Jin-Young Seo

Active substance-based Ballast Water Management Systems (BWMS) can generate disinfection by-products (DBPs) by reacting with dissolved organic matter (DOM). However, current IMO G9-based assessments often overlook qualitative DOM variations. This study investigated DBP formation following NaDCC treatment in natural seawater dominated by the diatom Skeletonema costatum and the dinoflagellate Akashiwo sanguinea. Laboratory-cultured DOM was also analyzed using ATR-FT-IR, PCA, and 2D-COS to evaluate structural differences. In field experiments, S. costatum treatment primarily produced brominated trihalomethanes (THMs) and specific haloacetic acids (HAAs) with a limited composition. Conversely, A. sanguinea treatment yielded a diverse range of DBPs, including nitrogenous DBPs (HANs). FT-IR results, supported by 2D-COS, revealed that A. sanguinea-derived DOM underwent non-monotonic structural changes and distinct sequential functional group reactions, suggesting multiple, time-delayed precursor interactions. These findings demonstrate that phytoplankton species-specific DOM composition significantly dictates DBP profiles and temporal dynamics. Therefore, environmental risk assessments for BWMS must incorporate the qualitative characteristics of biogenic DOM and dominant species traits, particularly during coastal bloom events, to ensure more accurate management strategies.

Ballast water management systems (BWMSs) using active substances (AS) have been subjected to land-based tests with artificially increased dissolved organic matter (DOM) and cultured species according to the International Maritime Organization G9 guidelines before the BWMS Code revision. Therefore, data on the environment risk assessment (ERA) of disinfection by-products (DBPs) for actual port DOM and natural species are limited. This study was conducted using seawater from Jangmok Bay, South Korea, during a phytoplankton bloom. In treated water with a high biological content (Group A), the DBPs concentration increased as the initial AS concentration increased. However, in treated water with a low biological content (Group B), the DBPs concentration did not increase as the initial AS concentrations. The higher the residual AS concentration on day 5, the more the DBPs concentration increased, and the composition ratio of the DBPs was also affected. The ERA to individual DBP was evaluated as low given <1 for the ratio of the predicted environmental concentration to the predicted no-effect concentration in port environments exposed to DBPs in discharged ballast water. This result may suggest that the ERA of IMO G9 performed with cultured species and additives could substitute the outcome obtained with natural plankton assemblages.

Herein, we evaluate the scientific basis for managing hull fouling of ships entering Korean ports, diagnose biological risks that may occur when in-water cleaning (IWC) systems remove hull fouling, and present a protocol for evaluating these risks (the Korean Infection Modes and Effects Analysis; K-IMEA). Protocol development included the selection of core elements and scenario design for IWC and the evaluation of regrowth experiments. The K-IMEA index was designed by considering the inoculation pathway of attaching organisms in all processes to ships that enter a port for in-water cleaning. A number of risk indices were defined: R1—Introduction/Establishment of alien species before in-water cleaning; R2—Establishment of alien species escaped during in-water cleaning; R3—Introduction/Establishment of alien species after in-water cleaning; and R4—Establishment of alien species in effluent water. K-IMEA regrowth experiments (R2 and R4) using the in-water cleaning effluent showed that the attachment and regrowth of prokaryotes, microalgae, and macroalgae were successfully detected. In particular, prokaryotes were observed in samples filtered through a 5 μm mesh of the in-water cleaning effluent, even at a low fouling rating (Levels 1–2). These experiments suggest a necessity to consider a secondary treatment method in addition to the primary filtration method for the treatment of in-water cleaning effluents.