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likely due to the combined contribution of bothwastewater and runoff. The levels
observedinCSOsarehigher thanthelevels instrictseparatedrunoff.For twoof the
threesamples,concentrationswerehigher than theconcentrations inwastewater.A
settlementofparticlesduringdryweatherperiodsand their re-suspensionwhen the
flow increases was described on the literature [22]. A similar behavior could be
expectedfor thefibers.The leveloffibersalsodependson theprevious rainevents:
thefirst samplingwasconductedafter a longperiodofheavy rainfall,whichmight
have induced adecrease in the amount offibers in the sewer system.
Levels of fragments vary between 35 and 3,100 fragments L 1. The levels are
especiallyhighevenif theyvarybytwoordersofmagnitude.Lowerconcentrations
of fragments in comparison tofibers canbeobservedexcept for the event present-
ing thehighest runoff contribution andvolume.
3.3 FiberFluxes inDifferentCompartments
As fibers are of utmost importance concerningMP pollution in freshwater, it is
especially interesting to assess the relative contribution of the various sources. In
thissection, thenumberoffiberfluxesisestimatedat thescaleof theParisMegacity
(surfaceareaaround2,500km2–10millioninhabitants).ThenumberofMPfibers is
used to estimate themassfluxes.Because thefibersweremeasured, the cumulated
total lengthof thefiberswascalculated.The lengthwascoupledwith their approx-
imated diameter to evaluate the volume. It was estimated that diameters ranged
between5and100μmwithanaveragediameterof25μm.Therefore,with the total
volume and specific densities of the plastic polymers (1 g cm 3 for the PA and
1.45 g cm 3 for the PET, corresponding to polymers widely used in the textile
industry), totalmasses canbe estimated.The results are summarized inFig. 2.
• Atmospheric fallout.According to theaverageatmosphericfluxof totalfibers at
theurbanandsuburbansites (110and53fibersm 2day 1),wecanestimate that
at the scale of theParis agglomerationbetween1.2 and2.5 1011fibers could
originateannually fromtheatmosphere.Accordingtoouranalyses,wecalculate
that 30% of these fibers are plastic polymers. Therefore, between 3.5 and
7.6 1010MPswould fall peryear fromtheatmosphereon theParis agglomer-
ation.Themasses of plastic fibers are likely between6and17metric tons.
• Gray water. Based on the water consumption for washingmachine in France
(14.4L inhab 1 day 1) and 10millions of inhabitants, we assess that between
4 1014 and 2 1015 fibers are discharged annually into the wastewater.
However, the washing machine fibers were not chemically characterized in
thiswork. Two hypotheses can be assumed. For the first one, we can consider
that, at a global scale, 60% of these fibers are synthetic, according to the
Europeans’ uses and supposing also that both categories of fibers tear off
similarly fromclothes. The secondhypothesis is based on a talk at theSETAC
Europe2016conference indicating thatMPsaccount for 5%of thefibers at the
76 R.Dris et al.
Freshwater Microplastics
Emerging Environmental Contaminants?
- Titel
- Freshwater Microplastics
- Untertitel
- Emerging Environmental Contaminants?
- Autoren
- Martin Wagner
- Scott Lambert
- Verlag
- Springer Open
- Datum
- 2018
- Sprache
- englisch
- Lizenz
- CC BY 4.0
- ISBN
- 978-3-319-61615-5
- Abmessungen
- 15.5 x 24.1 cm
- Seiten
- 316
- Kategorien
- Naturwissenschaften Chemie