scholarly journals Origin and Residence Time of Groundwater in the Shallow Coastal Aquifer of Eastern Dahomey Basin, Southwestern Nigeria, Using δ18O and δD Isotopes

2020 ◽  
Vol 10 (22) ◽  
pp. 7980
Author(s):  
Jamiu A. Aladejana ◽  
Robert M. Kalin ◽  
Ibrahim Hassan ◽  
Philippe Sentenac ◽  
Moshood N. Tijani

This study employed stable isotopes of δ18O and δ2H in conjunction with other hydrological parameters to understand the origin, inferred residence time, and seasonal effect of groundwater in the shallow aquifers of the eastern Dahomey Basin. A total of 230 groundwater samples (97 in the wet season and 133 in the dry season) were collected from the borehole and shallow aquifer between May 2017 and April 2018. Groundwater analysis included major ions and δ18O and δ2H, isotopes data in precipitation from three selected Global Network of Isotope in Precipitation (GNIP) stations across West Africa, Douala in Cameroon, Cotonou in Republic of Benin, and Kano in Nigeria were used in comparative analysis. Results of the hydrochemical model revealed Ca-HCO3 and Na-Cl as dominant water types with other mixing water types such as Ca–SO4, Ca–Cl, Na–SO4, and K–Mg–HCO3, which characterised early stage of groundwater transformation as it infiltrates through vadose zone into the aquifer. δ18O and δ2H precipitation data from the three stations plotted along with the groundwater samples indicate recent meteoric water origin, with little effect of evaporation during the dry season. The plot of Total Dissolved Solids (TDS) against δ18O showed clustering of the water samples between the recharge and the evaporation zone with dry season samples trending towards increased TDS, which is an indication of the subtle effect of evaporation during this period. Tracing groundwater types along the flow paths within the basin is problematic and attributed to the heterogeneity of the aquifer with anthropogenic influences. Moreover, a comparison of the δ18O and δ2H isotopic compositions of groundwater and precipitation in the three selected stations, with their respective deuterium excess (D-excess) values established low evapotranspiration induced isotope enrichment, which could be due to higher precipitation and humidity in the region resulting in low isotope fractionation; hence, little effect of seasonal variations. The study, therefore, suggested groundwater recharge in the shallow aquifer in the eastern Dahomey Basin is of meteoric origin with a short residence time of water flows from soils through the vadose zone to the aquifers.

1986 ◽  
Vol 23 (7) ◽  
pp. 938-947 ◽  
Author(s):  
K. W. F. Howard ◽  
P. Beck

Shallow aquifer systems in surficial Quaternary sediments are geometrically complex, with highly variable hydraulic characteristics. Consequently these systems are extremely difficult to assess hydrogeologically using conventional investigation techniques and are often poorly understood. In a 500 km2 area of southern Ontario, hydrochemical techniques were used to investigate the hydraulic integrity and regional flow behaviour of 14 aquifer systems defined within 100 m of Quaternary overburden. This type of approach had been used successfully in more extensive bedrock aquifer systems but had not previously been applied on a regional scale to shallow Quaternary systems where sediment geochemistry and flow conditions are highly variable and rarely known. The study involved analysis of over 260 well waters for pH, major ions (Ca, Mg, Na, K, HCO3, Cl, and SO4) and subsidiary ions (NO3, I, Br, and F). Selected samples were analyzed for tritium.The groundwaters are classified into eight water types, two of which are sodium chloride in character and of bedrock origin. Of the remaining six, four are related by a chemical evolutionary sequence showing transition from a tritiated (> 30 TU), low-iodide (< 5 μg/L) CaHCO3 recharge water to an ion-exchanged, NaHCO3 water low in tritium (< 15 TU) and enriched in iodide (> 15 μg/L). The existence of this sequence implies a regional, composite flow system involving seven supposedly discrete aquifer systems.The two remaining water types are recent tritiated waters (> 20 TU) contaminated by road salt (Cl > 40 mg/L) and agricultural nitrate (NO3 > 10 mg/L). Together with the CaHCO3 waters these clearly delineate major areas of recharge and show that the covering of Halton Till is extensively permeable.


Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 224 ◽  
Author(s):  
Jamiu A. Aladejana ◽  
Robert M. Kalin ◽  
Philippe Sentenac ◽  
Ibrahim Hassan

Despite the increasing interest in climate change and water security, research linking climate change and groundwater quality is still at an early stage. This study explores the seasonal effect of the change in biogeochemical process for the redox-sensitive ions and metals Fe2+, Mn2+, SO42−, and NO3− to assess the groundwater quality of the shallow coastal aquifer of Eastern Dahomey Basin in southwestern Nigeria. Field physicochemical measurement of EC, pH TDS, Eh, salinity, temperature, and the static water level (SWL) was carried out on 250 shallow wells; 230 water samples were collected for analysis between June 2017 and April 2018. A spatial distribution map of these ions and metals showed an increasing concentration in the dry season water samples compared to those of the wet season. This higher concentration could be attributed to change in the intensity of hydrochemical processes such as evaporation, redox, and mineral precipitation. Results of linear regression modelling established significant relationships between SWL, SO42−, NO3−, Fe, and Eh for both wet and dry seasons with the p-value falling between 75% and 95%, which can also be seen in the plots of Eh/ORP against Fe2+, Mn2+, SO42−, and NO3−. These results revealed the influence of the redox process for both seasons, while also having a higher impact in the dry season while variation of concentration revealed decrease with increase in depth, which could be attributed to a decrease in well hydraulic properties and aeration. An Eh-pH geochemical diagram revealed NO3− as the controlling biogeochemical process over Fe in most of the sample wells. Concentrations of NO3−, Fe, and Mn are above the World Health Organization’s (WHO) standard for drinking water in most water samples. This study has established the link between climate change and groundwater quality in shallow coastal aquifers and suggested the need for strategic groundwater management policy and planning to ameliorate groundwater quality deterioration.


2020 ◽  
Vol 21 (2) ◽  
pp. 139
Author(s):  
Evarista Ristin Pujiindiyati ◽  
Bungkus Pratikno

Aquifer in river bank area is mostly susceptive toward pollution occurring in river. One of parameters to determine the interaction process between groundwater and river is a natural isotope of 222Rn. The significant difference of radon concentration in groundwater and river water can be utilized as a scientific basis for investigating groundwater infiltration in river bank. Those studied parameters are residence time and infiltration rate. The research using 222Rn had been conducted in shallow groundwater of Ciliwung river bank - South Jakarta during rainy and dry season. The range of 222Rn concentration in shallow groundwater monitored in dry season was between 666 - 2590 Bq/m3 which was higher than that of rainy season ranging at 440 to 1546 Bq/m3. Otherwise, concentration of 222Rn in river water could not be detected (its 222Rn concentration = 0 Bq/m3) due to its much lower concentration either rainy or dry season. During dry season monitoring, equilibration between groundwater and river water was reached at the distance approximately 98 - 140 m away from river side. Estimating residence time based on 222Rn concentration at nearest site from the river and at equlibration area was 4.2 days such that the infiltration rate from river water into aquifer might be 7.8 m/day.Keywords: 222Rn, groundwater, residence time, infiltration rate.


Author(s):  
Vilim FILIPOVIĆ ◽  
Dragutin PETOŠIĆ ◽  
Ivan ŠIMUNIĆ ◽  
Ivan MUSTAĆ ◽  
Zlatko SVEČNJAK ◽  
...  

Agricultural activities are frequently associated with groundwater pollution. In this study, the goal is to evaluate the nitrate and phosphorus levels and it's impact to the groundwater. The investigation was located in the Eastern Croatia in the area of 6.600 ha of mainly agricultural land. Groundwater quality in the countertop part of the soil profile to 4.0 m depth was monitored by 40 installed hydropedological piezometers. Sampling water from piezometers was carried out every 60 days. In the groundwater samples nitrate, nitrite, ammonia and orthophosphate were analyzed. According to the indicators it was confirmed that at all locations during the observation period mean concentrations of NH4-N, NO3-N, total nitrogen (N) and phosphorus (P) in the groundwater from piezometers occasionally exceeded the value of maximum allowable concentration (MAC) which is prescribed by the Regulations. The mean concentrations of NO3-N were consistent and varied in the range from 2.42 to 4.61 mg NO3-N/l, the mean concentrations of nitrogen from ammonia exceed the permissible value (NH4-N) throughout the year, the average being higher than MAC (0.50 mg NH4-N/l) and were within the range of 0.57 mg NH4-N/l in to 1.21 mg NH4-N/l. The maximum concentration of phosphorus in groundwater were in the range of values from 0.40 to 1.11 mg P/l. Observation of traditional agricultural production in the investigation area with emphasis on leaching of nitrogen and phosphorus shows that it represents a potential threat to the future pollution of groundwater with nitrogen with phosphorus.


