The aim of the present study was to evaluate hepatitis A virus (HAV) and hepatitis E virus (HEV) contamination in mussels (Mytilus galloprovincialis) from Cherrat estuary (Moroccan Atlantic Coast), ...Morocco. In total, 52 samples (n = 12 mussels/each) were collected at four sites in the estuary, monthly, between March 2019 and March 2020. HAV and HEV were detected by real-time reverse transcription polymerase chain reaction (RT-PCR) according to the ISO/TS 15216 method. HAV was detected in 46.15% of analyzed samples. Conversely, HEV was not detected in any sample. Moreover, the HAV detection rate was significantly associated with seasonal rainfall variations. This qualitative study on HAV and HEV contamination highlights the interest of studying mussel samples from wild areas. As HAV presence in mussels represents a potential health risk, viral contamination surveillance of mussels is necessary to protect consumers. HAV shellfish contamination must be monitored at Cherrat estuary because of the role played by shellfish as HAV reservoirs and/or vehicles in fecal-oral HAV transmission.
This study aims to identify groundwater salinization origin and to determine seawater intrusion extension toward the inland in Chaouia, Morocco. To reach these objectives, firstly, 46 groundwater ...samples were analyzed for major chemical elements during January 2012 and, secondly, 10 electrical resistivity tomography (ERT) profiles were performed perpendicularly to the coastal fringe. Statistical analysis provided the distinction between three Clusters reflecting different hydrochemical processes. Cluster I and Cluster II-a showed a high water electrical conductivity (EC) (from 2.3 to 11.2mS/cm) with the dominance of Na+ (668mg/L on average) and Cl− (1735mg/L on average) ions as a consequence of seawater intrusion. However, Cluster II-b presented low ECs (from 0.5 to 1.7mS/cm) and Ca2+ (99.6mg/L on average) and HCO32− (235.2mg/L on average) ions dominance. Water chemistry in these wells was controlled by water-rock interaction, cation exchange, and anthropogenic activities. The Hydrochemical Facies Evolution Diagram highlighted the succession of different water facies developed between intrusion and freshening phases. The formation of Na-HCO3 facies, which characterizes the last facies of freshening phase, followed the succession of Na-Cl, MixNa-MixCl, MixCa-MixCl, MixCa-MixHCO3, and Na-HCO3. In contrast, Na-Cl facies formation, which characterizes the last facies of intrusion phase, followed the evolution of Ca-HCO3, Ca-MixHCO3, Ca-MixCl, MixCa-MixCl, MixCa-Cl, and Na-Cl. Moreover, the obtained ERT results allowed determining the extent of different hydrochemical facies and provided more details about seawater intrusion extension. The conductive level assigned to seawater contamination showed a resistivity less than 36Ω.m, which remains limited to 3000m from the ocean, where Na-Cl water type dominates. The seawater intrusion depth varied between 5 and 40m from the surface. Overall, this original study in Chaouia region demonstrated the effectiveness of combining hydrochemical and ERT methods to investigate seawater intrusion, particularly in areas with restrictive water chemistry data.
•Water salinization origin was determined by hydrochemical study in Chaouia, Morocco.•HFE-Diagram highlights water facies succession between intrusion and freshening.•Highly contaminated area by seawater intrusion was delimited using ERT study.•Seawater intrusion was significant at 3km from the ocean and over 40m depth.
In this study, the geohydraulic parameters of aquifers in the Sahel Doukkala region, western Morocco were estimated using a geostatistical method to transform vertical electrical soundings (VES) data ...into electrical resistivity tomography (ERT) profiles. The resulting ERT profiles covered a larger area than the original VES data, allowing for a more comprehensive analysis. The obtained results indicated that the apparent and inverted resistivities range from 16 to 1558 Ohm.m and from 4 to 6980 Ohm.m, respectively, with a low inversion error (RMS) of 6.1–13.1%, demonstrating the reliability of the proposed approach. Using the inverted resistivities, the estimated hydraulic conductivity, effective porosity, and transmissivity ranged from 0.2 to > 103.7 m/day, 11.6% to > 45.8%, and 1.7 to > 2028.6 m
2
/day, respectively. These values reflect the sand, clayey sand, and limestone lithology prevalent in the study area, with medium to high aquifer potential. The validation of our results with pumping test data showed that the estimated geohydraulic parameters are representative of the geological formations in the study area. In addition to providing a rapid interpretation of the data, the present study offers fundamental insights for future research, contributing to better planning and management of groundwater resources.
