TEXTE Environmental Impacts of Exhaust Gas Cleaning Systems for Reduction of SOx on Ships — Analysis of status quo 
Report compiled within the framework of the project ImpEx 
discharge water may have considerable effects on the growth of pelagic microplankton, 
especially in eutrophicated environments such as the Baltic Sea. 
Furthermore, a significant increase in bacterial biomass was reported. The reasons for this 
might be a higher availability of dissolved organic matter due to cell lysis, the presence of black 
carbon as carbon source or pulsed addition of sulphuric acid. The biotic effects were consistent 
with the results of the complementary laboratory experiments, where primary productivity was 
observed to be stimulated at the beginning of the experiments. 
The filamentous cyanobacteria N. spumigena showed negative responses in photosynthetic 
activity and the chain-forming diatom M. cf. arctica showed increased primary productivity at 
the end of the experiment, implying species-specific responses to EGCS discharge water. It is also 
discussed that potential adverse effects of metals in the EGCS discharge water may have been 
masked by the culture media. 
Magnusson et al. (2018) tested acute toxicity using Microtox bioassay (on luminescent bacteria) 
and chronic toxicity through experimental studies with zooplanktonic copepods and bottom- 
dwelling blue mussels. 
The acute toxicity was only slightly less after than before the treatment unit (as measured with 
Microtox bioassay method) despite the high reduction of hydrocarbons and metals in the water 
treatment. The authors explained this by the relatively low reduction of low molecular aromatic 
hydrocarbons, known for their acute toxicity, and by the high concentrations of copper and 
mercury in effluent water compared to water feeding into the unit. 
The aim of the chronic toxicity tests was to identify the lowest concentration of EGCS discharge 
water where a statistically significant effect was detected. Copepods resulted to be more 
sensitive than blue mussels. Since neither pH nor alkalinity differed from the clean seawater at 
‘he effect concentrations, it was concluded that the observed effects on copepods were primarily 
caused by toxic compounds present in the EGCS discharge water rather than by acidification. It 
should be noted that in both CL and OL exposures, the lowest tested concentrations (0.04-0.1% 
CL and 1.0% OL water) resulted in toxic effects on the juvenile copepods. Thus, it cannot be 
excluded that even lower concentrations would have been harmful to the tested zooplankton 
species. On the assays with blue mussels, byssus strength was the only endpoint measured 
showing a significant effect. 
The pollutant concentrations at the EGCS discharge water exposure level with observed 
detrimental effects were far below the toxic threshold values reported in the literature, 
suggesting that the constituents of the mixture might act with cumulative and synergistic effects. 
Thus, the authors stressed the importance of conducting risk assessment based on the whole 
effluent than a single pollutant approach. 
MLIT (2018) conducted acute WET tests with OL-EGCS discharge water according to 
standardized test methods using three species of marine organisms at different trophic levels: 
fish (3'd trophic level), crustacean (2 trophic level), and algae (1st trophic level). They followed 
‘he approach of the GESAMP group for the evaluation of ballast water management systems 
(BWMS) using active substances proposed in IMO document BWM.2/Circ.13/Rev.4 (MEPC, 
2017). 
In the algal toxicity test, no growth inhibition was observed in the concentration range of 
0.01%-32.0%, even slight growth stimulation is reported at some concentrations. In the 
crustacean toxicity test, the acute effects were expressed immediately; the cumulative mortality 
was the same after 24 hours and at the end of the test period (96 hours). The same observation 
was reported in the fish toxicity test. Furthermore, possible influence of low dissolved oxygen