Antifouling booster biocides in Latin America and the Caribbean: A 20-year review

Passive sampling-derived aqueous concentrations of organotins and booster biocides in the largest Port of South America (Southeastern Brazil)

Organotin compounds (OTs) used to be the most widely used biocide in antifouling paint systems, but the International Maritime Organization (IMO) banned them because of their high environmental toxicity to non-target organisms. Currently, at least 25 active ingredients are being employed as biocides in antifouling paint formulations. In the present study, silicone rubber-based passive sampling was used to determine the freely dissolved concentrations (Cw) of 6 OTs and 4 booster biocides in the water column at the entrance of Santos Port's main navigation channel, the largest Port of South America (southeastern Brazil). Fifteen sampling events of ∼45 days long were conducted over 2 years. Cw of OTs ranged from 1.1 to 2.5 ng Sn L-1 for monobutyltin (MBT), 0.2 to 4.7 ng Sn L-1 for dibutyltin (DBT), and 0.06 to 0.7 ng Sn L-1 for tributyltin (TBT), while triphenyltin (TPhT), diphenyltin (DPhT), and monophenyltin (MPhT) were always below their limits of detection ( Collapse

Key Words

• Aqueous phase
• Booster biocides
• Ecological risk
• Estuary
• Organotins
• Passive sampling

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Affiliation(s)

Alan Carlos de Almeida Programa de Pós-Graduação em Química Tecnológica e Ambiental (PPGQTA), Universidade Federal do Rio Grande (FURG), Rio Grande, RS 96203-900, Brazil; Instituto de Oceanografia, Universidade Federal do Rio Grande (IO-FURG), Av. Itália s/n, Rio Grande, RS 96203-900, Brazil
Rodrigo Moço Batista Programa de Pós-Graduação em Química Tecnológica e Ambiental (PPGQTA), Universidade Federal do Rio Grande (FURG), Rio Grande, RS 96203-900, Brazil; Instituto de Oceanografia, Universidade Federal do Rio Grande (IO-FURG), Av. Itália s/n, Rio Grande, RS 96203-900, Brazil
Ítalo Braga Castro Universidade Federal de São Paulo, Instituto do Mar, Santos, SP 11030-400, Brazil
Gilberto Fillmann Programa de Pós-Graduação em Química Tecnológica e Ambiental (PPGQTA), Universidade Federal do Rio Grande (FURG), Rio Grande, RS 96203-900, Brazil; Instituto de Oceanografia, Universidade Federal do Rio Grande (IO-FURG), Av. Itália s/n, Rio Grande, RS 96203-900, Brazil.

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Recent advances in emerging integrated anticorrosion and antifouling nanomaterial-based coating solutions

The rapid progress in the marine industry has resulted in notable challenges related to biofouling and surface corrosion on underwater infrastructure. Conventional coating techniques prioritise individual protective properties, such as offering either antifouling or anticorrosion protection. Current progress and innovations in nanomaterials and technologies have presented novel prospects and possibilities in the domain of integrated multifunctional coatings. These coatings can provide simultaneous protection against fouling and corrosion. This review study focuses on the potential applications of various nanomaterials, such as carbon-based nanostructures, nano-metal oxides, polymers, metal-organic frameworks, and nanoclays, in developing integrated multifunctional nano-based coatings. These emerging integrated multifunctional coating technologies recently developed and are currently in the first phases of development. The potential opportunities and challenges of incorporating nanomaterial-based composites into multifunctional coatings and their future prospects are discussed. This review aims to improve the reader's understanding of the integrated multifunctional nano-material composite coating design and encourage valuable contributions to its development.

Occurrence and Ecological Risk of Alkylamine Triazines in Chinese Estuarine Sediments: An Emerging Class of Persistent, Mobile, and Toxic Substances

Identifying persistent, mobile, and toxic (PMT) substances from synthetic chemicals is critical for chemical management and ecological risk assessment. Inspired by the triazine analogues (e.g., atrazine and melamine) in the original European Union's list of PMT substances, the occurrence and compositions of alkylamine triazines (AATs) in the estuarine sediments of main rivers along the eastern coast of China were comprehensively explored by an integrated strategy of target, suspect, and nontarget screening analysis. A total of 44 AATs were identified, of which 23 were confirmed by comparison with authentic standards. Among the remaining tentatively identified analogues, 18 were emerging pollutants not previously reported in the environment. Tri- and di-AATs were the dominant analogues, and varied geographic distributions of AATs were apparent in the investigated regions. Toxic unit calculations indicated that there were acute and chronic risks to algae from AATs on a large geographical scale, with the antifouling biocide cybutryne as a key driver. The assessment of physicochemical properties further revealed that more than half of the AATs could be categorized as potential PMT and very persistent and very mobile substances at the screening level. These results highlight that AATs are a class of PMT substances posing high ecological impacts on the aquatic environment and therefore require more attention.

