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| Titel |
Confronting the vicinity of the surface water and sea shore in a shallow glaciogenic aquifer in southern Finland |
| VerfasserIn |
S. Luoma, J. Okkonen, K. Korkka-Niemi, N. Hendriksson, B. Backman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 3 ; Nr. 19, no. 3 (2015-03-12), S.1353-1370 |
| Datensatznummer |
250120657
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| Publikation (Nr.) |
 copernicus.org/hess-19-1353-2015.pdf |
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| Zusammenfassung |
| The groundwater in a shallow, unconfined, low-lying coastal aquifer in
Santala, southern Finland, was chemically characterised by integrating
multivariate statistical approaches, principal component analysis (PCA) and
hierarchical cluster analysis (HCA), based on the stable isotopes δ2H
and δ18O, hydrogeochemistry and field monitoring data. PCA and HCA
yielded similar results and classified groundwater samples into six distinct
groups that revealed the factors controlling temporal and spatial variations
in the groundwater geochemistry, such as the geology, anthropogenic sources
from human activities, climate and surface water. High temporal variation in
groundwater chemistry directly corresponded to precipitation. With an
increase in precipitation, KMnO4 consumption, EC, alkalinity and Ca
concentrations also increased in most wells, while Fe, Al, Mn and SO4 were
occasionally increased during spring after the snowmelt under specific
geological conditions. The continued increase in NO3 and metal
concentrations in groundwater indicates the potential contamination risk to
the aquifer. Stable isotopes of δ18O and δ2H indicate
groundwater recharge directly from meteoric water, with an insignificant
contribution from lake water, and no seawater intrusion into the aquifer.
Groundwater geochemistry suggests that local seawater intrusion is
temporarily able to take place in the sulfate reduction zone along the
freshwater and seawater mixed zone in the low-lying coastal area, but the
contribution of seawater was found to be very low. The influence of lake
water could be observed from higher levels of KMnO4 consumption in wells
near the lake. The integration of PCA and HCA with conventional
classification of groundwater types, as well as with the hydrogeochemical
data, provided useful tools to identify the vulnerable groundwater areas
representing the impacts of both natural and human activities on water
quality and the understanding of complex groundwater flow system for the
aquifer vulnerability assessment and groundwater management in the future. |
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