Environmental release of engineered nanoparticles from shipyard activities.

Particle research in harbour areas typically focuses on ship (stack) or vehicular exhaust emissions, while high particle emissions may also occur from other harbour operations such as vessel refurbishment activities. The literature regarding these activities is scarce, especially in terms of particle chemical composition and toxicity.

The aim of this work was to characterize the chemical composition and toxicity of particles released during vessel refit operations. Airborne particle samples were collected inside the tents where abrasion of primer and top-coat paints with mechanical abraders took place in the Mallorca shipyard (Spain), during two experimental campaigns. On-line and offline aerosol instruments were placed at different monitoring locations to measure particle mass concentration and number concentrations, particle size distribution, chemical composition, morphology and cytotoxicity. Aerosol chemical composition of PM0.25, PM2.5, PM4 and PM10 was characterized using impaction cyclones. ELPI was used to obtain a more detailed composition from 0.006 μm to 10 μm. PM2 aerosols were sampled with a Biosampler, and in vitro analysis was performed with A549 lung cells. Particle morphology was determined by TEM. The dustiness index of the powders generated was determined using the rotating drum method (EN15051-).

Release of coarse, fine and ultrafine particles, including engineered nanoparticles, was evidenced during both campaigns. Aerosol composition was linked to the primer’s composition, with main tracers Ti (270 μg/m³ as mean during the daily shift), Mg (177 μg/m³) and Al (54 μg/m³) in PM10 aerosols. Different particle morphologies and tracers were observed by TEM which related to the main chemical components analyzed. On the TEM grids, particle sizes ranged between <50nm and >2000nm in diameter. In addition to the coarse, fine and ultrafine particles formed incidentally and emitted during abrasion of the primer and top-coats, the presence of markedly regular nanoparticles was also detected, which seemed to be engineered (ENPs) and probably used as nano-additives in the coatings (Miller et al., 2020). The ENP detected in the shipyard samples showed characteristic triangular and hexagonal shapes, as well as other polygonal shapes, and were detected as single nanoparticles with diameters <50 nm as well as embedded in larger aggregates formed by the major components of the coatings. In vitro assessments (MTT assay) indicated only moderate particle cytotoxicity. However, the results indicated potentially high oxidative stress, which showed differences across the different sampling days but which could not be directly linked to any specific activity (e.g., mechanical or manual abrasion sanding, spray-painting, …) due to the large mix of aerosols inside the tent. Overall, it was concluded that particles release during refit operations in shipyards have the potential to impact human health and that of the aquatic environment, and should thus be carefully monitored and regulated.

Acknowledgement: This work was carried out in the framework of project IDAEALPORT (RTI2018-098095-BC21).

Reference: Miller, R. J., Adeleye, A. S., Page, H. M., Kui, L., Lenihan, H. S., & Keller, A. A. (2020). Nano and traditional copper and zinc antifouling coatings: metal release and impact on marine sessile invertebrate communities. Journal of Nanoparticle Research, 22(5). https://doi.org/10.1007/s11051-020-04875-x