Analysis of Ballast Water Discharged in Port-A Case Study of the Port of Ploce (Croatia)

Ballast water is recognized as a major vector for the transfer of Harmful Aquatic Organisms and Pathogens (HAOP) and a source of sea pollution that negatively affects the environment and human health. Therefore, the International Maritime Organization (IMO) adopted the International Convention for the Control and Management of Ship's Ballast Water and Sediments (BWM Convention) in 2004. The BWM Convention introduced two standards, Ballast Water Exchange Standard (Regulation D-1) and Ballast Water Performance Standard (Regulation D-2). Ships are required to install Ballast Water Treatment (BWT) equipment in order to comply with Regulation D-2. However, the deadline for the installation of BWT is prolonged until September 2024, and many ships are still complying only with Regulation D-1. In addition, there are specific sea areas where Regulation D-1 cannot be complied with, and hence, HAOP could be easily transferred between ports. Consequently, it is essential to develop a system to protect the marine environment, human health and economy in coastal areas from the introduction of HAOP. This paper analyses ballast water discharged in the Port of Ploce (Croatia) according to ship type, age and flag they are flying. It was found that general cargo ships and bulk carriers discharged most of the ballast (87% of the total quantity) in the Port of Ploce. Moreover, discharged ballast water was analysed according to the origin, and it was found that 70% of discharged ballast originates from the Adriatic Sea. Based on the analysis of the research results and literature review, the ballast water risk assessment (BWRA) method was adopted, however, with certain modifications. The adopted method is modified by an additional risk factor (the deballasting ship's age), different risk scoring of the deballasting ship type and adding Paris MoU Grey and Black lists flag ships as high-risk ships. As a result, the BWRA method presented in the paper could be used as an early warning system and to facilitate the implementation of adequate measures to prevent pollution by discharged ballast water.