The coastal aquifer system of Chaouia is recognized as one of the most important aquifers in Morocco that is affected by salinization in the coastal fringe. The purpose of this study is to highlight ...the origin of salinization by sampling and analyzing groundwater from 44 wells for major elements. This study was carried out in May 2011. The results indicate that, in the central and downstream parts, the dominant facies are Mg2+, Na+ and Cl−, while Ca2+ and HCO3− dominate in the upstream zones. Ion exchange processes, under seawater intrusion, control the concentration of ions such as calcium, magnesium and sodium. Moreover, groundwater is oversaturated with respect to carbonate minerals (calcite and dolomite), and under-saturated with respect to evaporate minerals (gypsum, halite). The contribution of dissolved halite and gypsum in the groundwater mineralization is revealed by their positive correlation between (Na + Cl) and (Ca + SO4), respectively. Furthermore, the comparison of the hydrochemical results to drinking water quality standards by World Health Organization (2008) shows that more than a half of the water sampled is not suitable for drinking purposes, especially with respect to high levels of EC, TDS, Cl− and NO3−. In addition, high mineralization is found to be a consequence of seawater intrusion and anthropogenic activities.
•Samples were taken from 44 wells during May 2011 period.•This study aims to investigate origin and process of groundwater mineralization.•Distance from coast and anthropogenic activities emphasized mineralization.•Groundwater salinity was due to seawater intrusion in areas at 2 km from ocean.•Cation exchange, evaporation and evaporate dissolution induce groundwater salinity.
The Moul El Bergui area has been known since the 1980s for its high agricultural potential and its permanent irrigation systems. Recently, this area has suffered significant material damages due to ...collapse dolines that still threaten the population, infrastructures, and agricultural lands. Accordingly, this study was carried out aiming at identifying the mechanism and triggering factors of their occurrence through field inventory and geophysical survey. In the first phase of this study, a collapse dolines inventory was established using geomorphological approach. From the nine inventoried collapse dolines, five have occurred before 1962 and four have occurred after this date. They were found to be aligned following the main tectonic structures characterizing the study area. Moreover, the comparison of aerial photographs revealed that their diameters have expanded from 1962 to 2010. In the second phase, six electrical resistivity tomography profiles (ERT) were performed between the identified collapse dolines. The ERT profiles highlighted the different hydrogeological karst components and proved the presence of underground cavities as well as fractured zones. The obtained results demonstrate that the collapse dolines around the study area occur as a result of various associated processes, including dissolution of carbonated bedrock and presence of fractures and/or faults that facilitate the infiltration of meteorological and irrigation waters. Therefore, the heavy rainfall, consolidated dunes barriers, and irrigation may be considered as the main triggering and aggravating factors to collapse dolines occurrence. For this reason, using collapse dolines as outlets for any irrigation canal or floodwaters will necessarily lead to a faster and significant erosion process. In this case, catastrophic collapse and significant subsidence may occur in areas subject to water flows from irrigated plains.
•Collapse dolines occurrence was assessed using electrical resistivity tomography.•Collapse dolines were aligned following the main tectonic structures.•ERT profiles proved the presence of underground cavities and fractured zones.•Results indicated that hydrologic and geologic factors promote ground collapsing.•Using collapse dolines as outlets for excess water accelerated the erosion process.
This study aims to assess the evolution of seawater intrusion between 1992 and 2011 periods in the coastal aquifers of Oualidia. To achieve this objective, the combination of geoelectrical and ...hydrochemical methods was adopted. Apparent resistivity maps, using 74 Vertical Electrical Sounding (VES) performed on 1992, allowed to distinguish two different zones. The conductive one, with apparent resistivity ranging between 4 and 86Ω·m, is limited to 1km with respect to the ocean. Meanwhile, the resistant one is much farther from the coastline. Besides, results of Electrical Resistivity Tomography (ERT) profiles performed during 2011 are in good agreement with those obtained by apparent resistivity maps. The ERT profiles show a conductive level characterized by low resistivity below 30Ω·m assigned to seawater intrusion effect. Moreover, hydrochemical analysis, performed on 19 wells during three different periods, on June, December 2010 and May 2011, indicates that the most affected part with marine waters was at that time localized in the first kilometer from the ocean, with high amounts of Na+ and Cl− ions. Beyond this fringe, mineralization becomes very weak. Overall, the comparison of old VES with recent ERT coupled with hydrochemical results suggest no important evolution of the salt wedge since 1992.
•Increase of salinity in groundwater at coastal area of Oualidia•The geoelectrical method is used to determine the seawater intrusion.•Seawater intrusion extension does not exceed approximately 1000m from ocean.•The area affected by seawater remains limited at 1000m from ocean since 1992.
