Origin of the Salinity in the Coastal Aquifer of La Paz, Mexico (original) (raw)
Related papers
Environmental Geology
Groundwater quality in the Santo Domingo Irrigation District area in Baja California Sur, Mexico indicates the presence of various salinization processes, i) the geological matter of marine origin comprising the aquifer material suffers diagenetic effects due to its interaction with groundwater of low salinity, ii) the effects of intensive agriculture practices produce effluents that infiltrate to the saturated zone, and iii) the extraction of groundwater causes modifications in the natural flow system inducing lateral flow of sea-water from the coast line. However, groundwater management has been carried out believing that the latter is the main source of salinization. This has conduct to a policy of installing wells increasingly far from the coast, which is not solving the problem. Irrigation-return and seawater that remains in the geological units have been identified to be major sources of salinization. Controls should be imposed when installing wells in contact with clayey unit...
Environmental Earth Sciences, 2004
Groundwater quality in the Santo Domingo Irrigation District area in Baja California Sur, Mexico, indicates the presence of various salinization processes, (1) the geological matter of marine origin comprising the aquifer material suffers diagenetic effects due to its interaction with groundwater of low salinity, (2) the effects of intensive agriculture practices produce effluents that infiltrate to the saturated zone, and (3) the extraction of groundwater causes modifications in the natural flow system induces lateral flow of seawater from the coast line. However, groundwater management has been carried out with the belief that the latter is the main source of salinization. This has resulted in a policy of installing wells increasingly far from the coast, which is not solving the problem. Irrigation-return and seawater that remains in the geological units have been identified as major sources of salinization. Controls should be imposed when installing wells in contact with clayey units that form the base of the aquifer. Extracted groundwater consists of a mixture of (1) groundwater of relatively low salinity that circulates in the aquifer and (2) an extreme member with salinity different to seawater contained mainly in formations that have low permeability, which limits the aquifer underneath. The geochemistry of carbonates and cation-exchange reactions (both direct and reverse) control the concentration of Ca, Mg, Na, and HCO3, as well as pH values. The concentrations of dissolved trace elements (F, Li, Ba, Sr) suggest that the extreme saline member is different from the average seawater composition. A distinction between the salinization caused by farming practices and that blamed on seawater is defined by the use of NO3.
Environ Earth Sci, 1997
The coastal aquifer of Oropesa is affected by salinization processes undoubtedly associated with intense groundwater exploitation for agriculture supply. The aquifer corresponds geologically to a tectonic depression with Plioquaternary fill. Hydrogeologically, this aquifer is detrital, with intergranular porosity, which receives substantial recharge from adjacent Mesozoic aquifers. Contact with the sea, in addition to the presence of cultivated soil requiring extreme exploitation of groundwater, frequently give rise to processes of seawater intrusion. The present research is an attempt to understand the saltwater intrusion in this aquifer, using hydrochemical analyses of the behavior of certain minor ions that could help in the characterization process. In the case of the Oropesa sector, groundwater salinization does not appear to be attributable solely to the intrusion of seawater, but there are also anomalies related largely to the geology of the sector and its surroundings, the type of recharge, the hydrodynamic conditions in the specific area, etc.
Environmental Geology, 1997
The coastal aquifer of Oropesa is affected by salinization processes undoubtedly associated with intense groundwater exploitation for agriculture supply. The aquifer corresponds geologically to a tectonic depression with Plioquaternary fill. Hydrogeologically, this aquifer is detrital, with intergranular porosity, which receives substantial recharge from adjacent Mesozoic aquifers. Contact with the sea, in addition to the presence of cultivated soil requiring extreme exploitation of groundwater, frequently give rise to processes of seawater intrusion. The present research is an attempt to understand the saltwater intrusion in this aquifer, using hydrochemical analyses of the behavior of certain minor ions that could help in the characterization process. In the case of the Oropesa sector, groundwater salinization does not appear to be attributable solely to the intrusion of seawater, but there are also anomalies related largely to the geology of the sector and its surroundings, the type of recharge, the hydrodynamic conditions in the specific area, etc.
