scholarly journals Hydrodynamics, Hydrochemistry, and Stable Isotope Geochemistry to Assess Temporal Behavior of Seawater Intrusion in the La Yarada Aquifer in the Vicinity of Atacama Desert, Tacna, Peru

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3161
Author(s):  
Alissa Vera ◽  
Edwin Pino-Vargas ◽  
Mahendra P. Verma ◽  
Samuel Chucuya ◽  
Eduardo Chávarri ◽  
...  

The La Yarada aquifer is the primary water resource for municipal, irrigation, and industrial uses in the semi-arid Tacna, Peru. Presently, over-pumping has caused severe groundwater management problems, including the abandonment of saline water wells. This study presents multivariate analysis and chemical–isotopic trends in water to investigate seawater intrusion and hydrogeological processes affecting water quality. The chemical and isotopic analysis of water samples, collected in two campaigns in the dry (August 2020) and wet (November 2020) seasons, together with the 1988 data, were evaluated with a mixing model, cluster, and factor analysis. The hydrochemical and isotopic mixing model suggested the formation of a wedge with 20% seawater intrusion. The heterogeneity of piezometric map isolines corroborates the wedge formation associated with the groundwater movement. The spatial distributions of factors, FA1 and FA2, suggest two processes of seawater front movement: dispersion (diffusion) of chemical elements and different types of water mixing, respectively. At the edge of the La Yarada aquifer, the water head was relatively low, permitting seawater and freshwater mixing. On the other hand, along the sea-land boundary, the water head of the La Yarada aquifer was relatively high, avoiding seawater and freshwater mixing; however, the chemical species were migrating from the seawater to the groundwater due to the diffusion processes. The cluster 4 samples are in the region corresponding to the isotopic mixing process represented by the FA2, while cluster 4 describes the chemical diffusion process represented by the FA2. Thus, the integrated approach is helpful to assess the seawater intrusion mechanisms in coastal aquifers in a semi-arid region.

Author(s):  
A. J. Gomes Filho ◽  
S. C. de Paiva ◽  
G. M. C. Takaki ◽  
A. S. Messias

This study aims to analyze the reject produced by the desalinators implanted in the semi-arid Pernambuco in contact with the seeds of Moringa oleifera Lam. For this, Moringa seeds were collected and prepared with the following treatments: reject (control), reject with whole seed with and without husks, reject with crushed seed with and without husks, seed residue with and without husks, in five replicas. Each replica was constituted with doses equivalent to 2.0 g of Moringa seeds for 200 mL of reject, with contact time corresponding to 30, 60, 120 and 180 minutes, in a completely randomized design, under laboratory conditions, total of 140 experimental units. The physical-chemical and statistical analyses were performed through analysis of variance (ANOVA), and the F test, at confidence interval of 95%. It has been found through laboratory tests that seeds with crushed or ground Moringa husks are equally effective at adsorbing sodium from 1,868,0 mg/L to 24,6 mg/L (98,7 %), calcium from 1,005.0 mg/L to 894.6 mg/L (11%), magnesium from 741.0 mg/L to 728.3 mg/L (1.7%) and chloride from 6,997.5 mg/L to 6,782.4 mg/L (1.8%). Therefore, Moringa seed can be considered promising in the adsorption of chemical elements of saline water desalinizers.


2018 ◽  
Vol 374 (1764) ◽  
pp. 20180251 ◽  
Author(s):  
C. S. Pereira ◽  
I. Lopes ◽  
I. Abrantes ◽  
J. P. Sousa ◽  
S. Chelinho

