type in 2021 due to seawater intrusion. The results of PCA and HCA show the effects of seawater intrusion, human activities, and rock weathering on groundwater hydrochemistry. The evaluation results based on the EWQI revealed that the average value of the samples in 2021 was 101.36, which belonged to Class IV water quality standards, representing the poorest water quality among the 4 years. The southward migration of the saltwater interface led to the deterioration of groundwater quality in the groundwater depression cone areas, which gradually worsened from 2006 to 2021. The maximum increase in EWQI value was 174.68 during the period, shifting from Class III water quality to Class V water quality. Groundwater quality remained relatively better in the western and southern regions which were less affected or unaffected by seawater intrusion. The results of the study can provide a certain reference value for the sustainable management of groundwater resources and the management of groundwater pollution and seawater intrusion in the Weifang City area in the future.

Groundwater quality assessment in the La Mojana region of northern Colombia: implications for consumption, irrigation, and human health risks

Water quality is one of the most relevant issues related to water management, with water pollution and access to clean water for drinking and irrigation being common issues in developing countries. Groundwater is an available water source, especially where surface sources are scarce or unsuitable. In this sense, studies to improve knowledge of aquifers should be undertaken where information on groundwater resources is not available. In the current study, 50 groundwater samples were collected from rural and urban wells used by local communities for human consumption and to irrigate local crops. Several indices for drinking water and irrigation use have been used for the assessment of water quality. Conversely, the carcinogenic and noncarcinogenic human health risks due to exposure to heavy metals in the groundwater were estimated, as were the predominant hydrochemical characteristics. The groundwater water quality index (GWQI) shows values < 100 for all the samples; groundwater is recommended for drinking after disinfection. By contrast, the irrigation water quality index (IWQI) shows that 80% of groundwater samples pose a potential threat to irrigation, with restriction categories ranging from high to severe. The individual hazard quotients were < 1. However, the multielement and multipathway hazard index (HI) for children and adults were > 1, whereas As and Mn had a higher contribution to the HI. The Piper trilinear diagram shows that hydrochemical facies of Ca2+ and HCO3− are significantly dominant. By contrast, weathering of rocks and atmospheric precipitation is the dominant factors regulating the chemistry of groundwater in the aquifer system of La Mojana. Our findings indicate that there are significant potential noncarcinogenic health risks for local populations exposed to groundwater.

Spatiotemporal dynamics of dissolved organic matter in subtropical karst cave waters identified by optical properties

Natural dissolved organic matter (DOM) is ubiquitous in aquatic environments and is an essential component in the carbon cycle in karst areas. To improve understanding of the carbon cycle in karst caves with heterogeneous hydrological processes, we examined the spatiotemporal variability of DOM composition and further uncovered its source and fate. Results may also provide insights into the feedbacks of organic carbon to carbon sinks in karst regions. In this study, concentrations and compositions of DOM, partial pressure of aqueous carbon dioxide (pCO2), dissolved inorganic carbon, and other physicochemical parameters were investigated in a karst cave at Mahuang, Southwest China. Ultraviolet-visible absorption spectroscopy was coupled with multiple statistical analyses to identify the compositional variations and potential fates of DOM in cave waters. The results showed that DOM dynamics were regulated by both terrigenous and biogenic drivers under the control of meteorological conditions. With higher air temperature, precipitation, and microbial activity, fulvic fractions were consumed to generate CO2, leading to the accumulation of refractory DOM in cave waters and changing the hydrochemical features. When temperature and precipitation decreased, DOM was dominated by lignin fractions, which served as an indicator of terrestrial inputs and vascular plants, suggesting variation in the preferential fraction of biological consumption. In addition, different hydrological path patterns influenced DOM properties in cave waters due to differences in recharging, the leaching process, and subsurface reworking. Thus, hydrology could serve as an important constraint on the coupling between dissolved organic and inorganic carbon.

Assessment of the Hydrochemical Characteristics of the Carbon Observational Site ‘Carbon-Sakhalin’ (Aniva Bay, Sea of Okhotsk)

Following a tendency of many economies to shift towards carbon neutrality, there came the necessity for certain regions to be assessed in terms of their greenhouse gas emissions from the ocean. A carbon polygon was created in Sakhalin Oblast in order to evaluate the carbon balance of this marine ecosystem in a sub-arctic region, with the possibility of deploying carbon farms for additional CO2 absorption. To obtain such an assessment, it seems crucial to analyze hydrochemical parameters that reflect the situation of the marine environment in Aniva Bay as a basis of the carbon polygon. The article presents the results of the analysis of hydrochemical parameters in Aniva Bay waters and their spatial and seasonal variability. This research was based on available published sources and measurement databases for the period of 1948–1994. Additionally, the review uses hydrochemical data for Aniva Bay in 2001–2013 weather station data for the period of 2008–2023 and weather station data for 2008–2023. Some tendencies were discovered for spatial and temporal distributions of oxygen, pH, and biogenic matter (inorganic phosphorus, inorganic nitrogen, silicon). In surface layers, the mean oxygen year maximum (9.1 mg/L) is registered with the beginning of photosynthesis, i.e., immediately after the ice melting in April. The highest pH values 8.26 are registered in the euphotic layer in May. The lowest pH values was in August (7.96) in the near-bottom layer. The maximum annual P-PO4 registered on the surface (&gt;18 µg/L) immediately after ice melting, with a minimum (7.17 µg/L) at the end of July. Si-SiO3 concentrations have two maximums: at the end of June and at the beginning of October. N-NO2 concentration on the surface is &gt;2 µg/L in mid-July and on the 50 m depth it is &gt;3.5 µg/L in mid-September. Some spatial patterns of hydrochemical parameters were shown based on the analysis of maps.

