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In the realm of accelerated testing within controlled laboratory settings, the fidelity of the service environment assumes paramount importance. It is imperative to replicate real-world conditions while compressing the testing duration to facilitate early evaluations, thereby optimizing time and cost efficiencies. Traditional immersion protocols, reflective solely of full ballast tank conditions, inadequately expedite the corrosion process representative of an average ballast tank environment. Through the integration of immersion with fog/dry conditions, aligning the test protocol more closely with the internal conditions of an average ballast tank, heightened rates of general corrosion are achieved. This augmentation yields an acceleration factor of 7.82 times the standard test duration, under the assumption of a general corrosion rate of 0.4 mm/year for uncoated ballast tank steel, with both sides exposed. Subsequently, the fog/dry test protocol, albeit only resembling the environment of an empty ballast tank, closely trails in terms of acceleration efficacy. The fog/dry test protocol offers cost-effectiveness and replicability compared to the AMACORT CIFD-01 protocol, making it a strong competitor despite the relatively close acceleration factor.

To explore how to reduce the corrosion of ship ballast tanks while killing planktonic microorganisms in ship ballast water and meeting the prescribed ballast water discharge standards, an experimental system for inert flue gas pressure-loaded water treatment was established in this paper. The simulated seawater was treated with the combined inert flue gas of N 2 and CO 2 , and the corrosion weight loss of the ballast tank steel plate samples in different corrosive media was simulated. The results showed that when the dissolved oxygen concentration in the ballast water was 0.5 mg/L and the pH value was 6, the mortality of Chlorella reached 100%, the mortality of Escherichia coli was 99.98%, and the microbial lethality met the D-2 standard. The average corrosion rate of the samples in the corrosive medium with an oxygen concentration of 0.5 mg/L and a pH of 6 was 69.02% lower than the average corrosion rate of the samples in simulated seawater. The results were consistent with the results calculated by the weight loss method, which indicated that the use of the inert flue gas deoxygenation method to treat the ship’s ballast water reduced the corrosion rate of the ballast tanks.

PurposeThe International Maritime Organization’s (IMO) International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) was entered into force in September 2017. It deals with one of the greatest threats to coastal and marine environments around the world: aquatic invasive alien species (IAS) and harmful aquatic organisms and pathogens (HAOP). Although the control of IAS and HAOP through treatment of ballast water (BW) is appropriately dealt with in the Convention and its implementation, the problems generated by sediments are not treated in such a manner.Materials and methodsThere are many published technical and scientific papers, discussions and commentaries proposing the remediation of the present situation. They are discussed, and recommendations are summarized. Besides, several systems for the treatment of BW use a combination of two or three techniques, with filtration usually being the first and/or the last step. Presence of sediments in BW results in the reduced applicability of such an approach.Results and discussionThe requirements for sediment management procedures are discussed along with a proposal for their implementation. In the first step, the ballast tank sediments should be freed of active biological agents for the elimination of IAS and HAOP. Instead of biological agents, we advocate the use of radiation treatment by using an electron accelerator, preferably in an on-shore installation or as a mobile, additive, sea container size units with integral power, separated for water and sediment treatment. In the second step, the concentrations of heavy metals should be determined. We recommend the use of EDXRF as an analytical method. After the determination of sediment class, the recommended disposal procedures should be followed.ConclusionsSediment management procedures should specify the disposal requirements: (i) free of active biological agents, IAS and HAOP; (ii) chemical composition, no chemical elements in a toxic range (≤ Class 3); and (iii) displacement/storage requirements, displacing sediments characterized as harmful in appropriate sediment reception facilities/landfills.

The phenomenon of seawater flow-freezing exists during ballast water injection and drainage in polar vessels, but the heat transfer and ice evolution behaviors under low-temperature flow conditions remain unclear. This study developed a computational model for ballast tank freezing using the volume of fluid (VOF) and enthalpy–porosity method, and constructed a scaled experimental platform for the simulation model validation. Based on this model, the flow-heat transfer and ice evolution process in the ballast tank are analyzed in detail, with a focus on the influence of injection velocity, pipe diameter, and position on seawater freezing characteristics. The results show that during low-temperature water injection, phase change occurs preferentially in the tank bottom region, with ice presenting as a slurry morphology; when injection velocity increases from 0.25 m/s to 3.5 m/s, the maximum ice-phase volume fraction increases by 48.9%, indicating faster flow accelerates phase-change freezing; compared to other diameters, DN150 piping exhibits the highest turbulent kinetic energy (0.054 m[sup.2]/s[sup.2]) and the maximum shear stress (12.49 Pa), demonstrating optimal freezing resistance; compared to bottom injection, sidewall injection intensifies heat transfer/icing near tank walls and increases ice-clogging risk around ports. This study reveals intrinsic mechanisms of dynamic ice-blockage evolution, providing theoretical basis for anti-clogging design in polar ship systems.

