LAUSR

Microplastics (MPs) are emerging threat contaminants that have been shown to provide toxic pollutants, either from the environment or from their inherent toxic monomers and additives, a pathway into the aquatic food web. In the present study, the occurrence, abundance and composition of microplastic (MP) load in the surface water of Lake Naivasha was determined. The surface water physical chemical parameters were measured in situ whereas MP samples were collected using plankton net trawls and treated with H2 O2 to decompose organic matter. The MP particles recovered were classified via visual observation and ATR- FTIR spectroscopy respectively. The average MP concentration range in surface water was 0.183±0.017 to 0.633±0.067 particles/m2 , with the mean concentration determined as 0.407±0.135 particles/m2 . Fragments, fibers and films were identified and were majorly composed of polypropylene, polyethylene, and polyester. Moreover, correlational analysis done exhibited a strong positive association between the MP quantities and turbidity, total nitrogen and total phosphorus in the lake. The high variability in MP densities exhibited between the sampled locations was attributed to human activities, water and wastewater intake through rivers and tributaries, and the presence of local wind patterns responsible for the general water circulation. This assessment adds to the growing documentation of MPs presence in freshwater ecosystems, and provides a baseline for future monitoring and assessment in sediment and biota of Lake Naivasha and other Kenyan freshwater systems. This article is protected by copyright. All rights reserved.