Sixteen surface (5) and groundwater (11) samples were collected from the south-eastern part of Attica, Greece, and analysed for physico-chemical parameters and microplastics (MPs) by optical microscopy and Raman microspectroscopy (RS). A total of 3399 particles were optically identified in all sixteen samples, ranging from only 16 particles/L in a sample from a deeper borehole to 513 particles/L in a sample from a shallow water well. They were then visually classified into eight categories based on their color, texture, size, reflectivity, shape, and general morphological properties. Raman microspectroscopy was performed on the particles on the filters and revealed four different types of MPs, namely polyethylene (PE, 35%), polypropylene (PP, 30%), polystyrene (PS, 10%), and polyethylene terephthalate (PET, 25%). The samples from the shallow phreatic aquifer contained more MPs than the samples from the deeper borehole, which contained fewer MPs and categories. This is to be expected, since the phreatic aquifer (a) is generally more contaminated, as it is close to human activities that generate MPs and its infiltration depth is only a few metres, which means that many microplastics can infiltrate at such shallow depths, and (b) it is exposed to the atmosphere, so they can also be suspended in the air. On the other hand, it is interesting to note that MPs, especially PET and PE, were detected in the borehole sample, suggesting that MPs can migrate to greater depths through water infiltration. Chemical analyses of the groundwater samples revealed high values of E.C., Ca²⁺, Mg²⁺, Cl⁻, and Na⁺, which indicate that seawater intrusion is taking place in the coastal aquifer system of the Erasinos basin. The increased concentrations of NO₃⁻ and PO₄³⁻ also indicate the impact of agricultural activities.

At the end of surface mining activities, the remnant voids are of great concern regarding rehabilitating the final open pits. The investigation of the sustainability of pit lakes in post-mining regions constitutes a challenging research problem. This paper aims to highlight the effectiveness of pit lakes as a rehabilitation factor. In this framework, several cases worldwide and in Greece were examined in detail and evaluated. The results indicate that mine pit lakes must be evaluated as dynamic systems, natural or artificial, which demand rational mine water management to ensure their sustainability. Specifically in Greece, it is of great importance during the transition to the post-lignite era.

The hydrogeochemical processes and natural background levels (NBLs) of chromium in the ultramafic environment of Vermio Mountain, Western Macedonia, Greece, were studied. Seventy groundwater samples were collected from 15 natural springs between 2014–2020, and an extensive set of physical and chemical parameters were determined. The ultramafic-dominated environment of western Vermio Mt. favors elevated groundwater concentrations of dissolved magnesium (Mg²⁺), silicon (Si), nickel (Ni), and Cr in natural spring waters. Chromium was the principal environmental parameter that exhibited a wide range of concentrations, from 0.5 to 131.5 μg/L, systematically exceeding the permissible limit of 50 μg/L for drinking water. Statistical evaluation of hydrogeological, hydrochemical, and hydrological data highlighted the water-ultramafic rock process as the predominant contributor of Cr in groundwater. The NBL assessment for Cr and Cr(VI) was successfully applied to the typical ultramafic-dominated spring “Potistis” that satisfied all the methodology criteria. The NBLs of Cr and Cr(VI) were defined at 130 μg/L and 100 μg/L, respectively, revealing that a natural ultramafic-dominated environment exhibits the geochemical potential to contribute very high concentrations of geogenic Cr to groundwater. The holistic methodology, proposed herein, could be implemented in any catchment scale to assess geogenic and anthropogenic Cr-sources that degrade groundwater quality.

SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis is a useful tool for sustainable development and decision making about environmental planning and water resources management. This analysis was applied in order to evaluate the water resources of the wider area of Sperchios River. Sperchios River basin, with an average altitude of approximately 810m, covers an area of 2116 km2. The river is recharged by many streams of permanent and periodic flow and discharges in Maliakos Gulf. The steep slopes, which are present within approximately 2/3 of the total length of the river course, form a rather mountainous topography (streamy, with crucial flooding peaks and very intense sediment yield). Only in the last downstream part of Sperchios course, the topography gradually changes into a lowland relief, with an extent at the river mouth of 1830 km2. At this part of Sperchios severe cases of flooding have been occasionally observed and reported. Regarding the SWOT applications on the wider area of Sperchios River, various data were processed (geological, meteorological, hydrological, hydrogeological, land use, socio-economic and environmental parameters) in order to suggest a water management planning in the area.