Corrosion in maritime ballast tanks is a major driver of maintenance costs and operational risks for maritime assets. Inspections are hampered by complex geometries, hazardous conditions, and the limitations of conventional methods, particularly visual assessment, which struggles with subjectivity, accessibility, and early detection, especially under coatings. This paper critically examines these challenges and explores the potential of Light Detection and Ranging (LiDAR) and Hyperspectral Imaging (HSI) to form the basis of improved inspection approaches. We discuss LiDAR’s utility for accurate 3D mapping and providing a spatial framework and HSI’s potential for objective material identification and surface characterization based on spectral signatures along a wavelength range of 400-1000nm (visible and near infrared). Preliminary findings from laboratory tests are presented, demonstrating the basic feasibility of HSI for differentiating surface conditions (corrosion, coatings, bare metal) and relative coating thickness, alongside LiDAR’s capability for detailed geometric capture. Although these results do not represent a deployable system, they highlight how LiDAR and HSI could address key limitations of current practices and suggest promising directions for future research into integrated sensor-based corrosion assessment strategies.

In recent decades, ships’ ballast water and associated sediments have been recognized globally as significant vectors for the dissemination of non-indigenous species, which has attracted extensive attention due to its ecological and economic impacts. The characteristics of production of resting cysts in the dinoflagellate life cycle further increases the risk of biological invasions through ballast tank sediments. Despite extensive research which has characterized the species diversity of dinoflagellate cysts within ballast tank sediments, the possibility and importance of invasions caused by different ribosomal types of the same species have been paid little attention. In this study, two cultures of dinoflagellates were established through cyst germination from the ballast tank sediments collected from two ships (“THETIS” and “WARIYANAREE”) arriving at the Jiangyin Port (China) and identified as Wangodinium sinense Z. Luo, Zhangxi Hu, Yingzhong Tang and H.F. Gu by comprehensive phylogenetic analysis of rDNA sequences (including LSU, SSU, and ITS1-5.8S-ITS2). Despite the rDNA sequences of the isolates showing a generally high similarity to reference sequences, the LSU D1-D6 sequences contained up to 11 stable single nucleotide polymorphisms (SNPs), while SSU and ITS1-5.8S-ITS2 sequences exhibited up to five and two divergence sites, respectively. Moreover, phylogenetic analyses based on partial LSU and SSU rDNA sequences further indicated that strains germinated from ships’ ballast tank sediments formed a strongly supported sister clade to the strains previously isolated from Chinese and Korean waters, representing a novel ribo-type distinct from Chinese and Korean strains. Detailed morphological observations using light microscopy (LM) and scanning electron microscopy (SEM) did not find differences between our isolates and the holotype of the species in key diagnostic characteristics including the position and shape of the nucleus and chloroplasts, as well as the ASC structure, which suggested that no significant morphological divergence has occurred among these ribo-types. Acute toxicity exposure assays indicated that this ribo-type of W. sinense posed no lethal effect on rotifers at concentrations ≤ 104 cells/mL, yet it remains necessary to maintain vigilance regarding the potential risk of algal blooms resulting from higher cell density or environmental changes in the invaded ecosystems. This study reports the first successful germination of W. sinense cysts from ballast tank sediments, indicating that its cysts may be widely transferred through ballast tank sediments, and presents a potential risk of bio-invasions of new genotypes of species to a region where other genotypes of the same species have been present as indigenous species.

Ballast tanks are of great importance in the lifetime of modern merchant ships. Making a ballast tank less susceptible to corrosion can, therefore, prolong the useful life of a ship and, thereby, lower its operational cost. An option to reinforce a ballast tank is to construct it out of a corrosion-resistant steel type. Such steel was recently produced by POSCO Ltd., South Korea. After 6 months of permanent immersion, the average corrosion rate of A and AH steel (31 samples) was 535 g m −2  year −1 , while the Korean CRS was corroding with 378 g m −2 year −1 . This entails a gain of 29 %. Follow-up measurements after 10, 20, and 24 months confirmed this. The results after 6 months exposure to alternating wet/dry conditions are even more explicit. Furthermore, the physical and metallurgical properties of this steel show a density of 7.646 t/m 3 , the elasticity modulus 209.3 GPa, the tensile strength 572 MPa, and the hardness 169HV10. Microscopically, the metal consists of equiaxed and recrystallized grains (ferrite and pearlite), with an average size of between 20 and 30 µm (ASTM E 112—12 grain size number between 7 and 8) with a few elongated pearlitic grains. The structure is banded ferrite/pearlite. On the basis of a series of energy dispersive X-ray spectrometer measurements the lower corrosion rate of the steel can be attributed to the interplay of Al, Cr, their oxides, and the corroding steel. In addition, the role of each element in the formation of oxide layers and the mechanisms contributing to the corrosion resistance are discussed.

