Weathering Of Rock-forming Minerals Research Articles

Hydrogeochemical characterization and quality assessment of groundwater using self-organizing maps in the Hangjinqi gasfield area, Ordos Basin, NW China

Water resources are scarce in arid or semiarid areas, which not only limits economic development, but also threatens the survival of mankind. The local communities around the Hangjinqi gasfield depend on groundwater sources for water supply. A clear understanding of the groundwater hydrogeochemical characteristics and the groundwater quality and its seasonal cycle is invaluable and indispensable for groundwater protection and management. In this study, self- organizing maps were used in combination with the quantization and topographic errors and K-means clustering method to investigate groundwater chemistry datasets. The Piper and Gibbs diagrams and saturation index were systematically applied to investigate the hydrogeochemical characteristics of groundwater from both rainy and dry seasons. Further, the entropy-weighted theory was used to characterize groundwater quality and assess its seasonal variability and suitability for drinking purposes. Our hydrochemical groundwater dataset, consisting of 10 parameters measured during both dry and rainy seasons, was classified into 6 clusters, and the Piper diagram revealed three hydrochemical facies: Cl-Na type (clusters 1, 2 and 3), mixed type (clusters 4 and 5), and HCO3-Ca type (cluster 6). The Gibbs diagram and saturation index suggested that weathering of rock-forming minerals were the primary process controlling groundwater chemical composition and validated the credibility and practicality of the clustering results. Two-thirds of 45 groundwater samples were categorized as excellent- or good-quality and were suitable as drinking water. Cluster changes within the same and different clusters from the dry season to the rainy season were detected in approximately 78% of the collected samples. The main factors affecting the groundwater quality were hydrogeochemical characteristics, and dry season groundwater quality was better than rainy season groundwater quality. Based on this work, such results can be used to investigate the seasonal variation of hydrogeochemical characteristics and assess water quality accurately in the others similar area.

Hydrogeological and Hydrochemical Assessment of Basin Granitoids in Assin and Breman Districts of Ghana

Hydrogeological and hydrochemical assessments were carried out in Assin and Breman districts of Ghana. A multi-criteria approach was used in the assessment of the basin granitoids including; electrical resistivity survey, pumping test and water quality analysis. A total of twenty-five (25) representative boreholes were drilled, developed and pumped; obtaining data for aquifer hydraulic parameters estimation. Correlation analysis was used to determine relationships that exist between aquifer hydraulic parameters. Schoeller, Piper, Stiff plot and Gibbs diagrams were used to determine the hydrogeochemical facies, water types and the mechanism that control groundwater quality. The statistical analysis determined that aquifer hydraulic parameters discharge rate (Q), hydraulic conductivity (K) and Transmissivity (T) showed a strong positive correlation with specific capacity (Q/Sw) with R value 0.8462, 0.8738 and 0.8332 respectively. The K and T were respectively between 0.02 - 0.90 m/day and 0.36 - 13.47 m2/day with mean of 0.24 m/day and 3.03 m2/day respectively. The K values indicate a hydrogeological condition of aquiclude with relatively low permeability and medium water bearing capacity. The aquifer T magnitude is very low to low, groundwater potential is adequate for local water supply with limited and private consumption. All physicochemical parameters were within the permissible limits of Ghana Standards Authority (GSA) and World Health Organisation (WHO) except for apparent colour, pH, Fe and Mn. Distribution of major ions in groundwater samples was calculated and the general trend among cations and anions was found to be Ca2+ > Na+ > Mg2+ and Cl− > HCO3− > SO42− respectively. The study area shows five main water types namely; Ca-HCO3, Na-Mg-HCO3-SO4, Ca-SO4, Na-Cl and Mg-Na-Cl. Weathering of rock-forming minerals as the mechanism controlling the groundwater chemistry. Microbiological parameters were above the permissible limits. Groundwater is suitable for drinking after treatment with chlorination, aeration and slow sand filtration methods.

Hydrogeochemistry and quality of surface water and groundwater in the vicinity of Lake Monoun, West Cameroon: approach from multivariate statistical analysis and stable isotopic characterization.

