Microplastics as a threat to coral reef environments: Detection of phthalate esters in neuston and scleractinian corals from the Faafu Atoll, Maldives

The impact of microplastics (MPs) on reef-building corals are still largely unknown. The scientific literature provides evidence from lab feeding trials that coral may ingest MPs. Several adverse effects, i.e., necrosis and bleaching, have also been highlighted. However, field studies are limited. Here, we investigated for the first time the possible correlation between MP seawater contamination and the presence of phthalic acid esters (PAEs), a class of MP-associated contaminants, in scleractinian corals. The survey was carried out in a remote coral reef atoll in the Indian Ocean located in the Maldivian archipelago, considered as a case study. MPs and PAEs were monitored in subsurface neustonic tow samples and scleractinian corals across twelve sampling sites. The results showed widespread MP contamination and the presence of appreciable levels of PAEs in the scleractinian corals sampled inside the atoll rim near an inhabited island, which correlated with the highest MP concentration.

Saliu F., Montano S., Leoni B. and al., Marine Pollution Bulletin, Volume 142, May 2019, Pages 234-241

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Concentrations and distribution of phthalate esters in the seamount area of the Tropical Western Pacific Ocean

A total of 14 phthalate esters (PAEs) were analysed by gas chromatography–mass spectrometry (GC–MS) to better understand its occurrence and distribution in seawater samples of M2 seamount in the Tropical Western Pacific Ocean (TWPO). The concentrations of ΣPAEs in the seawater ranged from 12.13 ng L−1 to 60.69 ng L−1 (av. 28.86 ng L−1), dominated by dibutyl phthalate (DBP), di(2‑ethylhexyl) phthalate (DEHP) and diisobutyl phthalate (DiBP). ΣPAEs concentrations in the southwest of the seamount were lower than those in the northeast, with the minima appearing above the seamount summit. Current-seamount interaction was reckoned to be the principal driving factors in the distribution of PAEs. DEHP posed a medium risk in seawater, suggesting that marine plastic pollution has become an urgent environmental issue that calls for more attention and actions. Microplastics leaching and atmospheric deposition might be the potential sources of PAEs.

Q. Zhang, J. Song, X. Li and al., Marine Pollution Bulletin, Volume 140, March 2019, Pages 107-115

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Targeted quantification and untargeted screening of alkylphenols, bisphenol A and phthalates in aquatic matrices using ultra-high-performance liquid chromatography coupled to hybrid Q-Orbitrap mass spectrometry

Plasticizers and other plastics additives have been extensively used as ingredients of plastics and are as a result thereof easily released in the aquatic environment, due to different physical diffusion processes. In this context, a dedicated method was developed for the simultaneous quantification of 27 known and a virtually unlimited number of unknown alkylphenols, Bisphenol A and phthalates in 2 aquatic matrices, i.e. sea- and freshwater. To this extent, a novel instrumental HESI-UHPLC-HRMS (heated electro-spray ionization ultra-high performance liquid chromatographic high resolution mass spectrometric) method was devised for the simultaneous analysis of 7 phenols (i.e. 6 alkylphenols and Bisphenol A) and 20 phthalates within 10 min. Thereafter, a solid-phase extraction protocol was statistically (95% confidence interval, p > 0.05) optimized based on experimental designs. The method was proven fit-for-purpose through a successful validation at environmentally relevant nanomolar concentrations. Analytical precautions were taken for minimizing false-positive results to suppress in-house contamination. The method demonstrated an excellent analytical performance across all known plasticizers and plastics additives for sea- and freshwater, revealing good linearity (R2 > 0.99, n = 39), stable recoveries (98.5–105.8%), satisfactory repeatability (RSD < 8%, n = 54) and reproducibility (RSD < 10%, n = 36). Subsequently, a novel analytical strategy was devised for the tentative identification of unknown plasticizers and plastics additives using specific in-house determined fragments incorporated in a Python code. The applicability of the analytical platform was demonstrated by measuring 24 seawater samples. Interestingly, 16 out of 27 known plasticizers, plastics additives and primary metabolites could be quantified while the untargeted analysis uncovered 1042 compounds, whereof 5% (n = 46) could be assigned a plasticizer-plastics additive chemical identity, providing evidence for the severe plastic contamination status of our marine environment.

S. Huysman, L. Van Meulebroek, O. Janssens and al., Analytica Chimica Acta, Volume 1049, 21 February 2019, Pages 141-151

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Phthalate release from plastic fragments and degradation in seawater

Plastic debris in the environment contain plasticizers, such as phthalates (PAEs), that can be released during plastic aging. Here, two common plastic materials, i.e., an insulation layer of electric cables (polyvinylchloride, PVC-cables) and plastic garbage bag (polyethylene, PE-bags), were incubated in natural seawater under laboratory conditions, and the PAE migration to the seawater phase was studied with varying light and bacterial conditions over a 90-day time course. Free PAEs diluted in seawater were also studied for bacterial degradation. Our results showed that, within the first month of incubation, both plastic materials significantly leached out PAEs in surrounding water. We found that di-isobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP) were the main PAEs released from the PE-bags, with the highest values of 83.4 ± 12.5 and 120.1 ± 18.0 ng g-1 of plastic, respectively. Furthermore, dimethyl phthalate (DMP) and diethyl phthalate (DEP) were the main PAEs released from PVC-cables, with mass fractions as high as 9.5 ± 1.4 and 68.9 ± 10.3 ng g-1, respectively. Additionally, we found that light and bacterial exposure increased the total amount of PAEs released from PVC-cables by a factor of up to 5, whereas they had no influence in the case of PE-bags.

