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Voutsis N.,National and Kapodistrian University of Athens | Kelepertzis E.,National and Kapodistrian University of Athens | Tziritis E.,Soil and Water Resources Institute | Kelepertsis A.,National and Kapodistrian University of Athens
Journal of Geochemical Exploration | Year: 2015

Major ion and selected trace element compositions were analyzed in 102 groundwater samples from central and northern areas of Euboea Island, Greece, where both serpentinite dissolution and anthropogenic activities (agricultural) are in action. By integrating hydrogeochemical and two multivariate statistical methods, hierarchical cluster analysis (HCA) and principal component analysis (PCA), the chemistry of these groundwaters was assessed with the aim to understand the evolution of groundwater and assign the major processes that exert control on its composition. HCA classified the groundwater samples into three chemically distinct groups (C1-C3) according to their dominant chemical composition. These three clusters were further categorized by their electrical conductivity values: C1 (median EC: 480μS/cm), C2 (median EC: 608μS/cm), C3 (median EC: 1020μS/cm). PCA was performed to identify the underlying natural and anthropogenic processes affecting the chemistry of these groundwaters. The PCA results can be represented by two principal factors: (1) salinization by seawater intrusion and NO3 - contamination; and (2) enrichment of groundwater with Mg2+, HCO3 - and Cr following groundwater-serpentinite interaction. A third trivial component is associated with more local effects of the geological substrate. The three components of the PCA account for 70% of the total variance in the data. Dissolved Cr concentrations (up to 71μg/L) that rise environmental concerns are more pronounced in the groundwaters from the alluvial coastal area of Politika (C3 water samples). Results of this study demonstrate that appropriate measures should be taken to protect the vital groundwater resources in the alluvial coastal area including the regulation of the amount of chemical fertilizers applied to agricultural soils and the monitoring of groundwater pumping rates. © 2015 Elsevier B.V.

Tziritis E.,Soil and Water Resources Institute | Skordas K.,University of Thessaly | Kelepertsis A.,National and Kapodistrian University of Athens
Environmental Earth Sciences | Year: 2016

The present study investigates the hydrogeochemical regime of a complex aquifer system in a highly cultivated area of Thessaly, central Greece. To do so, totally forty (40) groundwater samples were collected for three aquifer units with diverse geological and hydrogeological attributes and analyzed for 77 parameters. Data processing was accomplished with the joint use of classic hydrogeochemical techniques including major ion molar ratios and graphical interpretation, as well as multivariate statistical methods including R-mode factor (FA) and hierarchical cluster analysis (HCA). Results showed that major ion hydrogeochemistry is characterized by the prevalence of calcium (median = 81 mg/L) and bicarbonates (median = 308 mg/L) in the following descending order of concentrations for cations Ca2+>Mg2+>Na+>K+ and anions HCO3 −>NO3 −>SO4 2−>Cl−, respectively. Nitrate values are elevated (median = 23 mg/L), especially in the porous quaternary aquifer, indicating the ongoing agricultural impact from the excessive use of nitrogen fertilizers and manure. The results of multivariate statistics highlighted four factors that chiefly control 81.4 % of overall hydrogeochemistry, related with both geogenic and anthropogenic impacts. The geogenic impact is mainly attributed to the geological substrate and secondarily to the ongoing geochemical (redox) conditions which in turn enrich or deplete groundwater solution with different ions; anthropogenic impact is mainly related with the extensive agricultural practices which favor nitrate enrichment and salinization due to irrigation water return flow. © 2016, Springer-Verlag Berlin Heidelberg.

Tziritis E.,Soil and Water Resources Institute | Tziritis E.,Aristotle University of Thessaloniki | Tzamos E.,Aristotle University of Thessaloniki | Vogiatzis P.,Aristotle University of Thessaloniki | And 5 more authors.
Desalination and Water Treatment | Year: 2015

Twenty-seven (27) tap water samples were collected during October 2012 from the supply network of Thermi Municipality (central Macedonia, northern Greece) in order to assess their hydrogeochemical signatures and the overall quality status according to the European legislation and international standards. Samples were analysed for a total of 25 environmentally significant parameters including physicochemical properties (pH, EC, colour, turbidity and hardness), major and minor ions (Ca2+, Mg2+, (Formula presented.), (Formula presented.), (Formula presented.), Cl−, (Formula presented.), F−, and CN−) and trace elements (B, Sb, As, Cd, Cr, Cu, Pb, Hg, Ni, Se, and Mn). The vast majority of the parameters appeared in values below the maximum admissible concentration for potable waters. Individual elevated concentrations of B and (Formula presented.) may be attributed to natural (geogenic) factors related with local lithology and anthropogenic influences possibly deriving from agricultural practices (excessive use of N-fertilizers). The assessments of the analytical results were validated with the use of PoS index, which classified nearly all samples of low to medium quality degradation and outlined the dominant triggering parameters affecting the hydrogeochemical status. These parameters included, apart from ammonium and boron, chromium, fluoride and nitrates. PoS index proved to be a versatile tool to communicate environmental information of groundwater quality characteristics, especially in environmental monitoring projects, since it abets to understand the overall evaluation of water quality. In addition, PoS application offers a valuable alternative for on-the-spot comprehensive and comparative analysis of all available water quality data, and may be used as a screening tool for environmental assessment applications. © 2015 Balaban Desalination Publications. All rights reserved.

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