Decadal Pollution Assessment and Monitoring along the Kenya Coast

Abstract

Marine contamination arising from land-based sources is on the rise along the Kenyan Coast. We carried out a decadal pollution survey between 2008 and 2018 to determine the levels of various pollutants (nutrients, trace metals, persistent organic pollutants, and 210 Po) in water, sediment, and biota collected from selected locations in Kenya. Nutrient levels in water ranged between <0.10 and 1560.00, <0.10 and 1320.00, and <0.10 and 3280.00 μg/L for PO 4 3−-P, (NO 2 − + NO 3 −)-N, and NH 4 +-N, respectively, while Chl-a values ranged between 0.02 and 119.37 mg/L. Total PAH, PCBs, and OCPs in sediment from the studied locations ranged from BDL-37800, 0.012-7.99 and BDL-6.10 ng/g. High level of PAH in Kilindini port was primarily from petroleum sources. DDD + DDE/DDT ratio was above 0.5 suggesting historical input. Sediment trace metal concentration from selected locations in Kenyan estuaries had various ranges, that is, Al (0.06-9804284.00 μg/g), Zn (3.82-367.20 μg/g), Cu (7.5-169.60), Cd (DL −2.40 μg/g), Mn (BDL-169.60 μg/g), Cr (2.55-239.10 μg/g), and Pb (BDL-135.60) μg/g dw. Surface sediment 210 Po activities ranged between 20.29 and 43.44 Bq kg −1 dw. Chl-a and PO 4 3−-P data revealed enhance primary productivity in Mombasa peri-urban creeks and estuarine areas. Although the reported concentrations of trace metals and POPs are low in most locations from Kenya, there is a potential risk of bioaccumulation of these contaminants in marine biota; thus, there is a need for continuous monitoring to protect both ecosystem and human health.

Trends in Water Quality in a Tropical Kenyan River-estuary System: Responses to Anthropogenic Activities

“…For the last five decades, rivers and estuarine systems have witnessed spatial-temporal variations in terms of water quality parameters and sediment loads that have drastically impaired these ecosystems [1,[20][21][22][23][24][25] Elevated agricultural activities, urbanization, industrialization, deforestation, river impoundments, and unregulated water abstractions have contributed to poor water quality downstream due to excessive nutrient and sediment loads [23,24]. It is estimated that over 350,000 chemical substances and about 70,000 undocumented ones are in regular application globally [26] (Wang et al, 2020).…”

“…Flowing in a mixed complex terrain characterized by numerous anthropogenic activities, the rivers carry different forms/levels of pollution into smaller respective distinct estuaries which when put together make up the larger south coast estuary of Kenya in the Western Indian Ocean (WIO) region. Like any other coastal regions of the world, the south coast of Kenya is dominated by urbanization developments owing to the conducive climate for human settlements [21,34]. High population is being experienced day in day out and this is cause of concern owing to huge waste generated amidst poor urban planning that is resulting into unsustainable way of handling waste.…”

“…It is against the above backdrop that there is an urgent need to assess and monitor changes in environmental variables/factors in relation to anthropogenic impacts to rivers and estuaries along the south coast of Kenya in the WIO region to inform its management for sustainable utilization of its resources. Despite the fact that a number of studies have been concentrated in the north coast of Kenya [21,23,43], no comprehensive studies have been undertaken along the south coast rivers and estuaries of Kenya in the region to document the sources of pollution and their impacts. Physico-chemical water quality attributes measured monthly based on numerous sampling sites throughout the larger south coast estuary of Kenya in the WIO region, were used in this study to investigate river-estuarine water quality on a spatial scale.…”

Metagenomics assessment of Anthropogenic impact on coral reef-associated microorganisms on the Kenyan Indian Ocean

“…It is bordered by sparsely populated coral islands and experiences the least human activities because it is 11 km offshore . There is no river serving the site (Okuku et al, 2019) and the most common activity here is snorkelling.…”