Spatio-temporal monitoring of potentially toxic elements in Lagos harbour water and its health risk implications

Abstract

Continuous discharge of industrial and domestic inputs from various processes into the Lagos lagoon has significantly affected the quality of the aquatic environment, as a result of potentially toxic elements (PTEs) being released into the harbour during anthropogenic activities. This study involved monitoring the concentration and distribution of heavy metals in Lagos harbour during the dry and wet seasons. The PTEs can pose a serious ecological threat to the marine environment as well as human beings when the level of priority metals like cadmium, lead, and chromium is beyond World Health Organization (WHO) limits of 0.003, 0.05, and 0.1 mg/L, respectively. The shipping activities within the harbour play a significant role in the generation of these toxic metals. The diverse nature of these metals coexisting with their oxidation states in aquatic environments and their bioaccumulation influences the toxicity of PTEs towards the living organism. The quantification of these metals with highly selective and accurate instrumentation is imperative. Ion-selective exchangers and other functionalized composite nanomaterial are critical for harbour water remediation because of the high risk that could be associated with prolonged exposure to these toxic elements especially when the carcinogenic risk value is greater than 1 × 10−6 mg/kg/day.

Possible influence of shipping operations on trace metals gradients along the Commodore Channel, Lagos State, Nigeria

“…Ihenyen (1991) observed that the part of the harbour where shipping activity was most intensive had low levels of heavy metal pollution, whereas the area around the harbour entrance and the northwest sections, associated with effluent release from industries had medium and high levels of pollution respectively. However, in a recent study, Basheeru et al (2022) investigated the health risk of potentially toxic elements (PTEs) in surface water of the Lagos harbor. The authors found variable amounts of Pb, Cd, Cr, and Ni in the harbour's water, with the greatest quantities found in industrial zones and shipping lanes.…”

“…The potential accumulation of waterborne heavy metals particularly Cadmium (Cd), Iron (Fe), Lead (Pb), Cobalt (Co) and Zinc (Zn) may have potential threat to marine communities and aggravate human health (Bryan and Langston, 1992). It should be noted that previous studies such as Chukwu and Akinyanmi (2018) and Basheeru et al (2022) have survey the impact of pollutants from shipping operations in the past. However, the results of those studies may have been influenced by various other sources such as river runoffs and atmospheric depositions.…”

Human Safety Evaluation of Heavy Metals, Physicochemical Parameters, and Microorganisms in Lagoon Water at Ikorodu Lighter Terminal in Lagos, Nigeria

“…Notably, Adeyemi et al [31] and Yahaya et al [20] found non-permissible levels of heavy metals in water samples collected from Ologe Lagoon in Lagos. Bawa-Allah et al [32] and Basheeru et al [10] also reported non-permissible levels as well as carcinogenic and non-carcinogenic health risks of some heavy metals in water samples obtained in the Lagos Lagoon. This consistency suggests that long-term exposure to water from lagoons in Lagos may cause health hazards.…”

“…These activities could potentially pollute the water, yet there is no documented study on the pollution index of the water at the terminal. Recent studies conducted in the Lagos Harbour and Epe sections of the lagoon by Basheeru et al [10] and Yahaya et al [11], respectively, detected non-permissible levels of heavy metals in the lagoon. To protect people's health, it is important to do similar studies at the Ikorodu Lighter Terminal.…”