Ecological Risk Assessment of Emerging Chemical Contaminants and their Impacts on Aquatic Organisms and Ecosystem Functions

Chemical contaminants emerging in freshwater environments do not necessarily link to biological effects and ecosystem functioning. This paper sought to combine the assessment of contaminants, ecological risk screening, and biological indicators to evaluate possible effects linked to wastewater and agricultural runoff. The suggested design would cover six river stations with four sampling events for twelve months. The chemical analysis would be done using solid-phase extraction and liquid chromatography-tandem mass spectrometry for five chemical contaminants. The biological analysis included algal growth inhibition and immobilization of Daphnia magna, while dissolved oxygen and gross primary production were selected as ecological and functional parameters. Risk quotients were used as a screening tool for potential ecological risks. Concentrations at the wastewater station reached 3.46 μg/L for carbamazepine and 2.84 μg/L for diclofenac. The maximum risk quotients varied between 2.05 and 42.10. The inhibitory effect on algae at site 2 was 24.7%, and the immobilization of Daphnia was 38.3%, compared with 4.6% and 6.7% upstream. Oxygen concentration fell from 7.21 to 4.61 mg/L and primary productivity from 8.42 to 5.63 mg O₂/L/day. This implies contamination went hand-in-hand with biological degradation of the ecosystems, which would support the integration of monitoring and management of wastewater. However, the whole water tests cannot determine specific compounds as the cause of the effects. This is proposed because the analysis is illustrative in nature and needs to be confirmed experimentally.