The transport of organisms in ships' ballast tanks is a dominant vector for aquatic invasions worldwide. Until recently, efforts to manage this vector have overlooked the potential transport of invertebrate resting stages in the residual waters and sediments within emptied ballast tanks, i.e. NOBOB ('No Ballast On Board') tanks. The resting stages (statoblasts) of freshwater bryozoans are often buoyant and locally abundant and thus can be taken up easily during ballasting operations. They are also resistant to extreme environmental conditions and can generate new colonies after being dormant for decades; as such, they would likely remain viable propagules after lengthy transport in ship ballast tanks. This study quantified the occurrence of freshwater bryozoan statoblasts in ballast tank sediments of transoceanic ships. North American Great Lakes. We quantified the frequency of occurrence, abundance and diversity of bryozoans (as statoblasts) in residual sediment samples taken from 51 NOBOB tanks of 33 transoceanic ships visiting the Great Lakes from 2000 to 2002. Our study identified 11 species, comprising nearly 12% of the total number of freshwater bryozoans known worldwide. These include two exotic species unrecorded in the Great Lakes (Fredericella sultana and Lophopus crystallinus), an exotic species already established in the region (Lophopodella carteri) and three cosmopolitan species (Plumatella casmiana, P. fungosa and P. repens). Our estimates suggest that a ship with NOBOB tanks may carry up to 10⁶ statoblasts. The discovery of species unrecorded in the Great Lakes and the potentially large numbers of statoblasts being transported in ship ballast tanks indicate a significant risk of new species introductions. Furthermore, the presence of cosmopolitan species and an exotic species already established in the Great Lakes suggests the strong possibility of cryptic invasions via the introduction of exotic genotypes.

The Great Lakes‐St Lawrence River basin is the world's most invaded freshwater system. Ballast water release from transoceanic shipping is deemed responsible for 65% of invasions in the basin since the modern St. Lawrence Seaway opened in 1959. Regulations requiring mid‐ocean exchange of ballast water applied in 1993 failed to stem ship‐mediated invasions because the procedure was not mandated for all ships. In 2006 and 2008, Canada and the United States, respectively, mandated that all transoceanic ships should conduct open ocean flushing to ensure that partially filled ballast tanks intended for discharge into the Great Lakes contained water of salinity ≥30 ppt before entering the Seaway. These regulations have been strictly enforced through record inspections and tests of ballast tank salinities of inbound ships. Before‐and‐after comparisons of total organismal abundance and species richness in ballast tanks revealed a substantial reduction in invasion risk from ships that conducted saltwater flushing. Since 2006, the rate of discovery of newly established non‐native species in the Great Lakes declined by 85% to its lowest level in two centuries. While multiple factors could plausibly contribute to this decline, empirical evidence supports the 2006/2008 ballast water regulation as the primary cause, highlighting the benefit of internationally coordinated vector control.

Ships’ ballast water and sediments are vectors that contribute to the unintentional spread of aquatic non-native species globally. Ballast water management, as well as commissioning testing of ballast water management systems and compliance monitoring under the regulations of the International Maritime Organization (IMO) aim at minimizing the unwanted spread of organisms. This study compiles data for treated ballast water samples collected and analyzed from 228 ships during 2017–2023. The samples were collected from the ballast discharge line or directly from the ballast tank for enumeration of living organism concentrations in the categories of ≥50µm and <50 to ≥10µm -sized organisms, as well as indicator microbes in comparison to the ballast water performance standard of the IMO (Regulation D-2). In addition, several ship-specific factors were examined to infer potential factors affecting compliance rates. Nearly all ships were compliant with the ballast water performance standard for indicator microbes and <50 to ≥10µm -sized organisms, whereas almost half of all samples exceeded the limit of ten viable organisms m-3 for the ≥50µm -sized organisms. Compliance testing results did not differ significantly between sampling years, indicating that compliance rate did not change through time. The rate of compliance was higher for commissioning testing than compliance testing. Clear ship- or system-specific factors that lead to compliance or non-compliance were not detected, even though type of ballast water management system, filter mesh size associated with the system and source of ballast water affected compliance significantly either for the samples taken from the discharge line, or ballast tank. As compliance did not improve significantly over time, compliance testing of ships’ ballast water should be undertaken to ensure that the systems remain operational after commissioning and ships meet requirements of the D-2 standard. Furthermore, the study outcomes promote further research on the efficiency of filter mesh sizes and different filtration units associated with ballast water management systems, to improve mechanical removal of larger organisms. Finally, as several ships exceeded the compliance limit by hundreds or thousands of living organisms, technological advancements and operational measures may be needed to improve the overall reliability of ballast water management.