Page - 136 - in Freshwater Microplastics - Emerging Environmental Contaminants?
Image of the Page - 136 -
Text of the Page - 136 -
4.1 Emission-BasedMassFlowModeling
Emission-basedmass flowormass balancemodels have been used for chemicals
[97] and have recently been implemented for engineered nanoparticles as well
[45, 98, 99]. The latter category ofmodels is of particular interest for this review,
becausemass flowmodels for plastic particles can relatively easily be developed
along the same lines.Basedonestimates of nanoparticle emissions fromproducts,
environmentalfluxesarecalculated to themajorcompartments likeair, soil,water,
sediment,andseveral technicalcompartments[45].Thecompartments typicallyare
considered homogeneous and well mixed [45, 98]. Deposition and removal of
particles within compartments are modeled as constant annual flows into a
sub-compartment of each box considered. Similar mass flowmodel applications
that calculate environmental concentration for plastic debris in allmedia (air, soil,
water, and sediment) have not been published yet. However, the essence of the
approachhasbeenused toestimateconcentrationsofmicroplastics fromcosmetics
inWWTP effluents in the Netherlands [90] andmass emissions ofmicroplastics
fromcosmetics fromEurope to theNorthSea [100].Thefirst study is discussed in
detail below.
MassFlowModelingofMicroplasticConcentrations inWWTPEffluents With the
useofamassflowmodelingapproach,VanWezeletal. [90]estimatedtheemission
ofmicroplastics fromconsumerproducts to the surfacewater viaWWTPeffluents
(Table1).Basedon theknownuseofmicroplastics in cosmetics andpersonal care
products, cleaning agents, and paints and coatings, emissionswere estimated. Per
product category, data on the use of the product, the market penetration, and
concentration ofmicroplastics in the productwere collected. Itwas estimated that
during thewastewater treatment, between 40 and 96%of themicroplasticswould
be retained by theWWTP. Themodel calculated the predicted concentration of
microplastics in a WWTP effluent as the product of the concentration of
microplastics in a product, the daily usage of that product, the fraction of
microplastics removedduringthewastewater treatment,andthemarketpenetration
of the products, divided by the volume of wastewater produced. The estimated
effluent concentrationofmicroplastic ranged from0.2ÎĽgL 1 for the conservative
estimate to 66ÎĽgL 1 for themaximumscenario.
Measured concentrations ofmicroplastics inWWTPeffluents range from20 to
150 particles L 1, as reported after a Dutch monitoring campaign [90]. These
particle numbers were converted to mass, based on the size range, the volume
assuming cubic shapes, and an average density. To validate themodel, themodel
outcomes were compared with the observations of the monitoring [90]. Three
different particle number-to-mass conversion categories were used, classified at
“little and light,” “intermediate,” and“bigandheavy”particles, thenames relating
to the assumed particle size, volume, and density. Themodel coincided bestwith
observationswhen“bigandheavy”particleswereassumed tobemeasured, that is,
particleswith a relativelyhighdensity, large size, and largevolume.However, the
136 M.Kooi et al.
Freshwater Microplastics
Emerging Environmental Contaminants?
- Title
- Freshwater Microplastics
- Subtitle
- Emerging Environmental Contaminants?
- Authors
- Martin Wagner
- Scott Lambert
- Publisher
- Springer Open
- Date
- 2018
- Language
- English
- License
- CC BY 4.0
- ISBN
- 978-3-319-61615-5
- Size
- 15.5 x 24.1 cm
- Pages
- 316
- Categories
- Naturwissenschaften Chemie