Changes in geochemical and isotopic contents in groundwater before seismic events in Ischia Island (Italy)

We analysed the hydrogeochemical and isotopic contents in groundwater for the period 2002–2020, in the Ischia Island, a volcanic island in Southern Italy, and compared them with seismic events that occurred in the same period. The study is based on a large hydrochemical database, which includes chem...

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Bibliographic Details
Published in:Chemosphere (Oxford) 2024-02, Vol.349, p.140935-140935, Article 140935
Main Authors: Del Gaudio, Elena, Stevenazzi, Stefania, Onorati, Giuseppe, Ducci, Daniela
Format: Article
Language:English
Subjects:
Earthquake
Environmental Monitoring - methods
Geochemistry
Groundwater
Groundwater - chemistry
Ischia
Isotopes
Isotopes - analysis
Trace Elements - analysis
Water Pollutants, Chemical - analysis
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Summary:We analysed the hydrogeochemical and isotopic contents in groundwater for the period 2002–2020, in the Ischia Island, a volcanic island in Southern Italy, and compared them with seismic events that occurred in the same period. The study is based on a large hydrochemical database, which includes chemical (major and minor compounds, metals and trace elements) and isotopic analyses (δ18O and δ2H). For each of the 34 seismic events occurred in the studied period, we considered coordinates, date, time, depth and magnitude. To exclude the influence of meteorological variability on the hydrochemistry, we examined rainfall time series measured in four stations located in the island. Results show hydrogeochemical anomalies for some chemical elements observed months before the seismic events. Arsenic, electrical conductivity, chromium and vanadium have been identified as potentially affected by hydrogeochemical anomalies related to the earthquakes. The variations in stable isotopes (δ2H and δ18O) in groundwater also seem associated with the earthquakes. This study aims to contribute to the individuation of components in groundwater prone to register sudden changes related to seismic events and it highlights the need of a continuous and long-term hydrogeochemical monitoring in seismic areas. Indeed, the conclusions of this study must be further confirmed by a future continuous monitoring of major compounds, trace elements and isotopes in groundwater to evaluate the effective temporal coincidence/lag with the seismic events. [Display omitted] •Hydrochemical anomalies occurred months before the seismic events in Ischia Island•Significant variations concern EC and the concentrations of As, V and Cr•After the events, these elements partially recovered their normal concentrations•Light changes in δ2H and δ18O were observed before the events•The variations can be related to changes in hydrothermal fluids circulation
ISSN:0045-6535
1879-1298
DOI:10.1016/j.chemosphere.2023.140935