2021 ◽  
Author(s):  
Abul Qasim ◽  
Satinder Pal Singh

&lt;p&gt;Major ions, Sr concentration, and &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr have been analyzed in groundwater of the coastal Gujarat Alluvial Plain, collected during monsoon, post-monsoon, and pre-monsoon seasons of 2016&amp;#8211;2017. The major objective of this study was to understand the regional groundwater salinization mechanism. In the study area, the groundwater is mostly characterized by Na-Cl facies, with few samples of Ca-Cl, Ca-Mg-Cl, Na-Ca-HCO&lt;sub&gt;3&lt;/sub&gt;, and Ca-Mg-HCO&lt;sub&gt;3&lt;/sub&gt; types. Whereas, the Narmada and the Tapi river water samples are particularly of Ca-Mg-HCO&lt;sub&gt;3&lt;/sub&gt; type. The hydrogeochemical facies evolution (HFE) diagram depicts the coastal groundwater freshening irrespective of the season ruling out the lateral seawater intrusion far inland. However, the &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr and Br/Cl ratios strongly suggest the modern marine influence on the regional groundwater. In the plot of 1/Sr versus &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr, most of the groundwater samples fall on the binary mixing line between the seepage groundwater and modern seawater endmembers. Therefore, we suspect that the up-coning of recently trapped seawater by groundwater over-extraction is the most plausible reason for the groundwater salinization, which indicate the vulnerability of the coastal Gujarat alluvial plain to the near future sea ingress under the global warming scenario. A few exceptional groundwater samples far north of the Narmada River show more radiogenic &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr indicative of silicate weathering.&lt;/p&gt;


2020 ◽  
Vol 69 (4) ◽  
pp. 398-414 ◽  
Author(s):  
Vasant Wagh ◽  
Shrikant Mukate ◽  
Aniket Muley ◽  
Ajaykumar Kadam ◽  
Dipak Panaskar ◽  
...  

Abstract The integration of pollution index of groundwater (PIG), multivariate statistical techniques including correlation matrix (CM), principal component analysis (PCA), cluster analysis (CA) and various ionic plots was applied to elucidate the influence of natural and anthropogenic inputs on groundwater chemistry and quality of the Kadava river basin. A total of 80 groundwater samples were collected and analysed for major ions during pre- and post-monsoon seasons of 2012. Analytical results inferred that Ca, Mg, Cl, SO4 and NO3 surpass the desirable limit (DL) and permissible limit (PL) of Bureau of Indian Standards (BIS) and the World Health Organization (WHO) in both the seasons. The elevated content of total dissolved solids (TDS), Cl, SO4, Mg, Na and NO3 is influenced by precipitation and agricultural dominance. PIG results inferred that 52.5 and 35%, 30 and 37.5%, 12.5 and 20%, 2.5 and 5% groundwater samples fall in insignificant, low, moderate and high pollution category (PC) in pre- and post-monsoon seasons, respectively. PC 1 confirms salinity controlled process due to high inputs of TDS, Ca, Mg, Na, Cl and SO4. Also, PC 2 suggests alkalinity influence by pH, CO3, HCO3 and F content. PIG and statistical techniques help to interpret the water quality data in an easier way.


2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Gilbert Feuyit ◽  
John Ngolui Lambi ◽  
Estella Njoyim-Tamungang ◽  
Samuel Laminsi

This study focuses on the assessment of the nutrients in the leachate and the groundwater quality around the Nkolfoulou landfill in Yaoundé known in French as “Centre de Traitement de Déchets (CTD).” Landfilling generates leachate that can pollute groundwater. Leachate along with groundwater samples (n=1+13) was collected in January (long dry season) and May (long wet season) 2014 and explored for various parameters including pH, temperature, EC, turbidity, TDS, TA, TSS, TH, BOD5, COD, Na+, K+, Mg2+, Ca2+, NH4+, NO3−, Cl−, F−, SO42−, PO43−, HCO3−, and colour using standard methods. In the leachate samples, values of TSS (700.2 and 130.2 mg/L), BOD5 (140 mg/L), COD (1350 and 1750 mg/L), NH4+ (82.50 and 39.51 mg/L), NO3− (159.32 and 74.82 mg/L), and Cl− (702.69 and 345.50 mg/L) exceeded the Cameroonian standards for effluent discharge. All the values of pH and some values of turbidity (4.55 and 4.50 NTU) and NH4+ (0.51 and 0.73 mg/L) in the groundwater samples violated the Cameroonian standards for drinking water. Based on the water quality index (WQI), an average of 11.53% of groundwater samples was improper for drinking in both seasons. Based on the parameters assessed, all the samples complied with the standard set for irrigation, poultry, and livestock. The hazard quotient (HQ) and the hazard index (HI) of NO3− and F− for children and adults were <1, and hence, the increased non-cancer risks due to these ions through the drinking of groundwater was low. From the statistical analysis, the Nkolfoulou landfill may not be the main source of major ions to the nearby groundwater.


