Occurrence and Distribution of Antifouling Biocide Diuron along the Coastal Areas of Zanzibar Island

Diuron (N-(3,4-dichlorophenyl)-N,N-dimethylurea) is one among the booster biocides substituted tributyltin as an antifouling agent. It has continued to be used ever since, though little is known about their levels in the maritime setting of Zanzibar. This paper details the occurrence and distribution of diuron around the coastline of Zanzibar Island. The reported concentrations of diuron in water ranged from Below Detection Limit to 1321.67 ± 52.3 ng/L at Bwawani. Majority of the sites showed levels above Environmental Risk Limit of 430 ng/L as proposed by the Dutch Authorities. The findings suggest the contamination is elevated especial in Harbor, Bwawani, Chapwani and even at Marine Protected Areas such Mnemba Island where the value of 620.33 ± 5.70 ng/L was recorded. The main possible sources of the contamination are cargo shipping, passenger speedboats, fishing, and tourism activities taking places in these areas. Therefore, future studies on the antifouling biocide diuron particularly on long term monitoring, chronic exposure, risk assessment, organisms’ responses and pollution models will add special value towards better understanding of the mechanisms and sustainable marine ecosystem health.