Q2. What have the authors stated for future works in "Microplastics as contaminants in the marine environment: a review" ?
Looking to the future, here the authors present a list of knowledge gaps they believe deserve further attention from the scientific community ( Table 2 ).
Q3. How can the authors separate plastics from benthic material?
To separate any plastics from the benthic material, saline water or mineral salts can be added to the sediment samples to increase water density, permitting lower-density microplastics to be separated via flotation.
Q4. What can be used to identify plastics?
A lipophilic dye (e.g. Nile Red) can then be used to stain the plastics to assist identification using a range of microscopy techniques (Andrady, 2011).
Q5. What is the reason for the abundance of plastics in beach sediments?
The presence of plastic debris not only increased the permeability of the sediment, but also decreased its heat absorbance so that the sediment would reach lower maximal temperatures than sediment without plastics present.
Q6. What are the sources of plastic that can enter the marine environment?
Coastal tourism, recreational and commercial fishing, marine vessels and marineindustries (e.g. aquaculture, oil-rigs) are all sources of plastic that can directly enter the marine environment, posing a risk to biota both as macroplastics, and as secondary microplastics following long-term degradation.
Q7. Why is the marine biota exposed to leached additives?
Due to the large surface-area-to-volume ratio of microplastics, marine biota may be directly exposed to leached additives after microplastics are ingested.
Q8. What is the way to determine the presence of microplastics in the open ocean?
Long-term data from Continuous Plankton Recorders (CPRs) are of particular benefit to determining microplastic abundance in the open ocean.
Q9. How many meshes can be used to collect microplastics?
330 µm aperture meshes have been used for many of the microplastic trawls documented in this review, but it is important to note that using meshes with different apertures can produce large variations in the quantity of microplastics collected: by utilising 80 μm meshes, KIMO Sweden found microplastics at 100,000 times higher concentrations than when using 450 μm meshes (Lozano and Mouat, 2009).
Q10. How did the plastic become less buoyant over time?
the plastic became less buoyant over time, and by the end of the experiment the plastic moved away from the surface and appeared neutrally buoyant.
Q11. What are the main reasons for microplastics being considered toxic?
Their composition and relatively large surface area make them prone to adhering waterborne organic pollutants and to the leaching of plasticisers that are considered toxic.
Q12. How can the authors determine the presence of microplastics in the sea?
Microplastics within the water column can be collected by conducting a trawl along a transect (i.e. manta trawls for sampling surface water, bongo nets for collecting midwater levels and benthic trawls to assess the seabed) using fine meshes (Browne et al., 2010; Ryan et al., 2009; Thompson et al., 2004).
Q13. What are the sources of plastics in marine litter?
Such plastics include primary microplastics used in cosmetics and air-blasting, improperly disposed “user” plastics and plastic leachates from refuse sites.
Q14. What is the role of additives in the degradation of plastics?
Such degradation may result in additives, designed to enhance durability and corrosion resistance, leaching out of the plastics (Talsness et al., 2009).
Q15. What is the reason for the decrease in the quantity of plastic pellets in the North Atlantic?
In 1991, under the auspices of the US Environmental Protection Agency, many American plastic manufacturers voluntarily committed to preventing or recapturing spilled pellets, an agreement that may explain significant decreases in quantities of resin pellets identified in the North Atlantic between 1986 and 2008 (Law et al.
Q16. How can plastic debris be monitored over time?
By repeating the beach combing process on a regular basis, accumulation of plastic debris can be monitored over time (Ryan et al., 2009).
Q17. What is the adsorption coefficient of the priority pollutant phenanthrene?
Using equilibrium partitioning modelling, the adsorption coefficients (Kd) of the priority pollutant phenanthrene were calculated for a range of plastic polymers in seawater and natural sediments (Teuten et al., 2007).
Q18. Why are microplastics so widespread in the benthic and pelagic ecosystems?
Owing to their small size and presence in both pelagic and benthic ecosystems, microplastics have the potential to be ingested by an array of marine biota (Betts, 2008; Thompson et al., 2009a).
Q19. How many plastic particles would be released into the marine environment over a 3-day period?
Extrapolating the resultantdata revealed that these two rivers alone would release over 2 billion plastic particles into the marine environment over a 3-day period.
Q20. What can be done to assess the presence of plastics in the Northwest Atlantic?
By dissecting beached marine animals, or by instigating regurgitation in some seabirds, their gut contents can be analysed for the presence of plastics, which can then be identified and quantified (van Franeker, 2010).
Q21. What is the way to determine the presence of microplastics?
Sediment sampling allows benthic material from beaches, estuaries and the seafloor to be assessed for the presence of microplastics (Claessens et al., 2011).
Q22. What are the main reasons for the lack of studies on microplastics?
Meta-studies are difficult to develop due to varieties of sampling methodologies, huge spatial variations in microplastic abundance, and lack of standardised size definitions of microplastics (Ryan, 2009; Barnes 2009).