"The great source" microplastic abundance and characteristics along the river Thames.

This study focused on quantifying the abundance of microplastics within the surface water of the River Thames, UK. Ten sites in eight areas were sampled within the tidal Thames, starting from Teddington and ending at Southend-on-Sea. Three litres of water was collected monthly at high tide from land-based structures from each site from May 2019 to May 2021. Samples underwent visual analysis for microplastics categorised based on type, colour and size. 1041 pieces were tested using Fourier transform spectroscopy to identify chemical composition and polymer type. 6401 pieces of MP were found during sampling with an average MP of 12.27 pieces L-1 along the river Thames. Results from this study show that microplastic abundance does not increase along the river.

Impact of the Covid-19 pandemic on microplastic abundance along the River Thames.

In April 2020, the Covid-19 pandemic changed human behaviour worldwide, creating an increased demand for plastic, especially single-use plastic in the form of personal protective equipment. The pandemic also provided a unique situation for plastic pollution studies, especially microplastic studies. This study looks at the impact of the Covid-19 pandemic and three national lockdowns on microplastic abundance at five sites along the river Thames, UK, compared to pre-Covid-19 levels. This study took place from May 2019-May 2021, with 3-L water samples collected monthly from each site starting at Teddington and ending at Southend-on-Sea. A total of 4480 pieces, the majority of fibres (82.1 %), were counted using light microscopy. Lockdown 2 (November 2020) had the highest average microplastic total (27.1 L-1). A total of 691 pieces were identified via Fourier Transform Infrared Spectroscopy (FTIR). Polyvinyl chloride (36.19 %) made up the most microplastics identified. This study documents changes in microplastic abundance before, during and after the Covid-19 pandemic, an unprecedented event, as well as documenting microplastic abundance along the river Thames from 2019 to 2021.

Microplastic abundance in the Thames River during the New Year period.

Microplastic pollution is widely studied; however, research into the effects of large-scale firework displays and the impact on surrounding waterways appears to be lacking. This study is potentially the first to look at microplastic abundance in rivers after a major firework event. To assess the impact of the 2020 New Year's firework display in London, a 3 litre water sample was collected over nine consecutive days at Westminster on the River Thames. A total of 2760 pieces of microplastics (99% fibres) were counted using light microscopy, and further analysis was performed on representative plastic samples (354) using Fourier Transform Infrared Spectroscopy (FTIR). Whilst anthropogenic microfibres made up 11%, most microplastic identified (13.3%) were polychloroprene. This study demonstrates the occurrence of a short-term influx of microplastics in the River Thames following the New Year fireworks, which will have an additional detrimental impact on the ecology and aquaculture of the river and neighbouring waterways.

The abundance of microplastics in cnidaria and ctenophora in the North Sea.

Microplastic (MP) ingestion has been widely recorded in aquatic organisms, but few studies focus on cnidarians and ctenophores, which form a significant contribution to marine trophic interactions. Scyphozoans (Cyanea capillata, C. lamarckii and Aurelia aurita), hydrozoan (Cosmetira pilosella) and ctenophores (Beroe cucumis and Pleurobrachia bachei) collected opportunistically from Orkney, Shetland and the North Sea were thermally disintegrated, with a subsample of ingested plastics analysed using FTIR. A total of 1,986 MPs were counted (94% fibres), the majority (84.4%) in the four cnidarian species. Highest MP concentrations were recorded in B. cucumis (0.956 ml-1), whilst C. pilosella yielded the lowest (0.014 ml-1). The main polymers in digestate were PET and PP, with 27% discounted as non-plastics. In feeding trials, A. aurita ingested a greater quantity of PET fibres (60-80%), compared to nylon (0%) and HDPE fibres (0%). This study demonstrates cnidarians and ctenophores, a largely overlooked group, are a potential route for MPs entry into food webs.