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.

"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.

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.

Recycling of manure nutrients: use of algal biomass from dairy manure treatment as a slow release fertilizer.

An alternative to land spreading of manure is to grow crops of algae on the N and P present in the manure and convert manure N and P into algal biomass. The objective of this study was to evaluate the fertilizer value of dried algal biomass that had been grown using anaerobically digested dairy manure. Results from a flask study using two soils amended with algal biomass showed that 3% of total algal nitrogen (N) was present as plant available N at day 0. Approximately 33% of algal N was converted to plant available N within 21 days at 25 degrees C in both soils. Levels of Mehlich-3 extractable phosphorus (P) in the two soils rose with increasing levels of algal amendment but were also influenced by existing soil P levels. Results from plant growth experiments showed that 20-day old cucumber and corn seedlings grown in algae-amended potting mix contained 15-20% of applied N, 46-60% of available N, and 38-60% of the applied P. Seedlings grown in algae-amended potting mixes were equivalent to those grown with comparable levels of fertilizer amended potting mixes with respect to seedling dry weight and nutrient content. These results suggest that dried algal biomass produced from treatment of anaerobically digested dairy manure can substitute for commercial fertilizers used for potting systems.