In coastal areas, intrusion/irrigation with seawater can threaten biodiversity along with crop yields, and the leaching of salts from areas affected by these processes can increase the salinity of water bodies nearby. The aims of this study were to evaluate the effects of salinization on coastal soil ecosystems due to saline intrusion/irrigation. Terrestrial model ecosystems were used to simulate two soil salinization scenarios: (i) seawater intrusion and irrigation with distilled water and (ii) seawater intrusion and irrigation with saline water. Three sampling periods were established: T0—after acclimation period; T1—salinization effects; and T2—populations' recovery. In each sampling period, the abundance of nematodes, enchytraeids, springtails, mites and earthworms, and plant biomass were measured. Immediate negative effects on enchytraeid abundance were detected, especially at the higher level of saltwater via intrusion+irrigation. Eight weeks after the cessation of saline irrigation, the abundance of enchytraeids fully recovered, and some delayed effects were observed in earthworm abundance and plant biomass, especially at the higher soil conductivity level. The observed low capacity of soil to retain salts suggests that, particularly at high soil conductivities, nearby freshwater bodies can also be endangered. Under saline conditions similar to the ones assayed, survival of some soil communities can be threatened, leading to the loss of biodiversity. This article is part of the theme issue ‘Salt in freshwaters: causes, ecological consequences and future prospects’.


Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 937 ◽  
Author(s):  
Cristina Mateus ◽  
Christian A. Guerrero ◽  
Galo Quezada ◽  
Daniel Lara ◽  
Valeria Ochoa-Herrera

Water quality in Galápagos has been deteriorating by increased human impacts over the past few decades. Water quality is a key environmental component and issue in need to be evaluated in the Pelican Bay Watershed, the biggest urban and economic development of Santa Cruz Island, for better management and regulation of water resources. This study assesses coastal and ground water bodies of Pelican Bay by employing a 9-year dataset obtained during a local water quality monitoring program conducted by the Galápagos National Park. Physical-chemical and microbial parameters were evaluated with respect to national and international water quality standards. A statistical integrated approach was performed to calculate environmental background levels of water quality parameters and to explore their seasonal and spatial variation. In addition, a sensitivity analysis was conducted to evaluate the impact of changes in tourism and residents in San Cruz Island in the degradation of water sources. Results highlighted are: (a) water is not suitable for drinking and domestic use at some inland sites; (b) saline water is used for irrigation in the highlands; (c) the presence of parameters of concern at coastal sites represent a risk for human and ecosystem health; (d) background levels may serve for defining site-specific limits to control water quality, and; (e) the influence of population change on water quality conditions varied at each site with a higher effect at coastal sites relatively to inland sites. This study provided valuable information of the water quality status in Santa Cruz Island and can serve as a baseline for effective water management and control of pollution.


Geosciences ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 47
Author(s):  
Valle Raidla ◽  
Joonas Pärn ◽  
Werner Aeschbach ◽  
György Czuppon ◽  
Jüri Ivask ◽  
...  

The Viimsi peninsula is located north-east of Tallinn, capital of Estonia. The Cambrian-Vendian (Cm-V) aquifer system is a sole source of drinking water in the area. Historically, the groundwater exploitation has led to freshening of groundwater in the peninsula, but in recent years an increase in chloride concentrations and enrichment in δ18O values has been detected, but in recent years hydrochemical parameters indicate an increasing influence of a saline water source. The exact origin of this saline water has remained unclear. The aim of the current study is to elucidate whether the increase in Cl− concentrations is related to seawater intrusion or to the infiltration of saline water from the underlying crystalline basement. To identify the source of salinity, chemical composition of the groundwater and the isotope tracers (e.g., δ18O and radium isotopes) were studied in the Viimsi peninsula in the period from 1987 to 2018. Our results show that chemical composition of Cm-V groundwater in the peninsula is clearly controlled by three-component mixing between glacial palaeogroundwater, saline water from the underling crystalline basement and modern meteoric water. The concentrations of Ra are also significantly affected by the mixing, but the spatial variation of radium isotopes (226Ra and 228Ra) suggests the widespread occurrence of the U in the surrounding sedimentary sequence. Our hypothesis is that, in addition to U originating from the crystalline basement, some U could be associated with secondary U deposits in sedimentary rocks. The formation of these secondary U deposits could be related to glacial meltwater intrusion in the Pleistocene. Although the results suggest that the infiltration of saline groundwater from the underlying crystalline basement as the main source of salinity in the study area, the risk of seawater intrusion in the future cannot be ruled out. It needs to be highlighted that the present groundwater monitoring networks may not be precise enough to detect the potential seawater intrusion and subsequent changes in water quality of the Cm-V aquifer system in the Viimsi peninsula.


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