Hydrochemical Characterization of Ground and Surface Water for Irrigation Application in Nigeria: A Review of Progress

Hydrochemical Characterization of Ground and Surface Water for Irrigation Application in Nigeria: A Review of Progress

Hydrochemical characterization and assessment of health risks of trace elements in the Huai River Basin of China.

Basin water pollution is a global problem, especially in the densely populated areas. The Huai River Basin (abbreviated as HRB), including the Huai River system and the Yishu River system, is the sixth-largest and most densely populated watershed in China. However, there is a lack of comprehensive studies of river and well water throughout the Huai River basin, including hydrochemistry characterization and assessment of health risks. This study investigated water quality and pollution sources of river and well water in the HRB based on the hydrochemistry analysis and different water quality indices. The water body in the HRB showed weak alkalinity (pH = 8.4 ± 0.7) and had high TDS values (TDS = 339 ± 186mg/L) with water types of HCO3-Ca-Mg and SO4-Cl-Ca-Mg in the Huai River system, and SO4-Cl-Ca-Mg in the Yishu River system. Atmospheric input and evaporation had less impact on hydrochemistry. Evaporite dissolution and carbonate weathering had a greater impact on hydrochemistry. Carbonate precipitation and cation exchange also influenced the dissolved solutes, especially Ca2+ and Na+. Samples had low to medium salinity hazards and sodium absorption ratios and were suitable for irrigation. For drinking purposes, samples were fresh water and have good or excellent according to the Water Quality Index (WQI). Land use types influenced water quality with the worst river water quality from cropland. Combining different assessment indices, the water quality of the Yishu River system performed betterthanthe Huai River system. Absolute principal component analysis-multiple linear regression and the positive matrix factorization models identified the main pollutants as As, Ba, Cr, Ni, and Mn, with natural sources of As, Ba, and Ni and anthropogenic inputs of Cr, and Mn. Although the water quality of the HRB has improved in recent years, high potential risk from As, Cr, Mn, Ba, and Ni should be noted. This study provided vital information for basin hydrochemistry analysis and water quality assessment.

Identifying the Hydrochemical Characteristics, Genetic Mechanisms and Potential Human Health Risks of Fluoride and Nitrate Enriched Groundwater in the Tongzhou District, Beijing, North China

AbstractFluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety, especially in aggregated population areas and economic hubs. This study focuses on the high F– and NO3– concentration groundwater in Tongzhou District, Beijing, North China. A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics, elucidate genetic mechanisms and evaluate the potential human health risks. The results of the analysis indicate: Firstly, most of the groundwater samples are characterized by Mg‐HCO3 and Na‐HCO3 with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471–2337 mg/L. The NO3– concentration in 38.89% groundwater samples and the F– concentration in 66.67% groundwater samples exceed the permissible limited value. Secondly, F– in groundwater originates predominantly from water‐rock interactions and the fluorite dissolution, which is also regulated by cation exchange, competitive adsorption of HCO3– and an alkaline environment. Thirdly, the effect of sewage disposal and agricultural activities have a significant effect on high NO3– concentration, while the high F– concentration is less influenced by anthropogenic activity. The alkaline environment favors nitrification, thus being conducive to the production of NO3–. Finally, the health risk assessment is evaluated for different population groups. The results indicate that high NO3– and F– concentration in groundwater would have the largest threat to children's health. The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.

Hydrochemical properties and heavy metal concentrations (ecological and human risk) of lake Rukwa

This study examined lake Rukwa's hydrochemical characteristics and heavy metal levels (ecological and health hazards). Results showed that the pH ranged from 8.83 to8.95, EC ranged from 1470 to 1572.22 µS/cm, and TDS ranged from 1053.04 to 1262.63 Mg/l. The findings revealed that lake Rukwa is characterized by Na-K-HCO3 water chemical type. Gibb's diagram revealed that rock weathering and evaporation regulate water's chemical composition. The calcite and sepiolite precipitation enriches the water with Na-CO3-SO4-Cl. The study suggests silicate mineral weathering, rock-water interactions, direct ion exchange, and secondary mineral precipitation govern the geochemical evolution of lake Rukwa. The results also revealed that 30% of samples had moderate ecological risk (30 < RI < 60), whereas 70% had severe risk (60 < RI < 120). The oral hazard quotient (HQ) values for lead (Pb) in children were significantly higher (HQ > 1) at all locations, indicating a potential health risk. However, the dermal HQ values were found to be within acceptable levels. Most sites had acceptable Hazard Index (HI) values, except for Pb in children and adults. In Monte Carlo simulations, heavy metal HQ values were below standard limits, except for oral Pb exposure, which exceeded 1 for adults (7.29E-04) and children (2.79E-03). The average CR values for oral and dermal Pb in adults (7.29E-04, 3.47E-04) and children (2.79E-03, 1.02E-03) exceeded 1.0E-04, suggesting carcinogenic potential. These findings highlight significant oral and dermal carcinogenic hazards from Pb exposure to lake Rukwa and the necessity for effective comprehensive measures to mitigate these risks.