The microplastic profile of an urban African stream

Heinrich T.J. Dahms, Gregg J. van Rensburg, Richard Greenfield

Research output: Contribution to journalArticlepeer-review

84 Citations (Scopus)

Abstract

Microplastics are small plastic fragments that have been found around the world, however, research into microplastics in Africa and freshwater systems remains insufficient. In this study, the snapshot microplastic profile of an urban stream was assessed in the Braamfontein Spruit, located in Johannesburg the largest city in South Africa. The abundance of microplastics was determined in water, Chironomus sp. larvae and sediment, while in situ parameters were taken to investigate their relationship to the microplastic profile of the different matrices. Microplastics were detected in water (mean of 705 particles mˉ3), Chironomus sp. larvae (mean of 53.4 particles gˉ1 wet weight) and sediment (mean of 166.8 particles kgˉ1 dry weight). The study found evidence of how urban stream characteristics such as a weir, stream depth and velocity could affect the abundance and dispersion of microplastics. The results indicate that areas of increased depth and decreased flow allowed microplastics to settle down to the sediment where benthic macroinvertebrates could ingest these fragments. Large obstructions like a weir also increased microplastic counts in sediment and invertebrates above the obstruction, with a decrease of fragments after the obstruction, however, microplastics in surface water were able to flow over the obstruction and increase in abundance downstream. This study concludes that first order urban streams such as the Braamfontein Spruit may be contributing large numbers of microplastics to higher order streams and large rivers in times of increased flow.

Original languageEnglish
Article number138893
JournalScience of the Total Environment
Volume731
DOIs
Publication statusPublished - 20 Aug 2020

Keywords

  • Chironomus sp. larvae
  • Microplastics
  • Sediment
  • South Africa
  • Urban stream

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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