Assessment of Geo-environmental Status of Trichonis Lake, Greece: Mineralogy, Sedimentology, and Chemistry

Sediments of Trichonis Lake are dominated by quartz and calcite, reflecting the lithological influence of surrounding limestone and flysch formations. Reduced nutrient levels in lake water since the late 1990s highlight the positive ecological impact of decreased agricultural pressures, providing a foundation for sustainable lake management strategies. Comprehensive assessment of the geo-environmental status in Trichonis Lake revealed insights into its sedimentological, mineralogical, and chemical characteristics, as well as into the impact of natural and anthropogenic factors. This study provides a baseline for understanding the geo-environmental dynamics of Trichonis Lake and offers valuable guidance for future conservation and management strategies aimed at maintaining the health of this vital freshwater ecosystem. Findings underscore the need for continued monitoring and sustainable land-use practices to mitigate anthropogenic pressures and preserve the ecological integrity of the lake.

Key conclusions include:
• The sediments are predominantly composed of quartz and calcite, reflecting a lithological influence of the surrounding flysch and limestone formations. Variations in sediment texture, ranging from sand to silty sand, highlight localized sediment transport and deposition processes.
• Organic matter content ranged from 0.1% to 6.2%, with higher values near areas of enhanced biological productivity, such as at the Trichonis-Lysimachia trench. This differentiation signifies the ecological importance of sedimentary organic matter accumulation in assessing ecosystem “health”.
• Physicochemical parameters, including pH, Eh, and TDS, are consistent with those expected in freshwater systems influenced by limestone and flysch. Elevated nutrient levels at specific sites point to agricultural runoff and urban influences, although the overall nutrient concentrations declined since the late 1990s, likely due to reduced agricultural pressures, including the cessation of tobacco cultivation.
• While some localized contamination is evident, such as elevated NH4+, NO3-, and PO43- levels near agricultural areas, the consistent SO₄²⁻ levels across sites suggest limited anthropogenic influence on this parameter. The mineralogical composition of the lake sediments also emphasizes the dominance of natural geochemical processes in shaping its chemistry.
• Overall, Trichonis Lake shares some commonalities with other Mediterranean lakes in terms of its sensitivity to anthropogenic impacts and nutrient dynamics. However, its distinct carbonate-rich sediment composition and relatively stable water chemistry highlight its unique geological and ecological context. This underscores the importance of tailored conservation efforts to preserve the lake’s ecological balance amidst regional anthropogenic pressures.