Multivariate assessment of groundwater contamination levels associated with saline intrusion processes in Mediterranean coastal aquifers

IF 4.4 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology Pub Date : 2026-03-01 Epub Date: 2026-02-09 DOI:10.1016/j.jconhyd.2026.104877

R. Álvarez-Alonso , P.A. Robledo Ardila , S. Deudero , C.A. Melo-Aguilar , C. Alomar , F. Micheo , J.J. Durán , S. Pérez , F. Árcega Cabrera , S. Martínez Pérez

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引用次数: 0

Abstract

Groundwater in Mediterranean coastal aquifers supplies a large part of the demand for freshwater but is increasingly threatened by seawater intrusion and anthropogenic pollution. During the springs of 2023 and 2024, six coastal carbonate aquifers in Mallorca were sampled to assess the present-day spatial and vertical variability of salinization and pollution. Hydrochemistry showed elevated Cl⁻ (2140–18,800 mg/L), Na⁺ (1317–10,983 mg/L) and SO₄²⁻ (440–2890 mg/L), with high electrical conductivity (7480–53,850 μS/cm in 2023 and 16,200–42,000 μS/cm in 2024). Nutrients (NO₃⁻, NH₄⁺, PO₄³⁻, NO₂⁻) and fecal indicators (Escherichia coli, Enterococci) were detected. Vertical profiles showed salinity increases with depth (except at Drac de Santanyí). The ƒ_sea index indicated marine intrusion in >96% of samples. Modified Piper indices (GQI_Piper(mix), GQI_Piper(dom)) and GQI_SWI values (28–56 in 2023; 32–51 in 2024) pointed to dominant to mixed NaCl facies. PCA and hierarchical clustering revealed marked hydrochemical heterogeneity among sites, with differences between 2023 and 2024 and site-specific anomalies associated with freshwater inputs and anthropogenic pressure. Overall, the results document widespread brackish to saline groundwater conditions and the co-occurrence of microbiological contamination in Mallorca's coastal aquifers, highlighting their high vulnerability to salinization and water-quality degradation.

This work presents a data-driven, site-specific conceptual model of the marine intrusion system in Mediterranean coastal aquifers, characterized by a laterally extensive brackish zone overlying saline groundwater and a limited or locally absent freshwater lens near the coast. These findings underscore the need for integrated groundwater management, including salinity monitoring, regulation of abstraction, and improved wastewater treatment, to mitigate ecological and public-health risks in Mediterranean coastal aquifer systems.

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地中海沿岸含水层中与盐水入侵过程相关的地下水污染水平的多变量评估

地中海沿岸含水层的地下水提供了大部分淡水需求，但日益受到海水入侵和人为污染的威胁。在2023年和2024年春季，对马略卡岛6个沿海碳酸盐含水层进行了采样，以评估当今盐渍化和污染的空间和垂直变化。水化学表现为Cl−(2140 ~ 18800 mg/L)、Na+ (1317 ~ 10983 mg/L)和SO₄2−(440 ~ 2890 mg/L)含量升高，电导率高（2023年为7480 ~ 53850 μS/cm， 2024年为16200 ~ 42000 μS/cm）。检测营养物质（NO₃−、NH₄+、PO₄3−、NO₂−）和粪便指标（大肠杆菌、肠球菌）。垂直剖面显示盐度随深度增加而增加（Drac de Santanyí除外）。ƒsea指数表明96%的样品有海洋入侵。修正后的Piper指数（GQIPiper（mix）、GQIPiper(dom)）和GQISWI值（2023年为28 ~ 56,2024年为32 ~ 51）表明以混合NaCl相为主。主成分分析和层次聚类结果表明，2023年和2024年各站点之间存在显著的水化学异质性，且站点特异性异常与淡水输入和人为压力有关。总体而言，研究结果记录了马略卡岛沿海含水层普遍存在半咸水到咸水的地下水状况，以及微生物污染的共存，突出了它们对盐碱化和水质退化的高度脆弱性。这项工作提出了地中海沿岸含水层海洋入侵系统的一个数据驱动的、特定地点的概念模型，其特点是在咸水地下水上有一个横向广泛的半咸水带，在海岸附近有一个有限或局部不存在的淡水透镜。这些发现强调需要对地下水进行综合管理，包括盐度监测、抽取规范和改进废水处理，以减轻地中海沿岸含水层系统的生态和公共卫生风险。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of contaminant hydrology 环境科学-地球科学综合

CiteScore

6.80

自引率

2.80%

发文量

129

审稿时长

68 days

期刊介绍： The Journal of Contaminant Hydrology is an international journal publishing scientific articles pertaining to the contamination of subsurface water resources. Emphasis is placed on investigations of the physical, chemical, and biological processes influencing the behavior and fate of organic and inorganic contaminants in the unsaturated (vadose) and saturated (groundwater) zones, as well as at groundwater-surface water interfaces. The ecological impacts of contaminants transported both from and to aquifers are of interest. Articles on contamination of surface water only, without a link to groundwater, are out of the scope. Broad latitude is allowed in identifying contaminants of interest, and include legacy and emerging pollutants, nutrients, nanoparticles, pathogenic microorganisms (e.g., bacteria, viruses, protozoa), microplastics, and various constituents associated with energy production (e.g., methane, carbon dioxide, hydrogen sulfide). The journal''s scope embraces a wide range of topics including: experimental investigations of contaminant sorption, diffusion, transformation, volatilization and transport in the surface and subsurface; characterization of soil and aquifer properties only as they influence contaminant behavior; development and testing of mathematical models of contaminant behaviour; innovative techniques for restoration of contaminated sites; development of new tools or techniques for monitoring the extent of soil and groundwater contamination; transformation of contaminants in the hyporheic zone; effects of contaminants traversing the hyporheic zone on surface water and groundwater ecosystems; subsurface carbon sequestration and/or turnover; and migration of fluids associated with energy production into groundwater.