Efficient microplastics extraction from sand. A cost effective methodology based on sodium iodide recycling

International audienceEvaluating the microplastics pollution on the shores requires overcoming the technological and economical challenge of efficient plastic extraction from sand. The recovery of dense microplastics requires the use of NaI solutions, a costly process. The aim of this study is to decrease this cost by recycling the NaI solutions and to determine the impact of NaI storage. For studying the NaI recyclability, the solution density and the salt mass have been monitored during ten life cycles. Density, pH and salt mass have been measured for 40 days to assess the storage effect. The results show that NaI solutions are recyclable without any density alterations with a total loss of 35.9% after the 10 cycles of use. During storage, chemical reactions may appear but are reversible. Consequently, the use of recycling methods allows for a significant cost reduction. How far the plastic extraction by dense solutions is representative is discussed. (C) 2016 Elsevier Ltd. All rights reserved

Microplastics elutriation system Part B Insight of the next generation

Elutriation is an efficient process for extracting microplastics. The development of a numerical model has shown the need for optimizing aspects of the design of the actual elutriation protocol as well as the dimensioning of the column to increase its efficiency. The study aims to propose new dimensioning data and protocol elements for designing an efficient column. Using a numerical model, the filling velocity was calculated as a function of the size and the density of the particles to prevent sand suspension. The sieving protocol was adapted to increase the density limit for the extraction of plastic particles from 1460 to > 1800 kg.m(-3). The durations of the elutriation and the column height were calculated to improve the control of the particle suspension. These results contribute to the development of the next generation of elutriation system and will accelerate the study of plasticome in the context of sandy sediments

Microplastics elutriation system. Part A: Numerical modeling

International audienceThe elutriation process has shown its efficiency to extract microplastics from sand and began to spread in the scientific community. This extraction technic requires knowing with accuracy the extraction velocities of particles. This study aims to test whether numerical modeling could help to calculate these velocities. From hydrodynamic equations, a numerical model has been developed and the outputs are compared to experimental extraction data. The results show, for the calculated velocities, the experimental plastic extraction yields will be higher than 90% for < 10% of sand contamination. The model also allows determining that, with the actual protocol, the maximum plastic density which can be extracted is about 1450 kg.m(-3) whereas the detrimental resuspension, which may occur during the column filling step, is highlighted. From model calculations, it arises that changes in the column dimensioning and the protocol operations need to be considered

Challenging the Microplastic Extraction from Sandy Sediments

International audienc

Microplastics in Mediterranean Sea: A protocol to robustly assess contamination characteristics

The study of microplastic pollution involves multidisciplinary analyses on a large number of microplastics. Therefore, providing an overview of plastic pollution is time consuming and, despite high throughput analyses, remains a major challenge. The objective of this study is to propose a protocol to determine how many microplastics must be analyzed to give a representative view of the particle size distribution and chemical nature, and calculate the associated margin error. Based on microplastic data from Tara Mediterranean campaign, this approach is explained through different examples. In this particular case, the results show that only 3% of the collected microplastics need to be analyzed to give a precise view on the scale of the North West Mediterranean Basin (error <5%), and 17.7% to give an overview manta per manta (error <10%). This approach could be an important practical contribution to microplastic studies

Statistical Methodology for Identifying Microplastic Samples Collected During TARA Mediterranean Campaign

International audienc

Chemical composition of microplastics floating on the surface of the Mediterranean Sea

The Mediterranean Sea is one of the most studied regions in the world in terms of microplastic (MP) contamination. However, only a few studies have analysed the chemical composition of MPs at the Mediterranean Sea surface. In this context, this study aims to describe the chemical composition as a function of particle size, mass and number concentrations of MPs collected in the surface waters of the Mediterranean Sea. The chemical composition showed a certain homogeneity at the Mediterranean Sea scale. The main polymers identified by Fourier Transform Infra-Red (FTIR) spectroscopy were poly(ethylene) (67.3 +/- 2.4%), poly(propylene) (20.8 +/- 2.1%) and poly(styrene) (3.0 +/- 0.9%). Nevertheless, discrepancies, confirmed by the literature, were observed at a mesoscale level. Thus, in the North Tyrrhenian Sea, the proportion of poly(ethylene) was significantly lower than the average value of the Mediterranean Sea (57.9 +/- 10.5%). Anthropic sources, rivers, or polymer ageing are assumed to be responsible for the variations observed

Threat of plastic ageing in marine environment. Adsorption/desorption of micropollutants

Ageing of various plastics in marine environment was monitored after immersion of two synthetic (polyvinylchloride, PVC, and polyethylene terephthalate, PET) and one biodegradable (poly(butylene adipate co-terephtalate), PBAT) plastics for 502 days in the bay of Lorient (Brittany, France). Data analysis indicates that aged PVC rapidly releases estrogenic, compounds in seawater with a later adsorption of heavy metals; PET undergoes a low weakening of the surface whereas no estrogenic activity is detected; PBAT ages faster in marine environment than PVC. Aged PBAT exhibits heterogeneous surface with some cavities likely containing clay minerals from the chlorite group. Besides, this degraded material occasionally shows a high estrogenic activity. Overall, this study reports, for the first time, that some aged plastics, without being cytotoxic, can release estrogenic compounds in marine environment

Avancement sur la mise au point d’une méthode de dosage des microplastiques par pyrolyse couplée à la spectrométrie de masse

National audienc

Avancement sur la mise au point d’une méthode de dosage des microplastiques par pyrolyse couplée à la spectrométrie de masse

National audienc