Study of the Ecotoxicological Effects of Metals from Scrubber Washwaters on Aquatic Biota

The maritime transport sector predominantly relies on fuel oil as the energy source for ships, leading to the emission of exhaust gases that comprise harmful substances, which could cause chronic toxicity (polycyclic aromatic hydrocarbons) and inherently persistent (heavy metals), posing substantial short and long-term risks to marine ecosystems. Exhaust Gas Cleaning Systems (EGCS), commonly referred to as scrubbers, play a crucial role in compliance with international maritime emissions regulations. While this technology effectively lowers SO2 emissions, the environmental challenges related to the subsequent discharge of scrubber water containing the aforementioned harmful substances remain. This study investigates the toxicity of the most prevalent heavy metals in scrubber effluents: iron, vanadium, nickel, and zinc, using two key marine model organisms widely used in toxicity bioassays: Artemia franciscana and Brachionus plicatilis. The results indicate a marked sensitivity of these organisms to the evaluated metals, particularly in early developmental stages of A. franciscana (nauplii). The study reveals that vanadium and iron were the most toxic metals. Furthermore, the metal mixture showed higher toxicity than any individual metal, indicating significant effects and representing a potentially underestimated environmental risk.