With the use of conventional hydrogeochemical techniques, multivariate statistical analysis, and stable isotope approaches, this paper investigates for the first time surface water and groundwater from the surrounding areas of Lake Monoun (LM), West Cameroon. The results reveal that waters are generally slightly acidic to neutral. The relative abundance of major dissolved species are Ca(2+)>Mg(2+)>Na(+)>K(+) for cations and HCO3 (-)≫NO3 (-)>Cl(-)>SO4 (2-) for anions. The main water type is Ca-Mg-HCO3. Observed salinity is related to water-rock interaction, ion exchange process, and anthropogenic activities. Nitrate and chloride have been identified as the most common pollutants. These pollutants are attributed to the chlorination of wells and leaching from pit latrines and refuse dumps. The stable isotopic compositions in the investigated water sources suggest evidence of evaporation before recharge. Four major groups of waters were identified by salinity and NO3 concentrations using the Q-mode hierarchical cluster analysis (HCA). Consistent with the isotopic results, group 1 represents fresh unpolluted water occurring near the recharge zone in the general flow regime; groups 2 and 3 are mixed water whose composition is controlled by both weathering of rock-forming minerals and anthropogenic activities; group 4 represents water under high vulnerability of anthropogenic pollution. Moreover, the isotopic results and the HCA showed that the CO2-rich bottom water of LM belongs to an isolated hydrological system within the Foumbot plain. Except for some springs, groundwater water in the area is inappropriate for drinking and domestic purposes but good to excellent for irrigation.

Hydrochemical evaluation of Rangit river, Sikkim, India: using Water Quality Index and multivariate statistics

This study is aiming to focus on hydrogeochemical investigation of water samples from Rangit river basin and assessment of water quality for human consumption and agricultural purposes. River water is neutral to mildly alkaline, with dominance of K+, Ca2+, HCO3 −, and SO4 2− in ionic strength. K+–Ca2+–Mg2+–HCO3 − is the major hydrochemical facies in upstream river water, whereas Ca2+–K+–Mg2+–HCO3 − water-type dominates in downstream stretches of river. The weathering of rock-forming minerals mainly controls the solute acquisition process. The high equivalent ratios of (Ca2+ + Mg2+)/(Na+ + K+) and the low ratio of (Na+ + K+/TZ+) reveal that the chemical composition of river water is mostly determined by carbonate weathering with partial contribution from silicate weathering. An evaluation of Water Quality Index of sampled river water indicates that the majority of the water samples are good–moderate for human consumption and domestic usages. Irrigation suitability of river water in relation to EC content, SAR, and RSC values suggests that river water is good–excellent type for agricultural applications.

Clustering spatio–seasonal hydrogeochemical data using self-organizing maps for groundwater quality assessment in the Red River Delta, Vietnam

Summary The Red River Delta (RRD) is the second largest delta in Vietnam, and its local communities depend on groundwater sources for water supply. A clear understanding of the groundwater hydrogeochemical properties, particularly their changes from the dry to rainy seasons and spatial characteristics, is invaluable and indispensable for the management and protection of this important water resource. In this study, self-organizing maps was systematically applied for the first time to investigate the seasonal and spatial hydrogeochemical characteristics of groundwater in the Pleistocene confined aquifer of the RRD. The hydrogeochemical characteristics clustered by SOM were further examined using the Gibbs Diagrams. The groundwater chemistry dataset used in the analysis comprised eight major dissolved ions (i.e., Ca 2+ , Mg 2+ , Na + , K + , HCO 3 − , Cl − , SO 4 2− , and CO 3 2− ) and total dissolved solids that were collected from 52 groundwater monitoring wells within the study area during the dry and rainy seasons. Based on the results, the hydrogeochemical groundwater data of the confined aquifer monitoring wells for the delta were classified into 8 clusters, which revealed three basic representative water types: high salinity (2 clusters), low salinity (3 clusters), and freshwater (3 clusters). The high-salinity types were located in the middle-stream and coastal areas of the RRD, while the low-salinity types were observed near the western and northeastern boundaries of the delta. Cluster changes from the dry to rainy seasons were detected in approximately one-third of the observation wells. The increase in groundwater recharge during the rainy season is the main reason for these changes. Based on Gibbs diagrams, the source of soluble ions in the groundwater of the freshwater types was found to be the weathering of rock-forming minerals, while evaporation and marine activities (leaching from salty paleowater and salt water intrusion) were found to be the main factors affecting the chemistry of the groundwater characterized by the low- and high- salinity types, respectively.

