Sodium dichloroisocyanurate (NaDCC)를 이용한 선박평형수 처리기술의 해양생태 및 인체위해성 연구

Abstract

On 2004, IMO (International Maritime Organization) adopted "International Convention for Control and Management of Ship's Ballast Water and Sediments (BWM Convention)" to prevent inflow of exotic species by ballaster water. Since then, it was developed many kinds of BWMSs (ballaster water management systems), and is mainly developing management technology of NaDCC (Sodium Dichloroisocyanurate) injection type in Korea. Active substances and DBPs (disinfection by-products) of the base of bromine & chlorine are included in ballast water treated with NaDCC. In this study, it was performed WET test (whole effluent toxicity test), ERA (ecological risk assessment) and HRA (human risk assessment) of effluent to verify the unacceptable effects on marine organisms and human, by ballast water treated with NaDCC. The test species for WET test was used 4 classified groups of marine species and freshwater species with diatoms (Skeletonema costatum and Navicula pelliculosa), green algae (Dunaliella tertiolecta and Pseudokirchneriella subcapitata), rotifer (Brachionus plicatilis and Brachionus calyciflorus) and fish (Cyprinodon variegatus and Pimephales promelas). As the result of WET test, it was shown apparent toxicity only in the growth inhibition test using diatoms and green algae, and it was shown the most sensitive effect such that NOEC (no observed effect concentration), LOEC (lowest observed effect concentration and EC50 (effect concentration, 50%) were 25.0%, 50.0% and > 100.0% respectively, under the test condition of seawater. Meanwhile, the test result of chemical analysis on effluent showed that it was detected 25 kinds of DBPs such as bromate, ICA (isocyanuric acid), FA (formaldehyde acid), THMs (trihalomethanes), HANs (halogenated acetonitriles) and HAAs (halogenated acetic acids). In the result of ERA, there was no substances to show all characteristics of P (persistence), B (bio-accumulation) and T (toxicity) in 25 DBPs. All materials did not exceed 1.0 for the ratios of PEC (predicted environmental concentration) / PNEC (predicted no effect concentration) in general harbour environment, but it was shown to have the risk that ICA, TBM (tribromomethane), CP (chloropicrin) and MCAA (monochloroacetic acid) exceeded 1.0 in near ship environment. But, as the result that it was applied NOEC (25.0%) of WET test result using the actual effluent, it is judged that it had not unacceptable ecological risk for harbour environment including the nearest region to the ship when ballast water treated with NaDCC was discharged into the harbour. In the result of HRA, it was detected 7 substances that showed the characteristics of C (carcinogenicity), M (mutagenicity) and R (reproductive toxicity) in 25 DBPs. All substances in the ratio of exposure amounts / DNEL (derived no effect Level did not exceed 1.0 by scenario respectively with the target of worker on board and the public around the harbour, but it was shown to have human risk that the ratio of exposure amounts / DMEL (derived minimal effect level) of TBM classified as carcinogenic substance exceeds 1.0 in the scenario of ballast water sampling. But, when it is weared impervious PPE (personal protective equipment) in case of ballast water sampling, it was shown that there is no carcinogenic risk. But, the WET test results of discharged water from BWMS using NaDCC means that NaDCC injection technology can affect negative influence to marine ecosystem, and the chemical analysis results means that the types and amounts of DBPs produced vary according to various requirements such as the NaDCC injection concentration and change of voyage period, which has unexpected negative effects to worker on board who directly manages ballast water. Therefore, the effect of NaDCC injection ballast water treatment technology on the marine ecosystem and human body must be continuously investigated and monitored to identify the cause of DBPs and the risk of such substances. In addition, data which is based on more various toxicity test result should be implemented to calculate more objective and actual PNEC & DNEL of each DBPs for risk assessment. And, it also should be arranged the methodology for reduction or regulation of residual toxicity in NaDCC injection technology considering the condition of domestic harbour, ecosystem and task scenario on board for human.