Impacts of exhaust gas cleaning systems (EGCS) discharge waters on planktonic biological indicators

Exhaust Gas Cleaning Systems (EGCS), operating in open-loop mode, continuously release acidic effluents (scrubber waters) to marine waters. Furthermore, scrubber waters contain high concentrations of metals, polycyclic aromatic hydrocarbons (PAHs), and alkylated PAHs, potentially affecting the plankton in the receiving waters. Toxicity tests evidenced significant impairments in planktonic indicators after acute, early-life stage, and long-term exposures to scrubber water produced by a vessel operating with high sulphur fuel. Acute effects on bacterial bioluminescence (Aliivibrio fischeri), algal growth (Phaeodactylum tricornutum, Dunaliella tertiolecta), and copepod survival (Acartia tonsa) were evident at 10 % and 20 % scrubber water, while larval development in mussels (Mytilus galloprovincialis) showed a 50 % reduction at similar to 5 % scrubber water. Conversely, larval development and reproductive success of A. tonsa were severely affected at scrubber water concentrations <= 1.1 %, indicating the risk of severe impacts on copepod populations which in turn may result in impairment of the whole food web.

Automated summary

Exhaust Gas Cleaning Systems (EGCS) in open-loop mode release acidic scrubber waters to marine waters, containing high concentrations of metals, PAHs, and alkylated PAHs, which can potentially harm plankton. Toxicity tests showed significant impairments in planktonic indicators after exposure to scrubber water from a vessel using high sulfur fuel. Various species exhibited acute effects and reduced survival or reproduction at different concentrations of scrubber water, indicating the risk of severe impacts on copepod populations and the entire food web.