GROUNDWATER QUALITY OF THE HYDROLOGICAL BASIN OF AMYROS RIVER, AGIA AREA THESSALY, GREECE

The area of Agia (Thessaly, Central Greece) is a highly cultivated region, whose hydrogeochemical status is influenced both by natural and manmade factors. Chemical analyses of 40 groundwater samples from the examined area, revealed that geology has a significant impact to aquifers chemistry, mainly expressed through the presence of carbonate rocks and evaporitic minerals of the Neogene formations of the area., as well as the ultrabasic rocks of the substrate. The manmade influence is assessed through the elevated values of nitrates (values up to 168,7 mg/L). Furthermore, the analytical results of the groundwaters revealed that NO3-, Fe and Se, in several samples, exceeded the EC and SMCL (USEPA) limits. More specifically, the 20% of NO3- samples exceeded the EC limits as well as the 2,5% of Se in samples. The 2,5% of Fe in samples exceeded both the EC and SMCL (USEPA) limits

Environmental geochemical research for the levels and the sources of toxic metals in the agricultural soils of Dimitra-Eleftherion and Platycampos region, Thessaly, Greece

The contents of eleven elements (Cu, Pb, Zn, Ni, Co, Mn, Fe, As, V, Cr and Mg) have been assayed in the agricultural soils of Dimitra-Eleftherion and Platycampos region (Thessaly, Greece). One hundred twenty two top soil samples were collected and analysed by ICP-AES after digestion with a mixture of HClO4-HNO3-HCl-HF Mean concentration of elements (1g g(-1)) in soil samples were: Cu,43; Pb,16; Zn,78; Ni,216; Co,27; Mn,1032; Fe 4.1%; As,5; V,109; Cr,254; Mg,2.5%. The contamination of the soils was assessed on the basis of comparison with average soil composition, phytotoxic levels and GLC guidelines. All the elements analysed except Pb and As have mean concentrations above the average soil comparison. The metals Zn, Ni and Cr show mean concentrations clearly higher than the phytotoxic levels. The metals Ni, Mn, V and Cr show concentrations that according to G.L.C guidelines the Dimitra-Eleftherion and Platycampos soils are classified as slightly contaminated to contaminated. Correlation analysis (CA) and principal component analysis (PCA) were applied to the data matrix to determine which elements have a common origin. PCA revealed that the studied area was mainly influenced from four sources, namely: natural (factors 1 and 2), traffic (factor 3), agricultural sources (factor 4). Cu, Zn, Co, Mn, Fe and V are associated together in iron and manganese oxideshydroxides; so grouping of these variables in the first factor reflects the adsorption of Cu,Zn, Co and V by the Fe-Mn oxides-hydroxides, as well as their weathering products. The existence of Ni,Co,Cr and Mg in the second factor explains the weathering products of ultrabasic rocks. The third factor is dominated by Pb and is related to the traffic emissions. Finally, the fourth factor is dominated by As and is related to the use of phosphate and other fertilizers

Diagenesis of the sedimentary rocks enclosing coaly layers in Gavatha area, Lesvos Island, based on silica polymorph's transformations

A Tertiary non-marine stratigraphic sequence composed of carbonates (limestone), siliceous carbonates, coaly layers overlain by pyroclastic rocks and lavas, outcrops in the Gavatha area of northwestern Lesvos Island. Pure carbonates consist almost completely of calcite, the siliceous carbonate sediments of quartz, opal-CT and calcite, the shales of quartz, opal-CT, K-feldspar, smectite-illite and calcite, and the coaly layers of organic matter, quartz, opal-CT, feldspars and pyrite. Geochemical data indicate that smectite-illite, feldspars and associated elements (La, Zr, Y, Ba, Ce) are the products of alteration of volcanic rocks in a subtropical area. A combination of sources is suggested for the formation of silica polymorphs: (a) biogenic or non-biogenic silica (opal-A) that was originally present in the form of diatom frustules or in the form of inorganically precipitated silica; (b) transformation of opal-A to opal-CT and quartz opal-C from alteration of volcanic glass of intercalated tuffites and overlying volcanics; and (c) opal-CT deposited primarily from hydrothermal solutions. © 1996 Institute of Geochemistry, Chinese Academy of Sciences