The Science of the total environment, 2015
Salinization of water bodies represents a significant risk in water systems. The salinization of waters in a small irrigated hydrological basin is studied herein through an integrated hydrogeochemical study including multivariate statistical analyses and geochemical modeling. The study zone has two well differentiated geologic materials: (i) Quaternary sediments of low salinity and high permeability and (ii) Tertiary sediments of high salinity and very low permeability. In this work, soil samples were collected and leaching experiments conducted on them in the laboratory. In addition, water samples were collected from precipitation, irrigation, groundwater, spring and surface waters. The waters show an increase in salinity from precipitation and irrigation water to ground- and, finally, surface water. The enrichment in salinity is related to the dissolution of soluble mineral present mainly in the Tertiary materials. Cation exchange, precipitation of calcite and, probably, incongrue...
Science of The Total Environment, 2002
The study of salinization of groundwater in the Detrital Aquifer of the Lower Andarax is highly complex due to the semiarid climate, the presence of evaporites, proximity to the sea and localized geothermal manifestations in the Ž . area. The salinization has been characterized by jointly studying the content of various minor ions B, Br and Li and Ž . a series of ionic relationships BrLi, SO rCl, NarCl, ClrB . The combined analysis of B and Li enabled the areas 4 with a marked marine influence to be distinguished from those with an evaporite or geothermal influence. Lithium is directly related to water temperature whilst B content increases in more saline areas, since it is associated with the presence of evaporitic andror marine influences. Bromine analysis enabled the identification of the principal processes that determine the salinity of the water along the coastal zone: the presence of Quaternary marine sediments and present-day marine intrusion. The brackish groundwaters that are related to old raised beaches showed a low ClrBr ratio. Areas affected by marine intrusion had ClrBr ratios similar to seawater and higher than in other areas along the coastal zone. At some points on the delta, a mixture of brackish water and recharge water was detected ᎏ the recharge water has a sulfate facies, which causes a drop in the ClrBr ratio and changes the general character of the water in the coastal zone. The coastal zone contains silty-clay intercalations that favor processes of ion exchange, anthropogenic pollution also occurs and together these processes hamper the interpretation of all the processes. ᮊ
Environmental Science and Pollution Research, 2014
Coastal aquifers are at threat of salinization in most parts of the world. This study was carried out in coastal shallow aquifers of Aousja-Ghar El Melh and Kalâat el Andalous, northeastern of Tunisia with an objective to identify sources and processes of groundwater salinization. Groundwater samples were collected from 42 shallow dug wells during July and September 2007. Chemical parameters such as Na + , Ca 2+ , Mg 2+ , K + , Cl − , SO 4 2− , HCO 3 − , NO 3 − , Br − , and F − were analyzed. The combination of hydrogeochemical, statistical, and GIS approaches was used to understand and to identify the main sources of salinization and contamination of these shallow coastal aquifers as follows: (i) water-rock interaction, (ii) evapotranspiration, (iii) saltwater is started to intrude before 1972 and it is still intruding continuously, (iv) irrigation return flow, (v) sea aerosol spray, and finally, (vi) agricultural fertilizers. During 2005/2006, the overexploitation of the renewable water resources of aquifers caused saline water intrusion. In 2007, the freshening of a brackish-saline groundwater occurred under natural recharge conditions by Ca-HCO 3 meteoric freshwater. The cationic exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. The sulfate reduction process and the neo-formation of clays minerals characterize the hypersaline coastal Sebkha environments. Evaporation tends to increase the concentrations of solutes in groundwater from the recharge areas to the discharge areas and leads to precipitate carbonate and sulfate minerals.
