Risk assessment of heavy metal contamination in sediments of a tropical lake

Abstract

The risk assessment of heavy metal contamination was carried out in sediments of an urban tropical lake system (Akkulam-Veli) under threat from rapid unplanned urbanization and poor sewage management. Heavy metals were selected due to their persistent and bioaccumulative nature. Sequential extraction of the metals was carried out to resolve the sediments to their component phases. Well-established models were employed for risk analysis. The two pathways of contamination-ingestion and dermal contact-were considered for assessing risk. Risk Assessment Code of each metal was determined based on the lability of it in the different component phases. Cd was found to be the most hazardous metal by virtue of its high concentration in exchangeable and carbonate phases. Hazard indices of the metals were determined based on their total concentration in Akkulam-Veli (AV) Lake sediments. All heavy metals studied fall well below the threshold limit. However, Cr, Pb, and As, on account of their known toxicity, need to be monitored. Ni content in the lake system could potentially cause cancer to 134 adults in a population of one million. Concentrations of other metals are at carcinogenically safe limits. The study stresses the looming hazard faced by the Akkulam-Veli Lake system by heavy metal contaminants and the urgency in formulating remedial management plans.

Human Health Risk and Bioaccessibility of Toxic Metals in Topsoils from Gbani Mining Community in Ghana

“…Enrichment factor (EF) was used to assess the degree of toxic metal pollution from anthropogenic sources and to differentiate between anthropogenic and naturally occurring sources 33. Concentration of Fe was used as the normalization reference 34.…”

“…An EF ≤ 1 indicates that the metal concentration is not enriched and may be from a natural source. An EF=1 indicates that the metal concentration and its reference value are the same 33…”

“…Toxic response factor for metals are in the order of Zn = 1, chromium (Cr) = 2, cobalt (Co) = Cu = Pb = 5, nickel (Ni) = 6, arsenic (As) = 10, Cd = 30 and Hg = 40 5,15. The degree of ecological risk was classified as PERI ≤ 40 (low risk), 40 ≤ PERI ≤ 80 (moderate risk), 80 ≤ PERI ≤ 160 (considerable risk), 160 ≤ PERI ≤ 320 (high risk), and PERI ≥ 320 (very high risk) 16,33…”

Environmental behaviour of strontium in some salt affected soils along the Western North coast of Egypt

“…The degree of contamination (Cd): The degree of contamination (C d ) is based on the CF of the pollutant and may be calculated according to the following equation (Swarnalatha et al(2015).…”

Characterisation of Temperate Urban Lacustrine Surface-Sediments for Minerals and Metals in Comparison with Geochemical Indices and Sediment Quality Criteria

“…Conversely, calcite rich clayey lacustrine sediments dilute metal enrichment or immobilize via sorption and precipitation [22]. The pH parameter supplemented with anoxic conditions and OM percentage control heavy metal lability in a lake [23]. [24] designated adsorption, retention and release of nutrients and metal to prevailing control factors of pH, temperature,…”