Evolution of Nuntași-Tuzla Lake Chemistry in the Context of Human Intervention

This paper analyzes the chemical evolution of Nuntași-Tuzla Lake (Romania) in the context of human intervention. Situated on the shore of the Black Sea, approximately 35 km north of Constanța, Nuntași-Tuzla Lake is part of the Razim–Sinoe Lake complex and a component of the Danube Delta Biosphere Reserve. This area has undergone significant transformations over the past 120 years: canalization of the connecting channels with the St. George arm, construction of polders for agriculture, closure of the connections to the Black Sea, and construction of the Razim–Sinoe irrigation system. After the irrigation system stopped working (around 2000), due to the isolation of the lake and the low flow coming from the two rivers that supply the lake with fresh water, it completely dried up in 2020. All these interventions have led to the ecological, hydrological, and chemical deterioration of the lake’s water. The main effects are (i) a decrease in water salinity and (ii) reduction in the production of sapropelic mud as the salinity decreases due to the influx of fresh water.