Andrea Paluselli, Vincent Fauvelle, Francois Galgani, and Richard Sempéré, Environ. Sci. Technol., 2019,  531166-175

Occurrences of organophosphorus esters and phthalates in the microplastics from the coastal beaches in north China

Chemical pollution in the microplastics has been concerned worldwide as pollutants might potentially transfer from the environment to living organisms via plastics. Here, we investigate organophosphorus esters (OPEs) and phthalic acid esters (PAEs) in the beached microplastics collected from 28 coastal beaches of the Bohai and Yellow Sea in north China. The analyzed microplastics included polyethylene (PE) pellets and fragments, polypropylene (PP) flakes and fragments and polystyrene (PS) foams. The tris-(2-chloroethyl)-phosphate (TCEP), tris (1-chloro-2-propyl) phosphate (TCPP) and di-(2-ethylhexyl) phthalate (DEHP) were the three predominant compounds found overall. The maximum Σ4 OPEs concentration was 84,595.9 ng g− 1, almost three orders of magnitude higher than the maximum Σ9 PAEs concentration. The PP flakes and PS foams contained the highest concentrations of the additives in contrast to the PE pellets which contained the lowest. The high concentration level of carcinogenic chlorinated OPEs and DEHP with endocrine disrupting effects implied the suggested potential hazards to coastal organisms. Spatial differences and compositional variation of the additives among the different microplastics suggests different origins and residence times in the coastal environment. This indicates that the characteristics of chemical additives might be a useful approach when tracing sources of microplastics in the environment.

Haibo Zhang, Qian Zhou, Zhiyong Xie and al., Science of The Total Environment, Available online 28 October 2017, In Press

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Occurrence of phthalate acid esters (PAEs) in the northwestern Mediterranean Sea and the Rhone River

Phthalate acid esters (PAEs) which are mainly anthropogenic molecules with endocrine disrupting effects in animals and humans, have been detected in terrestrial and aquatic environments. However, little is known about their distribution in the Mediterranean Sea, mainly because of analytical difficulties and the high possibility of ambient sample contamination. Here, we report the optimization of an existing protocol for the determination of PAEs in seawater and freshwater samples, as well as the first estimation of the source and distribution of phthalates acid esters (PAEs) in coastal waters from the NW Mediterranean Sea. By passing 1 L of sample through glass cartridges packed with 200 mg of Oasis HLB and eluted with 6 mL of ethyl acetate, the recoveries for DMP, DEP, DPP, DiBP, DnBP, BzBP, DEHP and DnOP were 101, 98, 115, 110, 99, 98, 103 and 95%, respectively, with acceptable blank values (below 0.4-4.0% of the masses measured in different seawater samples). By using this method, we detected PAEs in the Marseilles coastal area, offshore (2000 m depth) and in the Rhone River with total concentrations ranging from 75.3 ng/L offshore in surface water to 1207.1 ng/L a few meters above the bottom of the Marseilles Bay. High concentrations were also observed in deep waters offshore (310.2 ng/L) as well as in the Rhone River (615.1 ng/L). These results suggest that Marseilles urban area, Rhone River and sediment are potential sources of PAEs in the areas studied.

Andrea Paluselli, Yann Aminot, François Galgani, Sopheak Net, Richard Sempéré, Progress in Oceanography, Available online 21 June 2017, In Press

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Degradation of Various Plastics in the Environment

It is very important to understand the interaction between plastics and environment in ambient conditions. The plastics degrade because of this interaction and often their surface properties change resulting in the creation of new functional groups. The plastics after this change continue to interact with the environment and biota. It is a dynamic situation with continuous changing parameters. Polyethylene, polypropylene, and polyethylene terephthalate (PET) degrade through the mechanisms of photo-, thermal, and biodegradation. The three polymers degrade with different rates and different pathways. Under normal conditions, photo- and thermal degradation are similar. For polyethylene, photo-degradation results in sharper peaks in the bands which represent ketones, esters, acids, etc. on their infrared spectrum. The same is true for poly propylene but this polymer is more resistant to photo-degradation. The photo-oxidation of PET involves the formation of hydroperoxide species through oxidation of the CH2 groups adjacent to the ester linkages and the hydroperoxides species involving the formation of photoproducts through several pathways. For the three polymers, interaction with microbes and formation of biofilms are different. Generally, biodegradation results in the decrease of carbonyl indices if the sample has already been photo-degraded by exposure to UV. Studies with environmental samples agree with these findings but the degradation of plastics is very subjective to the local environmental conditions that are usually a combination of those simulated in laboratory conditions. For example, some studies suggested that fragmentation of plastic sheet by solar radiation can occur within months to a couple of years on beaches, whereas PET bottles stay intact over 15 years on sea bottoms.

Kalliopi N. Fotopoulou, Hrissi K. Karapanagioti, Chapter, Part of the series The Handbook of Environmental Chemistry, pp 1-22, Date: 13 April 2017

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