Microscopy and elemental analysis characterisation of microplastics in sediment of a freshwater urban river in Scotland, UK

Blair, R. M., Waldron, S. , Phoenix, V. and Gauchotte-Lindsay, C. (2019) Microscopy and elemental analysis characterisation of microplastics in sediment of a freshwater urban river in Scotland, UK. Environmental Science and Pollution Research, 26(12), pp. 12491-12504. (doi: 10.1007/s11356-019-04678-1) (PMID:30848429)

Abstract

Understanding of the sources, fate, and impact of microplastics (MPs, < 5 mm) remains limited, particularly in freshwater environments, while limited comparability across available surveys hinders adequate monitoring and risk assessment of these contaminants. Here, the distribution of microscopic debris in an urban river close to the marine environment in the West of Scotland was investigated to assess concentration and distribution of primary and secondary MPs. Also, the efficiency of light and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) was evaluated for characterisation and quantification of MPs sized 2.8 mm–11 μm. Bank sediment samples were collected twice from the River Kelvin in Glasgow and were size-fractionated and processed for extraction of MPs by density separation. Sample MPs spiking and use of procedural blanks allowed the influence of processing on field data quality to be considered. Total abundances were 161–432 MPs kg−1 dry sediment, with fibres as the dominant type, comprising > 88% of total counts. Nevertheless, fibres in blanks suggest potential contributions from atmospheric contamination. Moreover, fibres concentrated mainly in fractions < 0.09 mm suggesting that their fate may be influenced by drivers of fine sediment dynamics in rivers. While no primary MPs were observed, metallic and glass pellets were present in high abundances in settled material and could be easily misidentified by visual inspection, demonstrating that compositional analysis is needed to avoid analytical errors from MP misidentification and overestimation. SEM-EDS allowed for a quick screening of plastic vs non-plastic pellets and improved identification of smaller fragments, whereas more advanced techniques are needed for proper identification of fibres. This study is the first to report on MPs in freshwater rivers in Scotland and suggests that diffuse sources of pollution may be delivering secondary MPs to the river. Their sources, fate, and risk in these systems will thus warrant further attention.

• Item Type: Articles
• Additional Information: This work is funded by the Scottish Government’s Hydro Nation Scholars Programme. The programme is supported by CREW (Scotland’s Centre of Expertise for Waters) and administered by the James Hutton Institute.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Waldron, Professor Susan and Gauchotte-Lindsay, Professor Caroline and Phoenix, Dr Vernon and Blair Espinoza, Maricela
• Authors: Blair, R. M., Waldron, S., Phoenix, V., and Gauchotte-Lindsay, C.
• College/School: College of Science and Engineering; College of Science and Engineering > School of Engineering > Infrastructure and Environment; College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Environmental Science and Pollution Research
• Publisher: Springer
• ISSN: 0944-1344
• ISSN (Online): 1614-7499
• Published Online: 08 March 2019
• Copyright Holders: Copyright © 2019 The Author(s)
• First Published: First published in Environmental Science and Pollution Research 26(12):12491-12504
• Publisher Policy: Reproduced under a Creative Commons license