Protective personal equipment on coastal environments: Identifying key drivers at a global scale

The contamination of coastal ecosystems by personal protective equipment (PPE) emerged as a significant concern immediately following the declaration of the COVID-19 pandemic by the World Health Organization (WHO). Hence, numerous studies have assessed PPE occurrence on beaches worldwide. However, no predictors on PPE contamination was so far pointed out. The present study investigated social and landscape drivers affecting the PPE density in coastal environments worldwide using a meta-analysis approach. Spatial variables such as urban modification levels, coastal vegetation coverage, population density (HPD), distance from rivers (DNR), and poverty degree (GGRDI) were derived from global satellite data. These variables, along with the time elapsed after WHO declared the pandemic, were included in generalized additive models as potential predictors of PPE density. HPD consistently emerged as the most influential predictor of PPE density (p < 0.00001), exhibiting a positive effect. Despite the presence of complex non-linear relationships, our findings indicate higher PPE density in areas with intermediate GGRDI levels, indicative of emerging economies. Additionally, elevated PPE density was observed in areas located further away from rivers (p < 0.001), and after the initial months of the pandemic. Despite the uncertainties associated with the varied sampling methods employed by the studies comprising our database, this study offers a solid baseline for tackling the global problem of PPE contamination on beachesguiding monitoring assessments in future pandemics.

Coupling harmful algae derived nitrogen and sulfur co-doped carbon nanosheets with CeO2 to enhance the photocatalytic degradation of isothiazolinone biocide

Removing the algae from water bodies is an effective treatment toward the worldwide frequently occurred harmful algae blooms (HAB), but processing the salvaged algae waste without secondary pollution places another burden on the economy and environment. Herein, a green hydrothermal process without any chemical addition was developed to resource the HAB algae (Microcystis sp.) into autogenous nitrogen and sulfur co-doped carbon nanosheet materials C-CNS and W-CNS, whose alga precursors were collected from pure culture and a wild bloom pond, respectively. After coupling with CeO2, the obtained optimal C-CNS/CeO2 and W-CNS/CeO2 composites photocatalytically degraded 95.4% and 88.2% of the marine pollutant 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) in 90 min, significantly higher than that of pure CeO2 (63.15%). DCOIT degradation on CNS/CeO2 was further conducted under different conditions, including pH value, coexisting cations and anions, and artificial seawater. Although different influences were observed, the removal efficiencies were all above 76%. Along with the ascertained good stability and reusability in five consecutive runs, the great potential of CNS/CeO2 for practical application was validated. UV-vis DRS showed the increased light absorption of CNS/CeO2 in comparison to pure CeO2. PL spectra and photoelectrochemical measurements suggested the lowered charge transfer resistance and thereby inhibited charge recombination of CNS/CeO2. Meanwhile, trapping experiments and electron paramagnetic resonance (EPR) detection verified the primary roles of hydroxyl radical (OH) and superoxide radical (O2-) in DCOIT degradation, as well as their notably augmented generation by CNS. Consequently, a mechanism of CNS enhanced photocatalytic degradation of DCOIT was proposed. The intermediates involved in the reaction were identified by LC-QTOF-MS, giving rise to a deduced degradation pathway for DCOIT. This study offers a new approach for resourceful utilization of the notorious HAB algae waste. Besides that, photocatalytic degradation has been explored as an effective measure to remove DCOIT from the ocean.

Assessment of the effectiveness of antifouling solutions for recreational boats in the context of marine bioinvasions

The recreational boating sector is a major vector for the introduction of non-indigenous species (NIS) via biofouling. Despite applying control measures to prevent the growth of fouling communities, most vessels are NIS carriers. This study assessed the effectiveness of different antifouling strategies in a manipulative experiment by testing two common coating typologies (biocide-based and foul-release coatings), accompanied with simulated maintenance practices. The experiment was carried out in the Gulf of La Spezia (Italy) and samples were collected at two different periods. Results showed significant differences among antifouling treatments regarding community structure, diversity, coverage and biovolume of the sessile component, alongside a significant decrease in the performance of biocide-based coating with time. Interestingly, peracarid NIS/native species ratio was higher for biocide-based treatments, suggesting potential biocide resistance. This study highlights the urgent need to develop common and feasible biofouling management plans and provides insights towards identification of best practices for recreational vessels.

Assessing the spatiotemporal occurrence and ecological risk of antifouling biocides in a Brazilian estuary

Diuron and Irgarol are common antifouling biocides used in paints to prevent the attachment and growth of fouling organisms on ship hulls and other submerged structures. Concerns about their toxicity to non-target aquatic organisms have led to various restrictions on their use in antifouling paints worldwide. Previous studies have shown the widespread presence of these substances in port areas along the Brazilian coast, with a concentration primarily in the southern part of the country. In this study, we conducted six sampling campaigns over the course of 1 year to assess the presence and associated risks of Diuron and Irgarol in water collected from areas under the influence of the Maranhão Port Complex in the Brazilian Northeast. Our results revealed the absence of Irgarol in the study area, irrespective of the sampling season and site. In contrast, the mean concentrations of Diuron varied between 2.0 ng L-1 and 34.1 ng L-1 and were detected at least once at each sampling site. We conducted a risk assessment of Diuron levels in this area using the risk quotient (RQ) method. Our findings indicated that Diuron levels at all sampling sites during at least one campaign yielded an RQ greater than 1, with a maximum of 22.7, classifying the risk as "high" based on the proposed risk classification. This study underscores the continued concern regarding the presence of antifouling biocides in significant ports and marinas in Brazilian ports, despite international bans.