## 4 Conclusions  
Pollution of water bodies in large hydrographic basins from diverse sources, including urbanization, agriculture activities, untreated sewage, and industrialization, pose a great threat, with potentially severe ecological and human health impacts over time. Effective management and regulatory directives are crucial in order to mitigate this impact and protect water quality. Also, continued research and monitoring are essential to further understand the sources, pathways, and adverse effects of these contaminants, thereby ensuring a sustainable environment for both ecosystems and human populations. The present study provides a comprehensive assessment of surface water contamination in the lower Danube River, the Danube Delta, and the Romanian coastal waters of the Black Sea, highlighting the presence of various pollutants, including heavy metals, nutrients, pharmaceuticals, endocrine disruptors, and microbial contaminants. The findings indicate that certain sectors of the Danube River and its tributaries, particularly the Siret and Prut rivers, exhibit elevated levels of contamination. Industrial activities, untreated wastewater discharges, and agricultural runoffs contribute significantly to the presence of heavy metals and emerging contaminants in these areas. While some metals, such as arsenic and mercury, were found within acceptable ecological limits, others, including manganese, nickel, and lead, exceeded threshold values in specific locations, raising concerns about potential bioaccumulation and ecological impact. The detection of pharmaceutical residues, particularly diclofenac, carbamazepine, and bisphenol A, confirms the increasing issue of emerging contaminants in surface waters. These substances, often originating from wastewater treatment plants, have been detected at levels that may pose ecological risks. Given their persistence and potential effects on aquatic organisms, continuous monitoring and improved wastewater treatment technologies are necessary to mitigate their impact. Nutrient pollution, primarily from nitrates and phosphates, remains a major concern, as it contributes to eutrophication, leading to excessive algal growth and oxygen depletion. The presence of high nutrient concentrations in certain areas highlights the urgent need for better management of agricultural runoff and wastewater discharges to prevent further ecological degradation. Microbiological contamination, evidenced by high levels of total coliforms in several sampling sites, suggests a significant impact from untreated sewage and wastewater effluents. The correlation between coliform concentrations and anthropogenic activities underscores the necessity of stricter wastewater management policies and improved sanitation infrastructure to safeguard both environmental and public health. The microbial adaptation of xenobiotics, their multi-drug resistance, and gene transfers are aspects that must be investigated by single strain analysis behavior in in vitro conditions, in order to establish the correlation between pollution and microbiota. Overall, this study underscores the importance of continuous water quality monitoring and the need for effective measures to reduce pollution sources. Strengthening environmental policies, modernizing wastewater treatment facilities, and promoting sustainable agricultural practices are crucial steps toward ensuring the long-term protection of water resources in the Danube-Black Sea system. This work aims to establish a baseline for future monitoring of regional water quality, with the data obtained providing valuable insights for further research and policy development to preserve the ecological integrity of these interconnected aquatic ecosystems. Ongoing work focuses on synthesizing pollutant data to highlight the spatiotemporal dynamics of water quality within the MONITOX network, including Danube--Black Sea sediment contamination with metals, radioelements, and other trace elements, as well as regional pollution mapping.