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Description
Arsenic (As) is an element that occurs in the environment (soil, water, air and biocosm) in trace amounts. The presence of arsenic in soils and waters is due to natural (types of rocks, or geothermal fields) as well as anthropogenic causes (agricultural activities). This element occurs in natural waters in the form of trivalent (As (III)) and pentavalent (As (V)) arsenic, of which the most toxic is its trivalent form. The toxic effect of arsenic on humans depends on its concentration as well as the duration of human exposure to arsenic while exposure to it occurs through drinking water. In the area of Aridea of the Municipality of Almopia, following actions carried out by the competent services related to the quality of drinking water, increased concentrations of arsenic were detected (usually in concentrations from 11 to 17 μg / L but also up to 26 μg / L in some cases or 362 μg/L in the thermal spa of Pozar) exceeding the upper acceptable legal limits (10 μg/L), for human consumption of Join Ministerial Decision 3535/2023. The confirmed presence of arsenic in the groundwater systems of the Almopia region makes it imperative to investigate the source of arsenic and to distinguish the toxicity of its various forms in the environment. The main objectives of the project are mainly related to: i. Quantification and spatial distribution of As in groundwater, ii. Determination of the mineralogical-geochemical composition, rocks and soils, which act as natural sources for the enrichment of As and other trace elements in the environment of the study area. iii. Distinguishing the source of these elements, anthropogenic or geogenic iv. Investigation of the hydraulic connection of groundwater with the thermo-mineral and thermal waters of the wider area in combination with the design and implementation of special protection regulations v. determining conditions for the planning of new drinking water projects while protecting public health.
Summary of project results
The impacts of geothermal fluids to the water environment were addressed in the frame of this project. Distinguishing the anthropogenic and geogenic sources of pollution in the basin of Almopia was of great challenge in order to plan the new water management of the basin. The methodology of this project fulfilled the lack of data in the area and revealed the hydrodynamic regime of the groundwater. The results highlighted the role of water rock interaction and how it contributes to water quality.
Many campaigns of samplings and measurements were done in order to imprint the hydrogeological and hydrochemical conditions of the basin. Over 250 water samples were collected in three different time periods, and over 60 solid samples (rocks, soils, sediments). Full chemical analyses were done in water samples. In solid samples except the geochemical analyses, mineralogical study was carried out. Two pumping tests in wells were performed in order to evaluate the hydraulic characteristics of the aquifers. A tracing test was performed for defining the groundwater flow direction and the velocity of groundwater.
Also field experiments were done for estimating the rate of infiltration. This area was understudied, without time series data, and no significant hydrogeological knowledges for the capacity of the aquifers. The great output of this project was the suggestions to the local authorities for new infrastructure projects for the implementation of the outputs.
Now the public authorities of the region have the knowledge and all the necessary data for a rational water management of the basin, considering the quantity and quality of waters. The results of this project also contributed a lot to the local public authority for the water supply to ensure water of good quality for the people. Also, new sites for water exploitation were revealed based on the new data of the project and suggestions for the utilization of old-inactive wells were proposed.