Origin of the groundwater salinization in La Aldea coastal aquifer (Gran Canaria, Canary Islands)
Groundwater chemistry in La Aldea aquifer (Gran Canaria, Canary Islands) shows high contents of chloride and nitrate ions. The salinization process has been modelled using the geochemical data, taking into account the results of a previous flow model. The results allow to identify the salinity of the recharge from the rainfall under aridity conditions and the irrigation returns like the main causes of the groundwater salinization.
Environmental Earth Sciences, 2008
Integrated hydrogeochemical and geophysical methods were used to study the salinity of groundwater aquifers along the coastal area of north Kelantan. For the hydrogeochemical investigation, analysis of major ion contents of the groundwater was conducted, and other chemical parameters such as pH and total dissolved solids were also determined. For the geophysical study, both geoelectrical resistivity soundings and reflection seismic surveys were conducted to determine the characteristics of the subsurface and groundwater contained within the aquifers. The pH values range from 6.2 to 6.8, indicating that the groundwater in the study area is slightly acidic. Low content of chloride suggests that the groundwater in the first aquifer is fresh, with an average concentration of about 15.8 mg/l and high geoelectrical resistivity (>45 ohm m). On the other hand, the groundwater in the second aquifer is brackish, with chloride concentration ranging from 500 mg/l to 3,600 mg/l and very low geoelectrical resistivity (<45 ohm m) as well as high concentration of total dissolved solids (>1,000 mg/l). The groundwater in the third aquifer is fresh, with chloride concentrations generally ranging from 2 mg/l to 210 mg/l and geoelectrical resistivity of greater than 45 ohm m. Fresh and saltwater interface in the first aquifer is generally located directly in the area of the coast, but, for the second aquifer, both hydrogeochemical and geoelectrical resistivity results indicate that the fresh water and saltwater interface is located as far as 6 km from the beach. The considerable chloride ion content initially suggests that the salinity of the groundwater in the second aquifer is probably caused by the intrusion of seawater. However, continuous monitoring of the chloride content of the second aquifer indicated no significant changes with time, from which it can be inferred that the salinity of the groundwater is not affected by seasonal seawater intrusion. Schoeller diagrams illustrate that sulphate concentrations of the groundwater of the second aquifer are relatively low compared to those of the recent seawater. Therefore, this result suggests that the brackish water in the second aquifer is probably from ancient seawater that was trapped within the sediments for a long period of time, rather than due to direct seawater intrusion.
Determining Water Salinity in a Shallow Aquifer and Its Vulnerability to Coastline Erosion
Polish Journal of Environmental Studies, 2017
In most coastal areas in Mexico, there is an increase in housing development and facilities for tourism, consequently resulting in a negative impact on the environment. Due to this, an awareness of the critical role of groundwater in sustaining coastal populations, economies, and ecosystems is growing. The coastal zone of Sinaloa State is classified as an area with a high presence of saline groundwater in Mexico. The present work was performed in the Las Glorias Beach, Guasave, Sinaloa, Mexico. The results of the analysis of 19 soil and groundwater samples indicate the predominance of sandy soil and a wide range of water salinity, from slightly saline to brine. An electromagnetic profiling (EMP) survey was performed at the study site showing a low apparent electrical conductivity zone parallel to the coastline as indicative of the possible presence of fresh and/or slightly saline water. Apparent electrical conductivity values were compared with electrical conductivity values measured in groundwater samples collected in wells, resulting in a positive linear correlation (R = 0.97). This linear relation is explained by a φξ electromagnetic analytic model when 5.36 ≤ σ a ≤ 85.87 mS/cm. The linear relation was used to recalculate the apparent electrical conductivity values from EMP survey into electrical conductivity values of groundwater and, therefore, TDS values. The TDS map indicates the presence of a barrier of fresh/slightly saline groundwater parallel to the coastline that keeps a fragile balance that prevents the advance of saltwater intrusion from the sea of Cortés and from brine zones located in the northern part of the site. The advance of erosion in Las Glorias Beach exposes