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Investigation raises concerns over plastic waste accumulation on shores of Africa’s Rift Valley lakes

An investigation into the concentration of microplastics in some Africa Rift Valley lakes has found no traces of microplastics there. However, the plastic wastes are visible on the major landing sites, raising fears over the whereabouts of these dangerous residues.

Plastic waste
Plastic wastes on Zengebe landing site on Lake Kyoga

The shorelines are littered with polythene bags and used plastic bottles – some in decaying form, but their broken-down particles are not in the water. Are they accumulating at the bottom of the lakes?

The investigation by Bertha challenge fellow Fredrick Mugira and Dr. David Were from the Department of Environmental Management, Makerere University as the researcher, is aimed at assessing the concentration of microplastics in Uganda’s surface water bodies. The study focused on three Lakes: George and Edward which are lift valley lakes, and Kyoga.

One sample was obtained from each lake and transported to the Directorate of Government Analytical Laboratory (DGAL) in Kampala for analysis of the concentration of microplastics in the water.

The lab engaged the Fourier-transform infrared spectroscopy (FTIR), the most recommended technique to obtain the infrared range of absorption, emission, and photoconductivity of solid, liquid, and gaseous substance.

The location of the sampling point on each lake targeted the biggest landing site. Research elsewhere has shown a positive correlation between plastic pollution and urban growth. The water sampling was done at the Hamukungu landing site on Lake George, the Katwe landing site on Lake Edward, and the Zengebe landing site on Lake Kyoga.

The results from the lab analysis showed no traces of microplastics in the one-time sample taken from each of the three lakes.

But according to Mugira, from the observations around the sampling areas of all the three lakes plus Lake Albert, which he all explored to document the impact of plastic debris on these lakes, plastics and other solid wastes were indiscriminately littered at the shores, which can quickly end up in the lake.

He observes that on all these landing sites, “fishing nets are floated using plastic materials including used plastic water bottles, plastic sandals, and anchored using plastic bags filled with sand.”

And these, contends Dr. Were, “directly introduce plastics into deep-water areas of the lakes, increasing the chances of plastic pollution.”

Worldwide, studies by various researchers approximate that 70–80% of marine debris is plastic (Gacutan et al., 2022; Selvam et al., 2021)

So, where are these microplastics?

Various abiotic factors influence the degradation of plastics into smaller particles, such as sunlight exposure and the chemistry of additives for the degradation of plastics.

Albert Nkwasa – a Ph.D. researcher at Vrije Universiteit Brussel, focusing on water quality modeling from regional to global scales, believes the observation that there are no microplastics where there are visible plastic bottles at major boat landing sites is wrong.

He highlights that the breakdown times of all plastic types is very long, saying it takes them “years to decades or longer.”

“Once plastics are broken up into micro and nano plastics, lifetimes are more or less many years. No exceptions. Of course, unless there is a new phenomenon not previously observed acting, but this is not likely.”

He notes that using appropriate sampling and detection protocols, plastics are detected over many concentration ranges everywhere on earth.

“I have learned never to rule out unusual environmental results, but first, you must verify that the result you obtain is believable and correct.”

In agreement with Dr. Nkwatsa, Dr. Ayub M. O. Oduor, a senior lecturer and researcher at the Technical University of Kenya, Nairobi, believes that plastics seen on these sites and in water are yet to decay, “conventional plastics can take centuries to millennia to decompose.”

Dr. Oduor lectures and researches Plant Ecology and Evolution. He is currently doing some studies on conventional and biodegradable microplastics. Biodegradable microplastics are ostensibly designed to decompose within weeks to months. They are primarily used in various cosmetics, medicine, and agriculture industries. These are also significant forms of pollution in terrestrial and aquatic ecosystems globally.

Dr. Oduor’s data indicates that “both forms of plastics have significant negative impacts on plant growth and diversity.”

Likewise, environmental scientist and the southwestern region manager for Uganda’s national environment watchdog NEMA Jeconous Musingwire trusts that the accumulation of plastics adjacent to water bodies may automatically introduce them into the water in all forms: macro and micro pieces.

He states, “Plastics need high temperatures to disintegrate. At landing sites with high temperatures, they disintegrate and easily flow into the lake.” He, however, cautions that “with big water bodies, it is hard to trace plastic fibres since they float and are easily washed away by currents.”

In agreement with fellow researchers, Dr. Were says there is a need for further studies to confirm that there are no micro-plastic pollutants in the studied lakes because “samples were taken only once, yet the reliability of results related to water quality monitoring increases with increase in the number of samples taken and the duration of monitoring.”

He also believes that the samples taken in August 2022, a month characterised by heavy rainfall events, could have contributed to the “dilution of water in the lakes.”

Studies on microplastics in Uganda’s lakes

Whereas studies on plastic pollution in surface water bodies in Uganda are very limited, a few that have been conducted on Lake Victoria have reported micro-plastic pollution in the lake.

