Debris Surveys in Three African Cities Demonstrate Influence of Local Clean-Up Efforts

Abstract

Plastic debris is a significant problem aesthetically, environmentally, and across food chains. Hence it is important to increase understanding of the mechanisms of how this debris is distributed and potentially managed, especially in areas such as Africa with relatively large populations and poor infrastructure. Debris can be derived from local sources (such as the resident population) or from further afield via wind or ocean currents. We investigated these by systematically measuring debris density in sites on land and on coastal sites in three regions around Africa (Cape Town, Durban and Mombasa), and compared these between and within regions. We then compared them to simulated flows of debris on currents in the surrounding ocean to hypothesize likely sources of debris. Comparisons of relative quantity and makeup of inland and coastal debris suggested different patterns at different sites. We expected the Agulhas Current (coming from Indian Ocean and east coast Africa) to be a strong source of debris and therefore have a strong effect on the arrival of debris in eastern coastal sites, and the Benguela Current (from the southern Atlantic Ocean) to have a weaker effect. However, the evidence collected here seemed mixed in support of this and was greater in support of debris coming predominantly from local sources.