PMID- 37414166
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20230919
IS  - 1879-1026 (Electronic)
IS  - 0048-9697 (Linking)
VI  - 896
DP  - 2023 Oct 20
TI  - The impact of riverine particles on the vertical velocities of large 
      microplastics.
PG  - 165339
LID - S0048-9697(23)03962-1 [pii]
LID - 10.1016/j.scitotenv.2023.165339 [doi]
AB  - Microplastics interact with other suspended particles in aquatic systems, which 
      may impact their environmental fate. Little is known about aggregation between 
      suspended sediment and larger microplastics (1-5 mm), and how this impacts the 
      vertical velocities of microplastics, although it was hypothesised these are size 
      limited. Consumer items made of five common polymers: polypropylene (PP), high 
      density polyethylene (HDPE), polyethylene terephthalate (PET), polyvinyl chloride 
      (PVC) and polystyrene (PS), were fragmented by cryomilling and their vertical 
      velocities (rising/settling) measured experimentally before and after 24-hours of 
      aggregation with riverine particles. Microplastic size (microscopy), zeta 
      potential and density (density gradient column) were measured, with aggregation 
      quantified using microscopy. PP had an experimental density of 1052 kg.m(-3), and 
      sank in river water, although it is often stated as being buoyant based on 
      literature density values. Aggregation occurred with all five polymers: 39 %-72 % 
      of microplastics were observed to have sediment and/or organic particles adhered, 
      depending on the polymer type. PVC had the least negative zeta potential, 
      -8.0 +/- 3.0, and showed a much higher number of adhered sediment particles than 
      all other polymers: on average 4.55 particles, compared with <1.72 particles for 
      other polymers. For four polymers, aggregation did not significantly change 
      vertical velocities. However, PP particles showed a significantly slower settling 
      velocity after aggregation: a decrease of 6.3 % based on mean averages, from 
      9.7 x 10(-3) to 9.1 x 10(-3) m.s(-1). Theoretical calculations showed the amount 
      of adsorbed sediment or biofilm required to induce a microplastic density change 
      of  approximately 50 kg.m(-3) was much higher than observed experimentally. Overall, this study 
      indicates that the vertical velocities of larger microplastics are less 
      influenced by interactions with natural particles than smaller microplastics.
CI  - Copyright (c) 2023 The Authors. Published by Elsevier B.V. All rights reserved.
FAU - Stead, Jessica L
AU  - Stead JL
AD  - School of Sustainability, Civil and Environmental Engineering, University of 
      Surrey, Guildford GU2 7XH, UK.
FAU - Bond, Tom
AU  - Bond T
AD  - School of Sustainability, Civil and Environmental Engineering, University of 
      Surrey, Guildford GU2 7XH, UK. Electronic address: t.bond@surrey.ac.uk.
LA  - eng
PT  - Journal Article
DEP - 20230705
PL  - Netherlands
TA  - Sci Total Environ
JT  - The Science of the total environment
JID - 0330500
SB  - IM
OTO - NOTNLM
OT  - Aquatic systems
OT  - Environmental fate
OT  - Rising velocity
OT  - Sediment
OT  - Settling velocity
OT  - Water
COIS- Declaration of competing interest The authors declare that they have no known 
      competing financial interests or personal relationships that could have appeared 
      to influence the work reported in this paper.
EDAT- 2023/07/07 01:05
MHDA- 2023/07/07 01:06
CRDT- 2023/07/06 19:24
PHST- 2023/05/05 00:00 [received]
PHST- 2023/07/03 00:00 [revised]
PHST- 2023/07/03 00:00 [accepted]
PHST- 2023/07/07 01:06 [medline]
PHST- 2023/07/07 01:05 [pubmed]
PHST- 2023/07/06 19:24 [entrez]
AID - S0048-9697(23)03962-1 [pii]
AID - 10.1016/j.scitotenv.2023.165339 [doi]
PST - ppublish
SO  - Sci Total Environ. 2023 Oct 20;896:165339. doi: 10.1016/j.scitotenv.2023.165339. 
      Epub 2023 Jul 5.