A 2020 study by Egessa et al. found microplastics in both urban and rural parts of the lake. This study further revealed that the concentration of microplastic plastics was highest near the shores and reduces as you go deep in the open water. This finding is of great implication since most communities who obtain water for domestic use from lakes usually get it near the shores.

Another study by Biginagwa et al. in 2015 on the same lake reported the occurrence of microplastics in Nile Perch and Tilapia, indicating the occurrence of microplastic pollution in the water where the fish live. At the same time, the results also imply that people can be exposed to microplastics through water and fish consumption.

Interestingly, some studies have also reported traces of microplastics in the country’s piped and bottled drinking water. This observation implies microplastic pollution of the water sources from where the water is abstracted.

study by researchers at the Department of Agricultural and Biosystems Engineering at Makerere University suggests that urban areas surrounding Lakes Edward, George, Albert, and Kyoga combined produce almost as much plastic waste as those surrounding Lake Victoria, the leading polluted lake in the country. Most of these plastics end up flowing into nearby lakes.

Patrick Byamukama Byaruhanga, the Senior Fisheries Officer in the Directorate of Fisheries Resources of Uganda’s Ministry of Agriculture, Animal Industry and Fisheries, says, “Increasing population and urbanisation, along Uganda’s lakes, is leading to increased ‘plastic pollution’ on landing sites.”

He also blames this on the increased production and use of plastic containers for drinking water, soda, and other drinks and the “use of plastic fishing nets such as monofilament, which are prohibited in Ugandan waters.”

Landing sites’ leaders agree there’s a plastic waste crisis

Abas Bisaniko, the chairperson of the landing site at Kazinga channel which connects Lakes Edward and George, blames the introduction of plastics into the lakes on fishers who use plastic bottles as floaters. He estimates that fishers take over 100 plastic bottles to the lake daily at his landing site, and about 25 do not return. They are discarded into the lakes.

His committee encourages fishers to dispose of plastics in dustbins at the landing site.

Fishers at this landing site work with the local council authorities and Uganda Wildlife Authority officials to pick and burn plastic bottles from nearby incinerators. This plastic waste includes the plastic floats discarded by the fishers.

At the Kahenero II landing site on Lake George, Ramathan Musimenta, the secretary of the fishers’ association, says they are putting dustbins in place to manage plastic wastes.

He acknowledges the challenge of fishers picking and reusing the plastic bottles discarded in dustbins at the landing site as floats for their nets.

William Sande, who is in charge of sanitation and hygiene at the Katunguru landing site on Kazinga channel says residents regularly pick the plastic wastes so that they “do not become a menace at the site,” but urges support from the government to enable fishers to access sustainable floats for eco-friendly fishing. 

Alex Wajja, the chairperson of Lake Kyoga’s Zengebe landing site in Rwampanga town council, says they “regularly collect” and “burn” the plastic wastes at the landing site. However, supply keeps growing daily.

At Lake Albert, Fred Migirwa, the chairperson of the Kijangi landing site, acknowledges the challenge of amassed plastic waste at the shore. He says they regularly sensitise residents there about the proper disposal of plastics, but the occupants, “have kept a deaf ear.”

Some plastics that enter into Lakes Edward and Albert come from Uganda’s neighbouring Democratic Republic of Congo. Uganda and DR Congo share the two lakes.

Innocent Paluku Kawalina, DR Congo’s Lake Edward fishers’ committee coordinator, acknowledges that they have no plastic waste management mechanism and that plastic bottles are visible on landing sites and in the water.

“Indeed, plastic waste, in particular bottles, floats on the lake’s edge. We don’t have a proper crackdown mechanism. However, bottles that are in good condition can be reused. For us fishermen, these bottles are not seen as a problem or a danger on the lake,” narrates Paluku.

But, according to Steven Kambale, the head of the public service station in charge of the environment at Kyavinyonge landing site in Beni territory, North Kivu province, DR Congo, authorities at this site are considering helping fishermen to plant a wild tree species locally known as Mikohwa which produce wooden floaters known locally known as Vyandaghati. They are setting up tree nursery beds to grow and distribute seedlings to fishers free of charge.

“This will allow us to plant trees for generation of floaters instead of fishers using plastic bottles, but also to spare our Lake Edward, more particularly the Kyavinyonge fishery.”

Prioritise research and sensitisation

Given the evidence of microplastic pollution in Lake Victoria and the indiscriminate disposal of plastic and other solid wastes observed at the landing sites of the lakes Edward, George, and Kyoga considered in this study, these lakes are exposed to a high risk of microplastic pollution according to Dr. Were.

Further, given the potential of plastic pollutants to harm human health and aquatic organisms living in the water, it is time for the government, non-governmental organisations (NGOs), and other private actors to pick an interest in this issue and support researchers to conduct extended water quality sampling and monitoring for microplastics in surface water sources.

Also, funding needs to be availed to the researchers and media houses to create awareness among the local communities on the sustainable management of plastic and other wastes.

By Fredrick Mugira and David Were, Water Journalist Africa

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