Oligocene swamp sediments of Lesvos Island, Greece (geochemistry and mineralogy)

The Tertiary Lapsarna swamp sedimentary rocks include thin horizons (organic-rich sediments, up to 22% Corg). Analyses of major elements of carbonates, shaly and siliceous rocks, and a thin, intensively silicified coaly horizon were taken (10 representative samples). Pure carbonates consistalmost completely of calcite, the siliceous sediments of quartz and calcite, and the shales of montmorillonite, feldspar, quartz, dolomite and calcite. The shales contain montmorillonite as the only clay component. The presence of montmorillonite in all shales suggests that the chemistry of the clay-forming solutions lies within the stability field of montmorillonite. Geochemical data indicate that montmorillonite and associated immobile elements (La, Zr, Y, Nb) are the products of hydrolysis of volcanic material in a subtropical region. The intense silification of the coaly horizon is due to a contact with silica-rich solutions that formed during the formation of montmorillonite. Quartz is produced diagenetically by transformation of amorphous opal-A after burial. © 1992 Institut für Paläontologie, Universität Erlangen

Environmental impact of heavy metals (Fe, Ni, Cr, Co) in soils waters and plants of triada in Euboea from ultrabasic rocks and nickeliferous mineralisation

Soil, water and vegetation samples were collected from the Triada area of Central Euboea and analysed for heavy metals in order to evaluate their environmental impact. The geology of the are studied includes ultrabasic rocks that are overlaid by Upper Cretaceous limestones whereas Fe-Ni mineralisation is intercalated between either the ultrabasic parent rocks or the karstified Jurassic/Triassic carbonates and the transgressive Upper Cretaceous limestones. All the samples were analysed for heavy metals by using atomic absorption spectroscopy. The heavy metal ranges (in μg g-1) for soils samples are: Ni 480-4000, Cr 240-2720, Co 40-208, Fe 24,000-380,000, Mn 46-1680, Pb 16-56, Zn 40-144, Cu 2-82. The values of soil samples of the Triada area are much higher than the values found for Ni, Cr, Co and Fe, in normal soils of the world. The heavy metal ranges (in μg L-1) for water samples are: Ni 19-24, Cr 19-476, Co <5, Fe <100, Mn <100, Mg 5.7-220.5, As 30-69, Cd <2, Pd <10, Zn 5-11, Cu 2-7. The water samples of the Triada area have Cr and Mg concentrations higher than the permittable values. The heavy metal ranges (in μg g-1) for vegetation samples are: Ni 1-135, Cr 0-24, Co 1-21.5, Fe 20-680, Mn 10-206, Cd 0-10, Pb 0-14, Zn 14-70, Cu 0-10.5. The vegetation samples of the Triada area have so high values of Ni, Cr and Co that are considered toxic. The intercorrelated elements Fe, Ni, Cr, Co of the Triada soils, waters and vegetation reflect their association with the ultrabasic rocks and with the Fe-Ni mineralisation

Oligocene swamp sediments of Lesvos Island, Greece (geochemistry and mineralogy)

The Tertiary Lapsarna swamp sedimentary rocks include thin horizons (organic-rich sediments, up to 22% Corg). Analyses of major elements of carbonates, shaly and siliceous rocks, and a thin, intensively silicified coaly horizon were taken (10 representative samples). Pure carbonates consistalmost completely of calcite, the siliceous sediments of quartz and calcite, and the shales of montmorillonite, feldspar, quartz, dolomite and calcite. The shales contain montmorillonite as the only clay component. The presence of montmorillonite in all shales suggests that the chemistry of the clay-forming solutions lies within the stability field of montmorillonite. Geochemical data indicate that montmorillonite and associated immobile elements (La, Zr, Y, Nb) are the products of hydrolysis of volcanic material in a subtropical region. The intense silification of the coaly horizon is due to a contact with silica-rich solutions that formed during the formation of montmorillonite. Quartz is produced diagenetically by transformation of amorphous opal-A after burial. © 1992 Institut für Paläontologie, Universität Erlangen