Environmental Engineering Reference
In-Depth Information
consumer.TheconcernisbasedontheassumptionthatPOPsinmicrobeads
will be released in the gut of ingesting species. Studies suggest that gut
surfactants tend to enhance (Bakir et al., 2014; Sakai et al., 2000; Wright
et al., 2013) the release of the POPs increasing the likelihood of their
bioavailability. Bioavailability also depends primarily on the residence time
of the microplastics and the hydrophobicity of the gut contents of the
ingesting species. Species-specific information on gut-environment and
residence times are not available to reliably quantify the bioavailability of
the POPs and to estimate possible bio-magnification of their concentration
on transfer across trophic levels.
However,thecontributiontothebody-burdenofPOPsinhumanconsumers
viathismechanismislikelytobelow.Othertypesofmedia(air,water,dust)
in combination with ingestion with food will generally be more significant
routes of exposure.
10.4 OCEAN LITTER AND SUSTAINABILITY
The presence of plastics debris in general and microplastics in particular
in the ocean environment is a variant of the urban litter problem. Unlike
urban litter, however, both beach litter and microplastics are transported
by currents, eventually ending up in coastal communities or on pristine
beaches far away from their point of origin. They particularly concentrate
in several gyres (the North Pacific Gyre “garbage patch” is widely quoted in
statistically higher than in other areas. It is also a far more difficult problem
to deal with than urban litter as collection of these is both expensive and
impractical. A majority of plastics eventually end up in the benthic
sediment, and their impact on the bottom-dwelling fauna is important, but
has not been extensively studied as yet.
The potential transfer rates of POPs within the marine food web and the
adverse impact it can have on marine ecosystem services provided by the
oceans is a serious concern. Such impacts might manifest at two different
levels. With some species (for instance in fish bivalves in seafood (Van
Cauwenberghe, 2014)), POPs might be present at a level where they might
beofconcern tothehuman consumers. More importantly, themajor impact
might be on zooplankton populations that constitute the base of the marine
food web supporting the ocean fishery and perhaps even perturb the ability
