PMID- 37160184
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20230612
LR  - 20230612
IS  - 1879-1026 (Electronic)
IS  - 0048-9697 (Linking)
VI  - 886
DP  - 2023 Aug 15
TI  - Settling of buoyant microplastic in estuaries: The importance of flocculation.
PG  - 163976
LID - S0048-9697(23)02597-4 [pii]
LID - 10.1016/j.scitotenv.2023.163976 [doi]
AB  - Rivers and estuaries are regarded as major pathways of microplastic (MP) 
      transport from terrestrial areas to marine ecosystems. Despite this knowledge on 
      the transport dynamics and fate of MP in freshwater riverine and brackish 
      estuarine waters is limited. Via ex situ settling experiments emulating the 
      Msimbazi River and Estuary in Dar es-Salaam, Tanzania, we demonstrate that 
      flocculation and subsequent settling of positively buoyant MP and fine-grained 
      suspended sediment in riverine and estuarine waters are important for the 
      environmental fate of the plastic particles. Our results show that settling 
      velocities of MP and fine-grained sediment in estuarine water were between five 
      and 21 times larger than in freshwater, explained by the increase in ionic 
      strength that occurs when particles enter saline water. This confirms the concept 
      of increased flocculation and settling of fine-grained particles as they are 
      transported from freshwater to estuarine and marine waters. The implication is 
      that land-based sources of small positively buoyant high-density polyethylene 
      (HDPE) MP transported by rivers will tend to settle and accumulate in estuarine 
      environments and thereby lead to a decrease in the overall load of MPs delivered 
      to the wider marine environment. Thereby our results support the notion of 
      estuaries as MP traps and that flocculation explains the trapping of large 
      quantities of MP debris. Based on these findings we recommend that the 
      interaction of MP with fine-grained sediment should be taken into account when 
      transport models of this pollutant are established.
CI  - Copyright (c) 2023 The Authors. Published by Elsevier B.V. All rights reserved.
FAU - Laursen, Simon Nyboe
AU  - Laursen SN
AD  - Department of Geosciences and Natural Resource Management, University of 
      Copenhagen, Copenhagen, Denmark. Electronic address: snl@ign.ku.dk.
FAU - Fruergaard, Mikkel
AU  - Fruergaard M
AD  - Department of Geosciences and Natural Resource Management, University of 
      Copenhagen, Copenhagen, Denmark.
FAU - Dodhia, Maya Shakunt
AU  - Dodhia MS
AD  - Department of Geosciences and Natural Resource Management, University of 
      Copenhagen, Copenhagen, Denmark.
FAU - Posth, Nicole Rita
AU  - Posth NR
AD  - Department of Geosciences and Natural Resource Management, University of 
      Copenhagen, Copenhagen, Denmark.
FAU - Rasmussen, Maja Bar
AU  - Rasmussen MB
AD  - Department of Geosciences and Natural Resource Management, University of 
      Copenhagen, Copenhagen, Denmark.
FAU - Larsen, Marianne Nylandsted
AU  - Larsen MN
AD  - Department of Geosciences and Natural Resource Management, University of 
      Copenhagen, Copenhagen, Denmark.
FAU - Shilla, Dativa
AU  - Shilla D
AD  - Department of Chemistry, Dar es-Salaam University College of Education 
      (DUCE-UDSM), Tanzania.
FAU - Shilla, Daniel
AU  - Shilla D
AD  - Department of Aquatic Sciences and Fisheries Technology, University of Dar es 
      Salaam, Tanzania.
FAU - Kilawe, Jane James
AU  - Kilawe JJ
AD  - Department of Chemistry, Dar es-Salaam University College of Education 
      (DUCE-UDSM), Tanzania.
FAU - Kizenga, Hellen Joseph
AU  - Kizenga HJ
AD  - Institute of Marine Sciences, University of Dar es Salaam, P.O. Box 668, 
      Zanzibar, Tanzania.
FAU - Andersen, Thorbjorn Joest
AU  - Andersen TJ
AD  - Department of Geosciences and Natural Resource Management, University of 
      Copenhagen, Copenhagen, Denmark. Electronic address: tja@ign.ku.dk.
LA  - eng
PT  - Journal Article
DEP - 20230507
PL  - Netherlands
TA  - Sci Total Environ
JT  - The Science of the total environment
JID - 0330500
RN  - 0 (Microplastics)
RN  - 0 (Plastics)
RN  - 0 (Water Pollutants, Chemical)
SB  - IM
MH  - *Microplastics
MH  - Plastics
MH  - Estuaries
MH  - *Water Pollutants, Chemical/analysis
MH  - Flocculation
MH  - Ecosystem
MH  - Environmental Monitoring/methods
MH  - Rivers
OTO - NOTNLM
OT  - Buoyant microplastic
OT  - Estuary
OT  - Flocculation
OT  - Settling experiments
OT  - Urban catchment
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- 2023/05/10 00:41
MHDA- 2023/06/12 06:42
CRDT- 2023/05/09 19:14
PHST- 2022/12/13 00:00 [received]
PHST- 2023/05/01 00:00 [revised]
PHST- 2023/05/02 00:00 [accepted]
PHST- 2023/06/12 06:42 [medline]
PHST- 2023/05/10 00:41 [pubmed]
PHST- 2023/05/09 19:14 [entrez]
AID - S0048-9697(23)02597-4 [pii]
AID - 10.1016/j.scitotenv.2023.163976 [doi]
PST - ppublish
SO  - Sci Total Environ. 2023 Aug 15;886:163976. doi: 10.1016/j.scitotenv.2023.163976. 
      Epub 2023 May 7.