Seasonal variations of sea level have an important impact on coastal groundwater level and salinity. Consequently, they cause spatiotemporal changes in the seawater/freshwater interface. The oceanic ...tide effect on groundwater dynamics and salinity was investigated in the coastal aquifers of Sahel Doukkala, Morocco. Continuous monitoring of water level and electrical conductivity (EC) was carried out in two coastal wells (drawing from two different aquifers) over a period of 9 months. The main objective of the study was to characterize the aquifers’ exposure to anthropic pumping operations and oceanic tide oscillations. The obtained results showed that oceanic tide has a significant effect on groundwater level as well as on water salinity. The fluctuation periods of groundwater level and tidal level were found to be equal, with a specific time lag. Hydraulic diffusivity was calculated using both confined- and semi-confined-aquifer methods and by analyzing both the time lag and amplitude damping factor. Results indicate hydraulic diffusivity differences between the two aquifers. In addition, there were apparent differences depending on whether time lag or amplitude was analyzed, possibly due to effects of heterogeneity within the aquifers. A detailed study of water EC variation revealed the significant influence of daily and synodic tide on groundwater salinity. Water EC variations were significant when hydraulic diffusivity is higher, indicating that sea-level oscillations induce freshwater/seawater interface movement and consequently influence the groundwater quality.
Oualidia city is located on the Moroccan Atlantic coast. Groundwater is the only resource for agriculture irrigation in this area. This operation is done by intensive pumping mainly in the coastal ...fringe. In this study, hydrochemical and geophysical methods were conducted to evaluate both composition and processes which control groundwater mineralization in Oualidia. For this purpose, 19 samples of groundwater were analyzed in major ions. The results showed that the mineralization is mainly due to sea water intrusion, especially in the first kilometer over the ocean, with abundance of Na
+
(651.3 mg/l on average) and Cl
−
ions (1,425 mg/l on average). Beyond this fringe, 1 km, the mineralization is low, with an abundance of calcium (190.4 mg/l on average) and bicarbonate (241.1 mg/l on average) indicating the rock nature effect. Data interpretation from six profiles of electrical resistivity tomography (ERT), performed in the region, has led to detect seawater intrusion extension. The level assigned to the marine effect is characterized by a resistivity lower than 30 Ω m. Moreover, hydrochemical and geophysical studies were provided information on the mineralization extension in the aquifer of this zone, which is limited to 1 km from the ocean.
L'aquifère libre de la Chaouia côtière constitue un exemple des aquifères les plus exploités au Maroc. Ce travail est consacré à l'étude des processus de la salinisation des eaux souterraines par ...l'analyse physico-chimique de 39 puits répartis dans la zone. Deux types de faciès ont été révélés, l'un est chloruré-sodique dans la frange côtière ; l'autre faciès est de type chloruré bicarbonaté-calcique caractérisant les eaux exploitées dans les calcaires marneux du Crétacé. L'influence marine (aérosols et intrusion marine), la dissolution/précipitation de la roche aquifère et l'infiltration des eaux d'irrigation, sont parmi les causes de l'augmentation de la salinité des eaux souterraines, en plus de l'exploitation excessive de l'eau souterraine.
The objective of this study is to identify the influence of different hydrochemical processes, potential salinity sources, and seawater intrusion on groundwater quality in the coastal region of ...Oualidia. For this purpose, chemical analyses were performed on 19 wells sampled during three campaigns: June and December, 2010 and May, 2011. Investigations were conducted to identify the significant chemical variations between different campaigns. In addition, chemical variations were controlled by two main factors, which are the distance from the coast and the morphological aspect. Furthermore, statistical analysis allows the identification of two clusters of samples. The first groups, near the ocean, are highly mineralized with dominance of Na+ and Cl− ions, while the second group, much farther from the coast, are slightly mineralized with dominance of Ca2+ and HCO3− ions. Besides, ionic ratio, ionic delta, saturation index, and Gibbs diagram were applied to evaluate geochemical processes responsible for groundwater mineralization. Results showed that salinity was due mainly to seawater intrusion, especially in the first kilometers from the ocean covering the first group of wells. Moreover, cation exchange between Na+, Ca2+, Mg2+, and K+, evaporation, and evaporate dissolution are principal processes, which also contribute to groundwater salinization. In overall, this investigation provided a basis of geochemical data to effectively manage groundwater resource and efficiently mitigate impacts on aquifers.
•Samples were taken from 19 wells during June, December 2010, and May 2011 periods.•This study aims to investigate origin and process of groundwater mineralization.•Distance from coast and morphological aspect emphasized mineralization.•Groundwater salinity was due to seawater intrusion in areas at 1 km from ocean.•Cation exchange, evaporation and evaporate dissolution induce groundwater salinity.
