Reviewing the interdecadal dynamics of micropollutants in the Tanzanian coastal zone from 2002 to 2022.

The Tanzanian coast is a vastly diversified ecosystem offering ecological, cultural, and economic services. However, anthropogenic and environmental stressors threaten its productivity and sustainability, prompting extensive research to understand the contamination extent, sources, and impacts. This review covers 77 original field research studies published between 2002 and 2022, focusing on the Tanzanian coastal area. A summary of information on the occurrences, levels, distributions, sources, and impacts of organic and inorganic micropollutants in environmental and biological compartments is provided. The studies were further discussed based on their research focus, where seven key areas were identified, which included the types of micropollutants analyzed, the parameters sampled, the locations investigated, and the crucial conclusions reached. The aim was to evaluate the research trends and identify gaps for future investigations. The studies reveal varying contamination levels, from low to severe, encompassing metals, persistent organic pollutants, pesticide residues, nutrients, and microbial contaminants. However, data gaps exist for micropollutant concentrations in ambient air, microplastics, pharmaceuticals, and emerging contaminants of concern. With increasing urbanization and socio-economic activities, the review emphasizes the necessity for solution-based research to remove and control micropollutants in the area. Addressing these challenges is crucial for sustaining the diverse ecological nature of this vital coastal system.

Spatial monitoring of organohalogen compounds in surface water and sediments of a rural-urban river basin in Tanzania.

The presence of persistent organic pollutants in Tanzanian environment is not well monitored despite the existing pollution potential from a number of sources. In this study, we investigated for the first time, the concentration profiles of different organohalogen compounds such as organochlorine pesticide residues (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in environmental samples (water and sediments) from the Pangani river basin (PRB). The PRB is one of the largest drainage basins in Tanzania, with its watershed exposed to multiple input sources of trace organic contaminants. Surface water and sediments were sampled from 12 representative stations of diverse characteristics and land-use practices, in three distinct seasons, and extracted by liquid-liquid and Soxhlet extraction methods, respectively. Water samples were analyzed by GC-ECD for OCPs only, while sediment samples were analyzed for OCPs, PCBs and PBDEs by GC/MS. Seven compounds, dominated by HCH isomers (510-4,460 pg/L) and DDT analogs (160-1,460 pg/L),were detected in the water samples. These concentrations are far below the WHO guidelines for drinking water quality. A total of 42 compounds (8 OCPs, 28 PCB congeners and 6 PBDE congeners) were detected in the sediment samples. Their respective total concentration ranges were 245-10,230; 357-11,000 and 38-2,175 pg/g dry weight. The spatial distribution patterns and Hierarchical Cluster Analysis reflected the impact of historical agricultural usage in sugarcane plantations (OCPs), and urbanization (PCBs and PBDEs). Risk assessment using sediment quality guidelines indicated no ecotoxicological risks. The results we have found provide preliminary data on levels of the organic contaminants in Pangani river basin as a new insight on the environmental quality of the area.