Hydrology ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 36 ◽  
Author(s):  
Yacob T. Tesfaldet ◽  
Avirut Puttiwongrak

Understanding the recharge mechanisms in the vadose zone is crucial to groundwater management and artificial recharge development. In this study, a systematic characterization of seasonal groundwater recharge was done using time-lapse electrical resistivity tomography (time-lapse ERT). The objective of this study was to characterize the seasonal groundwater recharge through the vadose zone and streams. A total of six electrical resistivity surveys in two locations were taken during the dry and rainy seasons using an advanced geosciences incorporated (AGI) SuperSting R2 resistivity meter in 2018. Then, time-lapse inversion was calculated using the dry season ERT as the base model and the rainy season ERTs as the monitoring datasets. The results showed a significant decrease in inverted resistivity from the dry season to the rainy season, which suggests rainwater infiltration through the vadose zone. Similarly, significant water level rise was observed in wells monitored during the survey indicating groundwater recharge. The time-lapse ERT showed, in one case, the Nang Dak stream and the unsaturated zones are the preferential groundwater recharge zones throughout the year; in another case, the Rieng stream is the groundwater discharge zone and the vadose zone is the preferential recharge zone. Finally, a simplified conceptual hydrogeological model representing the study area is presented to visualize the recharge mechanisms in the study area.


2020 ◽  
Vol 7 (4) ◽  
pp. 825-835
Author(s):  
Hao Yu ◽  
Herong Gui ◽  
Honghai Zhao ◽  
Meichen Wang ◽  
Jun Li ◽  
...  

AbstractThe aim of this study is to evaluate the hydrogeochemical characteristics and water environmental quality of shallow groundwater in the Suxian mining area of Huaibei coalfield, China. The natural formation process of shallow groundwater in Suxian is explored using Piper trilinear charts and Gibbs diagrams, and by examining the ratios between the major ions. United States Salinity Laboratory (USSL) charts, Wilcox diagrams, and the water quality index (WQI) are further employed to quantify the differences in water quality. The results reveal that the main hydrochemical facies of groundwater are HCO3–Ca, and that silicate dissolution is the main factor controlling the ion content in shallow groundwater. The USSL charts and Wilcox diagrams show that most of the water samples would be acceptable for use in irrigation systems. The WQI results for each water sample are compared and analyzed, and the quality of groundwater samples around collapse ponds is found to be relatively poor.


2015 ◽  
Vol 10 (2) ◽  
pp. 390-401 ◽  
Author(s):  
He-rong Gui ◽  
Man-li Lin ◽  
Wei-hua Peng

Six groundwater samples were collected from four aquifers in Renlou coal mine, northern Anhui Province, China, and concentration, temporal variation and speciation of five heavy metals (Cr, Cu, Ni, Pb and Zn) were analyzed. The results of physicochemical parameters and major ions showed that the selected groundwater were representative samples of Quaternary aquifer (QA), coal measure aquifer (CA), Taiyuan limestone aquifer (TA) and Ordovician limestone aquifer (OA). Cr, Ni and Zn increased in the four aquifers from 2002 to 2014, but Pb decreased from 2006 to 2014. Cu concentration increased in QA and TA, but decreased in CA and OA. Although all monitoring results met the standards recommended by WHO and GB5749-2006, Cr and Cu in some groundwater samples exceeded GB/T 14848-93, especially in CA. Soluble metallic hydroxides were the dominant species of heavy metals in QA, while free ions were the main species in TA and OA. Excepted Ni2+ and Zn2+, CuCO3(aq) and PbCO3(aq) were the dominant species of Cu and Pb in CA, respectively, indicating more CO2 had been flooded and dissolved in groundwater from ground atmospheric environment. The enhanced concentration and special dominant species of heavy metals revealed that the ‘closed’ characteristics of CA in Renlou coal mine might have been broken due to coal mining activity.


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