Pesticides play an important role in boosting agricultural production by controlling pests. Pesticides can be algicides, antimicrobials, disinfectants, herbicides, insecticides, molluscicides, pheromones, rodenticides (raticides), and biopesticides. Despite regulations, pesticide pollution remains a threat to human health, food security, and the environment. Pesticides can harm the environment, affecting water quality and biodiversity, and can be toxic to non-target species. This study aimed to assess the impact of pesticide residues on the surface waters of the Danube River through concentrations determined in the period 1995–2023 in the Danube River Basin. In the present study, scientific techniques were used to collect scientific evidence, consulting academic literature databases such as Google Scholar, Science Direct, MDPI, etc. The study also looked at the quantities of pesticides used in the countries of the Danube River Basin compared to agricultural production during 2014–2022. Five compounds from the pesticide class were selected from the literature. This selection was based on the frequency of determination in surface waters from the Danube River Basin. Pesticides have a negative effect on both the aquatic ecosystem and humans, directly affecting the proper functioning of the body. Continuous monitoring of pesticide residues is essential for determining the quality of the Danube water, as well as for biodiversity.

In this study, we report the findings regarding the toxicity of surface waters collected in March 2023 from five sampling stations in the Zaghen restoration area, located within the Danube Delta Biosphere Reserve, Romania. The assessment of acute toxicity was conducted using two microbiotests: the Thamnotoxkit F and the Daphtoxkit F^TM magna. Even if the acute toxicity effects are less than 50% and do not allow the calculation of a toxicity score for the water samples, the experiments show a different vulnerability of the two zooplanktonic species to the presence of heavy metals in the water with mortality being higher in Thamnocephalus platyurus (20%) than in Daphnia magna (15%).

This study aims to provide a comparative analysis of nutrient concentrations in two lakes with controlled hydrological regimes that are directly influenced by the Danube River. The lakes are differentiated by their distinct geographical settings: one located in a pre-deltaic area and the other within the deltaic zone. Eight chemical indicators were analysed in surface water samples collected seasonally between 2019 and 2023. The results show higher concentrations of nitrates and nitrites in Lake Fortuna, associated with its natural hydrological connectivity, whereas Lake Parcheș exhibited a higher proportion of organic nitrogen and phosphorus and better self-purification capacity. These findings suggest that the hydrological regime plays a significant role in nutrient dynamics and potential eutrophication risk.

The Danube Delta, a dynamic alluvial plain, serves as a substantial carbon sink due to its extensive stands of reeds, specifically Phragmites australis. This study quantifies carbon storage across five distinct reedbed types based on substrate characteristics, using biomass assessment, soil carbon analysis, and GIS-based spatial mapping. Results show that reeds on salinized organic soils (S-Pa) have the highest carbon storage capacity (8.595 t/ha C), while those on gleyic soils (S-F) have the lowest storage levels (0.463 t/ha C). Furthermore, an analysis of heavy metal contamination (Cr, Ni, Pb, Zn) over 5 years revealed concentrations below regulatory thresholds, with a declining trend. The analysis indicates that reeds have notable potential for pollutant sequestration, particularly in aquatic vegetation and soil. These findings highlight the crucial role of deltaic wetland ecosystems in carbon sequestration and contaminant retention, underscoring the need for sustainable management strategies.