Assessment of groundwater quality in Kavaratti Island in the Lakshadweep Archipelagos, India

This study attempts to address the processes controlling the chemical composition of the Kavaratti aquifer system of Lakshadweep Island in India. Major ions and other physico-chemical parameters were determined for the premonsoon period in the Kavaratti of the Lakshadweep Island system. The trilinear diagram confirms the ingress of sea water into the shallow lens of freshwater in the islands by the changing water types. The abundance of major cations varied in the order Na>Ca>Mg>K and anions in the order Cl>HCO3>SO4. The ionic relations suggest that the higher concentration Na and Cl are the results of ion exchange and evaporation. The plots of data on the Gibbs diagram suggest that chemical weathering of rock-forming minerals and evaporation are the dominant factors controlling groundwater chemistry in the area. The hydrochemistry concept was deduced by the multivariate analysis for better understanding on the dynamic and complexity of the groundwater chemical processes. By the multivariate analytical techniques, the samples were grouped into two: one with saline water dominance and the other with freshwater characteristics. Thus proper management of these aquifers should be assured to retain their freshwater yield in the future.

Environmental geochemistry and quality assessment of surface and subsurface water of Mahi River basin, western India

The hydrogeochemical study of surface and subsurface water of Mahi River basin was undertaken to assess the major ion chemistry, solute acquisition processes and water quality in relation to domestic and irrigation uses. The analytical results show the mildly acidic to alkaline nature of water and dominance of Na+ and Ca2+ in cationic and HCO3− and Cl− in anionic composition. In general, alkaline-earth elements (Ca2+ + Mg2+) exceed alkalis (Na+ + K+) and weak acids (HCO3−) dominate over strong acids (SO42+ + Cl−) in majority of the surface and groundwater samples. Ca2+–Mg2+–HCO3− is the dominant hydrochemical facies both in surface and groundwater of the area. The weathering of rock-forming minerals mainly controlled the solute acquisition process with secondary contribution from marine and anthropogenic sources. The higher concentration of sodium and dissolved silica, high equivalent ratios of (Na+ + K+/TZ+), (Na+ + K+/Cl−) and low ratio of (Ca2+ + Mg2+)/(Na+ + K+) suggest that the chemical composition of the water is largely controlled by silicate weathering with limited contribution from carbonate weathering and marine and anthropogenic sources. Kaolinite is the possible mineral that is in equilibrium with the water, implying that the chemistry of river water favors kaolinite formation. Assessment of water samples for drinking purposes suggests that the majority of the water samples are suitable for drinking. At some sites concentrations of TDS, TH, F−, NO3− and Fe are exceeding the desirable limit of drinking. However, these parameters are well within the maximum permissible limit except for some cases. To assess the suitability for irrigation, parameters like SAR, RSC and %Na were calculated. In general, both surface and groundwater is of good to suitable category for irrigation uses except at some sites where high values of salinity, %Na and RSC restrict its uses.

Atmospheric versus lithogenic contribution to the composition of first- and second-order stream waters in Seoul and its vicinity

The spatial variations in the chemistry of first- and second-order stream waters ( N=65) were investigated in the easterly bound of Seoul in order to assess the effects of urban air pollution on surface water chemistry. The sulfate (SO 4 2−) was high (range 3.9–17.8 mg l −1, mean 11.8 mg l −1) within 30 km away from the center of Seoul, compared to the levels (range 1.1–7.7 mg l −1, mean 4.3 mg l −1) observed in remote areas (30–70 km away). Both graphical examination and statistical evaluation (variogram) of sulfate concentration data consistently showed the decrease of sulfate concentration with increasing distance. The results of mass balance modeling also indicate that the concentrations of SO 4 2−, Cl − and Na + may be affected mainly by dry/wet deposition. However, the spatial variations of major cations such as Ca 2+ and Na + are well explained by the reaction of rainwater with diverse rocks in the watercourse. The water type was found to change from Ca(–Na)–SO 4 type to Ca(–Na)–HCO 3 type with the increasing distance. It is thus inferred that the pollutants like SO 2 emitted from strong man-made source areas of Seoul are transported to the considerable distance (at least 30 km away) by westerlies and that such mechanism may lead to the changes of the anion composition in surface water. In the remote area (>30 km away from Seoul), the stream water chemistry appears to be influenced more effectively by the weathering of rock-forming minerals.

Formation processes of clay minerals through weathering of rock-forming minerals

Formation processes of clay minerals through weathering of rock-forming minerals