Abstract
Municipal landfill leachates are a source of toxic heavy metals that have been shown to have a detrimental effect on human health and the environment. This study aimed to assess heavy metal contamination in leachates, surface water, and sediments from non-sanitary landfills in Uyo, Nigeria, and to identify potential health and environmental effects of leachate contamination. Over the wet and dry seasons, surface water and sediment samples were collected from an impacted freshwater ecosystem, and leachates samples from six monitoring wells. Elemental analyses of samples were conducted following standard analytical procedures and methods. The results indicated that leachate, surface water, and sediment samples all had elevated levels of heavy metals, implying a significant impact from landfills. Pollution indices such as the potential ecological risk index (PERI), pollution load index (PLI), degree of contamination (Cd), modified degree of contamination (mCd), enrichment factor (EF), geoaccumulation index (Igeo), and Nemerov pollution index (NPI) were used to assess the ecological impacts of landfill leachates. The following values were derived: PERI (29.09), PLI (1.96E-07), Cd (0.13), mCd (0.16), EF (0.97–1.79E-03), Igeo (0), and NPI (0.74). Pollution indicators suggested that the sediment samples were low to moderately polluted by chemical contaminants from the non-sanitary landfills, and may pose negative risks due to bioaccumulation. Human health risks were also assessed using standard risk models. For adults, children, and kids, the incremental lifetime cancer rate (ILCR) values were within the acceptable range of 1.00E-06–1.00E-04. The lifetime carcinogenicity risks associated with oral ingestion exposure to heavy metals were 9.09E-05, 1.21E-05, and 3.60 E-05 for kids, adults, and children, respectively. The mean cumulative risk values for dermal exposures were 3.24E-07, 1.89E-06, and 1.17E-05 for adults, children, and kids, respectively. These findings emphasized the risks of human and biota exposure to contaminants from landfills.
Highlights
Anthropogenic activities and processes tend to generate tons of waste that may consist of biodegradable and non-degradable to very hazardous wastes
The primary objectives of this study were (i) to determine the concentrations of potentially toxic metals in landfill leachates, sediments, and surface water samples collected from an ecosystem that receives waste directly from municipal waste dumpsites, (ii) to assess the contamination levels of heavy metals using different pollution indices, (iii) to assess the ecotoxicological and human health risks associated with toxic metals in leachates and the receiving freshwater ecosystems using risk assessment models
The present study revealed no significant differences in heavy metal concentrations in sediment samples across the landfill leachate impacted sites
Summary
Anthropogenic activities and processes tend to generate tons of waste that may consist of biodegradable and non-degradable to very hazardous wastes. The manner in which such wastes are collected, processed, stored, managed and disposed of, represents sources of potential environmental and human health risks. In rapidly expanding municipalities in developing countries, the dilemmas of solid waste management are of significant concern [1]. In most developed nations, large-scale disposal of municipal solid wastes (MSW) may not pose a big problem due to the availability of waste management facilities. Given the likelihood that waste management facilities are sparse in developing countries, including Nigeria, the collection, processing and disposal of solid waste are mainly done through direct labour, intensive operations, and many opportunities for direct contact and exposure to hazardous substances are possible
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