Freshwater

Freshwater

Select from the tabs below

• Overview
• Actions
• Legend

Waste pollution in freshwater environments, such as lakes and rivers, can occur through careless and deliberate actions. These can result from recreational activities such as fishing and boating, and from wastes transported by wind and stormwater.

Freshwater areas where plastic accumulates can be roughly divided into:

• surface
• floor (benthos)
• water column
• living things (biota).

According to the Healthy Land and Water 2019 Annual report, seven tonnes of litter were collected in nine South East Queensland freshwater waterways.

The amount of waste found in clean-ups such as this shows that rivers themselves can act as significant impact areas, locking the waste in the freshwater system[7]. In Townsville, 92 percent of the waste collected from a stormwater outlet on the Ross River was plastic, with the remainder being metal, glass, cloth, footwear, paper, wood and unknowns[2].

Much of the waste entering rivers from industrial and populated areas is food and beverage containers according to a 2011 study. The types of industries close to waterways also influence how much waste enters freshwater systems[4].

Research has shown that river deltas receive 52 percent of river-borne plastic pollution, though they make up less than 1 percent of global coastlines. Rocky shores, in contrast, receive only 6 percent of the plastic pollution, though they make up 73 percent of global coastlines. No type of coastal environment is unaffected by river-borne plastic pollution[8].

The abundance and nature of plastic pollution in freshwater systems in Queensland requires further investigation[11][3].

Surface

Waste is often found floating on the surface of freshwater lakes, dams and rivers. It can remain on the surface until it either breaks up, breaks down, floats in the water column, sinks to the bottom or gets deposited elsewhere. As microplastics and nanoplastics are light, it is not surprising that they are found on the surface of freshwater[5][11]. Some studies suggest they may adsorb contaminants that can have toxicological effects on freshwater biota[11].

Water column

The fate of plastic as it breaks up in the ocean and freshwater systems is unclear. It was believed that it either floated or sank. Recent evidence has demonstrated that plastic also exists in the water-column and its buoyancy depends on its make-up and how many organisms attach to it, affecting its density[6]. The attachment of bacteria and algae to plastic is called biofouling. Waste can cycle from the surface through the waste column, to the bottom sediment and up again as it acquires waterborne organisms and other material (see diagram above).

Floor (Benthos)

The impacts of waste pollution, buried in freshwater sediment, is poorly documented. Most of the existing research has measured plastic, which appears to occur in all water layers including the bottom sediment layer[1][12].

Living things (Biota)

Although some studies have investigated plastic in biota in freshwater systems, a 2019 paper suggests that methodologies for understanding the effects of plastic on biota are not standardised and further research is required[10].

One study suggests that the impacts on biota in freshwater systems will mirror those in the marine environment[9].

Vegetated wetlands act as litter traps, removing large quantities of litter that would otherwise remain in waterways.

References

1. ^ Ballent, A, Corcoran, PL, Madden, O, Helm, PA & Longstaffe, FJ (2016), 'Sources and sinks of microplastics in Canadian Lake Ontario nearshore, tributary and beach sediments', Marine Pollution Bulletin. [online], vol. 110, no. 1, pp. 383-395. Available at: http://www.sciencedirect.com/science/article/pii/S0025326X16304416.
2. ^ Bauer-Civiello, A, Critchell, K, Hoogenboom, M & Hamann, M (2019), 'Input of plastic debris in an urban tropical river system', Marine Pollution Bulletin. [online], vol. 144, pp. 235-242. Available at: http://www.sciencedirect.com/science/article/pii/S0025326X19303492.
3. ^ Blettler, MCM, Abrial, E, Khan, FR, Sivri, N & Espinola, LA (2018), 'Freshwater plastic pollution: Recognizing research biases and identifying knowledge gaps', Water Research. [online], vol. 143, pp. 416-424. Available at: http://www.sciencedirect.com/science/article/pii/S0043135418304597.
4. ^ Buranyi, S (2020), 'The missing 99%: why can't we find the vast majority of ocean plastic?', The Guardian. [online] Available at: https://www.theguardian.com/us-news/2019/dec/31/ocean-plastic-we-cant-see.
5. ^ Dris, R, Imhof, H, Sanchez, W, Gasperi, J, Galgani, F, Tassin, B & Laforsch, C (2015), 'Beyond the ocean: contamination of freshwater ecosystems with (micro-)plastic particles', Environmental Chemistry. [online], vol. 12, no. 5, pp. 539-550. Available at: https://doi.org/10.1071/EN14172.
6. ^ Erni-Cassola, G, Zadjelovic, V, Gibson, MI & Christie-Oleza, JA (2019), 'Distribution of plastic polymer types in the marine environment; A meta-analysis', Journal of Hazardous Materials. [online], vol. 369, pp. 691-698. Available at: http://www.sciencedirect.com/science/article/pii/S0304389419301979.
7. ^ eV Oko-Institut (2011), Study on land-sourced litter (LSL) in the marine environment.l, Insitut fur angewandte Okologie, Freiburg, Germany.
8. ^ Harris, PT, Westerveld, L, Nyberg, B, Maes, T, Macmillan-Lawler, M & Appelquist, LR (15 May 2021), 'Exposure of coastal environments to river-sourced plastic pollution', Science of The Total Environment. [online], vol. 769, p. 145222. Available at: https://www.sciencedirect.com/science/article/pii/S0048969721002886 [Accessed 10 March 2021].
9. ^ Meng, Y, Kelly, FJ & Wright, SL (2020), 'Advances and challenges of microplastic pollution in freshwater ecosystems: A UK perspective', Environmental Pollution. [online], vol. 256, p. 113445. Available at: http://www.sciencedirect.com/science/article/pii/S0269749119310607.
10. ^ O'Connor, JD, Mahon, AM, Ramsperger, AFRM, Trotter, B, Redondo-Hasselerharm, PE, Koelmans, AA, Lally, HT & Murphy, S (2020), 'Microplastics in Freshwater Biota: A Critical Review of Isolation, Characterization, and Assessment Methods', Global Challenges. [online], vol. 4, no. 6, p. 1800118. Available at: https://onlinelibrary.wiley.com/doi/abs/10.1002/gch2.201800118.
11. ^ a b c Strungaru, SA, Jijie, R, Nicoara, M, Plavan, G & Faggio, C (2019), 'Micro- (nano) plastics in freshwater ecosystems: Abundance, toxicological impact and quantification methodology', TrAC Trends in Analytical Chemistry. [online], vol. 110, pp. 116-128. Available at: http://www.sciencedirect.com/science/article/pii/S0165993618304254.
12. ^ Wang, W, Gao, H, Jin, S, Li, R & Na, G (2019), 'The ecotoxicological effects of microplastics on aquatic food web, from primary producer to human: A review', Ecotoxicology and Environmental Safety. [online], vol. 173, pp. 110-117. Available at: http://www.sciencedirect.com/science/article/pii/S0147651319300776.

Last updated: 10 May 2021